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Shan Y, Farmer SM, Wray S. Drebrin regulates cytoskeleton dynamics in migrating neurons through interaction with CXCR4. Proc Natl Acad Sci U S A 2021; 118:e2009493118. [PMID: 33414275 PMCID: PMC7826346 DOI: 10.1073/pnas.2009493118] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Stromal cell-derived factor-1 (SDF-1) and chemokine receptor type 4 (CXCR4) are regulators of neuronal migration (e.g., GnRH neurons, cortical neurons, and hippocampal granule cells). However, how SDF-1/CXCR4 alters cytoskeletal components remains unclear. Developmentally regulated brain protein (drebrin) stabilizes actin polymerization, interacts with microtubule plus ends, and has been proposed to directly interact with CXCR4 in T cells. The current study examined, in mice, whether CXCR4 under SDF-1 stimulation interacts with drebrin to facilitate neuronal migration. Bioinformatic prediction of protein-protein interaction highlighted binding sites between drebrin and crystallized CXCR4. In migrating GnRH neurons, drebrin, CXCR4, and the microtubule plus-end binding protein EB1 were localized close to the cell membrane. Coimmunoprecipitation (co-IP) confirmed a direct interaction between drebrin and CXCR4 using wild-type E14.5 whole head and a GnRH cell line. Analysis of drebrin knockout (DBN1 KO) mice showed delayed migration of GnRH cells into the brain. A decrease in hippocampal granule cells was also detected, and co-IP confirmed a direct interaction between drebrin and CXCR4 in PN4 hippocampi. Migration assays on primary neurons established that inhibiting drebrin (either pharmacologically or using cells from DBN1 KO mice) prevented the effects of SDF-1 on neuronal movement. Bioinformatic prediction then identified binding sites between drebrin and the microtubule plus end protein, EB1, and super-resolution microscopy revealed decreased EB1 and drebrin coexpression after drebrin inhibition. Together, these data show a mechanism by which a chemokine, via a membrane receptor, communicates with the intracellular cytoskeleton in migrating neurons during central nervous system development.
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Affiliation(s)
- Yufei Shan
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
| | - Stephen Matthew Farmer
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
| | - Susan Wray
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
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Characterizing the Role of SMYD2 in Mammalian Embryogenesis-Future Directions. Vet Sci 2020; 7:vetsci7020063. [PMID: 32408548 PMCID: PMC7357037 DOI: 10.3390/vetsci7020063] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 04/28/2020] [Accepted: 05/02/2020] [Indexed: 11/26/2022] Open
Abstract
The SET and MYND domain-containing (SMYD) family of lysine methyltransferases are essential in several mammalian developmental pathways. Although predominantly expressed in the heart, the role of SMYD2 in heart development has yet to be fully elucidated and has even been shown to be dispensable in a murine Nkx2-5-associated conditional knockout. Additionally, SMYD2 was recently shown to be necessary not only for lymphocyte development but also for the viability of hematopoietic leukemias. Based on the broad expression pattern of SMYD2 in mammalian tissues, it is likely that it plays pivotal roles in a host of additional normal and pathological processes. In this brief review, we consider what is currently known about the normal and pathogenic functions of SMYD2 and propose specific future directions for characterizing its role in embryogenesis.
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Howard SR, Dunkel L. Delayed Puberty-Phenotypic Diversity, Molecular Genetic Mechanisms, and Recent Discoveries. Endocr Rev 2019; 40:1285-1317. [PMID: 31220230 PMCID: PMC6736054 DOI: 10.1210/er.2018-00248] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 01/31/2019] [Indexed: 02/07/2023]
Abstract
This review presents a comprehensive discussion of the clinical condition of delayed puberty, a common presentation to the pediatric endocrinologist, which may present both diagnostic and prognostic challenges. Our understanding of the genetic control of pubertal timing has advanced thanks to active investigation in this field over the last two decades, but it remains in large part a fascinating and mysterious conundrum. The phenotype of delayed puberty is associated with adult health risks and common etiologies, and there is evidence for polygenic control of pubertal timing in the general population, sex-specificity, and epigenetic modulation. Moreover, much has been learned from comprehension of monogenic and digenic etiologies of pubertal delay and associated disorders and, in recent years, knowledge of oligogenic inheritance in conditions of GnRH deficiency. Recently there have been several novel discoveries in the field of self-limited delayed puberty, encompassing exciting developments linking this condition to both GnRH neuronal biology and metabolism and body mass. These data together highlight the fascinating heterogeneity of disorders underlying this phenotype and point to areas of future research where impactful developments can be made.
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Affiliation(s)
- Sasha R Howard
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
| | - Leo Dunkel
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
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Pandolfi EC, Tonsfeldt KJ, Hoffmann HM, Mellon PL. Deletion of the Homeodomain Protein Six6 From GnRH Neurons Decreases GnRH Gene Expression, Resulting in Infertility. Endocrinology 2019; 160:2151-2164. [PMID: 31211355 PMCID: PMC6821215 DOI: 10.1210/en.2019-00113] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 06/11/2019] [Indexed: 12/12/2022]
Abstract
Hypothalamic GnRH (luteinizing hormone-releasing hormone) neurons are crucial for the hypothalamic-pituitary-gonadal (HPG) axis, which regulates mammalian fertility. Insufficient GnRH disrupts the HPG axis and is often associated with the genetic condition idiopathic hypogonadotropic hypogonadism (IHH). The homeodomain protein sine oculis-related homeobox 6 (Six6) is required for the development of GnRH neurons. Although it is known that Six6 is specifically expressed within a more mature GnRH neuronal cell line and that overexpression of Six6 induces GnRH transcription in these cells, the direct role of Six6 within the GnRH neuron in vivo is unknown. Here we find that global Six6 knockout (KO) embryos show apoptosis of GnRH neurons beginning at embryonic day 14.5 with 90% loss of GnRH neurons by postnatal day 1. We sought to determine whether the hypogonadism and infertility reported in the Six6KO mice are generated via actions within the GnRH neuron in vivo by creating a Six6-flox mouse and crossing it with the LHRHcre mouse. Loss of Six6 specifically within the GnRH neuron abolished GnRH expression in ∼0% of GnRH neurons. We further demonstrated that deletion of Six6 only within the GnRH neuron leads to infertility, hypogonadism, hypogonadotropism, and delayed puberty. We conclude that Six6 plays distinct roles in maintaining fertility in the GnRH neuron vs in the migratory environment of the GnRH neuron by maintaining expression of GnRH and survival of GnRH neurons, respectively. These results increase knowledge of the role of Six6 in the brain and may offer insight into the mechanism of IHH.
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Affiliation(s)
- Erica C Pandolfi
- Department of Obstetrics, Gynecology and Reproductive Sciences, Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, California
| | - Karen J Tonsfeldt
- Department of Obstetrics, Gynecology and Reproductive Sciences, Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, California
| | - Hanne M Hoffmann
- Department of Obstetrics, Gynecology and Reproductive Sciences, Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, California
- Department of Animal Science, Michigan State University, East Lansing, Michigan
| | - Pamela L Mellon
- Department of Obstetrics, Gynecology and Reproductive Sciences, Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, California
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Cho HJ, Shan Y, Whittington NC, Wray S. Nasal Placode Development, GnRH Neuronal Migration and Kallmann Syndrome. Front Cell Dev Biol 2019; 7:121. [PMID: 31355196 PMCID: PMC6637222 DOI: 10.3389/fcell.2019.00121] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 06/14/2019] [Indexed: 12/22/2022] Open
Abstract
The development of Gonadotropin releasing hormone-1 (GnRH) neurons is important for a functional reproduction system in vertebrates. Disruption of GnRH results in hypogonadism and if accompanied by anosmia is termed Kallmann Syndrome (KS). From their origin in the nasal placode, GnRH neurons migrate along the olfactory-derived vomeronasal axons to the nasal forebrain junction and then turn caudally into the developing forebrain. Although research on the origin of GnRH neurons, their migration and genes associated with KS has identified multiple factors that influence development of this system, several aspects still remain unclear. This review discusses development of the olfactory system, factors that regulate GnRH neuron formation and development of the olfactory system, migration of the GnRH neurons from the nose into the brain, and mutations in humans with KS that result from disruption of normal GnRH/olfactory systems development.
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Affiliation(s)
- Hyun-Ju Cho
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Yufei Shan
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Niteace C Whittington
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Susan Wray
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
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Pandolfi EC, Hoffmann HM, Schoeller EL, Gorman MR, Mellon PL. Haploinsufficiency of SIX3 Abolishes Male Reproductive Behavior Through Disrupted Olfactory Development, and Impairs Female Fertility Through Disrupted GnRH Neuron Migration. Mol Neurobiol 2018; 55:8709-8727. [PMID: 29589282 PMCID: PMC6156938 DOI: 10.1007/s12035-018-1013-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 03/16/2018] [Indexed: 12/17/2022]
Abstract
Mating behavior in males and females is dependent on olfactory cues processed through both the main olfactory epithelium (MOE) and the vomeronasal organ (VNO). Signaling through the MOE is critical for the initiation of male mating behavior, and the loss of MOE signaling severely compromises this comportment. Here, we demonstrate that dosage of the homeodomain gene Six3 affects the degree of development of MOE but not the VNO. Anomalous MOE development in Six3 heterozygote mice leads to hyposmia, specifically disrupting male mounting behavior by impairing detection of volatile female estrus pheromones. Six3 is highly expressed in the MOE, main olfactory bulb (MOB), and hypothalamus; all regions essential in the proper migration of the gonadotropin-releasing hormone (GnRH) neurons, a key reproductive neuronal population that migrates along olfactory axons from the developing nose into the brain. Interestingly, we find that the reduction in Six3 expression in Six3 heterozygote mice compromises development of the MOE and MOB, resulting in mis-migration of GnRH neurons due to improper olfactory axon targeting. This reduction in the hypothalamic GnRH neuron population, by 45% in adulthood, leads to female subfertility, but does not impact male hormone levels, suggesting that male infertility is not related to GnRH neuron numbers, but exclusively linked to abnormal olfaction. We here determine that Six3 is haploinsufficient for MOE development, GnRH neuron migration, and fertility, and represents a novel candidate gene for Kallmann syndrome, a form of inherited infertility.
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Affiliation(s)
- Erica C Pandolfi
- Department of Reproductive Medicine, Center for Reproductive Science and Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0674, USA
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Hanne M Hoffmann
- Department of Reproductive Medicine, Center for Reproductive Science and Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0674, USA
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Erica L Schoeller
- Department of Reproductive Medicine, Center for Reproductive Science and Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0674, USA
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Michael R Gorman
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA, 92093, USA
- Department of Psychology, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Pamela L Mellon
- Department of Reproductive Medicine, Center for Reproductive Science and Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0674, USA.
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA, 92093, USA.
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Hoffmann HM, Pandolfi EC, Larder R, Mellon PL. Haploinsufficiency of Homeodomain Proteins Six3, Vax1, and Otx2 Causes Subfertility in Mice via Distinct Mechanisms. Neuroendocrinology 2018; 109:200-207. [PMID: 30261489 PMCID: PMC6437011 DOI: 10.1159/000494086] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Accepted: 09/26/2018] [Indexed: 12/17/2022]
Abstract
Haploinsufficiency occurs when loss of one copy of a diploid gene (hemizygosity) causes a phenotype. It is relatively rare, in that most genes can produce sufficient mRNA and protein from a single copy to prevent any loss of normal activity and function. Reproduction is a complex process relying on migration of GnRH neurons from the olfactory placode to the hypothalamus during development. We have studied 3 different homeodomain genes Otx2, Vax1, and Six3 and found that the deletion of one allele for any of these genes in mice produces subfertility or infertility in one or both sexes, despite the presence of one intact allele. All 3 heterozygous mice have reduced numbers of GnRH neurons, but the mechanisms of subfertility differ significantly. This review compares the subfertility phenotypes and their mechanisms.
