Kisspeptin papers

pubmed: 2006

NCBI pubmed
  • GPR54 and KiSS-1: role in the regulation of puberty and reproduction.
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    GPR54 and KiSS-1: role in the regulation of puberty and reproduction.

    Rev Endocr Metab Disord. 2006 Dec;7(4):257-63

    Authors: Kuohung W, Kaiser UB

    The finding of inactivating mutations in GPR54 in IHH patients and the lack of reproductive maturation of the GPR54 null mouse have uncovered a previously unrecognized role for GPR54 and KiSS-1 in the physiologic regulation of puberty and reproduction. This newly identified function for GPR54 and its cognate ligand, kisspeptin, has led to additional studies that have localized GPR54 and KiSS-1 mRNA in the hypothalamus, colocalized GPR54 in GnRH neurons, demonstrated GnRH-dependent activation of LH and FSH release by kisspeptin, and shown increased hypothalamic KiSS-1 and GPR54 mRNA levels at the time of puberty. Taken together, these findings establish the role of the kisspeptin-GPR54 system in the stimulation of GnRH neurons during puberty. The mechanisms by which kisspeptin activates GnRH release, as well as the trigger for this pathway at the onset of puberty, are yet to be elucidated. In the future, modulators of GPR54 activity, including kisspeptin, may prove valuable in clinical applications in the fields of both cancer therapy and reproductive medicine.

    PMID: 17206526 [PubMed - indexed for MEDLINE]



  • KISS: the kinetoplastid RNA editing sequence search tool.
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    KISS: the kinetoplastid RNA editing sequence search tool.

    RNA. 2007 Jan;13(1):1-4

    Authors: Ochsenreiter T, Cipriano M, Hajduk SL

    Kinetoplastid mitochondrial mRNA editing is a post-transcriptional process of uridine insertion and deletion. Editing is mediated by small RNA molecules termed guide RNAs (gRNAs). Most gRNAs are encoded by numerous small circular DNA minicircles, while the protein coding mitochondrial genes are encoded on a separate, larger genome called the maxicircle. In order to provide a workbench for the analysis of RNA editing in kinetoplastids and a well-annotated set of guide RNAs for Trypanosoma brucei, we generated the kinetoplastid RNA editing sequence search tool (KISS) (http://gmod.mbl.edu/kiss/). KISS is a pipeline and database that uses BLAST comparisons and minicircle sequence motifs to annotate potential gRNAs and cognate mRNA editing sequence. KISS 1.0 contains all previously known minicircle and maxicircle data from Trypanosoma brucei plus >400 new minicircle sequences. Using an online format, KISS 1.0 allows the mapping and visualization of all known T. brucei gRNAs to minicircle genes and to potential mRNA substrates for RNA editing.

    PMID: 17123956 [PubMed - indexed for MEDLINE]



  • [Expression of trophoblast invasion related genes mRNA and protein in human placenta in preeclampsia]
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    [Expression of trophoblast invasion related genes mRNA and protein in human placenta in preeclampsia]

    Zhonghua Fu Chan Ke Za Zhi. 2006 Aug;41(8):509-13

    Authors: Zhang H, Lin QD, Qiao C

    OBJECTIVE: To study the mRNA and protein expression of matrix metalloproteinase (MMP) 9, 2, metastasis suppressor gene KiSS-1, tissue inhibitor of metalloproteinase-1 (TIMP-1) and TIMP-2 in placenta of preeclampsia patients and their relation to the pathogenesis of preeclampsia. METHODS: Expression of MMP-9, MMP-2, KiSS-1, TIMP-1, TIMP-2 mRNAs and proteins in placenta from 27 cases of preeclampsia, 10 cases of gestational hypertension and 30 cases of normal term pregnant women was detected by semi-quantitative RT-PCR, western blotting, and enzyme activity of MMP-9 and MMP-2 was measured by gelatin zymography. RESULTS: (1) Expression of MMP-9 and MMP-2 mRNA in placenta of preeclampsia (0.39 +/- 0.05 and 0.71 +/- 0.16) was significantly lower than that in normal term pregnancy (0.78 +/- 0.11 and 1.63 +/- 0.31, P < 0.05). Expression of KiSS-1 and TIMP-1 mRNAs in placenta of preeclampsia (1.97 +/- 0.21 and 1.11 +/- 0.18) was significantly higher than that in normal term pregnancy (0.69 +/- 0.27 and 0.65 +/- 0.19) (P < 0.05.). There was no significant difference in TIMP-2 mRNA level between preeclampsia and normal pregnancy (P > 0.05). (2) Expression of MMP-9 and MMP-2 proteins in preeclampsia (1.07 +/- 0.35 and 0.74 +/- 0.23) was significantly lower than that in normal term pregnancy (2.43 +/- 0.92 and 1.48 +/- 0.78) (P < 0.05). Expression of KiSS-1 and TIMP-1 proteins in placenta of preeclampsia (2.46 +/- 0.39 and 1.51 +/- 0.40) was significantly higher than that in normal pregnancy (0.91 +/- 0.35 and 0.93 +/- 0.56) (P < 0.05). There was no significant difference in TIMP-2 protein level between preeclampsia and normal pregnancy (P > 0.05). (3) Enzyme activity of MMP-9 and MMP-2 in placenta of preeclampsia [(2.67 +/- 0.53) gray level.g(-1).L(-1) and (1.13 +/- 0.28) gray level.g(-1).L(-1))] was significantly lower than that in placenta of normal pregnancy [(8.44 +/- 3.70) gray level.g(-1).L(-1) and (3.87 +/- 1.43) gray level.g(-1).L(-1)] (P < 0.05). CONCLUSION: Abnormal expression of MMP-9, MMP-2, KiSS-1 and TIMP-1 can cause insufficiency invasion of trophoblast in preeclampsia and superficial placentation, which may play an important role in the pathogenesis and development of preeclampsia.

    PMID: 17083831 [PubMed - indexed for MEDLINE]



  • The role of KiSS-1 in the regulation of puberty in higher primates.
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    The role of KiSS-1 in the regulation of puberty in higher primates.

    Eur J Endocrinol. 2006 Nov;155 Suppl 1:S11-6

    Authors: Plant TM

    Puberty in higher primates is triggered by resurgence in the pulsatile secretion of hypothalamic GnRH after a hiatus in the robust release of this hypophysiotropic signal during childhood and juvenile development. Interestingly, the prepubertal decline in GnRH release is not associated with a marked reduction in the expression of either the gene that codes for GnRH (GnRH-1) or the decapeptide itself, and the network of GnRH neurons in the hypothalamus of the juvenile may by activated prematurely and with surprising ease by intermittent neurochemical stimulation with N-methyl-d-aspartate (NMDA), a glutamate receptor agonist. KiSS-1, a gene that encodes for kisspeptin-121, which is proteolytically cleaved to a 54 amino acid peptide, metastin, was initially studied in the context of tumor suppression. In 2003, however, inactivating mutations in the metastin receptor, GPR54, were reported to be associated with hypogonadotropic hypogonadism and absent puberty in man. Subsequent studies in the rhesus monkey have shown that GPR54 and KiSS-1 are expressed in the mediobasal hypothalamus (MBH), KiSS-1 expression in the MBH increases at the time of the pubertal resurgence in GnRH release and pulsatile, but not continuous, i.v. administration of metastin 45-54 in the juvenile male monkey elicits sustained GnRH release precociously. The significance of these findings in the context of the initiation of the onset of puberty is discussed.

    PMID: 17074983 [PubMed - indexed for MEDLINE]



  • KiSS-1 peptide induces release of LH by a direct effect on the hypothalamus of ovariectomized ewes.
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    KiSS-1 peptide induces release of LH by a direct effect on the hypothalamus of ovariectomized ewes.

    Anim Reprod Sci. 2007 Oct;101(3-4):265-75

    Authors: Arreguin-Arevalo JA, Lents CA, Farmerie TA, Nett TM, Clay CM

    The objectives of this study were: to determine if peripheral administration of the ovine C-terminal decapeptide (oKiSS-1) increases secretion of LH and FSH in ovariectomized (OVX) ewes; to evaluate the effect of ovarian steroid hormones on the predicted increase in gonadotropin secretion induced by oKiSS-1; to establish if the stimulatory effect of oKiSS-1 is due to a direct action on the hypothalamus or was mediated directly at the anterior pituitary gland. Intravenous injection of 3mg oKiSS-1 to OVX ewes (n=6) increased (P<0.01) basal and mean serum concentrations of LH. The amplitude and the area under the curve (AUC) of LH induced by oKiSS-1 was greater (P<0.01) than the highest pulse of LH detected before oKiSS-1. Pre-treatment with steroid hormones (1mg progesterone plus 50 microg estradiol-17beta for 3 days) in OVX ewes (n=6) reduced (P<0.1) the magnitude of the stimulatory effect of oKiSS-1 on LH secretion. In these animals, oKiSS-1 increased (P<0.1) basal and mean concentrations of LH, and the amplitude of the pulse of LH induced by oKiSS-1, but not the AUC (P>0.1). In our hands, oKiSS-1 failed to increase serum concentration of FSH at the dose used in this study. Administration of GnRH antiserum completely suppressed the secretory patterns of LH and prevented the increase in secretion of LH induced by oKiSS-1. We conclude that the rapid increase in secretion of LH induced by peripheral administration of oKiSS-1 is the result of a direct action on the hypothalamus.

    PMID: 17055196 [PubMed - indexed for MEDLINE]



  • Elevated KiSS-1 expression in the arcuate nucleus prior to the cyclic preovulatory gonadotrophin-releasing hormone/lutenising hormone surge in the ewe suggests a stimulatory role for kisspeptin in oestrogen-positive feedback.
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    Elevated KiSS-1 expression in the arcuate nucleus prior to the cyclic preovulatory gonadotrophin-releasing hormone/lutenising hormone surge in the ewe suggests a stimulatory role for kisspeptin in oestrogen-positive feedback.

