scholarly journals The Differential Roles for Neurodevelopmental and Neuroendocrine Genes in Shaping GnRH Neuron Physiology and Deficiency

2021 ◽  
Vol 22 (17) ◽  
pp. 9425
Author(s):  
Roberto Oleari ◽  
Valentina Massa ◽  
Anna Cariboni ◽  
Antonella Lettieri
Keyword(s):  
Phenotypic Variability ◽  
Hypogonadotropic Hypogonadism ◽  
Neuroendocrine Cells ◽  
Delayed Puberty ◽  
Neuronal System ◽  
Gnrh Neuron ◽  
Neuron Development ◽  
Gnrh Neurons ◽  
Genes Encoding ◽  
Functional Relevance

Gonadotropin releasing hormone (GnRH) neurons are hypothalamic neuroendocrine cells that control sexual reproduction. During embryonic development, GnRH neurons migrate from the nose to the hypothalamus, where they receive inputs from several afferent neurons, following the axonal scaffold patterned by nasal nerves. Each step of GnRH neuron development depends on the orchestrated action of several molecules exerting specific biological functions. Mutations in genes encoding for these essential molecules may cause Congenital Hypogonadotropic Hypogonadism (CHH), a rare disorder characterized by GnRH deficiency, delayed puberty and infertility. Depending on their action in the GnRH neuronal system, CHH causative genes can be divided into neurodevelopmental and neuroendocrine genes. The CHH genetic complexity, combined with multiple inheritance patterns, results in an extreme phenotypic variability of CHH patients. In this review, we aim at providing a comprehensive and updated description of the genes thus far associated with CHH, by dissecting their biological relevance in the GnRH system and their functional relevance underlying CHH pathogenesis.

scholarly journals Deletion of the Homeodomain Protein Six6 From GnRH Neurons Decreases GnRH Gene Expression, Resulting in Infertility

Endocrinology ◽  
2019 ◽  
Vol 160 (9) ◽  
pp. 2151-2164 ◽  
Author(s):  
Erica C Pandolfi ◽  
Karen J Tonsfeldt ◽  
Hanne M Hoffmann ◽  
Pamela L Mellon
Keyword(s):  
Hypogonadotropic Hypogonadism ◽  
Neuronal Cell ◽  
Delayed Puberty ◽  
Homeodomain Protein ◽  
Gnrh Neuron ◽  
Direct Role ◽  
Hpg Axis ◽  
Gnrh Neurons

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.

scholarly journals Defects in GnRH Neuron Migration/Development and Hypothalamic-Pituitary Signaling Impact Clinical Variability of Kallmann Syndrome

Genes ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 868
Author(s):  
Małgorzata Kałużna ◽  
Bartłomiej Budny ◽  
Michał Rabijewski ◽  
Jarosław Kałużny ◽  
Agnieszka Dubiel ◽  
...  
Keyword(s):  
Phenotypic Variability ◽  
Hypogonadotropic Hypogonadism ◽  
Kallmann Syndrome ◽  
Gene Panel ◽  
Gnrh Neuron ◽  
Neuron Development ◽  
Pituitary Development ◽  
Targeted Ngs ◽  
Uncertain Significance ◽  
Next Generation Sequencing Ngs

Kallmann syndrome (KS) is a combination of isolated hypogonadotropic hypogonadism (IHH) with olfactory dysfunction, representing a heterogeneous disorder with a broad phenotypic spectrum. The genetic background of KS has not yet been fully established. This study was conducted on 46 Polish KS subjects (41 males, 5 females; average age: 29 years old). The studied KS patients were screened for defects in a 38-gene panel with next-generation sequencing (NGS) technology. The analysis revealed 27 pathogenic and likely pathogenic (P/LP) variants, and 21 variants of uncertain significance (VUS). The P/LP variants were detected in 20 patients (43.5%). The prevalence of oligogenic P/LP defects in selected genes among KS patients was 26% (12/46), whereas the co-occurrence of other variants was detected in 43% (20 probands). The examined KS patients showed substantial genotypic and phenotypic variability. A marked difference in non-reproductive phenotypes, involving defects in genes responsible for GnRH neuron development/migration and genes contributing to pituitary development and signaling, was observed. A comprehensive gene panel for IHH testing enabled the detection of clinically relevant variants in the majority of KS patients, which makes targeted NGS an effective molecular tool. The significance of oligogenicity and the high incidence of alterations in selected genes should be further elucidated.

scholarly journals Anti-Müllerian Hormone, Growth Hormone, and Insulin-Like Growth Factor 1 Modulate the Migratory and Secretory Patterns of GnRH Neurons

2021 ◽  
Vol 22 (5) ◽  
pp. 2445
Author(s):  
Rossella Cannarella ◽  
Alyssa J.J. Paganoni ◽  
Stefania Cicolari ◽  
Roberto Oleari ◽  
Rosita A. Condorelli ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Growth Factor ◽  
Cell Line ◽  
Hypogonadotropic Hypogonadism ◽  
Delayed Puberty ◽  
Insulin Like Growth Factor ◽  
Gnrh Neuron ◽  
Neuron Migration ◽  
Gnrh Secretion ◽  
Gnrh Neurons