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Affiliation(s)
- Hanne M Hoffmann
- Department of Obstetrics, Gynecology, and Reproductive Sciences and the Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, California, USA
- Department of Animal Science, Michigan State University, East Lansing, Michigan, USA
| | - Erica C Pandolfi
- Department of Obstetrics, Gynecology, and Reproductive Sciences and the Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, California, USA
| | - Rachel Larder
- Department of Obstetrics, Gynecology, and Reproductive Sciences and the Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, California, USA
| | - Pamela L Mellon
- Department of Obstetrics, Gynecology, and Reproductive Sciences and the Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, California, USA,
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8
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Dairaghi L, Flannery E, Giacobini P, Saglam A, Saadi H, Constantin S, Casoni F, Howell BW, Wray S. Reelin Can Modulate Migration of Olfactory Ensheathing Cells and Gonadotropin Releasing Hormone Neurons via the Canonical Pathway. Front Cell Neurosci 2018; 12:228. [PMID: 30127721 PMCID: PMC6088185 DOI: 10.3389/fncel.2018.00228] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 07/13/2018] [Indexed: 01/14/2023] Open
Abstract
One key signaling pathway known to influence neuronal migration involves the extracellular matrix protein Reelin. Typically, signaling of Reelin occurs via apolipoprotein E receptor 2 (ApoER2) and very low-density lipoprotein receptor (VLDLR), and the cytoplasmic adapter protein disabled 1 (Dab1). However, non-canonical Reelin signaling has been reported, though no receptors have yet been identified. Cariboni et al. (2005) indicated Dab1-independent Reelin signaling impacts gonadotropin releasing hormone-1 (GnRH) neuronal migration. GnRH cells are essential for reproduction. Prenatal migration of GnRH neurons from the nasal placode to the forebrain, juxtaposed to olfactory axons and olfactory ensheathing cells (OECs), has been well documented, and it is clear that alterations in migration of these cells can cause delayed or absent puberty. This study was initiated to delineate the non-canonical Reelin signaling pathways used by GnRH neurons. Chronic treatment of nasal explants with CR-50, an antibody known to interfere with Reelin homopolymerization and Dab1 phosphorylation, decreased the distance GnRH neurons and OECs migrated. Normal migration of these two cell types was observed when Reelin was co-applied with CR-50. Immunocytochemistry was performed to determine if OECs might transduce Reelin signals via the canonical pathway, and subsequently indirectly altering GnRH neuronal migration. We show that in mouse: (1) both OECs and GnRH cells express ApoER2, VLDLR and Dab1, and (2) GnRH neurons and OECs show a normal distribution in the brain of two mutant reeler lines. These results indicate that the canonical Reelin pathway is present in GnRH neurons and OECs, but that Reelin is not essential for development of these two systems in vivo.
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Affiliation(s)
- Leigh Dairaghi
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, MD, United States
| | - Ellen Flannery
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, MD, United States
- Coriell Institute for Medical Research, Camden, NJ, United States
| | - Paolo Giacobini
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, MD, United States
- Laboratory of Development and Plasticity of the Neuroendocrine Brain, Jean Pierre Aubert Research Centre, INSERM U1172, Lille, France
| | - Aybike Saglam
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, MD, United States
| | - Hassan Saadi
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, MD, United States
| | - Stephanie Constantin
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, MD, United States
| | - Filippo Casoni
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, MD, United States
- Division of Neuroscience, San Raffaele Scientific Institute, Università Vita-Salute San Raffaele, Milan, Italy
| | - Brian W. Howell
- Neuroscience and Physiology, Upstate Medical University, Syracuse, NY, United States
| | - Susan Wray
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, MD, United States
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Larco DO, Bauman BM, Cho-Clark M, Mani SK, Wu TJ. GnRH-(1-5) Inhibits TGF-β Signaling to Regulate the Migration of Immortalized Gonadotropin-Releasing Hormone Neurons. Front Endocrinol (Lausanne) 2018; 9:45. [PMID: 29515521 PMCID: PMC5826220 DOI: 10.3389/fendo.2018.00045] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Accepted: 02/02/2018] [Indexed: 01/17/2023] Open
Abstract
Gonadotropin-releasing hormone (GnRH) neurons originate outside the central nervous system (CNS) in the nasal placode where their migration to the basal forebrain is dependent on the integration of multiple signaling cues during development. The proper migration and establishment of the GnRH neuronal population within the CNS are critical for normal pubertal onset and reproductive function. The endopeptidase EP24.15 is expressed along the migratory path of GnRH neurons and cleaves the full-length GnRH to generate the metabolite GnRH-(1-5). Using the GN11 cell model, which is considered a pre-migratory GnRH neuronal cell line, we demonstrated that GnRH-(1-5) inhibits cellular migration in a wound closure assay by binding the orphan G protein-coupled receptor 173 (GPR173). In our current experiments, we sought to utilize an in vitro migration assay that better reflects the external environment that migrating GnRH neurons are exposed to during development. Therefore, we used a transwell assay where the inserts were coated with or without a matrigel, a gelatinous mixture containing extracellular matrix (ECM) proteins, to mimic the extracellular environment. Interestingly, GnRH-(1-5) inhibited the ability of GN11 cells to migrate only through ECM mimetic and was dependent on GPR173. Furthermore, we found that GN11 cells secrete TGF-β1, 2, and 3 but only TGF-β1 release and signaling were inhibited by GnRH-(1-5). To identify potential mechanisms involved in the proteolytic activation of TGF-β, we measured a panel of genes implicated in ECM remodeling. We found that GnRH-(1-5) consistently increased tissue inhibitors of metalloproteinase 1 expression, which is an inhibitor of proteinase activity, leading to a decrease in bioactive TGF-β and subsequent signaling. These results suggest that GnRH-(1-5) activating GPR173 may modulate the response of migrating GnRH neurons to external cues present in the ECM environment via an autocrine-dependent mechanism involving TGF-β.
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Affiliation(s)
- Darwin O. Larco
- Department of Obstetrics and Gynecology, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - Bradly M. Bauman
- Department of Obstetrics and Gynecology, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - Madelaine Cho-Clark
- Department of Obstetrics and Gynecology, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - Shaila K. Mani
- Department of Molecular, Baylor College of Medicine, Houston, TX, United States
- Department of Cellular Biology and Neuroscience, Baylor College of Medicine, Houston, TX, United States
| | - T. John Wu
- Department of Obstetrics and Gynecology, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
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Trofimova T, Lizneva D, Suturina L, Walker W, Chen YH, Azziz R, Layman LC. Genetic basis of eugonadal and hypogonadal female reproductive disorders. Best Pract Res Clin Obstet Gynaecol 2017; 44:3-14. [DOI: 10.1016/j.bpobgyn.2017.05.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 04/20/2017] [Accepted: 05/02/2017] [Indexed: 12/21/2022]
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Kreisman MJ, Song CI, Yip K, Natale BV, Natale DR, Breen KM. Androgens Mediate Sex-Dependent Gonadotropin Expression During Late Prenatal Development in the Mouse. Endocrinology 2017; 158:2884-2894. [PMID: 28911172 PMCID: PMC5659668 DOI: 10.1210/en.2017-00285] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 07/05/2017] [Indexed: 12/22/2022]
Abstract
Central organization of the hypothalamic-pituitary-gonadal axis is initiated during fetal life. At this critical time, gonadal hormones mediate sex-specific development of the hypothalamic-pituitary axis, which then dictates reproductive physiology and behavior in adulthood. Although studies have investigated the effects of prenatal androgens on central factors influencing gonadotropin-releasing hormone (GnRH) release, the impact of fetal androgens on gonadotrope function has been overlooked. In the current study, we demonstrated that gonadotropin gene expression and protein production were robustly elevated in female mice compared with males during late fetal development and that this sex difference was dependent on fetal androgens. Treatment of dams from embryonic day (E)15.5 to E17.5 with testosterone, dihydrotestosterone (DHT), or the androgen antagonist flutamide eliminated the sex difference at E18.5. Specifically, flutamide relieved the suppression in male gene expression, elevating the level to that of females, whereas testosterone or DHT attenuated female gene expression to male levels. The gonadotrope population is equivalent in males and females, and gonadotropic cells in both sexes express androgen receptors, suggesting that androgen-dependent transcriptional regulation can occur in these cells in either sex. Studies using mouse models lacking GnRH signaling show that GnRH is necessary for enhanced gonadotropin expression in females and is therefore required to observe the sex difference. Collectively, these data suggest that circuits controlling GnRH input to the fetal pituitary are unrestrained in females yet robustly inhibited in males via circulating androgens and demonstrate plasticity in gonadotropin synthesis and secretion in both sexes depending on the androgen milieu during late prenatal development.
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Affiliation(s)
- Michael J. Kreisman
- Department of Reproductive Medicine, University of California, San Diego, La Jolla, California 92093-0674
- Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, California 92093-0674
| | - Christopher I. Song
- Department of Reproductive Medicine, University of California, San Diego, La Jolla, California 92093-0674
- Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, California 92093-0674
| | - Kathleen Yip
- Department of Reproductive Medicine, University of California, San Diego, La Jolla, California 92093-0674
- Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, California 92093-0674
| | - Bryony V. Natale
- Department of Reproductive Medicine, University of California, San Diego, La Jolla, California 92093-0674
| | - David R. Natale
- Department of Reproductive Medicine, University of California, San Diego, La Jolla, California 92093-0674
| | - Kellie M. Breen
- Department of Reproductive Medicine, University of California, San Diego, La Jolla, California 92093-0674
- Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, California 92093-0674
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12
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Oyola MG, Handa RJ. Hypothalamic-pituitary-adrenal and hypothalamic-pituitary-gonadal axes: sex differences in regulation of stress responsivity. Stress 2017; 20:476-494. [PMID: 28859530 PMCID: PMC5815295 DOI: 10.1080/10253890.2017.1369523] [Citation(s) in RCA: 355] [Impact Index Per Article: 50.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Gonadal hormones play a key role in the establishment, activation, and regulation of the hypothalamic-pituitary-adrenal (HPA) axis. By influencing the response and sensitivity to releasing factors, neurotransmitters, and hormones, gonadal steroids help orchestrate the gain of the HPA axis to fine-tune the levels of stress hormones in the general circulation. From early life to adulthood, gonadal steroids can differentially affect the HPA axis, resulting in sex differences in the responsivity of this axis. The HPA axis influences many physiological functions making an organism's response to changes in the environment appropriate for its reproductive status. Although the acute HPA response to stressors is a beneficial response, constant activation of this circuitry by chronic or traumatic stressful episodes may lead to a dysregulation of the HPA axis and cause pathology. Compared to males, female mice and rats show a more robust HPA axis response, as a result of circulating estradiol levels which elevate stress hormone levels during non-threatening situations, and during and after stressors. Fluctuating levels of gonadal steroids in females across the estrous cycle are a major factor contributing to sex differences in the robustness of HPA activity in females compared to males. Moreover, gonadal steroids may also contribute to epigenetic and organizational influences on the HPA axis even before puberty. Correspondingly, crosstalk between the hypothalamic-pituitary-gonadal (HPG) and HPA axes could lead to abnormalities of stress responses. In humans, a dysregulated stress response is one of the most common symptoms seen across many neuropsychiatric disorders, and as a result, such interactions may exacerbate peripheral pathologies. In this review, we discuss the HPA and HPG axes and review how gonadal steroids interact with the HPA axis to regulate the stress circuitry during all stages in life.
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Affiliation(s)
- Mario G Oyola
- a Department of Biomedical Sciences , Colorado State University , Fort Collins , CO , USA
| | - Robert J Handa
- a Department of Biomedical Sciences , Colorado State University , Fort Collins , CO , USA
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13
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Koizumi M, Ida S, Shoji Y, Etani Y, Hatsukawa Y, Okamoto N. Endocrine status of patients with septo-optic dysplasia: fourteen Japanese cases. Clin Pediatr Endocrinol 2017; 26:89-98. [PMID: 28458461 PMCID: PMC5402310 DOI: 10.1297/cpe.26.89] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 02/20/2017] [Indexed: 11/17/2022] Open
Abstract
A clinical diagnosis of septo-optic dysplasia (SOD) is made when two or more of the
classical triad of optic nerve hypoplasia, pituitary hormone abnormalities or midline
brain defects. To date, a clinical study of SOD, regarding its endocrinological features
in particular, has not been undertaken in Japan. We retrospectively evaluated 14 SOD
patients at our institution. Hormonal dysfunction was present in 78% of cases: ten cases
presented combined hypopituitarism and one case presented precocious puberty. GHD and
hypothyroidism were the most common endocrinopathies. A thin pituitary stalk and a gradual
decrease in hormone secretion were the main characteristics. SOD patients usually visited
ophthalmologists during early infancy because of eye problems; however, the medical
examination did not always lead to endocrine assessments being made. Consequently,
children who have eye problems with optic nerve hypoplasia should undergo head MRI
imaging. If diagnosed with SOD, it is very important to evaluate pituitary functions.