    J Neuroendocrinol. 2006 Oct;18(10):806-9

    Authors: Estrada KM, Clay CM, Pompolo S, Smith JT, Clarke IJ

    Kisspeptins are encoded by the gene KiSS-1 and regulate gonadotrophin-releasing hormone (GnRH) and gonadotrophin secretion in various species, including humans. Here, we quantify gene expression of KiSS-1 in the arcuate nucleus (ARC) across the ovine oestrous cycle and demonstrate an increase in the caudal division of the ARC during the preovulatory period. These data strongly suggest that kisspeptins are involved in the generation of the preovulatory GnRH and luteinising hormone surge.

    PMID: 16965299 [PubMed - indexed for MEDLINE]



  • Transcriptional regulation of KiSS-1 gene expression in metastatic melanoma by specificity protein-1 and its coactivator DRIP-130.
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    Transcriptional regulation of KiSS-1 gene expression in metastatic melanoma by specificity protein-1 and its coactivator DRIP-130.

    Oncogene. 2007 Mar 15;26(12):1739-47

    Authors: Mitchell DC, Stafford LJ, Li D, Bar-Eli M, Liu M

    Loss of the metastasis suppressor gene, KiSS-1 has been strongly correlated to the progression of metastases in numerous types of cancers. The mechanism through which KiSS-1 is lost during metastasis, however, is still not completely known. Previous studies have shown that genetic material on human chromosome 6q16.3-q23 is essential for KiSS-1 expression in normal tissues. Additionally, microcell-mediated transfer of this chromosome in cancerous tissue results in rescued expression of KiSS-1 and reduced metastatic phenotype. Here, we show that loss of Sp1-coactivator protein DRIP-130, which is encoded by human chromosome 6q16.3-q23, results in reduced KiSS-1 promoter activation in highly malignant melanoma cells. Co-expression of Sp1 and DRIP-130 not only rescues KiSS-1 expression, but also induces an inhibition of the invasive and migratory behavior in highly metastatic melanoma cells, similar to the overexpression of KiSS-1 metastasis suppressor gene in those cells. Furthermore, we demonstrate that KiSS-1 expression is regulated by Sp1 elements within the first 100-bp region of the KiSS-1 promoter and that targeted deletion of a single GC-rich region spanning -93 to -58 interrupts Sp1- and DRIP-130-modulated transcriptional control of KiSS-1 expression. Our results thus suggest that DRIP-130 is a key regulator in KiSS-1 transactivation in normal tissue, and that the loss of DRIP-130 expression, as a result of the gross loss of human chromosome 6q16.3-q23, provokes increased tumor metastasis.

    PMID: 16964286 [PubMed - indexed for MEDLINE]



  • Postnatal development of kisspeptin neurons in mouse hypothalamus; sexual dimorphism and projections to gonadotropin-releasing hormone neurons.
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    Postnatal development of kisspeptin neurons in mouse hypothalamus; sexual dimorphism and projections to gonadotropin-releasing hormone neurons.

    Endocrinology. 2006 Dec;147(12):5817-25

    Authors: Clarkson J, Herbison AE

    The neuropeptide kisspeptin has recently been implicated as having a critical role in the activation of the GnRH neurons to bring about puberty. We examined here the postnatal development of kisspeptin neuronal populations and their projections to GnRH neurons in the mouse. Three populations of kisspeptin neurons located in the 1) anteroventral periventricular nucleus (AVPV) and the preoptic periventricular nucleus (PeN), 2) dorsomedial hypothalamus, and 3) arcuate nucleus were identified using an antisera raised against mouse kisspeptin-10. A marked 10-fold (P<0.01), female-dominant sex difference in the numbers of kisspeptin neurons existed in the AVPV/PeN but not elsewhere. Kisspeptin neurons in the AVPV/PeN of both sexes displayed a similar pattern of postnatal development with no cells detected at postnatal day (P) 10, followed by increases from P25 to reach adult levels by puberty onset (P<0.01; P31 females and P45 males). This pattern was not found in the dorsomedial hypothalamus or arcuate nucleus. Dual immunofluorescence experiments demonstrated close appositions between kisspeptin fibers and GnRH neuron cell bodies that were first apparent at P25 and increased across postnatal development in both sexes. These studies demonstrate kisspeptin peptide expression in the mouse hypothalamus and reveal the postnatal development of a sexually dimorphic continuum of kisspeptin neurons within the AVPV and PeN. This periventricular population of kisspeptin neurons reaches adult-like proportions at the time of puberty onset and is the likely source of the kisspeptin inputs to GnRH neurons.

    PMID: 16959837 [PubMed - indexed for MEDLINE]



  • Quantitative distribution of a panel of circulating mRNA in preeclampsia versus controls.
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    Quantitative distribution of a panel of circulating mRNA in preeclampsia versus controls.

    Prenat Diagn. 2006 Dec;26(12):1115-20

    Authors: Farina A, Sekizawa A, Purwosunu Y, Rizzo N, Banzola I, Concu M, Morano D, Giommi F, Bevini M, Mabrook M, Carinci P, Okai T

    OBJECTIVE: The aim of this study was to evaluate whether the quantitative distribution of a panel of circulating mRNAs from maternal whole blood of normal pregnancies is statistically different from those complicated with preeclampsia (PE) with or without intrauterine growth restriction (IUGR). METHODS: Maternal whole blood of six subjects with mild or severe PE with or without IUGR and 30 matched controls (1:5 match for gestational age) were retrospectively examined for circulating mRNA markers. Seven specific mRNA markers were identified and chosen based on previous microarray mRNA expressions performed on placental tissue from normal and PE patients. They were human placental lactogen (hPL), inhibin A, KISS-1, pregnancy-associated plasma protein-A (PAPP-A), plasminogen activator inhibitor type 1 (PAI-1), selectin-P and vascular endothelial growth factor receptor (VEGFR), which were therefore quantified for statistical purposes. RESULTS: Median gestational age was 229 (178-283) and 232 (194-262) days for controls and cases respectively. All mRNA markers but PAPP-A, showed statistically different median values. They were hPL, inhibin A, KISS-1, PAI-1, Selectin-P, and VEGFR. Inhibin A, Selectin-P and VEGFR showed higher values than expected for controls. Instead, hPL, KISS-1 and PAI-1 values of PE patients were lower than those of controls. Selectin-P was the marker with the most aberrant difference, followed by VEGFR and KISS-1. CONCLUSION: This preliminary analysis revealed that the median values of a panel of mRNAs from the maternal blood of PE patients were different from those of the same gestational age control group at the third trimester. If prospective studies at the second trimester could detect a related marker sufficiently able to discriminate between affected and unaffected patients and thus detect the disease before its clinical onset, then a screening project using a panel of mRNAs would be feasible.

    PMID: 16952198 [PubMed - indexed for MEDLINE]



  • Kisspeptin mediates the photoperiodic control of reproduction in hamsters.
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    Kisspeptin mediates the photoperiodic control of reproduction in hamsters.

    Curr Biol. 2006 Sep 5;16(17):1730-5

    Authors: Revel FG, Saboureau M, Masson-Pévet M, Pévet P, Mikkelsen JD, Simonneaux V

    The KiSS-1 gene encodes kisspeptin, the endogenous ligand of the G-protein-coupled receptor GPR54. Recent data indicate that the KiSS-1/GPR54 system is critical for the regulation of reproduction and is required for puberty onset. In seasonal breeders, reproduction is tightly controlled by photoperiod (i.e., day length). The Syrian hamster is a seasonal model in which reproductive activity is promoted by long summer days (LD) and inhibited by short winter days (SD). Using in situ hybridization and immunohistochemistry, we show that KiSS-1 is expressed in the arcuate nucleus of LD hamsters. Importantly, the KiSS-1 mRNA level was lower in SD animals but not in SD-refractory animals, which spontaneously reactivated their sexual activity after several months in SD. These changes of expression are not secondary to the photoperiodic variations of gonadal steroids. In contrast, melatonin appears to be necessary for these seasonal changes because pineal-gland ablation prevented the SD-induced downregulation of KiSS-1 expression. Remarkably, a chronic administration of kisspeptin-10 restored the testicular activity of SD hamsters despite persisting photoinhibitory conditions. Overall, these findings are consistent with a role of KiSS-1/GPR54 in the seasonal control of reproduction. We propose that photoperiod, via melatonin, modulates KiSS-1 signaling to drive the reproductive axis.

    PMID: 16950111 [PubMed - indexed for MEDLINE]



  • KiSS-1 and reproduction: focus on its role in the metabolic regulation of fertility.
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    KiSS-1 and reproduction: focus on its role in the metabolic regulation of fertility.

    Neuroendocrinology. 2006;83(5-6):275-81

    Authors: Tena-Sempere M

    Unraveling of the master role of kisspeptins, the products of the KiSS-1 gene, and their receptor, GPR54, in the control of reproduction has been a major breakthrough in contemporary neuroendocrinology. Indeed, since the disclosure of their reproductive dimension in late 2003, an ever-growing number of genetic, molecular, physiologic and pharmacological studies have defined the crucial role of KiSS-1 neurons as central processors for the dynamic regulation of the gonadotropic axis and its full activation at puberty. Yet, the potential role of the hypothalamic KiSS-1 system as an intermediary factor for the well-known interplay between energy status and reproduction initially received little attention. Recent data, however, strongly suggest a prominent role of KiSS-1 in the metabolic control of fertility, as expression of KiSS-1 gene at the hypothalamus is down-regulated in conditions of negative energy balance and kisspeptin administration is capable of overcoming the hypogonadotropic state observed in undernutrition and disturbed metabolic conditions. Leptin, the adipocyte hormone signaling the size of body energy stores, is likely to play a pivotal role in the metabolic control of the KiSS-1 system, since kisspeptin neurons express leptin receptors and leptin is able to normalize defective KiSS-1 gene expression in models of impaired gonadotropin secretion linked to hypoleptinemia, such as the ob/ob mouse and streptozotocin-induced diabetic rat. In sum, these data provide strong evidence for a central role of kisspeptins and GPR54 as molecular conduits for the metabolic regulation of reproductive function - a phenomenon with potential physiopathologic and therapeutic implications.