Their endocrinological status should be followed for a long time, even if they do not
exhibit any endocrinological problems at evaluation.
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Affiliation(s)
- Mikiko Koizumi
- Department of Gastroenterology and Endocrinology, Osaka Medical Center and Research Institute for Maternal and Child Health, Osaka, Japan
| | - Shinobu Ida
- Department of Gastroenterology and Endocrinology, Osaka Medical Center and Research Institute for Maternal and Child Health, Osaka, Japan
| | - Yasuko Shoji
- Department of Gastroenterology and Endocrinology, Osaka Medical Center and Research Institute for Maternal and Child Health, Osaka, Japan
| | - Yuri Etani
- Department of Gastroenterology and Endocrinology, Osaka Medical Center and Research Institute for Maternal and Child Health, Osaka, Japan
| | - Yoshikazu Hatsukawa
- Department of Ophthalmology, Osaka Medical Center and Research Institute for Maternal and Child Health, Osaka, Japan
| | - Nobuhiko Okamoto
- Department of Medical Genetics, Osaka Medical Center and Research Institute for Maternal and Child Health, Osaka, Japan
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A Novel Gonadotropin-Releasing Hormone 1 (Gnrh1) Enhancer-Derived Noncoding RNA Regulates Gnrh1 Gene Expression in GnRH Neuronal Cell Models. PLoS One 2016; 11:e0158597. [PMID: 27389022 PMCID: PMC4936741 DOI: 10.1371/journal.pone.0158597] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 06/18/2016] [Indexed: 12/22/2022] Open
Abstract
Gonadotropin-releasing hormone (GnRH), a neuropeptide released from a small population of neurons in the hypothalamus, is the central mediator of the hypothalamic-pituitary-gonadal axis, and is required for normal reproductive development and function. Evolutionarily conserved regulatory elements in the mouse, rat, and human Gnrh1 gene include three enhancers and the proximal promoter, which confer Gnrh1 gene expression specifically in GnRH neurons. In immortalized mouse hypothalamic GnRH (GT1-7) neurons, which show pulsatile GnRH release in culture, RNA sequencing and RT-qPCR revealed that expression of a novel long noncoding RNA at Gnrh1 enhancer 1 correlates with high levels of GnRH mRNA expression. In GT1-7 neurons, which contain a transgene carrying 3 kb of the rat Gnrh1 regulatory region, both the mouse and rat Gnrh1 enhancer-derived noncoding RNAs (GnRH-E1 RNAs) are expressed. We investigated the characteristics and function of the endogenous mouse GnRH-E1 RNA. Strand-specific RT-PCR analysis of GnRH-E1 RNA in GT1-7 cells revealed GnRH-E1 RNAs that are transcribed in the sense and antisense directions from distinct 5’ start sites, are 3’ polyadenylated, and are over 2 kb in length. These RNAs are localized in the nucleus and have a half-life of over 8 hours. In GT1-7 neurons, siRNA knockdown of mouse GnRH-E1 RNA resulted in a significant decrease in the expression of the Gnrh1 primary transcript and Gnrh1 mRNA. Over-expression of either the sense or antisense mouse GnRH-E1 RNA in immature, migratory GnRH (GN11) neurons, which do not express either GnRH-E1 RNA or GnRH mRNA, induced the transcriptional activity of co-transfected rat Gnrh1 gene regulatory elements, where the induction requires the presence of the rat Gnrh1 promoter. Together, these data indicate that GnRH-E1 RNA is an inducer of Gnrh1 gene expression. GnRH-E1 RNA may play an important role in the development and maturation of GnRH neurons.
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15
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Howard SR, Guasti L, Ruiz-Babot G, Mancini A, David A, Storr HL, Metherell LA, Sternberg MJ, Cabrera CP, Warren HR, Barnes MR, Quinton R, de Roux N, Young J, Guiochon-Mantel A, Wehkalampi K, André V, Gothilf Y, Cariboni A, Dunkel L. IGSF10 mutations dysregulate gonadotropin-releasing hormone neuronal migration resulting in delayed puberty. EMBO Mol Med 2016; 8:626-42. [PMID: 27137492 PMCID: PMC4888853 DOI: 10.15252/emmm.201606250] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Early or late pubertal onset affects up to 5% of adolescents and is associated with adverse health and psychosocial outcomes. Self‐limited delayed puberty (DP) segregates predominantly in an autosomal dominant pattern, but the underlying genetic background is unknown. Using exome and candidate gene sequencing, we have identified rare mutations in IGSF10 in 6 unrelated families, which resulted in intracellular retention with failure in the secretion of mutant proteins. IGSF10 mRNA was strongly expressed in embryonic nasal mesenchyme, during gonadotropin‐releasing hormone (GnRH) neuronal migration to the hypothalamus. IGSF10 knockdown caused a reduced migration of immature GnRH neurons in vitro, and perturbed migration and extension of GnRH neurons in a gnrh3:EGFP zebrafish model. Additionally, loss‐of‐function mutations in IGSF10 were identified in hypothalamic amenorrhea patients. Our evidence strongly suggests that mutations in IGSF10 cause DP in humans, and points to a common genetic basis for conditions of functional hypogonadotropic hypogonadism (HH). While dysregulation of GnRH neuronal migration is known to cause permanent HH, this is the first time that this has been demonstrated as a causal mechanism in DP.‡
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Affiliation(s)
- Sasha R Howard
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Leonardo Guasti
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Gerard Ruiz-Babot
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Alessandra Mancini
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Alessia David
- Centre for Integrative Systems Biology and Bioinformatics, Department of Life Sciences, Imperial College London, London, UK
| | - Helen L Storr
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Lousie A Metherell
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Michael Je Sternberg
- Centre for Integrative Systems Biology and Bioinformatics, Department of Life Sciences, Imperial College London, London, UK
| | - Claudia P Cabrera
- Centre for Translational Bioinformatics, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK NIHR Barts Cardiovascular Biomedical Research Unit, Queen Mary University of London, London, UK
| | - Helen R Warren
- NIHR Barts Cardiovascular Biomedical Research Unit, Queen Mary University of London, London, UK Department of Clinical Pharmacology, William Harvey Research Institute, Barts and The London School of Medicine, Queen Mary University of London, London, UK
| | - Michael R Barnes
- Centre for Translational Bioinformatics, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK NIHR Barts Cardiovascular Biomedical Research Unit, Queen Mary University of London, London, UK
| | - Richard Quinton
- Institute of Genetic Medicine University of Newcastle-upon-Tyne, Newcastle-upon-Tyne, UK
| | - Nicolas de Roux
- Unité Mixte de Recherche 1141, Institut National de la Santé et de la Recherche Médicale, Paris, France Université Paris Diderot, Sorbonne Paris Cité, Hôpital Robert Debré, Paris, France Laboratoire de Biochimie, Assistance Publique-Hôpitaux de Paris, Hôpital Robert Debré, Paris, France
| | - Jacques Young
- Univ Paris-Sud, Le Kremlin Bicêtre, France INSERM UMR-1185, Le Kremlin Bicêtre, France Assistance Publique-Hôpitaux de Paris, Bicêtre Hospital, Le Kremlin-Bicêtre, France Department of Reproductive Endocrinology, Bicêtre Hospital, Le Kremlin-Bicêtre, France
| | - Anne Guiochon-Mantel
- Univ Paris-Sud, Le Kremlin Bicêtre, France INSERM UMR-1185, Le Kremlin Bicêtre, France Assistance Publique-Hôpitaux de Paris, Bicêtre Hospital, Le Kremlin-Bicêtre, France
| | - Karoliina Wehkalampi
- Children's Hospital, Helsinki University Hospital and University of Helsinki, Helsinki, Finland
| | - Valentina André
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Milan, Italy
| | - Yoav Gothilf
- Department of Neurobiology, The George S. Wise Faculty of Life Sciences and Sagol School of Neuroscience, Tel-Aviv University, Tel Aviv, Israel
| | - Anna Cariboni
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Milan, Italy Institute of Ophthalmology, University College London (UCL), London, UK
| | - Leo Dunkel
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
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16
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Soga T, Lim WL, Khoo ASB, Parhar IS. Kisspeptin Activates Ankrd 26 Gene Expression in Migrating Embryonic GnRH Neurons. Front Endocrinol (Lausanne) 2016; 7:15. [PMID: 26973595 PMCID: PMC4771921 DOI: 10.3389/fendo.2016.00015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Accepted: 01/28/2016] [Indexed: 12/27/2022] Open
Abstract
Kisspeptin, a newly discovered neuropeptide, regulates gonadotropin-releasing hormone (GnRH). Kisspeptins are a large RF-amide family of peptides. The kisspeptin coded by KiSS-1 gene is a 145-amino acid protein that is cleaved to C-terminal peptide kisspeptin-10. G-protein-coupled receptor 54 (GPR54) has been identified as a kisspeptin receptor, and it is expressed in GnRH neurons and in a variety of cancer cells. In this study, enhanced green fluorescent protein (EGFP) labeled GnRH cells with migratory properties, which express GPR54, served as a model to study the effects of kisspeptin on cell migration. We monitored EGFP-GnRH neuronal migration in brain slide culture of embryonic day 14 transgenic rat by live cell imaging system and studied the effects of kisspeptin-10 (1 nM) treatment for 36 h on GnRH migration. Furthermore, to determine kisspeptin-induced molecular pathways related with apoptosis and cytoskeletal changes during neuronal migration, we studied the expression levels of candidate genes in laser-captured EGFP-GnRH neurons by real-time PCR. We found that there was no change in the expression level of genes related to cell proliferation and apoptosis. The expression of ankyrin repeat domain-containing protein (ankrd) 26 in EGFP-GnRH neurons was upregulated by the exposure to kisspeptin. These studies suggest that ankrd 26 gene plays an unidentified role in regulating neuronal movement mediated by kisspeptin-GPR54 signaling, which could be a potential pathway to suppress cell migration.
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Affiliation(s)
- Tomoko Soga
- Brain Research Institute, School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway, Malaysia
| | - Wei Ling Lim
- Brain Research Institute, School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway, Malaysia
| | - Alan Soo-Beng Khoo
- Molecular Pathology Unit, Cancer Research Centre, Institute for Medical Research, Kuala Lumpur, Malaysia
| | - Ishwar S. Parhar
- Brain Research Institute, School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway, Malaysia
- *Correspondence: Ishwar S. Parhar,
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Laissue P. Aetiological coding sequence variants in non-syndromic premature ovarian failure: From genetic linkage analysis to next generation sequencing. Mol Cell Endocrinol 2015; 411:243-57. [PMID: 25960166 DOI: 10.1016/j.mce.2015.05.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Revised: 04/14/2015] [Accepted: 05/04/2015] [Indexed: 01/19/2023]
Abstract
Premature ovarian failure (POF) is a frequent pathology affecting 1-1.5% of women under 40 years old. Despite advances in diagnosing and treating human infertility, POF is still classified as being idiopathic in 50-80% of cases, strongly suggesting a genetic origin for the disease. Different types of autosomal and X-linked genetic anomalies can originate the phenotype in syndromic and non-syndromic POF cases. Particular interest has been focused on research into non-syndromic POF causative coding variants during the past two decades. This has been based on the assumption that amino acid substitutions might modify the intrinsic physicochemical properties of functional proteins, thereby inducing pathological phenotypes. In this case, a restricted number of mutations might originate the disease. However, like other complex pathologies, POF might result from synergistic/compensatory effects caused by several low-to-mildly drastic mutations which have frequently been classified as non-functional SNPs. Indeed, reproductive phenotypes can be considered as quantitative traits resulting from the subtle interaction of many genes. Although numerous sequencing projects have involved candidate genes, only a few coding mutations explaining a low percentage of cases have been described. Such apparent failure to identify aetiological coding sequence variations might have been due to the inherent molecular complexity of mammalian reproduction and to the difficulty of simultaneously analysing large genomic regions by Sanger sequencing. The purpose of this review is to present the molecular and cellular effects caused by non-synonymous mutations which have been formally associated, by functional tests, with the aetiology of hypergonadotropic non-syndromic POF. Considerations have also been included regarding the polygenic nature of reproduction and POF, as well as future approaches for identifying novel aetiological genes based on next generation sequencing (NGS).
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Affiliation(s)
- Paul Laissue
- Unidad de Genética, Grupo GENIUROS, Escuela de Medicina y Ciencias de la Salud, Universidad del Rosario, Bogotá, Colombia.
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18
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Salian-Mehta S, Xu M, McKinsey TA, Tobet S, Wierman ME. Novel Interaction of Class IIb Histone Deacetylase 6 (HDAC6) with Class IIa HDAC9 Controls Gonadotropin Releasing Hormone (GnRH) Neuronal Cell Survival and Movement. J Biol Chem 2015; 290:14045-56. [PMID: 25873389 DOI: 10.1074/jbc.m115.640482] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Indexed: 12/19/2022] Open
Abstract
The impact of histone deacetylases (HDACs) in the control of gonadotropin releasing hormone (GnRH) neuronal development is unknown. We identified an increase in many HDACs in GT1-7 (differentiated) compared with NLT (undifferentiated) GnRH neuronal cell lines. Increased HDAC9 mRNA and protein and specific deacetylase activity in GT1-7 cells suggested a functional role. Introduction of HDAC9 in NLT cells protected from serum withdrawal induced apoptosis and impaired basal neuronal cell movement. Conversely, silencing of endogenous HDAC9 in GT1-7 cells increased apoptosis and cell movement. Comparison of WT and mutant HDAC9 constructs demonstrated that the HDAC9 pro-survival effects required combined cytoplasmic and nuclear localization, whereas the effects on cell movement required a cytoplasmic site of action. Co-immunoprecipitation demonstrated a novel interaction of HDAC9 selectively with the Class IIb HDAC6. HDAC6 was also up-regulated at the mRNA and protein levels, and HDAC6 catalytic activity was significantly increased in GT1-7 compared with NLT cells. HDAC9 interacted with HDAC6 through its second catalytic domain. Silencing of HDAC6, HDAC9, or both, in GT1-7 cells augmented apoptosis compared with controls. HDAC6 and -9 had additive effects to promote cell survival via modulating the BAX/BCL2 pathway. Silencing of HDAC6 resulted in an activation of movement of GT1-7 cells with induction in acetylation of α-tubulin. Inhibition of HDAC6 and HDAC9 together resulted in an additive effect to increase cell movement but did not alter the acetylation of αtubulin. Together, these studies identify a novel interaction of Class IIa HDAC9 with Class IIb HDAC6 to modulate cell movement and survival in GnRH neurons.
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Affiliation(s)
| | - Mei Xu
- From the Division of Endocrinology, Metabolism, and Diabetes and
| | - Timothy A McKinsey
- Division of Cardiology, University of Colorado School of Medicine, Aurora, Colorado 80045
| | - Stuart Tobet
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado 80523
| | - Margaret E Wierman
- From the Division of Endocrinology, Metabolism, and Diabetes and Research Service Veterans Affairs Medical Center, Denver, Colorado 80220, and
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Vastagh C, Schwirtlich M, Kwakowsky A, Erdélyi F, Margolis FL, Yanagawa Y, Katarova Z, Szabó G. The spatiotemporal segregation of GAD forms defines distinct GABA signaling functions in the developing mouse olfactory system and provides novel insights into the origin and migration of GnRH neurons. Dev Neurobiol 2014; 75:249-70. [PMID: 25125027 DOI: 10.1002/dneu.22222] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Revised: 07/18/2014] [Accepted: 08/06/2014] [Indexed: 01/26/2023]
Abstract
Gamma-aminobutyric acid (GABA) has a dual role as an inhibitory neurotransmitter in the adult central nervous system (CNS) and as a signaling molecule exerting largely excitatory actions during development. The rate-limiting step of GABA synthesis is catalyzed by two glutamic acid decarboxylase isoforms GAD65 and GAD67 coexpressed in the GABAergic neurons of the CNS. Here we report that the two GADs show virtually nonoverlapping expression patterns consistent with distinct roles in the developing peripheral olfactory system. GAD65 is expressed exclusively in undifferentiated neuronal progenitors confined to the proliferative zones of the sensory vomeronasal and olfactory epithelia In contrast GAD67 is expressed in a subregion of the nonsensory epithelium/vomeronasal organ epithelium containing the putative Gonadotropin-releasing hormone (GnRH) progenitors and GnRH neurons migrating from this region through the frontonasal mesenchyme into the basal forebrain. Only GAD67+, but not GAD65+ cells accumulate detectable GABA. We further demonstrate that GAD67 and its embryonic splice variant embryonic GAD (EGAD) concomitant with GnRH are dynamically regulated during GnRH neuronal migration in vivo and in two immortalized cell lines representing migratory (GN11) and postmigratory (GT1-7) stage GnRH neurons, respectively. Analysis of GAD65/67 single and double knock-out embryos revealed that the two GADs play complementary (inhibitory) roles in GnRH migration ultimately modulating the speed and/or direction of GnRH migration. Our results also suggest that GAD65 and GAD67/EGAD characterized by distinct subcellular localization and kinetics have disparate functions during olfactory system development mediating proliferative and migratory responses putatively through specific subcellular GABA pools.
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Affiliation(s)
- Csaba Vastagh
- Division of Medical Gene Technology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary; Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
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20
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Salian-Mehta S, Xu M, Pierce A, Bliesner B, Tobet S, Wierman ME. Loss of Growth arrest specific gene 6 (Gas6) results in altered GnRH neuron migration, delayed vaginal opening and sexual maturation in mice. Mol Cell Endocrinol 2014; 393:164-70. [PMID: 24978606 PMCID: PMC4130768 DOI: 10.1016/j.mce.2014.06.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2014] [Revised: 06/08/2014] [Accepted: 06/20/2014] [Indexed: 11/26/2022]
Abstract
Prior work has shown the importance of TAM (Tyro3, Axl, Mer) receptor tyrosine kinases in GnRH neuronal development and reproductive function. It is unclear if TAM receptor actions are dependent on ligand activation for their functional effects; thus, we characterized reproductive phenotype of ligand Growth arrest specific gene (Gas6) null mice. Gas6 null mice showed delayed vaginal opening and delayed first estrus. Animals eventually attained normal estrous cycles as adults. The GnRH neuronal population was significantly decreased in Gas6 null adults and embryos, but the final positioning of cell bodies in the hypothalamus was normal. Vaginal tissue showed up-regulation of TAM receptor mRNAs in the absence of the ligand. These data confirm that Gas6 plays a role in early GnRH neuronal development and during vaginal opening. The phenotype of Gas6 KO mice suggests that TAMs function in a ligand-dependent and independent manner to control GnRH neuron development to modulate normal reproductive function.
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Affiliation(s)
- Smita Salian-Mehta
- Departments of Medicine, University of Colorado, School of Medicine, Aurora, CO 80045, USA
| | - Mei Xu
- Departments of Medicine, University of Colorado, School of Medicine, Aurora, CO 80045, USA
| | - Angela Pierce
- Departments of Medicine, University of Colorado, School of Medicine, Aurora, CO 80045, USA
| | - Brian Bliesner
- Departments of Medicine, University of Colorado, School of Medicine, Aurora, CO 80045, USA
| | - Stuart Tobet
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Margaret E Wierman
- Departments of Medicine, University of Colorado, School of Medicine, Aurora, CO 80045, USA; Research Service VAMC, Denver, CO 80220, USA.
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Salian-Mehta S, Xu M, Knox AJ, Plummer L, Slavov D, Taylor M, Bevers S, Hodges RS, Crowley WF, Wierman ME. Functional consequences of AXL sequence variants in hypogonadotropic hypogonadism. J Clin Endocrinol Metab 2014; 99:1452-60. [PMID: 24476074 PMCID: PMC3973777 DOI: 10.1210/jc.2013-3426] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Prior studies showed that Axl /Tyro3 null mice have delayed first estrus and abnormal cyclicity due to developmental defects in GnRH neuron migration and survival. OBJECTIVE The objective of the study was to test whether the absence of Axl would alter reproductive function in mice and that mutations in AXL are present in patients with Kallmann syndrome (KS) or normosmic idiopathic hypogonadotropic hypogonadism (nIHH). DESIGN AND SETTING The sexual maturation of Axl null mice was examined. The coding region of AXL was sequenced in 104 unrelated, carefully phenotyped KS or nIHH subjects. Frequency of mutations was compared with other causes of GnRH deficiency. Functional assays were performed on the detected mutations. RESULTS Axl null mice demonstrated delay in first estrus and the interval between vaginal opening and first estrus. Three missense AXL mutations (p.L50F, p.S202C, and p.Q361P) and one intronic variant 6 bp upstream from the start of exon 5 (c.586-6 C>T) were identified in two KS and 2 two nIHH subjects. Comparison of the frequencies of AXL mutations with other putative causes of idiopathic hypogonadotropic hypogonadism confirmed they are rare variants. Testing of the c.586-6 C>T mutation revealed no abnormal splicing. Surface plasmon resonance analysis of the p.L50F, p.S202C, and p.Q361P mutations showed no altered Gas6 ligand binding. In contrast, GT1-7 GnRH neuronal cells expressing p.S202C or p.Q361P demonstrated defective ligand dependent receptor processing and importantly aberrant neuronal migration. In addition, the p.Q361P showed defective ligand independent chemotaxis. CONCLUSIONS Functional consequences of AXL sequence variants in patients with idiopathic hypogonadotropic hypogonadism support the importance of AXL and the Tyro3, Axl, Mer (TAM) family in reproductive development.
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Affiliation(s)
- S Salian-Mehta
- Division of Endocrinology, Metabolism, and Diabetes (S.S.-M., M.X., A.J.K., M.E.W.), Division of Cardiology (D.S., M.T.), and Department of Biochemistry and Molecular Genetics (S.B., R.S.H.), University of Colorado School of Medicine, Aurora, Colorado 80045; Veterans Affairs Research Service (M.E.W.), Veterans Affairs Medical Center, Denver, Colorado 80220; and Harvard Reproductive Endocrine Science Center and the Reproductive Endocrine Unit (L.P., W.F.C.), Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114
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22
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Lim WL, Soga T, Parhar IS. Maternal Dexamethasone Exposure Inhibits the Gonadotropin-Releasing Hormone Neuronal Movement in the Preoptic Area of Rat Offspring. Dev Neurosci 2014; 36:95-107. [DOI: 10.1159/000360416] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 02/06/2014] [Indexed: 11/19/2022] Open
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Layman LC. The genetic basis of female reproductive disorders: etiology and clinical testing. Mol Cell Endocrinol 2013; 370:138-48. [PMID: 23499866 PMCID: PMC3767392 DOI: 10.1016/j.mce.2013.02.016] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Accepted: 02/21/2013] [Indexed: 01/02/2023]
Abstract
With the advent of improved molecular biology techniques, the genetic basis of an increasing number of reproductive disorders has been elucidated. Mutations in at least 20 genes cause hypogonadotropic hypogonadism including Kallmann syndrome in about 35-40% of patients. The two most commonly involved genes are FGFR1 and CHD7. When combined pituitary hormone deficiency includes hypogonadotropic hypogonadism as a feature, PROP1 mutations are the most common of the six genes involved. For hypergonadotropic hypogonadism, mutations in 14 genes cause gonadal failure in 15% of affected females, most commonly in FMR1. In eugonadal disorders, activating FSHR mutations have been identified for spontaneous ovarian hyperstimulation syndrome; and WNT4 mutations have been described in mullerian aplasia. For other eugonadal disorders, such as endometriosis, polycystic ovary syndrome, and leiomyomata, specific germline gene mutations have not been identified, but some chromosomal regions are associated with the corresponding phenotype. Practical genetic testing is possible to perform in both hypogonadotropic and hypergonadotropic hypogonadism and spontaneous ovarian hyperstimulation syndrome. However, clinical testing for endometriosis, polycystic ovary syndrome, and leiomyomata is not currently practical for the clinician.
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Affiliation(s)
- Lawrence C Layman
- Section of Reproductive Endocrinology, Infertility, & Genetics, Department of Obstetrics & Gynecology, Institute of Molecular Medicine and Genetics, Neuroscience Program, Medical College of Georgia, Georgia Regents University, Augusta, GA 30912, USA.