    PMID: 16940711 [PubMed - indexed for MEDLINE]



  • Expression of hypothalamic KiSS-1 system and rescue of defective gonadotropic responses by kisspeptin in streptozotocin-induced diabetic male rats.
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    Expression of hypothalamic KiSS-1 system and rescue of defective gonadotropic responses by kisspeptin in streptozotocin-induced diabetic male rats.

    Diabetes. 2006 Sep;55(9):2602-10

    Authors: Castellano JM, Navarro VM, Fernández-Fernández R, Roa J, Vigo E, Pineda R, Dieguez C, Aguilar E, Pinilla L, Tena-Sempere M

    Hypogonadotropism is a common feature of uncontrolled diabetes, for which the ultimate mechanism remains to be elucidated. Kisspeptins, ligands of G protein-coupled receptor 54 (GPR54) encoded by the KiSS-1 gene, have recently emerged as major gatekeepers of the gonadotropic axis. Alteration in the hypothalamic KiSS-1 system has been reported in adverse metabolic conditions linked to suppressed gonadotropins, such as undernutrition. However, its potential contribution to defective gonadotropin secretion in diabetes has not been evaluated. We report herein analyses of luteinizing hormone (LH) responses to kisspeptin and hypothalamic expression of the KiSS-1 gene in streptozotocin (STZ)-induced diabetic male rats. In addition, functional studies involving kisspeptin replacement or continuous administration of leptin and insulin to diabetic male rats are presented. Kisspeptin administration evoked robust LH and testosterone bursts and enhanced postgonadectomy LH concentrations, despite prevailing attenuation of gonadotropic axis in diabetic animals. In addition, hypothalamic KiSS-1 mRNA levels were unambiguously decreased in diabetic male rats, and the postorchidectomy rise in KiSS-1 mRNA was severely blunted. Repeated administration of kisspeptin to diabetic rats evoked persistent LH and testosterone responses and partially rescued prostate and testis weights. In addition, central infusion of leptin, but not insulin, was sufficient to normalize hypothalamic KiSS-1 mRNA levels, as well as LH and testosterone concentrations. In summary, we provide evidence for altered expression of the hypothalamic KiSS-1 system in a model of uncontrolled diabetes. This observation, together with the ability of exogenous kisspeptin to rescue defective LH responses in diabetic rats, unravel the physiopathological implication, and potential therapeutic intervention, of the KiSS-1 system in altered gonadotropin secretion of type 1 diabetes.

    PMID: 16936210 [PubMed - indexed for MEDLINE]



  • Mechanisms of Disease: the first kiss-a crucial role for kisspeptin-1 and its receptor, G-protein-coupled receptor 54, in puberty and reproduction.
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    Mechanisms of Disease: the first kiss-a crucial role for kisspeptin-1 and its receptor, G-protein-coupled receptor 54, in puberty and reproduction.

    Nat Clin Pract Endocrinol Metab. 2006 Jun;2(6):328-34

    Authors: Seminara SB

    Although the hypothalamic secretion of gonadotropin-releasing hormone (GnRH) is the defining hormonal event of puberty, the physiologic mechanisms that drive secretion of GnRH at the time of sexual maturation have been difficult to identify. After puberty is initiated, the factors that modulate the frequency and amplitude of GnRH secretion in rapidly changing sex-steroid environments (i.e. the female menstrual cycle) also remain unknown. The discovery that, in both humans and mouse models, loss-of-function mutations in the gene that encodes G-protein-coupled receptor 54 result in phenotypes of hypogonadotropic hypogonadism with an absence of pubertal development has unearthed a novel pathway regulating GnRH secretion. Ligands for G-protein-coupled receptor 54 (KiSS-1R), including metastin (derived from the parent compound, kisspeptin-1) and metastin's C-terminal peptide fragments, have been shown to be powerful stimulants for GnRH release in vivo via their stimulation of G-protein-coupled receptor 54. This article reviews the discovery of the GPR54 gene, places it into the appropriate biological context, and explores the data from in vitro and in vivo studies that point to this ligand-receptor system as a major driver of GnRH secretion.

    PMID: 16932310 [PubMed - indexed for MEDLINE]



  • Ontogeny and mechanisms of action for the stimulatory effect of kisspeptin on gonadotropin-releasing hormone system of the rat.
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    Ontogeny and mechanisms of action for the stimulatory effect of kisspeptin on gonadotropin-releasing hormone system of the rat.

    Mol Cell Endocrinol. 2006 Sep 26;257-258:75-83

    Authors: Castellano JM, Navarro VM, Fernández-Fernández R, Castaño JP, Malagón MM, Aguilar E, Dieguez C, Magni P, Pinilla L, Tena-Sempere M

    Kisspeptins have recently emerged as essential regulators of gonadotropin secretion and puberty onset. These functions are primarily conducted by stimulation of hypothalamic gonadotropin-releasing hormone (GnRH) secretion. However, relevant aspects of KiSS-1 physiology, including the ontogeny and major signaling systems of its stimulatory action, remain to be fully elucidated. To cover these issues, the effects of kisspeptin-10 on GnRH and LH secretion were monitored at early stages of postnatal maturation, and potential changes in the sensitivity to kisspeptin were assessed along the pubertal transition in the rat. In addition, the signaling cascades involved in kisspeptin-induced GnRH secretion were explored by means of pharmacological blockade using rat hypothalamic explants. Despite sexual immaturity, kisspeptin-10 potently elicited GnRH release ex vivo and LH secretion in vivo at early stages (neonatal to juvenile) of postnatal development. Yet, LH responsiveness to low doses of kisspeptin was enhanced in peri-pubertal animals. Concerning GnRH secretion, the stimulatory action of kisspeptin-10 required activation of phospholipase-C, mobilization of intracellular Ca2+ and recruitment of ERK1/2 and p38 kinases, but was preserved after blockade of type 2 cyclo-oxygenase and prostaglandin synthesis. In summary, our present data document the ontogeny, sensitivity and intracellular signals for the stimulatory action of kisspeptin on the GnRH/LH axis in the rat. Although LH responses to low doses of kisspeptin appeared to be enhanced at puberty, kisspeptin was able to readily activate the GnRH system at early stages of postnatal maturation. These observations further stress the essential role of kisspeptin in normal, and eventually pathological, timing of puberty.

    PMID: 16930819 [PubMed - indexed for MEDLINE]



  • The roles of kisspeptins and G protein-coupled receptor-54 in pubertal development.
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    The roles of kisspeptins and G protein-coupled receptor-54 in pubertal development.

    Curr Opin Pediatr. 2006 Aug;18(4):442-7

    Authors: Tena-Sempere M

    PURPOSE OF REVIEW: This review summarizes the experimental data demonstrating the fundamental role of kisspeptins and their G protein-coupled receptor GPR54 in the control of reproduction, with special emphasis on their function at puberty. RECENT FINDINGS: Kisspeptins, products of the KiSS-1 gene, were originally identified as metastasis suppressor peptides with the ability to bind G protein-coupled receptor GPR54. In late 2003, loss-of-function mutations of the GPR54 gene were found in patients suffering from hypogonadotropic hypogonadism. This finding kicked off the analysis of the role of the KiSS-1/GPR54 system in the control of reproduction. Kisspeptins are very potent elicitors of gonadotropin secretion, primarily through stimulation of gonadotropin-releasing hormone release. Enhanced expression of KiSS-1 and GPR54 genes, as well as increased GPR54 signaling, are detected at the hypothalamus during pubertal development, and activation of GPR54 by administration of kisspeptin is sufficient to induce precocious activation of the gonadotropic axis in immature rodents and monkeys. Hypothalamic KiSS-1 also functions as an essential integrator for peripheral inputs, including gonadal steroids and nutritional signals, controlling gonadotropin-releasing hormone and gonadotropin secretion. SUMMARY: Kisspeptins and their putative receptor, GPR54, have recently emerged as indispensable factors for pubertal development, with a key role as gatekeepers of gonadotropin-releasing hormone release neurons and, hence, of reproductive function.

    PMID: 16915001 [PubMed - indexed for MEDLINE]



  • Structure-activity relationship study on small peptidic GPR54 agonists.
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    Structure-activity relationship study on small peptidic GPR54 agonists.

    Bioorg Med Chem. 2006 Nov 15;14(22):7595-603

    Authors: Tomita K, Niida A, Oishi S, Ohno H, Cluzeau J, Navenot JM, Wang ZX, Peiper SC, Fujii N

    Metastin (kisspeptin-54) is an endogenous ligand that modulates gonadotropin-releasing hormone (GnRH) secretion through the interaction with a G protein-coupled receptor (GPCR), GPR54. The short-chain C-terminal decapeptide amide, metastin (45-54) (kisspeptin-10), exerts the identical bioactivities to metastin, such as metastasis suppression of cancer cells and inhibition of trophoblast migration and invasion. In order to understand the structural requirement for GPR54 agonistic activity, structure-activity relationship (SAR) study on pentapeptide-based C-terminal metastin analogues was carried out. As a result, H-Amb-Nal(2)-Gly-Leu-Arg-Trp-NH2 34 was identified as a novel GPR54 agonist that possessed the most potent GPR54 agonistic activity reported so far.

    PMID: 16879969 [PubMed - indexed for MEDLINE]



  • Driving reproduction: RFamide peptides behind the wheel.
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    Driving reproduction: RFamide peptides behind the wheel.