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Stevenson EL, Corella KM, Chung WCJ. Ontogenesis of gonadotropin-releasing hormone neurons: a model for hypothalamic neuroendocrine cell development. Front Endocrinol (Lausanne) 2013; 4:89. [PMID: 23882261 PMCID: PMC3712253 DOI: 10.3389/fendo.2013.00089] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 07/02/2013] [Indexed: 02/02/2023] Open
Abstract
The vertebrate hypothalamo-pituitary-gonadal axis is the anatomical framework responsible for reproductive competence and species propagation. Essential to the coordinated actions of this three-tiered biological system is the fact that the regulatory inputs ultimately converge on the gonadotropin-releasing hormone (GnRH) neuronal system, which in rodents primarily resides in the preoptic/hypothalamic region. In this short review we will focus on: (1) the general embryonic temporal and spatial development of the rodent GnRH neuronal system, (2) the origin(s) of GnRH neurons, and (3) which transcription - and growth factors have been found to be critical for GnRH neuronal ontogenesis and cellular fate-specification. Moreover, we ask the question whether the molecular and cellular mechanisms involved in GnRH neuronal development may also play a role in the development of other hypophyseal secreting neuroendocrine cells in the hypothalamus.
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Affiliation(s)
- Erica L. Stevenson
- Department of Biological Sciences, School of Biomedical Sciences, Kent State University, Kent, OH, USA
| | - Kristina M. Corella
- Department of Biological Sciences, School of Biomedical Sciences, Kent State University, Kent, OH, USA
| | - Wilson C. J. Chung
- Department of Biological Sciences, School of Biomedical Sciences, Kent State University, Kent, OH, USA
- *Correspondence: Wilson C. J. Chung, Department of Biological Sciences, School of Biomedical Sciences, Kent State University, 222 Cunningham Hall, Kent, OH 44242, USA e-mail:
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Di Giorgio NP, Catalano PN, López PV, González B, Semaan SJ, López GC, Kauffman AS, Rulli SB, Somoza GM, Bettler B, Libertun C, Lux-Lantos VA. Lack of functional GABAB receptors alters Kiss1 , Gnrh1 and Gad1 mRNA expression in the medial basal hypothalamus at postnatal day 4. Neuroendocrinology 2013; 98:212-23. [PMID: 24080944 PMCID: PMC3915412 DOI: 10.1159/000355631] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Accepted: 09/10/2013] [Indexed: 01/01/2023]
Abstract
BACKGROUND/AIMS Adult mice lacking functional GABAB receptors (GABAB1KO) show altered Gnrh1 and Gad1 expressions in the preoptic area-anterior hypothalamus (POA-AH) and females display disruption of cyclicity and fertility. Here we addressed whether sexual differentiation of the brain and the proper wiring of the GnRH and kisspeptin systems were already disturbed in postnatal day 4 (PND4) GABAB1KO mice. METHODS PND4 wild-type (WT) and GABAB1KO mice of both sexes were sacrificed; tissues were collected to determine mRNA expression (qPCR), amino acids (HPLC), and hormones (RIA and/or IHC). RESULTS GnRH neuron number (IHC) did not differ among groups in olfactory bulbs or OVLT-POA. Gnrh1 mRNA (qPCR) in POA-AH was similar among groups. Gnrh1 mRNA in medial basal hypothalamus (MBH) was similar in WTs but was increased in GABAB1KO females compared to GABAB1KO males. Hypothalamic GnRH (RIA) was sexually different in WTs (males > females), but this sex difference was lost in GABAB1KOs; the same pattern was observed when analyzing only the MBH, but not in the POA-AH. Arcuate nucleus Kiss1 mRNA (micropunch-qPCR) was higher in WT females than in WT males and GABAB1KO females. Gad1 mRNA in MBH was increased in GABAB1KO females compared to GABAB1KO males. Serum LH and gonadal estradiol content were also increased in GABAB1KOs. CONCLUSION We demonstrate that GABABRs participate in the sexual differentiation of the ARC/MBH, because sex differences in several reproductive genes, such as Gad1, Kiss1 and Gnrh1, are critically disturbed in GABAB1KO mice at PND4, probably altering the organization and development of neural circuits governing the reproductive axis.
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MESH Headings
- Animals
- Animals, Newborn
- Arcuate Nucleus of Hypothalamus/growth & development
- Arcuate Nucleus of Hypothalamus/metabolism
- Female
- Gene Expression Regulation, Developmental
- Glutamate Decarboxylase/deficiency
- Glutamate Decarboxylase/genetics
- Gonadotropin-Releasing Hormone/deficiency
- Gonadotropin-Releasing Hormone/genetics
- Hypothalamus, Middle/growth & development
- Hypothalamus, Middle/metabolism
- Kisspeptins/deficiency
- Kisspeptins/genetics
- Male
- Mice
- Mice, Inbred BALB C
- Mice, Knockout
- Protein Precursors/deficiency
- Protein Precursors/genetics
- RNA, Messenger/biosynthesis
- RNA, Messenger/genetics
- Receptors, GABA-B/deficiency
- Receptors, GABA-B/genetics
- Sex Differentiation/genetics
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Affiliation(s)
- Noelia P Di Giorgio
- Laboratorio de Neuroendocrinología, Instituto de Biología y Medicina Experimental (IBYME-CONICET), Buenos Aires, Argentina
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Rochester JR, Chung WCJ, Hayes TB, Tsai PS. Opposite-sex housing reactivates the declining GnRH system in aged transgenic male mice with FGF signaling deficiency. Am J Physiol Endocrinol Metab 2012; 303:E1428-39. [PMID: 23047985 PMCID: PMC3532464 DOI: 10.1152/ajpendo.00289.2012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The continued presence of gonadotropin-releasing hormone (GnRH) neurons is required for a healthy reproductive lifespan, but factors that maintain postnatal GnRH neurons have not been identified. To begin to understand these factors, we investigated whether 1) fibroblast growth factor (FGF) signaling and 2) interactions with the opposite sex are involved in the maintenance of the postnatal GnRH system. A transgenic mouse model (dnFGFR mouse) with the targeted expression of a dominant-negative FGF receptor (dnFGFR) in GnRH neurons was used to examine the consequence of FGF signaling deficiency on postnatal GnRH neurons. Male dnFGFR mice suffered a significant loss of postnatal GnRH neurons within the first 100 days of life. Interestingly, this loss was reversed after cohabitation with female, but not male, mice for 300-550 days. Along with a rescue in GnRH neuron numbers, opposite-sex housing in dnFGFR males also increased hypothalamic GnRH peptide levels, promoted a more mature GnRH neuronal morphology, facilitated litter production, and enhanced testicular morphology. Last, mice hypomorphic for FGFR3 exhibited a similar pattern of postnatal GnRH neuronal loss as dnFGFR males, suggesting FGF signaling acts, in part, through FGFR3 to enhance the maintenance of the postnatal GnRH system. In summary, we have shown that FGF signaling is required for the continued presence of postnatal GnRH neurons. However, this requirement is not absolute, since sexual interactions can compensate for defects in FGFR signaling, thereby rescuing the declining GnRH system. This suggests the postnatal GnRH system is highly plastic and capable of responding to environmental stimuli throughout adult life.
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Affiliation(s)
- Johanna R Rochester
- Department of Integrative Physiology, University of Colorado, Boulder, CO 80309, USA.
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27
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Siegel ET, Kim HG, Nishimoto HK, Layman LC. The molecular basis of impaired follicle-stimulating hormone action: evidence from human mutations and mouse models. Reprod Sci 2012. [PMID: 23184658 DOI: 10.1177/1933719112461184] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The pituitary gonadotropin follicle-stimulating hormone (FSH) interacts with its membrane-bound receptor to produce biologic effects. Traditional functions of FSH include follicular development and estradiol production in females, and the regulation of Sertoli cell action and spermatogenesis in males. Knockout mice for both the ligand (Fshb) and the receptor (Fshr) serve as models for FSH deficiency, while Fshb and Fshr transgenic mice manifest FSH excess. In addition, inactivating mutations of both human orthologs (FSHB and FSHR) have been characterized in a small number of patients, with phenotypic effects of the ligand disruption being more profound than those of its receptor. Activating human FSHR mutants have also been described in both sexes, leading to a phenotype of normal testis function (male) or spontaneous ovarian hyperstimulation syndrome (females). As determined from human and mouse models, FSH is essential for normal puberty and fertility in females, particularly for ovarian follicular development beyond the antral stage. In males, FSH is necessary for normal spermatogenesis, but there are differences in human and mouse models. The FSHB mutations in humans result in azoospermia; while FSHR mutations in humans and knockouts of both the ligand and the receptor in mice affect testicular function but do not result in absolute infertility. Available evidence also indicates that FSH may also be necessary for normal androgen synthesis in males and females.
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Affiliation(s)
- Eric T Siegel
- Department of Obstetrics & Gynecology, Section of Reproductive Endocrinology, Infertility, & Genetics, Medical College of Georgia, Georgia Health Sciences University Augusta, GA 30912, USA
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Low VF, Fiorini Z, Fisher L, Jasoni CL. Netrin-1 stimulates developing GnRH neurons to extend neurites to the median eminence in a calcium- dependent manner. PLoS One 2012; 7:e46999. [PMID: 23056554 PMCID: PMC3467286 DOI: 10.1371/journal.pone.0046999] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Accepted: 09/11/2012] [Indexed: 11/23/2022] Open
Abstract
Hypothalamic gonadotropin-releasing hormone (GnRH) neurons are required for fertility in all mammalian species studied to date. In rodents, GnRH neuron cell bodies reside in the rostral hypothalamus, and most extend a single long neuronal process in the caudal direction to terminate at the median eminence (ME), the site of hormone secretion. The molecular cues that GnRH neurites use to grow and navigate to the ME during development, however, remain poorly described. Reverse transcription-PCR (RT-PCR) identified mRNAs encoding Netrin-1, and its receptor, DCC, in the fetal preoptic area (POA) and mediobasal hypothalamus (MBH), respectively, from gestational day 12.5 (GD12.5), a time when the first GnRH neurites extend toward the MBH. Moreover, a subpopulation of GnRH neurons from GD14.5 through GD18.5 express the Netrin-1 receptor, DCC, suggesting a role for Netrin-1/DCC signaling in GnRH neurite growth and/or guidance. In support of this notion, when GD15.5 POA explants, containing GnRH neurons actively extending neurites, were grown in three-dimensional collagen gels and challenged with exogenous Netrin-1 (100 ng/ml or 400 ng/ml) GnRH neurite growth was stimulated. In addition, Netrin-1 provided from a fixed source was able to stimulate outgrowth, although it did not appear to chemoattract GnRH neurites. Finally, the effects of Netrin-1 on the outgrowth of GnRH neurites could be inhibited by blocking either L-type voltage-gated calcium channels (VGCCs) with nifedipine (10 µM), or ryanodine receptors with ryanodine (10 µM). This is consistent with the role of Ca2+ from extra- and intracellular sources in Netrin-1/DCC-dependent growth cone motility in other neurons. These results indicate that Netrin-1 directly stimulates the growth of a subpopulation of GnRH neurites that express DCC, provide further understanding of the mechanisms by which GnRH nerve terminals arrive at their site of hormone secretion, and identify an additional neuronal population whose neurites utilize Netrin-1/DCC signaling for their development.
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Affiliation(s)
- Victoria F. Low
- Centre for Neuroendocrinology, Department of Anatomy, University of Otago, School of Medical Sciences, Dunedin, New Zealand
| | - Zeno Fiorini
- Centre for Neuroendocrinology, Department of Anatomy, University of Otago, School of Medical Sciences, Dunedin, New Zealand
| | - Lorryn Fisher
- Centre for Neuroendocrinology, Department of Anatomy, University of Otago, School of Medical Sciences, Dunedin, New Zealand
| | - Christine L. Jasoni
- Centre for Neuroendocrinology, Department of Anatomy, University of Otago, School of Medical Sciences, Dunedin, New Zealand
- * E-mail:
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Turning sex inside-out: Peripheral contributions to sexual differentiation of the central nervous system. Biol Sex Differ 2012; 3:12. [PMID: 22640590 PMCID: PMC3464926 DOI: 10.1186/2042-6410-3-12] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Accepted: 05/28/2012] [Indexed: 02/04/2023] Open
Abstract
Sexual differentiation of the nervous system occurs via the interplay of genetics, endocrinology and social experience through development. Much of the research into mechanisms of sexual differentiation has been driven by an implicit theoretical framework in which these causal factors act primarily and directly on sexually dimorphic neural populations within the central nervous system. This review will examine an alternative explanation by describing what is known about the role of peripheral structures and mechanisms (both neural and non-neural) in producing sex differences in the central nervous system. The focus of the review will be on experimental evidence obtained from studies of androgenic masculinization of the spinal nucleus of the bulbocavernosus, but other systems will also be considered.