    Horm Behav. 2006 Dec;50(5):655-66

    Authors: Kriegsfeld LJ

    The availability of tools for probing the genome and proteome more efficiently has allowed for the rapid discovery of novel genes and peptides that play important, previously uncharacterized roles in neuroendocrine regulation. In this review, the role of a class of neuropeptides containing the C-terminal Arg-Phe-NH(2) (RFamide) in regulating the reproductive axis will be highlighted. Neuropeptides containing the C-terminal Phe-Met-Arg-Phe-NH(2) (FMRFamide) were first identified as cardioregulatory elements in the bi-valve mollusk Macrocallista nimbosa. During the past two decades, numerous studies have shown the presence of structurally similar peptides sharing the RFamide motif across taxa. In vertebrates, RFamide peptides have pronounced influences on opiatergic regulation and neuroendocrine function. Two key peptides in this family are emerging as important regulators of the reproductive axis, kisspeptin and gonadotropin-inhibitory hormone (GnIH). Kisspeptin acts as the accelerator, directly driving gonadotropin-releasing hormone (GnRH) neurons, whereas GnIH acts as the restraint. Recent evidence suggests that both peptides play a role in mediating the negative feedback effects of sex steroids. This review presents the hypothesis that these peptides share complementary roles by responding to internal and external stimuli with opposing actions to precisely regulate the reproductive axis.

    PMID: 16876801 [PubMed - indexed for MEDLINE]



  • A role for kisspeptin in islet function.
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    A role for kisspeptin in islet function.

    Diabetologia. 2006 Sep;49(9):2131-5

    Authors: Hauge-Evans AC, Richardson CC, Milne HM, Christie MR, Persaud SJ, Jones PM

    AIMS/HYPOTHESIS: We investigated the production of kisspeptin (KISS1) and the KISS1 receptor, GPR54, in pancreatic islets and determined the effects of exogenous kisspeptin on insulin secretion. METHODS: RT-PCR and immunohistochemistry were used to detect expression of KISS1 and GPR54 mRNAs and the production of KISS1 and GPR54 in human and mouse islets and in beta (MIN6) and alpha- (alphaTC1) cell lines. The effects of KISS1 on basal and glucose-induced insulin secretion from mouse and human islets were measured in a perifusion system. RESULTS: KISS1 and GPR54 mRNAs were both detected in human and mouse islets, and GPR54 mRNA expression was also found in the MIN6 and alphaTC1 endocrine cell lines. In sections of mouse pancreas, KISS1 and GPR54 immunoreactivities were co-localised in both beta and alpha cells within islets, but were not detected in the exocrine pancreas. Exposure of mouse and human islets to KISS1 caused a stimulation of glucose-induced (20 mmol/l) insulin secretion, but had no effect on the basal rate of secretion at a sub-stimulatory concentration of glucose (2 mmol/l). In contrast, KISS1 inhibited insulin secretion from MIN6 cells at both 2 and 20 mmol/l glucose. KISS1 had no significant effect on glucagon secretion from mouse islets. CONCLUSIONS/INTERPRETATION: This is the first report to show that the GPR54/KISS1 system is expressed in the endocrine pancreas, where it influences beta cell secretory function. These observations suggest an important role for this system in the normal regulation of islet function.

    PMID: 16826407 [PubMed - indexed for MEDLINE]



  • Expression of KiSS-1 in rat ovary: putative local regulator of ovulation?
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    Expression of KiSS-1 in rat ovary: putative local regulator of ovulation?

    Endocrinology. 2006 Oct;147(10):4852-62

    Authors: Castellano JM, Gaytan M, Roa J, Vigo E, Navarro VM, Bellido C, Dieguez C, Aguilar E, Sánchez-Criado JE, Pellicer A, Pinilla L, Gaytan F, Tena-Sempere M

    Kisspeptins, the products of KiSS-1 gene, and their receptor, GPR54, have recently emerged as essential gatekeepers of reproduction, mainly through regulation of GnRH secretion at the hypothalamus. However, the profound hypogonadotropism linked to GPR54 inactivation is likely to mask additional functions of this system at other levels of the gonadal axis, in which expression of KiSS-1 and GPR54 has been preliminarily reported. We describe herein the expression of KiSS-1 gene and kisspeptin immunoreactivity (IR) in rat ovary and evaluate its developmental and hormonal regulation. KiSS-1 and GPR54 mRNAs were persistently detected in adult ovary along estrous cycle. Yet, contrary to GPR54, ovarian KiSS-1 levels fluctuated in a cyclic-dependent manner, with a robust increase in the afternoon of proestrus, i.e. preceding ovulation. In addition, kisspeptin-IR was observed in rat ovary, with strong signals in theca layers of growing follicles, corpora lutea, and interstitial gland, compartments in which modest GPR54-IR was also detected. Interestingly, the rise in ovarian KiSS-1 mRNA at proestrus was prevented by blockade of preovulatory gonadotropin surge and restored by replacement with human chorionic gonadotropin as superagonist of LH. In addition, immature ovaries showed low to negligible levels of KiSS-1 mRNA, which were significantly enhanced by gonadotropin priming. In summary, we present novel evidence for the developmental and hormonally regulated expression of the KiSS-1 gene, and the presence of kisspeptin-IR, in rat ovary. The ability of the LH surge to timely induce ovarian expression of KiSS-1 at the preovulatory period strongly suggests a previously unsuspected role of locally produced kisspeptin in the control of ovulation.

    PMID: 16825322 [PubMed - indexed for MEDLINE]



  • Dynamic and integrative aspects of the regulation of reproduction by metabolic status in male sheep.
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    Dynamic and integrative aspects of the regulation of reproduction by metabolic status in male sheep.

    Reprod Nutr Dev. 2006 Jul-Aug;46(4):379-90

    Authors: Blache D, Zhang S, Martin GB

    Change in metabolic status, defined as a change in the availability of nutrients and energy to the tissues, is a powerful regulator of the reproductive function in small ruminants, especially in genotypes that are not strongly responsive to photoperiod such as the Merino sheep. In this paper, the dynamics of the response of the reproductive axis to changes in metabolic status are reviewed in the light of recent studies. The nature and the roles of the various components of the pathways linking metabolic status to reproduction are considered: nutrients and metabolites, the endocrine system, and the nervous system. We discuss the role of leptin and insulin in detail because of the central role of these two hormones in both the early gonadotrophin response to increase in nutrition and the long-term response of the testis to dietary stimulation. The possible roles of recently identified peptides, such as ghrelin and kisspeptin, are also considered as we develop a general hypothesis that encompasses the different levels of integration necessary to explain the complex interactions between reproductive function and metabolic status, and the possible existence of a "metabolic memory" in this interaction.

    PMID: 16824447 [PubMed - indexed for MEDLINE]



  • Chronic subcutaneous administration of kisspeptin-54 causes testicular degeneration in adult male rats.
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    Chronic subcutaneous administration of kisspeptin-54 causes testicular degeneration in adult male rats.

    Am J Physiol Endocrinol Metab. 2006 Nov;291(5):E1074-82

    Authors: Thompson EL, Murphy KG, Patterson M, Bewick GA, Stamp GW, Curtis AE, Cooke JH, Jethwa PH, Todd JF, Ghatei MA, Bloom SR

    The kisspeptins are KiSS-1 gene-derived peptides that signal through the G protein-coupled receptor-54 (GPR54) and have recently been shown to be critical regulators of reproduction. Acute intracerebroventricular or peripheral administration of kisspeptin stimulates the hypothalamic-pituitary-gonadal (HPG) axis. This effect is thought to be mediated via the hypothalamic gonadotropin-releasing hormone (GnRH) system. Chronic administration of GnRH agonists paradoxically suppresses the HPG axis after an initial agonistic stimulation. We investigated the effects of continuous peripheral kisspeptin administration in male rats by use of Alzet minipumps. Initially we compared the effects of acute subcutaneous administration of kisspeptin-10, -14, and -54 on the HPG axis. Kisspeptin-54 produced the greatest increase in plasma LH and total testosterone at 60 min postinjection and was used in the subsequent continuous administration experiments. Chronic subcutaneous long-term administration of 50 nmol kisspeptin-54/day for 13 days decreased testicular weight. Histological examination showed degeneration of the seminiferous tubules associated with a significant decrease in the circulating levels of the testes-derived hormone, inhibin B. Plasma free and total testosterone were also lower, although these changes did not reach statistical significance. Further studies examined the effects of shorter periods of continuous kisspeptin administration. Subcutaneous administration of 50 nmol kisspeptin-54 for 1 day increased plasma LH and testosterone. This effect was lost after 2 days of administration, suggesting a downregulation of the HPG axis response to kisspeptin following continuous administration. These findings indicate that kisspeptin may provide a novel tool for the manipulation of the HPG axis and spermatogenesis.

    PMID: 16787965 [PubMed - indexed for MEDLINE]



  • Kisspepeptin-GPR54 signaling in the neuroendocrine reproductive axis.
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    Kisspepeptin-GPR54 signaling in the neuroendocrine reproductive axis.

    Mol Cell Endocrinol. 2006 Jul 25;254-255:91-6

    Authors: Gottsch ML, Clifton DK, Steiner RA

    Kisspeptins, which are products of the Kiss1 gene, and their receptor, GPR54, have emerged as key players in the regulation of gonadotropin-releasing hormone (GnRH) secretion. Mutations or targeted deletions of GPR54 produce isolated hypogonadotropic hypogonadism in humans and mice, indicating that signaling through this receptor is a prerequisite for sexual maturation. Centrally administered kisspeptins stimulate GnRH and gonadotropin secretion in prepubertal and adult animals. Kisspeptin-expressing neurons are direct targets for the negative and positive feedback actions of sex steroids, which differentially regulate the expression of KiSS-1 mRNA in various regions of the forebrain. This review highlights what is currently known about kisspeptin-GPR54 signaling in the regulation of the neuroendocrine reproductive axis.

    PMID: 16762492 [PubMed - indexed for MEDLINE]



  • Novel signals for the integration of energy balance and reproduction.
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    Novel signals for the integration of energy balance and reproduction.

    Mol Cell Endocrinol. 2006 Jul 25;254-255:127-32

    Authors: Fernandez-Fernandez R, Martini AC, Navarro VM, Castellano JM, Dieguez C, Aguilar E, Pinilla L, Tena-Sempere M

    Although the close link between body weight and fertility has been known for eons, only recently have the peripheral signals and neuroendocrine networks responsible for such a phenomenon begun to be identified. A key event in this field was the cloning of the adipocyte-derived hormone leptin, which has been demonstrated as a pivotal regulator for the integration of energy homeostasis and reproduction. In addition, other metabolic hormones, such as insulin, contribute to this physiological integration. Moreover, compelling experimental evidence implicates hormonal products of the gastrointestinal tract as adjuncts in the complex coordination and regulation of body weight and reproduction. Here, we review recent studies evaluating the reproductive effects and sites of action of ghrelin and PYY3-36, two hormonal signals of gastrointestinal origin involved in the control food intake and energy balance. In addition, we summarize the potential contribution of kisspeptin, the recently characterized gatekeeper of the GnRH system encoded by Kiss1 gene, to integrating reproductive function and energy status. Evidence suggests that besides having direct gonadal effects, ghrelin may participate in the regulation of gonadotropin secretion and it may influence the timing of puberty. Likewise, PYY3-36 modulates GnRH and gonadotropin release. In addition, the hypothalamic KiSS-1 system is sensitive to nutritional status, and its diminished expression during states of negative energy balance might contribute to the suppression of reproductive function in such conditions. We propose that the peripheral hormones, ghrelin and PYY3-36, and the central neuropeptide, kisspeptin, are 'novel' players in the neuroendocrine networks that integrate energy balance and reproduction.

    PMID: 16759792 [PubMed - indexed for MEDLINE]



  • Plasma kisspeptin is raised in patients with gestational trophoblastic neoplasia and falls during treatment.
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    Plasma kisspeptin is raised in patients with gestational trophoblastic neoplasia and falls during treatment.

    Am J Physiol Endocrinol Metab. 2006 Nov;291(5):E878-84

    Authors: Dhillo WS, Savage P, Murphy KG, Chaudhri OB, Patterson M, Nijher GM, Foggo VM, Dancey GS, Mitchell H, Seckl MJ, Ghatei MA, Bloom SR

    Kisspeptin is a 54-amino acid peptide, encoded by the anti-metastasis gene KiSS-1, that activates G protein-coupled receptor 54 (GPR54). The kisspeptin-GPR54 system is critical to normal reproductive development. KiSS-1 gene expression is increased in the human placenta in normal and molar pregnancies. Circulating kisspeptin is dramatically increased in normal pregnancy, but levels in GTN have not previously been reported. The present study was designed to determine whether plasma kisspeptin levels are altered in patients with malignant GTN. Thirty-nine blood samples were taken from 11 patients with malignant GTN at presentation during and after chemotherapy. Blood was also sampled from nonpregnant and pregnant volunteers. Plasma kisspeptin IR and hCG concentrations were measured. Plasma kisspeptin IR concentration in nonpregnant (n = 16) females was <2 pmol/l. Plasma kisspeptin IR in females was 803 +/- 125 pmol/l in the first trimester of pregnancy (n = 13), 2,483 +/- 302 pmol/l in the third trimester of pregnancy (n = 7), and <2 pmol/l on day 15 postpartum (n = 7). Plasma kisspeptin IR and hCG concentrations in patients with malignant GTN were elevated at presentation and fell during and after treatment with chemotherapy in each patient (mean plasma kisspeptin IR: prechemotherapy 1,363 +/- 1,076 pmol/l vs. post-chemotherapy <2 pmol/l, P < 0.0001; mean plasma hCG: prechemotherapy 227,191 +/- 152,354 U/l vs. postchemotherapy 2 U/l, P < 0.0001). Plasma kisspeptin IR strongly positively correlated with plasma hCG levels (r(2) = 0.99, P < 0.0001). Our results suggest that measurement of plasma kisspeptin IR may be a novel tumor marker in patients with malignant GTN.

    PMID: 16757546 [PubMed - indexed for MEDLINE]



  • GPR54 and kisspeptin in reproduction.
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    GPR54 and kisspeptin in reproduction.

    Hum Reprod Update. 2006 Sep-Oct;12(5):631-9

    Authors: Tena-Sempere M

    Kisspeptins, the peptide products of the KiSS-1 gene, were identified in 2001 as natural ligands of the previously orphan G protein-coupled receptor, GPR54. They include, among others, metastin and kisspeptin-10. The known biological functions of kisspeptins were initially restricted to their ability to suppress tumour metastasis, hence the name of metastin. However, in late 2003, two groups independently reported that loss-of-function mutations of the GPR54 gene are linked to absence of puberty onset and hypogonadotrophic hypogonadism in humans--a phenotype that was reproduced in GPR54-null mice. Those seminal observations revealed a totally unexpected, fundamental role of the KiSS-1/GPR54 system in control of puberty and reproductive function and boosted an extraordinary interest for the characterization of these novel facets of kisspeptin physiology. Indeed, in the last 2 years, metastin and kisspeptin-10 have been demonstrated as very potent stimulators of the gonadotrophic axis, in a number of species and through different routes of administration. In addition, the hypothalamic KiSS-1/GPR54 system has been proven as an essential gatekeeper of GnRH neurons, involved in their activation at puberty and their regulation by gonadal steroids and (probably) metabolic factors. This review comprehensively examines the experimental evidence obtained to date supporting a pivotal role of kisspeptins and GPR54 in the control of reproduction.

    PMID: 16731583 [PubMed - indexed for MEDLINE]



  • KiSS-1: a likely candidate for the photoperiodic control of reproduction in seasonal breeders.
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    KiSS-1: a likely candidate for the photoperiodic control of reproduction in seasonal breeders.

    Chronobiol Int. 2006;23(1-2):277-87

    Authors: Revel FG, Saboureau M, Masson-Pévet M, Pévet P, Mikkelsen JD, Simonneaux V

    In seasonal species, photoperiod exerts tight regulation of reproduction to ensure that birth occurs at the most favorable time of yr. A distinct photoneuroendocrine circuit composed of the retina, suprachiasmatic nucleus (SCN) of the hypothalamus, and pineal gland transduces daylength into a rhythmic secretion of melatonin. The duration of the night-time rise of this hormone conveys daylength information to the organism. Melatonin is known to mediate the control of seasonal reproduction, but how it modulates sexual activity is far from understood. Recent data indicate that the product of the KiSS-1 gene is a potent stimulator of the hypothalamic-pituitary-gonadal axis and may play, together with its receptor GPR54, a central role in the neuroendocrine regulation of gonadotropin secretion. This article briefly reviews these findings and presents arguments that KiSS-1 could take part in the seasonal control of reproduction.

    PMID: 16687301 [PubMed - indexed for MEDLINE]



  • Plasma metastin levels are negatively correlated with insulin resistance and free androgens in women with polycystic ovary syndrome.
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    Plasma metastin levels are negatively correlated with insulin resistance and free androgens in women with polycystic ovary syndrome.

    Fertil Steril. 2006 Jun;85(6):1778-83

    Authors: Panidis D, Rousso D, Koliakos G, Kourtis A, Katsikis I, Farmakiotis D, Votsi E, Diamanti-Kandarakis E

    OBJECTIVE: This study was designed to: [1] measure, for the first time, metastin (kisspeptin) levels in women with polycystic ovary syndrome (PCOS), a condition associated with hypersecretion of LH and hyperandrogenemia; and [2] investigate the possible correlations between metastin and PCOS-related reproductive and metabolic disturbances. DESIGN: Clinical study. SETTING: University hospital. PATIENT(S): Twenty-eight obese and overweight (body mass index [BMI] >25 kg/m2) women with PCOS, 28 normal weight (BMI <25 kg/m2) women with the syndrome, and 13 obese and overweight controls (ovulatory women without clinical or biochemical hyperandrogenemia) were selected. INTERVENTION(S): Blood samples were collected between day 3 and day 6 of a spontaneous bleeding episode in the PCOS groups and a menstrual cycle of the controls, at 9:00 AM, after an overnight fast. MAIN OUTCOME MEASURE(S): Circulating levels of LH, FSH, PRL, T, Delta4-androstenedione (A), DHEAS, 17alpha-OH-P, sex hormone-binding globulin (SHBG), insulin, glucose, and metastin were measured. RESULT(S): Both normal weight women with PCOS and obese controls were less insulin resistant and had significantly higher metastin levels, compared to obese and overweight women with the syndrome. Plasma kisspeptin levels were negatively correlated with BMI, free androgen index, and indices of insulin resistance. CONCLUSION(S): These results indicate that metastin is negatively associated with free androgen levels. The PCOS-associated insulin resistance and consequent hyperinsulinemia probably contribute to this effect by [1] stimulating androgen synthesis by the polycystic ovary (PCO) and [2] suppressing SHBG production in the liver.

    PMID: 16650418 [PubMed - indexed for MEDLINE]



  • Administration of kisspeptin-54 into discrete regions of the hypothalamus potently increases plasma luteinising hormone and testosterone in male adult rats.
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    Administration of kisspeptin-54 into discrete regions of the hypothalamus potently increases plasma luteinising hormone and testosterone in male adult rats.

    J Neuroendocrinol. 2006 May;18(5):349-54

    Authors: Patterson M, Murphy KG, Thompson EL, Patel S, Ghatei MA, Bloom SR

    Kisspeptin-54 is the peptide product of the KiSS-1 gene and an endogenous agonist of the GPR54 receptor. KiSS-1 was initially discovered as a metastasis suppressor gene, but recent studies demonstrate that the kisspeptin/GPR54 system is a key regulator of the reproductive system. Disrupted GPR54 signalling causes hypogonadotrophic hypogonadism in rodents and man. Intracerebroventricular or peripheral administration of kisspeptin potently stimulates the hypothalamic-pituitary-gonadal (HPG) axis via the hypothalamic gonadotrophin-releasing hormone system. We have investigated the effect of injection of kisspeptin-54 into discrete hypothalamic regions on the HPG axis. To construct a dose-response curve for the effects of intrahypothalamic kisspeptin administration, adult male Wistar rats were cannulated into the medial preoptic area (MPOA) at the level of the organum vasculosum laminae terminalis (OVLT). Kisspeptin-54 was injected into the MPOA at doses of 0.01, 0.1, 1, 10 and 100 pmol. At 60 min following injection of 1, 10 or 100 pmol kisspeptin-54, plasma luteinising hormone (LH) and total testosterone levels were significantly increased. Adult male Wistar rats were then cannulated into the rostral preoptic area at the level of the OVLT (RPOA), the MPOA, the paraventricular (PVN), dorsomedial (DMN) and arcuate hypothalamic nuclei, and the lateral hypothalamic area. A dose of 1 pmol kisspeptin-54 was administered into all areas. The circulating levels of LH and total testosterone were significantly increased 60 min postinjection of kisspeptin-54 into the RPOA, MPOA, PVN and arcuate nucleus. Our results suggest that kisspeptin may mediate its effects on the HPG axis via these regions of the hypothalamus.