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Soga T, Dalpatadu SL, Wong DW, Parhar IS. Neonatal dexamethasone exposure down-regulates GnRH expression through the GnIH pathway in female mice. Neuroscience 2012; 218:56-64. [PMID: 22626647 DOI: 10.1016/j.neuroscience.2012.05.023] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Revised: 04/12/2012] [Accepted: 05/09/2012] [Indexed: 10/28/2022]
Abstract
Synthetic glucocorticoid (dexamethasone; DEX) treatment during the neonatal stage is known to affect reproductive activity. However, it is still unknown whether neonatal stress activates gonadotropin-inhibitory hormone (GnIH) synthesizing cells in the dorsomedial hypothalamus (DMH), which could have pronounced suppressive action on gonadotropin-releasing hormone (GnRH) neurons, leading to delayed pubertal onset. This study was designed to determine the effect of neonatal DEX (1.0mg/kg) exposure on reproductive maturation. Therefore, GnRH, GnIH and GnIH receptors, G-protein coupled receptors (GPR) 147 and GPR74 mRNA levels were measured using quantitative real-time PCR in female mice at postnatal (P) days 21, 30 and in estrus stage mice, aged between P45-50. DEX-treated females of P45-50 had delayed vaginal opening, and irregular estrus cycles and lower GnRH expression in the preoptic area (POA) when compared with age-matched controls. The expression levels of GPR147 and GPR74 mRNA in the POA increased significantly in DEX-treated female mice of P21 and P45-50 compared to controls. In addition, GPR147 and GPR74 mRNA expression was observed in laser captured single GnRH neurons in the POA. Although there was no difference in GnIH mRNA expression in the DMH, immunostained GnIH cell numbers in the DMH increased in DEX-treated females of P45-50 compared to controls. Taken together, the results show that the delayed pubertal onset could be due to the inhibition of GnRH gene expression after neonatal DEX treatment, which may be accounted for in part by the inhibitory signals from the up-regulated GnIH-GnIH receptor pathway to the POA.
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Affiliation(s)
- T Soga
- Brain Research Institute, School of Medicine and Health Sciences, Monash University Sunway Campus, 46150, Malaysia.
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31
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Oboti L, Peretto P, Marchis SD, Fasolo A. From chemical neuroanatomy to an understanding of the olfactory system. Eur J Histochem 2011; 55:e35. [PMID: 22297441 PMCID: PMC3284237 DOI: 10.4081/ejh.2011.e35] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Accepted: 09/20/2011] [Indexed: 02/04/2023] Open
Abstract
The olfactory system is the appropriate model for studying several aspects of neuronal physiology spanning from the developmental stage to neural network remodelling in the adult brain. Both the morphological and physiological understanding of this system were strongly supported by classical histochemistry. It is emblematic the case of the Olfactory Marker Protein (OMP) staining, the first, powerful marker for fully differentiated olfactory receptor neurons and a key tool to investigate the dynamic relations between peripheral sensory epithelia and central relay regions given its presence within olfactory fibers reaching the olfactory bulb (OB). Similarly, the use of thymidine analogues was able to show neurogenesis in an adult mammalian brain far before modern virus labelling and lipophilic tracers based methods. Nowadays, a wealth of new histochemical techniques combining cell and molecular biology approaches is available, giving stance to move from the analysis of the chemically identified circuitries to functional research. The study of adult neurogenesis is indeed one of the best explanatory examples of this statement. After defining the cell types involved and the basic physiology of this phenomenon in the OB plasticity, we can now analyze the role of neurogenesis in well testable behaviours related to socio-chemical communication in rodents.
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Affiliation(s)
- L Oboti
- Department of Animal and Human Biology, University of Turin, Italy
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32
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Regulation of temporal and spatial organization of newborn GnRH neurons by IGF signaling in zebrafish. J Neurosci 2011; 31:11814-24. [PMID: 21849542 DOI: 10.1523/jneurosci.6804-10.2011] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
When and how newborn neurons are organized to form a functional network in the developing brain remains poorly understood. An attractive model is the gonadotropin-releasing hormone (GnRH) neuron system, master regulator of the reproductive axis. Here we show that blockage of IGF signaling, a central growth-promoting signaling pathway, by the induced expression of a dominant-negative form of IGF1 receptor (IGF1R) or specific IGF1R inhibitors delayed the emergence of GnRH2 neurons in the midbrain and GnRH3 neurons in the olfactory bulb region. Blockage of IGF signaling also resulted in an abnormal appearance of GnRH3 neurons outside of the olfactory bulb region, although it did not change the locations of other olfactory neurons, GnRH2 neurons, or brain patterning. This IGF action is developmental stage-dependent because the blockade of IGF signaling in advanced embryos had no such effect. An application of phosphatidylinositol 3-kinase (PI3K) inhibitors phenocopied the IGF signaling deficient embryos, whereas the MAPK inhibitors had no effect, suggesting that this IGF action is mediated through the PI3K pathway. Real-time in vivo imaging studies revealed that the ectopic GnRH3 neurons emerged at the same time as the normal GnRH3 neurons in IGF-deficient embryos. Further experiments suggest that IGF signaling affects the spatial distribution of newborn GnRH3 neurons by influencing neural crest cell migration and/or differentiation. These results suggest that the IGF-IGF1R-PI3K pathway regulates the precise temporal and spatial organization of GnRH neurons in zebrafish and provides new insights into the regulation of GnRH neuron development.
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Abstract
Gonadotrophin-releasing hormone (GnRH)-secreting neurones are the final output of the central nervous system driving fertility in all mammals. Although it has been known for decades that the efficiency of communication between the hypothalamus and the pituitary depends on the pulsatile profile of GnRH secretion, how GnRH neuronal activity is patterned to generate pulses at the median eminence is unknown. To date, the scattered distribution of the GnRH cell bodies remains the main limitation to assessing the cellular events that could lead to pulsatile GnRH secretion. Taking advantage of the unique developmental feature of GnRH neurones, the nasal explant model allows primary GnRH neurones to be maintained within a micro-network where pulsatile secretion is preserved and where individual cellular activity can be monitored simultaneously across the cell population. This review summarises the data obtained from work using this in vitro model, and brings some insights into GnRH cellular physiology.
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Affiliation(s)
- S Constantin
- Department of Physiology, Centre for Neuroendocrinology, University of Otago, Dunedin, New Zealand.
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Bhattarai JP, Park SA, Park JB, Lee SY, Herbison AE, Ryu PD, Han SK. Tonic extrasynaptic GABA(A) receptor currents control gonadotropin-releasing hormone neuron excitability in the mouse. Endocrinology 2011; 152:1551-61. [PMID: 21285326 DOI: 10.1210/en.2010-1191] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
It is well established that the GABA(A) receptor plays an important role in regulating the electrical excitability of GnRH neurons. Two different modes of GABA(A) receptor signaling exist: one mediated by synaptic receptors generating fast (phasic) postsynaptic currents and the other mediated by extrasynaptic receptors generating a persistent (tonic) current. Using GABA(A) receptor antagonists picrotoxin, bicuculline methiodide, and gabazine, which differentiate between phasic and tonic signaling, we found that ∼50% of GnRH neurons exhibit an approximately 15-pA tonic GABA(A) receptor current in the acute brain slice preparation. The blockade of either neuronal (NO711) or glial (SNAP-5114) GABA transporter activity within the brain slice revealed the presence of tonic GABA signaling in ∼90% of GnRH neurons. The GABA(A) receptor δ subunit is only found in extrasynaptic GABA(A) receptors. Using single-cell RT-PCR, GABA(A) receptor δ subunit mRNA was identified in GnRH neurons and the δ subunit-specific agonist 4,5,6,7-tetrahydroisoxazolo [5,4-c] pyridin-3-ol was found to activate inward currents in GnRH neurons. Perforated-patch clamp studies showed that 4,5,6,7-tetrahydroisoxazolo [5,4-c] pyridin-3-ol exerted the same depolarizing or hyperpolarizing effects as GABA on juvenile and adult GnRH neurons and that tonic GABA(A) receptor signaling regulates resting membrane potential. Together, these studies reveal the presence of a tonic GABA(A) receptor current in GnRH neurons that controls their excitability. The level of tonic current is dependent, in part, on neuronal and glial GABA transporter activity and mediated by extrasynaptic δ subunit-containing GABA(A) receptors.
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Affiliation(s)
- Janardhan P Bhattarai
- Department of Oral Physiology and Institute of Oral Bioscience, School of Dentistry, Chonbuk National University, Jeonju, 561-756, Korea
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Diaczok D, DiVall S, Matsuo I, Wondisford FE, Wolfe AM, Radovick S. Deletion of Otx2 in GnRH neurons results in a mouse model of hypogonadotropic hypogonadism. Mol Endocrinol 2011; 25:833-46. [PMID: 21436260 DOI: 10.1210/me.2010-0271] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
GnRH is the central regulator of reproductive function responding to central nervous system cues to control gonadotropin synthesis and secretion. GnRH neurons originate in the olfactory placode and migrate to the forebrain, in which they are found in a scattered distribution. Congenital idiopathic hypogonadotropic hypogonadism (CIHH) has been associated with mutations or deletions in a number of genes that participate in the development of GnRH neurons and expression of GnRH. Despite the critical role of GnRH in mammalian reproduction, a comprehensive understanding of the developmental factors that are responsible for regulating the establishment of mature GnRH neurons and the expression of GnRH is lacking. orthodenticle homeobox 2 (OTX2), a homeodomain protein required for the formation of the forebrain, has been shown to be expressed in GnRH neurons, up-regulated during GnRH neuronal development, and responsible for increased GnRH promoter activity in GnRH neuronal cell lines. Interestingly, mutations in Otx2 have been associated with human hypogonadotropic hypogonadism, but the mechanism by which Otx2 mutations cause CIHH is unknown. Here we show that deletion of Otx2 in GnRH neurons results in a significant decrease in GnRH neurons in the hypothalamus, a delay in pubertal onset, abnormal estrous cyclicity, and infertility. Taken together, these data provide in vivo evidence that Otx2 is critical for GnRH expression and reproductive competence.
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Affiliation(s)
- Daniel Diaczok
- Division of Pediatric Endocrinology, The Johns Hopkins University School of Medicine, 600 North Wolfe Street, Baltimore, Maryland 21287, USA
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Abstract
Gonadotropin-releasing hormone-1 (GnRH-1) neurons migrate from the nasal placode to the forebrain where they control gonadal function via the hypothalamic-pituitary-gonadal axis. The birth of GnRH-1-expressing neurons is one of the first neurogenic events in the developing nasal placode. By gene expression screening on single GnRH-1 neurons, amyloid precursor binding protein-1 (FE65) was identified in migratory GnRH-1 neurons. FE65 has been shown to modulate β1-integrin dynamics, actin cytoskeleton, cell motility, and FE65/amyloid precursor protein signaling has been described in neuro/glial cell fate determination as well as in modulating neurogenesis. Analysis of two mouse lines, one deficient for the 97 kDa FE65 isoform and a second deficient for the 97 and 60 kDa forms of FE65, showed overlapping phenotypes. In both lines, no migratory defects of the GnRH-1 neurons were observed, but a 25% increase in GnRH-1 neuronal number during embryonic development was found. Bromodeoxyuridine birth tracing and spatiotemporal tracking of GnRH-1 cell precursors demonstrated that the lack of the N-terminal portion of FE65, which includes part of the functional nuclear translocation/gene transcription domain of FE65 (WW domain), extends the timing of GnRH-1 neurogenesis in the developing nasal placode without affecting proliferation of GnRH-1 neuronal progenitors or cell death. The observed changes in the dynamics of GnRH-1 neurogenesis highlight a unique role for the 97 kDa isoform of FE65 and suggest that GnRH-1 cells, which have a short neurogenic window, originate from multipotent progenitors able to generate distinct cell types as GnRH-1 neurogenesis declines in response to environmental changes.