    PMID: 16629833 [PubMed - indexed for MEDLINE]



  • Kisspeptin immunoreactive cells of the ovine preoptic area and arcuate nucleus co-express estrogen receptor alpha.
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    Kisspeptin immunoreactive cells of the ovine preoptic area and arcuate nucleus co-express estrogen receptor alpha.

    Neurosci Lett. 2006 Jul 3;401(3):225-30

    Authors: Franceschini I, Lomet D, Cateau M, Delsol G, Tillet Y, Caraty A

    Kisspeptins are peptide ligands of the G protein-coupled receptor GPR54, recently shown to be essential to reproductive function. We have raised specific rabbit antisera against a highly conserved 10 amino acid-amidated peptide (kp10) common to all kisspeptin isoforms isolated so far and mapped the distribution of kp10-immunoreactive (ir) cells in the ovine hypothalamus. Kp10-ir cells were predominant in the caudal arcuate nucleus, the dorsomedial nucleus and the medial preoptic area. Numerous varicose kp10-ir fibers were found in the preoptic area where GnRH neurons reside and in the median eminence, seemingly projecting around small capillaries in its external zone. Within the caudal arcuate nucleus, nearly all kp10-ir cells showed an intense estradiol receptor alpha immunofluorescent signal compared with approximately half of kp10-ir cells in the preoptic area. The pattern of distribution of kp10 immunoreactivity in the hypothalamus suggests a role for kisspeptin in the estrogen-dependent regulation of GnRH and LH secretion in the ewe.

    PMID: 16621281 [PubMed - indexed for MEDLINE]



  • Regulation of the neuroendocrine reproductive axis by kisspeptin-GPR54 signaling.
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    Regulation of the neuroendocrine reproductive axis by kisspeptin-GPR54 signaling.

    Reproduction. 2006 Apr;131(4):623-30

    Authors: Smith JT, Clifton DK, Steiner RA

    The Kiss1 gene codes for a family of peptides that act as endogenous ligands for the G protein-coupled receptor GPR54. Spontaneous mutations or targeted deletions of GPR54 in man and mice produce hypogonadotropic hypogonadism and infertility. Centrally administered kisspeptins stimulate gonadotropin secretion by acting directly on GnRH neurons. Sex steroids regulate the expression of KiSS-1 mRNA in the brain through direct action on KiSS-1 neurons. In the arcuate nucleus (Arc), sex steroids inhibit the expression of KiSS-1, suggesting that these neurons serve as a conduit for the negative feedback regulation of gonadotropin secretion. In the anteroventral periventricular nucleus (AVPV), sex steroids induce the expression of KiSS-1, implying that KiSS-1 neurons in this region may have a role in the preovulatory LH surge (in the female) or sexual behavior (in the male).

    PMID: 16595713 [PubMed - indexed for MEDLINE]



  • Parathyroid hormone-related protein regulates tumor-relevant genes in breast cancer cells.
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    Parathyroid hormone-related protein regulates tumor-relevant genes in breast cancer cells.

    J Biol Chem. 2006 May 26;281(21):14563-72

    Authors: Dittmer A, Vetter M, Schunke D, Span PN, Sweep F, Thomssen C, Dittmer J

    The effect of endogenous parathyroid hormone-related protein (PTHrP) on gene expression in breast cancer cells was studied. We suppressed PTHrP expression in MDA-MB-231 cells by RNA interference and analyzed changes in gene expression by microarray analysis. More than 200 genes showed altered expression in response to a PTHrP-specific small interfering (si) RNA (siPTHrP). Cell cycle-regulating gene CDC2 and genes (CDC25B and Tome-1) that control CDC2 activity showed increased expression in the presence of siPTHrP. CDC2 activity was also found to be higher in siPTHrP-treated cells. Studies with PTHrP peptides 1-34 and 67-86, forskolin, and a PTH1 receptor (PTH1R)-specific siRNA showed that PTHrP regulates CDC2 and CDC25B, at least in part, via PTH1R in a cAMP-independent manner. Other siPTHrP-responsive genes included integrin alpha6 (ITGA6), KISS-1, and PAI-1. When combined, siRNAs against ITGA6, PAI-1, and KISS-1 could mimic the negative effect of siPTHrP on migration, whereas siKISS-1 and siPTHrP similarly reduced the proliferative activity of the cells. Comparative expression analyses with 50 primary breast carcinomas revealed that the RNA level of ITGA6 correlates with that of PTHrP, and higher CDC2 and CDC25B values are found at low PTHrP expression. Our data suggest that PTHrP has a profound effect on gene expression in breast cancer cells and, as a consequence, contributes to the regulation of important cellular activities, such as migration and proliferation.

    PMID: 16551631 [PubMed - indexed for MEDLINE]



  • Hypothalamic expression of KiSS-1 system and gonadotropin-releasing effects of kisspeptin in different reproductive states of the female Rat.
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    Hypothalamic expression of KiSS-1 system and gonadotropin-releasing effects of kisspeptin in different reproductive states of the female Rat.

    Endocrinology. 2006 Jun;147(6):2864-78

    Authors: Roa J, Vigo E, Castellano JM, Navarro VM, Fernández-Fernández R, Casanueva FF, Dieguez C, Aguilar E, Pinilla L, Tena-Sempere M

    Kisspeptins, products of the KiSS-1 gene with ability to bind G protein-coupled receptor 54 (GPR54), have been recently identified as major gatekeepers of reproductive function with ability to potently activate the GnRH/LH axis. Yet, despite the diversity of functional states of the female gonadotropic axis, pharmacological characterization of this effect has been mostly conducted in pubertal animals or adult male rodents, whereas similar studies have not been thoroughly conducted in the adult female. In this work, we evaluated maximal LH and FSH secretory responses to kisspeptin-10, as well as changes in sensitivity and hypothalamic expression of KiSS-1 and GPR54 genes, in different physiological and experimental models in the adult female rat. Kisspeptin-10 (1 nmol, intracerebroventricular) was able to elicit robust LH bursts at all phases of the estrous cycle, with maximal responses at estrus; yet, in diestrus LH, responses to kisspeptin were detected at doses as low as 0.1 pmol. In contrast, high doses of kisspeptin only stimulated FSH secretion at diestrus. Removal of ovarian sex steroids did not blunt the ability of kisspeptin to further elicit stimulated LH and FSH secretion, but restoration of maximal responses required replacement with estradiol and progesterone. Finally, despite suppressed basal levels, LH and FSH secretory responses to kisspeptin were preserved in pregnant and lactating females, although the magnitude of LH bursts and the sensitivity to kisspeptin were much higher in pregnant dams. Interestingly, hypothalamic KiSS-1 gene expression significantly increased during pregnancy, whereas GPR54 mRNA levels remained unaltered. In summary, our current data document for the first time the changes in hypothalamic expression of KiSS-1 system and the gonadotropic effects (maximal responses and sensitivity) of kisspeptin in different functional states of the female reproductive axis. The present data may pose interesting implications in light of the potential therapeutic use of kisspeptin analogs in the pharmacological manipulation of the gonadotropic axis in the female.

    PMID: 16527840 [PubMed - indexed for MEDLINE]



  • Effects of single or repeated intravenous administration of kisspeptin upon dynamic LH secretion in conscious male rats.
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    Effects of single or repeated intravenous administration of kisspeptin upon dynamic LH secretion in conscious male rats.

    Endocrinology. 2006 Jun;147(6):2696-704

    Authors: Tovar S, Vázquez MJ, Navarro VM, Fernández-Fernández R, Castellano JM, Vigo E, Roa J, Casanueva FF, Aguilar E, Pinilla L, Dieguez C, Tena-Sempere M

    The ability of kisspeptins, ligands of the G protein-coupled receptor 54, to potently elicit LH secretion is now undisputed. Yet, most of the pharmacological characterization of their gonadotropin-releasing effects has been conducted after intracerebral administration. In contrast, the effects of peripheral injection of kisspeptin remains less well defined. In this study, dynamic LH secretory responses to iv administration of kisspeptin-10 in different experimental settings are presented, and compared with those evoked by kisspeptin-52, using a protocol of serial blood sampling in conscious, freely moving male rats. LH responsiveness to peripheral administration of kisspeptin appeared extremely sensitive, as doses as low as 0.3 nmol/kg (0.1 microg/rat) evoked robust LH bursts, the magnitude of which was dose-dependent and apparently maximal in response to 3.0 and 30 nmol/kg kisspeptin-10. The ability of kisspeptin-10 to stimulate LH release was fully preserved, and even doubled in terms of relative increases, after short-term fasting despite suppression of prevailing LH levels. Repeated injections of kisspeptin-10 (four boluses, at 75-min intervals) evoked associated LH secretory pulses, the magnitude of which remained constant along the study period. Moreover, in this setting, in vivo LH responses to a terminal injection of GnRH were preserved, whereas basal and depolarization-induced GnRH release ex vivo was significantly enhanced. Finally, iv administration of kisspeptin-52 elicited dynamic LH responses analogous to that of kisspeptin-10; yet, their net magnitude and duration was slightly greater. In summary, we present in this study a series of experiments on the effects of systemic (iv) injection of single or repeated doses of kisspeptin upon dynamic LH secretion in conscious male rats. Aside from potential physiologic relevance, our present data might contribute to setting the basis for the rational therapeutic use of kisspeptin analogs in the pharmacological manipulation of the gonadotropic axis.