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Xu N, Kim HG, Bhagavath B, Cho SG, Lee JH, Ha K, Meliciani I, Wenzel W, Podolsky RH, Chorich LP, Stackhouse KA, Grove AMH, Odom LN, Ozata M, Bick DP, Sherins RJ, Kim SH, Cameron RS, Layman LC. Nasal embryonic LHRH factor (NELF) mutations in patients with normosmic hypogonadotropic hypogonadism and Kallmann syndrome. Fertil Steril 2011; 95:1613-20.e1-7. [PMID: 21300340 DOI: 10.1016/j.fertnstert.2011.01.010] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2010] [Revised: 12/28/2010] [Accepted: 01/03/2011] [Indexed: 01/09/2023]
Abstract
OBJECTIVE To determine if mutations in NELF, a gene isolated from migratory GnRH neurons, cause normosmic idiopathic hypogonadotropic hypogonadism (IHH) and Kallmann syndrome (KS). DESIGN Molecular analysis correlated with phenotype. SETTING Academic medical center. PATIENT(S) A total of 168 IHH/KS patients as well as unrelated control subjects were studied for NELF mutations. INTERVENTION(S) NELF coding regions/splice junctions were subjected to polymerase chain reaction (PCR)-based DNA sequencing. Eleven additional IHH/KS genes were sequenced in three patients with NELF mutations. MAIN OUTCOME MEASURE(S) Mutations were confirmed by sorting intolerant from tolerant, reverse-transcription (RT)-PCR, and Western blot analysis. RESULT(S) Three novel NELF mutations absent in 372 ethnically matched control subjects were identified in 3/168 (1.8%) IHH/KS patients. One IHH patient had compound heterozygous NELF mutations (c.629-21G>C and c.629-23C>G), and he did not have mutations in 11 other known IHH/KS genes. Two unrelated KS patients had heterozygous NELF mutations and mutation in a second gene: NELF/KAL1 (c.757G>A; p.Ala253Thr of NELF and c.488_490delGTT; p.Cys163del of KAL1) and NELF/TACR3 (c.1160-13C>T of NELF and c.824G>A; p.Trp275X of TACR3). In vitro evidence of these NELF mutations included reduced protein expression and splicing defects. CONCLUSION(S) Our findings suggest that NELF is associated with normosmic IHH and KS, either singly or in combination with a mutation in another gene.
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Affiliation(s)
- Ning Xu
- Section of Reproductive Endocrinology, Infertility, and Genetics, Department of Obstetrics and Gynecology, Medical College of Georgia, Augusta, Georgia 30912, USA
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Zaninetti R, Fornarelli A, Ciarletta M, Lim D, Caldarelli A, Pirali T, Cariboni A, Owsianik G, Nilius B, Canonico PL, Distasi C, Genazzani AA. Activation of TRPV4 channels reduces migration of immortalized neuroendocrine cells. J Neurochem 2011; 116:606-15. [PMID: 21166676 DOI: 10.1111/j.1471-4159.2010.07144.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Calcium is a universal signal, and its capacity to encode intracellular messages via spatial, temporal and amplitude characteristics allows it to participate in most cellular events. In a specific context, calcium plays a pivotal role in migration, although its role has not been elucidated fully. By using immortalized gonadotropin-releasing hormone-secreting neurons (GN11), we have now investigated the role of TRPV4, a member of the vanilloid family of Ca(2+) channels, in neuronal migration. Our results show that TRPV4 channels are present and functional in GN11 cells and their localization is polarized and enriched in lamellipodial structures. TRPV4 activation leads to a retraction of the lamellipodia and to a decrease in migratory behaviour; moreover cells migrate slower and in a more random manner. We therefore provide evidence for a new regulation of gonadotropin-releasing hormone neurons and a new role for calcium at the leading edge of migratory cells.
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Affiliation(s)
- Roberta Zaninetti
- Dipartimento di Scienze Chimiche, Alimentari, Farmaceutiche e Farmacologiche, Università degli Studi del Piemonte Orientale A. Avogadro, Novara, Italy
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Wierman ME, Kiseljak-Vassiliades K, Tobet S. Gonadotropin-releasing hormone (GnRH) neuron migration: initiation, maintenance and cessation as critical steps to ensure normal reproductive function. Front Neuroendocrinol 2011; 32:43-52. [PMID: 20650288 PMCID: PMC3008544 DOI: 10.1016/j.yfrne.2010.07.005] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Revised: 07/08/2010] [Accepted: 07/14/2010] [Indexed: 12/23/2022]
Abstract
GnRH neurons follow a carefully orchestrated journey from their birth in the olfactory placode area. Initially, they migrate along with the vomeronasal nerve into the brain at the cribriform plate, then progress caudally to sites within the hypothalamus where they halt and send projections to the median eminence to activate pituitary gonadotropes. Many factors controlling this precise journey have been elucidated by the silencing or over-expression of candidate genes in mouse models. Importantly, a number of these factors may not only play a role in normal physiology of the hypothalamic-pituitary-gonadal axis but also be mis-expressed to cause human disorders of GnRH deficiency, presenting as a failure to undergo normal pubertal development. This review outlines the current cadre of candidates thought to modulate GnRH neuronal migration. The further elucidation and characterization of these factors that impact GnRH neuron development may shed new light on human reproductive disorders and provide potential targets to develop new pro-fertility or contraceptive agents.
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Affiliation(s)
- Margaret E Wierman
- Department of Medicine, University of Colorado-Denver, Aurora, CO 80045, USA
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Fiorini Z, Jasoni CL. A novel developmental role for kisspeptin in the growth of gonadotrophin-releasing hormone neurites to the median eminence in the mouse. J Neuroendocrinol 2010; 22:1113-25. [PMID: 20722977 DOI: 10.1111/j.1365-2826.2010.02059.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The puberty- and fertility-regulating neuropeptide kisspeptin (KISS1) exerts dramatic effects on the physiology of adult gonadotrophin-releasing hormone (GnRH) neurones as a master regulator of mammalian reproduction. Given the action of KISS1 directly on adult GnRH neurones, and that KISS1 activates a signal transduction cascade involved in neurite growth in other neurones, we investigated whether KISS1 may play a role in the normal growth of GnRH neurites to the median eminence. A reverse transcription-polymerase chain reaction demonstrated the expression of Kiss1 mRNA in the embryonic mediobasal hypothalamus, the target region for GnRH neurite termination, as early as embryonic day 13.5 (E13.5), a time when the first GnRH neurites are arriving. Complementary expression of the mRNA encoding the KISS1 receptor, Kiss1r, in the preoptic area (POA) at E13.5 was also observed, suggesting that POA-resident GnRH neurones can respond to KISS1 from an early age. To examine the effects of KISS1 on GnRH neurite growth in isolation, E15.5 POA explants, containing GnRH neurones actively extending neurites, were grown in three-dimensional collagen gels. In the presence of KISS1 (1 μm), both the number and length of GnRH neurites were increased significantly compared to controls without KISS1. The effects of KISS1 on GnRH neurite growth could be inhibited by pretreatment with the phospholipase C inhibitor U73122 (50 μm), indicating that embryonic and adult GnRH neurones respond to KISS1 with the same intracellular signalling pathway. KISS1 provided in a concentration gradient from a fixed source had no effect on GnRH neurite growth, indicating that KISS1 does not function as a long-range chemoattractant. Taken together, these results identify KISS1 as a stimulator of GnRH neurite growth, and suggest that it influences GnRH neurites at close-range to innervate the median eminence. These data add a novel developmental role to the repertoire of the functions of KISS1 in mammalian reproduction.
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Affiliation(s)
- Z Fiorini
- Centre for Neuroendocrinology, Department of Anatomy & Structural Biology, University of Otago School of Medical Sciences, Dunedin, New Zealand
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Vaziri Sani F, Kaartinen V, El Shahawy M, Linde A, Gritli-Linde A. Developmental changes in cellular and extracellular structural macromolecules in the secondary palate and in the nasal cavity of the mouse. Eur J Oral Sci 2010; 118:221-36. [PMID: 20572855 DOI: 10.1111/j.1600-0722.2010.00732.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The aim of this study was to analyse the hitherto largely unknown expression patterns of some specific cellular and extracellular molecules during palate and nasal cavity development. We showed that epithelia of the developing palate and the vomerine epithelium express similar sets of structural proteins. With the exception of keratin 15, which becomes barely detectable in the elevated palatal shelves, nearly all of these proteins become upregulated at the presumptive areas of fusion and in the adhering epithelia of the palate and nasal septum. In vivo and in vitro analyses indicated that reduction in the amount of keratin 15 protein is independent of Tgfbeta-Alk5 signalling. Foxa1 expression also highlighted the regionalization of the palatal and nasal epithelia. Owing to the lack of reliable markers of the palatal periderm, the fate of peridermal cells has been controversial. We identified LewisX/stage-specific embryonic antigen-1 as a specific peridermal marker, and showed that numerous peridermal cells remain trapped in the medial epithelial seam (MES). The fate of these cells is probably apoptosis together with the rest of the MES cells, as we provided strong evidence for this event. Heparan sulphate, chondroitin-6-sulphate, and versican displayed dynamically changing distribution patterns. The hitherto-unknown innervation pattern of the developing palate was revealed. These findings may be of value for unravelling the pathogenesis of palatal clefting.
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Affiliation(s)
- Forugh Vaziri Sani
- Department of Oral Biochemistry, Sahlgrenska Academy at the University of Gothenburg, Göteborg, Sweden
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Embryonic gonadotropin-releasing hormone signaling is necessary for maturation of the male reproductive axis. Proc Natl Acad Sci U S A 2010; 107:16372-7. [PMID: 20805495 DOI: 10.1073/pnas.1000423107] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Gonadotropin-releasing hormone (GnRH) signaling regulates reproductive physiology in mammals. GnRH is released by a subset of hypothalamic neurons and binds to GnRH receptor (GnRHR) on gonadotropes in the anterior pituitary gland to control production and secretion of gonadotropins that in turn regulate the activity of the gonads. Central control of reproduction is well understood in adult animals, but GnRH signaling has also been implicated in the development of the reproductive axis. To investigate the role of GnRH signaling during development, we selectively ablated GnRHR-expressing cells in mice. This genetic strategy permitted us to identify an essential stage in male reproductive axis development, which depends on embryonic GnRH signaling. Our experiments revealed a striking dichotomy in the gonadotrope population of the fetal anterior pituitary gland. We show that luteinizing hormone-expressing gonadotropes, but not follicle-stimulating hormone-expressing gonadotropes, express the GnRHR at embryonic day 16.75. Furthermore, we demonstrate that an embryonic increase in luteinizing hormone secretion is needed to promote development of follicle-stimulating hormone-expressing gonadotropes, which might be mediated by paracrine interactions within the pituitary. Moreover, migration of GnRH neurons into the hypothalamus appeared normal with appropriate axonal connections to the median eminence, providing genetic evidence against autocrine regulation of GnRH neurons. Surprisingly, genetic ablation of GnRHR expressing cells significantly increased the number of GnRH neurons in the anterior hypothalamus, suggesting an unexpected role of GnRH signaling in establishing the size of the GnRH neuronal population. Our experiments define a functional role of embryonic GnRH signaling.
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Provenzano C, Pascucci B, Lupari E, Civitareale D. Large scale analysis of transcription factor TTF-1/NKX2.1 target genes in GnRH secreting cell line GT1-7. Mol Cell Endocrinol 2010; 323:215-23. [PMID: 20211691 DOI: 10.1016/j.mce.2010.02.038] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2009] [Revised: 02/26/2010] [Accepted: 02/28/2010] [Indexed: 11/24/2022]
Abstract
TTF-1/Nkx2.1 is a homeodomain-containing transcription factor required for the proper development of ventral forebrain, including some structures of the hypothalamus. TTF-1/Nkx2.1 remains expressed in the hypothalamus after birth and it plays a crucial role during sexual development. To identify putative TTF-1/Nkx2.1 target genes in GnRH neurons, we have studied the gene expression profile of the GT1-7 cells exogenously expressing TTF-1/Nkx2.1 coding gene. Our transcriptome analysis confirms that TTF-1/Nkx2.1 is involved in neuron morphogenesis and differentiation. Many of the newly identified TTF-1/Nkx2.1 target genes have a direct involvement with the central regulation of sexual maturity. In particular, we have identified Sparc as a gene directly regulated by TTF-1/Nkx2.1 at the promoter level. To further support the role of TTF-1 in GnRH neurons, we show that Sparc is involved in the regulation of the GnRH secretion in GT1-7 cells.
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Affiliation(s)
- Claudia Provenzano
- Institute of Neurobiology and Molecular Medicine, CNR, Via Fosso del Cavaliere 100, 00133 Rome, Italy
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Abstract
Gonadotrophin-releasing hormone-1 (GnRH-1) is essential for mammalian reproduction, controlling release of gonadotrophins from the anterior pituitary. GnRH-1 neurones migrate from the nasal placode into the forebrain during development. Although first located within the nasal placode, the embryonic origin/lineage of GnRH-1 neurones is still unclear. The migration of GnRH-1 cells is the best characterised example of neurophilic/axophilic migration, with the cells using a subset of olfactory-derived vomeronasal axons as their pathway and numerous molecules to guide their movement into the forebrain. Exciting work in this area is beginning to identify intersecting pathways that orchestrate the movement of these critical neuroendocrine cells into the central nervous system, both spatially and temporally, through a diverse and changing terrain. Once within the forebrain, little is known about how the axons target the median eminence and ultimately secrete GnRH-1 in a pulsatile fashion.
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Affiliation(s)
- S Wray
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA.
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Jasoni CL, Romanò N, Constantin S, Lee K, Herbison AE. Calcium dynamics in gonadotropin-releasing hormone neurons. Front Neuroendocrinol 2010; 31:259-69. [PMID: 20594958 DOI: 10.1016/j.yfrne.2010.05.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Revised: 05/25/2010] [Accepted: 05/27/2010] [Indexed: 02/04/2023]
Abstract
The gonadotropin-releasing hormone (GnRH) neurons represent the key output cells of the neuronal network controlling fertility. Intracellular calcium ion concentration ([Ca(2+)](i)) is likely to be a key signaling tool used by GnRH neurons to regulate and co-ordinate multiple cell processes. This review examines the dynamics and control of [Ca(2+)](i) in GT1 cells, embryonic GnRH neurons in the nasal placode culture, and adult GnRH neurons in the acute brain slice preparation. GnRH neurons at all stages of development display spontaneous [Ca(2+)](i) transients driven, primarily, by their burst firing. However, the intracellular mechanisms generating [Ca(2+)](i) transients, and the control of [Ca(2+)](i) by neurotransmitters, varies markedly across the different developmental stages. The functional roles of [Ca(2+)](i) transients are beginning to be unraveled with one key action being that of regulating the dynamics of GnRH neuron burst firing.
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Affiliation(s)
- Christine L Jasoni
- Centre for Neuroendocrinology, Departments of Physiology, University of Otago, Dunedin 9054, New Zealand
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Murakami S, Ohki-Hamazaki H, Watanabe K, Ikenaka K, Ono K. Netrin 1 provides a chemoattractive cue for the ventral migration of GnRH neurons in the chick forebrain. J Comp Neurol 2010; 518:2019-34. [PMID: 20394056 DOI: 10.1002/cne.22319] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Hypothalamic gonadotropin-releasing hormone (GnRH) neurons originate in the olfactory placode and migrate to the forebrain during embryonic development. We found that GnRH neurons migrated in two different modes in the chick medial telencephalon: they initially underwent axophilic migration in association with a subset of olfactory fibers in a dorsocaudal direction. This was followed by ventrally directed tangential migration to the basal forebrain. Since many of the ventrally migrating GnRH neurons did not follow distinct fiber fascicles, it is proposed that diffusible guidance molecules played a role in this migratory process. A long-range diffusible factor, netrin 1, was expressed in the lower part of the commissural plate and the subpallial septum, but not along the axophilic migratory route of GnRH neurons. Failure of ventrally directed migration of GnRH neurons and their misrouting to the dorsomedial forebrain was induced by misexpression of netrin 1 in the dorsocaudal part of the septum near the top of the commissural plate, which is where the migration of GnRH neurons changed to a ventral direction. In such cases, a subset of olfactory fibers also extended, but close contact between aberrant fibers and misrouted GnRH neurons did not exist. A coculture experiment demonstrated that netrin 1 exerts an attractive effect on migrating GnRH neurons. These results provide evidence that netrin 1 acts as chemoattractant to migrating GnRH neurons at the dorsocaudal part of the septum and has the potential to regulate the ventral migration of GnRH neurons to the ventral septum and the preoptic area.
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Affiliation(s)
- Shizuko Murakami
- Department of Cell Biology and Neuroscience, Juntendo University School of Medicine, Hongo, Tokyo 113-8421, Japan.
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Wadas BC, Hartshorn CA, Aurand ER, Palmer JS, Roselli CE, Noel ML, Gore AC, Veeramachaneni DNR, Tobet SA. Prenatal exposure to vinclozolin disrupts selective aspects of the gonadotrophin-releasing hormone neuronal system of the rabbit. J Neuroendocrinol 2010; 22:518-26. [PMID: 20236232 PMCID: PMC2902197 DOI: 10.1111/j.1365-2826.2010.01973.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Developmental exposure to the agricultural fungicide vinclozolin can impair reproductive function in male rabbits and was previously found to decrease the number of immunoreactive-gonadotrophin-releasing hormone (GnRH) neurones in the region of the organum vasculosum of the lamina terminalis and rostral preoptic area by postnatal week (PNW) 6. In the present study, in an aim to further examine the disruption of GnRH neurones by foetal vinclozolin exposure, pregnant rabbits were dosed orally with vinclozolin, flutamide or carrot paste vehicle for the last 2 weeks of gestation. Offspring were euthanised at birth (males and females), PNW 6 (females), PNW 26 (adult males) or PNW 30 (adult females) of age. At birth and in adults, brains were sectioned and processed for immunoreactive GnRH. The numbers of immunoreactive GnRH neuronal perikarya were significantly decreased in vinclozolin-treated rabbits at birth and in adult littermates. By contrast, there was an increase in GnRH immunoreactivity in the terminals in the region of the median eminence. Analysis of PNW 6 female brains by radioimmunoassay revealed a two-fold increase in GnRH peptide content in the mediobasal hypothalamus in vinclozolin-treated rabbits. This finding was complemented by immunofluorescence analyses, which revealed a 2.8-fold increase in GnRH immunoreactivity in the median eminence of vinclozolin compared to vehicle-treated females at PNW 30. However, there was no difference between treatment groups in the measures of reproduction that were evaluated: ejaculation latency, conception rates or litter size. These results indicate that sub-acute, prenatal vinclozolin treatment is sufficient to create perdurable alterations in the GnRH neuronal network that forms an important input into the reproductive axis. Finally, the effect of vinclozolin on the GnRH neuronal network was not comparable to that of flutamide, suggesting that vinclozolin was not acting through anti-androgenic mechanisms.
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Affiliation(s)
- B C Wadas
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO, USA
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48
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Chung WCJ, Tsai PS. Role of fibroblast growth factor signaling in gonadotropin-releasing hormone neuronal system development. FRONTIERS OF HORMONE RESEARCH 2010; 39:37-50. [PMID: 20389084 DOI: 10.1159/000312692] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
There is growing evidence demonstrating that fibroblast growth factor (FGF) signaling is important for the development of the gonadotropin-releasing hormone (GnRH) neuronal system. In humans, loss-of-function mutations in FGF receptor 1 (Fgfr1) and Fgf8 lead to hypogonadotropic hypogonadism (HH) with or without anosmia. Insights into how FGF signaling deficiency disrupts the GnRH system in humans are beginning to emerge from studies using transgenic mouse models. In this review, we summarize GnRH system defects in several lines of FGF signaling-deficient mice. We showed that FGF signaling is critically required for olfactory placode induction, differentiation, and GnRH neuronal fate specification and postnatal maintenance. Extrapolating from these transgenic mouse data, we suggest that idiopathic HH in patients harboring loss-of-function Fgfr1 and/or Fgf8 mutations is not merely a result of defective GnRH neuronal migration, but also insults accumulated in the GnRH system during fate specification and postnatal development.
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Catalano PN, Di Giorgio N, Bonaventura MM, Bettler B, Libertun C, Lux-Lantos VA. Lack of functional GABA(B) receptors alters GnRH physiology and sexual dimorphic expression of GnRH and GAD-67 in the brain. Am J Physiol Endocrinol Metab 2010; 298:E683-96. [PMID: 20009027 DOI: 10.1152/ajpendo.00532.2009] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
GABA, the main inhibitory neurotransmitter, acts through GABA(A/C) and GABA(B) receptors (GABA(B)Rs); it is critical for gonadotropin regulation. We studied whether the lack of functional GABA(B)Rs in GABA(B1) knockout (GABA(B1)KO) mice affected the gonadotropin axis physiology. Adult male and female GABA(B1)KO and wild-type (WT) mice were killed to collect blood and tissue samples. Gonadotropin-releasing hormone (GnRH) content in whole hypothalami (HT), olfactory bulbs (OB), and frontoparietal cortexes (CT) were determined (RIA). GnRH expression by quantitative real-time PCR (qRT-PCR) was evaluated in preoptic area-anterior hypothalamus (POA-AH), medial basal-posterior hypothalamus (MBH-PH), OB, and CT. Pulsatile GnRH secretion from hypothalamic explants was measured by RIA. GABA, glutamate, and taurine contents in HT and CT were determined by HPLC. Glutamic acid decarboxylase-67 (GAD-67) mRNA was measured by qRT-PCR in POA-AH, MBH-PH, and CT. Gonadotropin content, serum levels, and secretion from adenohypophyseal cell cultures (ACC) were measured by RIA. GnRH mRNA expression was increased in POA-AH of WT males compared with females; this pattern of expression was inversed in GABA(B1)KO mice. MBH-PH, OB, and CT did not follow this pattern. In GABA(B1)KO females, GnRH pulse frequency was increased and GABA and glutamate contents were augmented. POA-AH GAD-67 mRNA showed the same expression pattern as GnRH mRNA in this area. Gonadotropin pituitary contents and serum levels showed no differences between genotypes. Increased basal LH secretion and decreased GnRH-stimulated gonadotropin response were observed in GABA(B1)KO female ACCs. These results support the hypothesis that the absence of functional GABA(B)Rs alters GnRH physiology and critically affects sexual dimorphic expression of GnRH and GAD-67 in POA-AH.
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Affiliation(s)
- Paolo N Catalano
- Instituto de Biología y Medicina Experimental-Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
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Palevitch O, Abraham E, Borodovsky N, Levkowitz G, Zohar Y, Gothilf Y. Cxcl12a-Cxcr4b signaling is important for proper development of the forebrain GnRH system in zebrafish. Gen Comp Endocrinol 2010; 165:262-8. [PMID: 19595689 DOI: 10.1016/j.ygcen.2009.07.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2009] [Revised: 06/22/2009] [Accepted: 07/03/2009] [Indexed: 01/09/2023]
Abstract
Hypothalamic gonadotropin-releasing hormone (GnRH) neurons control pituitary gonadotropin secretion and gametogenesis. In the course of development, these neurons migrate from the olfactory placode to the hypothalamus. The precise molecular mechanism of this neuronal migration is unclear. Here, we investigated whether the chemokine receptor, Cxcr4b, and its cognate ligand, Cxcl12a, are required for proper migration of GnRH3 neurons in zebrafish. Deviated GnRH3 axonal projections and neuronal migration were detected in larvae that carry a homozygote cxcr4b mutation. Similarly, knockdown of Cxcr4b or Cxcl12a led to the appearance of abnormal GnRH3 axonal projections and cell migration, including absence of the characteristic lateral crossing of GnRH3 axons at the anterior commissure and optic chiasm. Double-labeling analysis has shown that cxcr4b and cxcl12a are expressed along the GnRH3 migration pathway (i.e. olfactory placode, terminal nerve and the optic chiasm). The results of this study suggest that the Cxcl12a-Cxcr4b ligand-receptor pair are involved in the migration of GnRH3 neurons in zebrafish, and are therefore crucial for the development of this system.
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Affiliation(s)
- Ori Palevitch
- Department of Neurobiology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel Aviv 69978, Israel.
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