    PMID: 16513831 [PubMed - indexed for MEDLINE]



  • KiSS-1 neurones are direct targets for leptin in the ob/ob mouse.
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    KiSS-1 neurones are direct targets for leptin in the ob/ob mouse.

    J Neuroendocrinol. 2006 Apr;18(4):298-303

    Authors: Smith JT, Acohido BV, Clifton DK, Steiner RA

    Leptin is an adipocyte-derived hormone that acts on the hypothalamus to influence feeding, metabolism and reproduction, but the cellular and molecular targets for the action of leptin in the brain have yet to be fully elucidated. Kisspeptins are encoded by the Kiss1 gene, which is expressed in the hypothalamus and has been implicated in the neuroendocrine regulation of gonadotrophin-releasing hormone secretion. We tested the hypothesis that kisspeptin-expressing neurones are targets for leptin. First, we examined whether leptin regulates the expression of Kiss1 by comparing levels of KiSS-1 mRNA in the arcuate nucleus among groups of mice having different circulating levels of leptin: (i) wild-type (WT); (ii) leptin-deficient ob/ob; and (iii) ob/ob mice treated with leptin. All mice were castrated to control for endogenous concentrations of gonadal steroids. KiSS-1 mRNA was significantly reduced in ob/ob compared to WT mice and levels of KiSS-1 mRNA in ob/ob mice treated with leptin were increased, but not fully restored to that found in WT animals. Second, we performed double-label in situ hybridisation for KiSS-1 mRNA and the leptin receptor (Ob-Rb) mRNA and found that almost one-half (approximately 40%) of KiSS-1 mRNA-expressing cells in the arcuate nucleus expressed Ob-Rb mRNA. These results demonstrate that KiSS-1 neurones are direct targets for regulation by leptin and suggest that the reproductive deficits associated with leptin-deficient states may be attributable, in part, to diminished expression of Kiss1.

    PMID: 16503925 [PubMed - indexed for MEDLINE]



  • Continuous human metastin 45-54 infusion desensitizes G protein-coupled receptor 54-induced gonadotropin-releasing hormone release monitored indirectly in the juvenile male Rhesus monkey (Macaca mulatta): a finding with therapeutic implications.
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    Continuous human metastin 45-54 infusion desensitizes G protein-coupled receptor 54-induced gonadotropin-releasing hormone release monitored indirectly in the juvenile male Rhesus monkey (Macaca mulatta): a finding with therapeutic implications.

    Endocrinology. 2006 May;147(5):2122-6

    Authors: Seminara SB, Dipietro MJ, Ramaswamy S, Crowley WF, Plant TM

    The effect of continuous administration of the C-terminal fragment of metastin, the ligand for the G protein-coupled receptor, GPR54, on GnRH-induced LH secretion was examined in three agonadal, juvenile male monkeys whose responsiveness to GnRH was heightened by pretreatment with a chronic pulsatile iv infusion of synthetic GnRH. After bolus injection of 10 microg human (hu) metastin 45-54 (equivalent to kisspeptin 112-121), the GPR54 agonist was infused continuously at a dose of 100 microg/h and elicited a brisk LH response for approximately 3 h. This rise was then followed by a precipitous drop in LH despite continuous exposure of GPR54 to metastin 45-54. On d 4, during the final 3 h of the infusion, single boluses of hu metastin 45-54 (10 microg), N-methyl-DL-aspartic acid (NMDA) (10 mg/kg) and GnRH (0.3 microg) were administered to interrogate each element of the metastin-GPR54-GnRH-GnRH receptor cascade. Although the NMDA and GnRH boluses were able to elicit LH pulses, that of hu metastin 45-54 was not, demonstrating functional integrity of GnRH neurons (NMDA) and GnRH receptors (NMDA and GnRH) but desensitization of GPR54. The desensitization of GPR54 by continuous hu metastin 45-54 administration has therapeutic implications for a variety of conditions currently being treated by GnRH and its analogs, including restoration of fertility in patients with abnormal GnRH secretion (i.e. idiopathic hypogonadotropic hypogonadism and hypothalamic amenorrhea) and selective, reversible suppression of the pituitary-gonadal axis to achieve suppression of gonadal steroids (i.e. precocious puberty, endometriosis, uterine fibroids, and prostate cancer).

    PMID: 16469799 [PubMed - indexed for MEDLINE]



  • Comparative analysis of the effects of ghrelin and unacylated ghrelin on luteinizing hormone secretion in male rats.
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    Comparative analysis of the effects of ghrelin and unacylated ghrelin on luteinizing hormone secretion in male rats.

    Endocrinology. 2006 May;147(5):2374-82

    Authors: Martini AC, Fernández-Fernández R, Tovar S, Navarro VM, Vigo E, Vazquez MJ, Davies JS, Thompson NM, Aguilar E, Pinilla L, Wells T, Dieguez C, Tena-Sempere M

    Ghrelin, the endogenous ligand of GH secretagogue receptor type 1a, has emerged as pleiotropic modulator of diverse biological functions, including energy homeostasis and, recently, reproduction. Although inhibitory actions of ghrelin on LH secretion and puberty onset have been reported previously, the receptor mechanisms mediating these actions, and the potential gonadotropic effects of the unacylated isoform of ghrelin (UAG), remain unclear. In this work, the effects of single and repeated administration of ghrelin or UAG on LH secretion were compared in pubertal and adult male rats. In addition, the effects of ghrelin were assessed in models of transient or persistent hypergonadotropism. Daily injection of ghrelin or UAG throughout puberty similarly decreased LH levels and partially delayed balanopreputial separation. Likewise, chronic infusion of ghrelin or UAG to adult males resulted in significant decreases in circulating LH and FSH concentrations. Moreover, acute injection of ghrelin induced a transient reduction in LH levels in freely moving males, an effect that was fully mimicked by administration of UAG. Yet in contrast to ghrelin, UAG failed to modify GH secretion. Finally, injection of ghrelin moderately, but significantly, reduced the duration of LH secretory responses to the potent gonadotropin secretagogue kisspeptin-10, whereas ghrelin infusion in a model of chronic elevation of serum gonadotropin levels (the transgenic growth retarded male rat) evoked a significant reduction of LH concentrations. Altogether our present results further substantiate the inhibitory effect of ghrelin on basal and stimulated LH secretion in a wide array of experimental conditions. Moreover, our data are the first to demonstrate the ability of UAG, originally considered an inert form of the molecule, to mimic the actions of acylated ghrelin on LH release. These observations reinforce the contention that ghrelin, as putative signal for energy insufficiency, may operate as negative modifier of male puberty and LH secretion, an effect that might be, at least partially, conducted through a GH secretagogue receptor type 1a-independent mechanism.

    PMID: 16455774 [PubMed - indexed for MEDLINE]



  • Minireview: the neuroendocrine regulation of puberty: is the time ripe for a systems biology approach?
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    Minireview: the neuroendocrine regulation of puberty: is the time ripe for a systems biology approach?

    Endocrinology. 2006 Mar;147(3):1166-74

    Authors: Ojeda SR, Lomniczi A, Mastronardi C, Heger S, Roth C, Parent AS, Matagne V, Mungenast AE

    The initiation of mammalian puberty requires an increase in pulsatile release of GnRH from the hypothalamus. This increase is brought about by coordinated changes in transsynaptic and glial-neuronal communication. As the neuronal and glial excitatory inputs to the GnRH neuronal network increase, the transsynaptic inhibitory tone decreases, leading to the pubertal activation of GnRH secretion. The excitatory neuronal systems most prevalently involved in this process use glutamate and the peptide kisspeptin for neurotransmission/neuromodulation, whereas the most important inhibitory inputs are provided by gamma-aminobutyric acid (GABA)ergic and opiatergic neurons. Glial cells, on the other hand, facilitate GnRH secretion via growth factor-dependent cell-cell signaling. Coordination of this regulatory neuronal-glial network may require a hierarchical arrangement. One level of coordination appears to be provided by a host of unrelated genes encoding proteins required for cell-cell communication. A second, but overlapping, level might be provided by a second tier of genes engaged in specific cell functions required for productive cell-cell interaction. A third and higher level of control involves the transcriptional regulation of these subordinate genes by a handful of upper echelon genes that, operating within the different neuronal and glial subsets required for the initiation of the pubertal process, sustain the functional integration of the network. The existence of functionally connected genes controlling the pubertal process is consistent with the concept that puberty is under genetic control and that the genetic underpinnings of both normal and deranged puberty are polygenic rather than specified by a single gene. The availability of improved high-throughput techniques and computational methods for global analysis of mRNAs and proteins will allow us to not only initiate the systematic identification of the different components of this neuroendocrine network but also to define their functional interactions.

    PMID: 16373420 [PubMed - indexed for MEDLINE]



  • Minireview: kisspeptin neurons as central processors in the regulation of gonadotropin-releasing hormone secretion.
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    Minireview: kisspeptin neurons as central processors in the regulation of gonadotropin-releasing hormone secretion.

    Endocrinology. 2006 Mar;147(3):1154-8

    Authors: Dungan HM, Clifton DK, Steiner RA

    The Kiss1 gene encodes a family of peptides called kisspeptins, which bind to the G protein-coupled receptor GPR54. Kisspeptin(s) and its receptor are expressed in the forebrain, and the discovery that mice and humans lacking a functional GPR54 fail to undergo puberty and exhibit hypogonadotropic hypogonadism implies that kisspeptin signaling plays an essential role in reproduction. Studies in several mammalian species have shown that kisspeptins stimulate the secretion of gonadotropins from the pituitary by stimulating the release of GnRH from the forebrain after the activation of GPR54, which is expressed by GnRH neurons. Kisspeptin is expressed abundantly in the arcuate nucleus (Arc) and the anteroventral periventricular nucleus (AVPV) of the forebrain. Both estradiol and testosterone regulate the expression of the Kiss1 gene in the Arc and AVPV; however, the response of the Kiss1 gene to these steroids is exactly opposite between these two nuclei. Estradiol and testosterone down-regulate Kiss1 mRNA in the Arc and up-regulate its expression in the AVPV. Thus, kisspeptin neurons in the Arc may participate in the negative feedback regulation of gonadotropin secretion, whereas kisspeptin neurons in the AVPV may contribute to generating the preovulatory gonadotropin surge in the female. Hypothalamic levels of Kiss1 and GPR54 mRNA increase dramatically at puberty, suggesting that kisspeptin signaling could mediate the neuroendocrine events that trigger the onset of puberty. Together, these observations demonstrate that kisspeptin-GPR54 signaling in the brain serves as an important conduit for controlling GnRH secretion in the developing and adult animal.

    PMID: 16373418 [PubMed - indexed for MEDLINE]



  • Role of metastin in the release of gonadotropin-releasing hormone from the hypothalamus of the male rat.
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    Role of metastin in the release of gonadotropin-releasing hormone from the hypothalamus of the male rat.

    J Androl. 2006 May-Jun;27(3):444-9

    Authors: Nazian SJ

    Recent genetic analysis has suggested that the expression of the orphan receptor GPR54 is essential for the onset of puberty in both rodents and humans. Indirect evidence has suggested that this action is via gonadotropin-releasing hormone induction of luteinizing hormone release. The experiments described here were intended to provide direct evidence that metastin, the naturally occurring ligand for GPR54, was capable of stimulating GnRH secretion by examining GnRH release from an immortalized hypothalamic cell line (GT1-7) and from male rat hypothalamic explants. GT1-7 cells were treated for 2(1/2) hours and overnight with the biologically active fragment of metastin, metastin(45-54), in amounts ranging from 0.1 nM to 1 muM. Hypothalamic fragments were obtained from infantile male rats and exposed to progressively increasing concentrations of metastin(45-54) (0.1 nM to 1 muM) for 1-hour periods. In both experiments, GnRH release was measured by radioimmunoassay (RIA). The release of metastin from hypothalami obtained from infantile and adult male rats was also determined. Explants were incubated for 6 hours, and the release of metastin into the media was determined by RIA. The results support the hypothesis that metastin stimulates GnRH secretion from the hypothalamus. The data indicate that an increase in the secretion of metastin, rather than the appearance of the receptor, is required for puberty onset. The results also suggest that metastin influences the GnRH-secreting neurons indirectly via an interneuron rather than acting directly on the GnRH-secreting neurons.

    PMID: 16339453 [PubMed - indexed for MEDLINE]



  • Colocalization of kisspeptin and gonadotropin-releasing hormone in the ovine brain.
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    Colocalization of kisspeptin and gonadotropin-releasing hormone in the ovine brain.

    Endocrinology. 2006 Feb;147(2):804-10

    Authors: Pompolo S, Pereira A, Estrada KM, Clarke IJ

    Kisspeptin is a peptide that has been implicated in the regulation of GnRH cells in the brain. Immunohistochemical studies were undertaken to examine the distribution of kisspeptin-immunoreactive (IR) cells in the ovine diencephalon and determine the effect of ovariectomy in the ewe. We report that kisspeptin colocalizes to a high proportion of GnRH-IR cells in the preoptic area, which is a novel finding. A high level of colocalization of kisspeptin and GnRH was also seen in varicose neuronal fibers within the external, neurosecretory zone of the median eminence. Apart from the kisspeptin/GnRH cells, a population of single-labeling kisspeptin-IR cells was also observed in the preoptic area. Within the hypothalamus, kisspeptin-IR cells were found predominantly in the arcuate nucleus, and there was an increase in the number of immunohistochemically identified cell within this nucleus after ovariectomy. Kisspeptin-IR cells were also found in the periventricular nucleus of the hypothalamus, but the number observed was similar in gonad-intact and ovariectomized ewes. The colocalization of GnRH and kisspeptin within cells of the preoptic area and GnRH neurosecretory terminals of the median eminence suggests that the two peptides might be cosecreted into the hypophyseal portal blood to act on the pituitary gland. Effects of ovariectomy on the non-GnRH, Kisspeptin-IR cells of the hypothalamus suggest that kisspeptin production is negatively regulated by ovarian steroids.

    PMID: 16293663 [PubMed - indexed for MEDLINE]



  • Repetitive activation of hypothalamic G protein-coupled receptor 54 with intravenous pulses of kisspeptin in the juvenile monkey (Macaca mulatta) elicits a sustained train of gonadotropin-releasing hormone discharges.
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    Repetitive activation of hypothalamic G protein-coupled receptor 54 with intravenous pulses of kisspeptin in the juvenile monkey (Macaca mulatta) elicits a sustained train of gonadotropin-releasing hormone discharges.

    Endocrinology. 2006 Feb;147(2):1007-13

    Authors: Plant TM, Ramaswamy S, Dipietro MJ

    The purpose of the present study was to further examine the hypothesis that activation of G protein-coupled receptor 54 (GPR54) signaling at the end of the juvenile phase of primate development is responsible for initiation of gonadarche and the onset of puberty. Accordingly, we determined whether repetitive iv administration of the GPR54 receptor agonist kisspeptin-10 (2 microg as a brief 1-min infusion once every hour for 48 h) to the juvenile male rhesus monkey would prematurely elicit sustained, pulsatile release of hypothalamic GnRH, the neuroendocrine trigger for gonadarche. GnRH release was monitored indirectly by measuring LH secretion from the in situ pituitary, the GnRH responsiveness of which had been heightened before the experiment with an intermittent iv infusion of synthetic GnRH. Agonadal animals (n = 4) were employed to eliminate any confounding and secondary effects of changing feedback signals from the testis. The first brief infusion of kisspeptin-10 evoked an LH discharge that mimicked those produced by GnRH priming, and this was followed by a train of similar LH discharges in response to hourly activation of GPR54 by repetitive kisspeptin-10 administration. Concomitant treatment with a GnRH receptor antagonist, acyline, abolished kisspeptin-10-induced LH release. Repetitive kisspeptin-10 administration also provided a GnRH-dependent signal to FSH secretion. These findings are consistent with the notion that, in primates, the transition from the juvenile (attenuated GnRH release) to pubertal (robust GnRH release) state is controlled by activation of GPR54 resulting from increased expression of hypothalamic KiSS-1 and release of kisspeptin in this region of the brain.

    PMID: 16282350 [PubMed - indexed for MEDLINE]



  • Regulation of KiSS-1 metastasis suppressor gene expression in breast cancer cells by direct interaction of transcription factors activator protein-2alpha and specificity protein-1.
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    Regulation of KiSS-1 metastasis suppressor gene expression in breast cancer cells by direct interaction of transcription factors activator protein-2alpha and specificity protein-1.

    J Biol Chem. 2006 Jan 6;281(1):51-8

    Authors: Mitchell DC, Abdelrahim M, Weng J, Stafford LJ, Safe S, Bar-Eli M, Liu M

    KiSS-1 has been shown to function as a tumor metastasis suppressor gene and reduce the number of metastases in different cancers. The expression of KiSS-1 or KiSS1, like other tumor suppressor, is commonly reduced or completely ablated in a variety of cancers via an unknown mechanism. Here we show that the loss of KiSS-1 expression in highly metastatic breast cancer cell lines correlates directly with the expression levels of two transcription factors, activator protein-2alpha (AP-2alpha) and specificity protein 1 (Sp1), which synergistically activate the transcriptional regulation of KiSS-1 in breast cancer cells. Although the KiSS-1 promoter contains multiple AP-2alpha binding elements, AP-2alpha-mediated regulation occurs indirectly through Sp1 sites, as determined by deletion and mutation analysis. Overexpression of AP-2alpha into highly metastatic breast cell lines did not alter KiSS-1 promoter-driven luciferase gene activity. However, co-transfection of AP-2alpha wild-type or the dominant negative form of AP-2 lacking its C-terminal DNA-binding domain, AP-2B, together with Sp1, increased KiSS-1 promoter activity dramatically, suggesting that AP-2alpha regulation of KiSS-1 transcription does not require direct binding to the KiSS-1 promoter. Furthermore, we demonstrated that AP-2alpha directly interacted with Sp1 to form transcription complexes at two tandem Sp1-binding sites of the promoter to activate KiSS-1 transcription. Together, our results indicate that AP-2alpha and Sp1 are strong transcriptional regulators of KiSS-1 and that loss or decreased expression of AP-2alpha in breast cancer may account for the loss of tumor metastasis suppressor KiSS-1 expression and thus increased cancer metastasis.

    PMID: 16260418 [PubMed - indexed for MEDLINE]



  • Design and synthesis of downsized metastin (45-54) analogs with maintenance of high GPR54 agonistic activity.
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    Design and synthesis of downsized metastin (45-54) analogs with maintenance of high GPR54 agonistic activity.

    Bioorg Med Chem Lett. 2006 Jan 1;16(1):134-7

    Authors: Niida A, Wang Z, Tomita K, Oishi S, Tamamura H, Otaka A, Navenot JM, Broach JR, Peiper SC, Fujii N

    Metastin has been identified as a metastasis suppressor gene product that mediates its function through a G protein coupled receptor, GPR54. To refine insight into the critical pharmacophore for the activation of GPR54, we have conducted alanine and d-amino acid scanning on a biologically active metastin fragment (45-54). Based on these data and structures of peptides previously reported to activate GPR54, a series of shortened metastin (45-54) derivatives were synthesized and tested for the ability to induce GPR54 signaling. These biological experiments were performed in yeast containing human GPR54 that was coupled to the pheromone response pathway and a pheromone responsive lacZ reporter gene. Compounds 32, 33, and 39, which possess an N-terminal basic group and a C-terminal RW-amide motif, were strong agonists, similar to the level of metastin. This may provide an approach to reverse the pro-metastatic effect of metastin deletion in multiple malignant tumors.

    PMID: 16242330 [PubMed - indexed for MEDLINE]