Anti-Müllerian hormone (AMH) is secreted by Sertoli or granulosa cells. Recent evidence suggests that AMH may play a role in the pathogenesis of hypogonadotropic hypogonadism (HH) and that its serum levels could help to discriminate HH from delayed puberty. Moreover, the growth hormone (GH)/insulin-like growth factor 1 (IGF1) system may be involved in the function of gonadotropin-releasing hormone (GnRH) neurons, as delayed puberty is commonly found in patients with GH deficiency (GHD) or with Laron syndrome, a genetic form of GH resistance. The comprehension of the stimuli enhancing the migration and secretory activity of GnRH neurons might shed light on the causes of delay of puberty or HH. With these premises, we aimed to better clarify the role of the AMH, GH, and IGF1 on GnRH neuron migration and GnRH secretion, by taking advantage of previously established models of immature (GN11 cell line) and mature (GT1-7 cell line) GnRH neurons. Expression of Amhr, Ghr, and Igf1r genes was confirmed in both cell lines. Cells were then incubated with increasing concentrations of AMH (1.5–150 ng/mL), GH (3–1000 ng/mL), or IGF1 (1.5–150 ng/mL). All hormones were able to support GN11 cell chemomigration. AMH, GH, and IGF1 significantly stimulated GnRH secretion by GT1-7 cells after a 90-min incubation. To the best of our knowledge, this is the first study investigating the direct effects of GH and IGF1 in GnRH neuron migration and of GH in the GnRH secreting pattern. Taken together with previous basic and clinical studies, these findings may provide explanatory mechanisms for data, suggesting that AMH and the GH-IGF1 system play a role in HH or the onset of puberty.

scholarly journals Defective AMH signaling disrupts GnRH neuron development and function and contributes to hypogonadotropic hypogonadism

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Samuel Andrew Malone ◽  
Georgios E Papadakis ◽  
Andrea Messina ◽  
Nour El Houda Mimouni ◽  
Sara Trova ◽  
...  
Keyword(s):  
Hypogonadotropic Hypogonadism ◽  
Abnormal Development ◽  
Loss Of Function ◽  
Neuron Development ◽  
Motility Factor ◽  
Congenital Hypogonadotropic Hypogonadism ◽  
Whole Exome ◽  
Gnrh Neurons ◽  
And Function ◽  
Deficient Mice

Congenital hypogonadotropic hypogonadism (CHH) is a condition characterized by absent puberty and infertility due to gonadotropin releasing hormone (GnRH) deficiency, which is often associated with anosmia (Kallmann syndrome, KS). We identified loss-of-function heterozygous mutations in anti-Müllerian hormone (AMH) and its receptor, AMHR2, in 3% of CHH probands using whole-exome sequencing. We showed that during embryonic development, AMH is expressed in migratory GnRH neurons in both mouse and human fetuses and unconvered a novel function of AMH as a pro-motility factor for GnRH neurons. Pathohistological analysis of Amhr2-deficient mice showed abnormal development of the peripheral olfactory system and defective embryonic migration of the neuroendocrine GnRH cells to the basal forebrain, which results in reduced fertility in adults. Our findings highlight a novel role for AMH in the development and function of GnRH neurons and indicate that AMH signaling insufficiency contributes to the pathogenesis of CHH in humans.

scholarly journals Projections of Arcuate Nucleus and Rostral Periventricular Kisspeptin Neurons in the Adult Female Mouse Brain

Endocrinology ◽  
2011 ◽  
Vol 152 (6) ◽  
pp. 2387-2399 ◽  
Author(s):  
Shel-Hwa Yeo ◽  
Allan E. Herbison
Keyword(s):  
Mouse Brain ◽  
Female Mouse ◽  
Arcuate Nucleus ◽  
Third Ventricle ◽  
Retrograde Tracing ◽  
Neuron Activity ◽  
Neuronal System ◽  
Gnrh Neuron ◽  
Gnrh Neurons ◽  
Tracing Techniques

The important role of kisspeptin neurons in the regulation of GnRH neuron activity is now well accepted. However, the ways in which kisspeptin neurons located in the arcuate nucleus (ARN) and rostral periventricular area of the third ventricle (RP3V) control GnRH neurons are poorly understood. The present study used anterograde and retrograde tracing techniques to establish the neuronal projection patterns of kisspeptin cell populations in the female mouse brain. Anterograde tracing studies revealed that kisspeptin neurons in the ARN innervated a wide number of hypothalamic and associated limbic region nuclei, whereas RP3V kisspeptin neurons projected to a smaller number of mostly medially located hypothalamic nuclei. Retrograde tracing confirmed a major projection of RP3V kisspeptin neurons to the ARN and showed that kisspeptin neurons located in the rostral half of the ARN projected to the rostral preoptic area. Peripheral administration of Fluorogold was found to label the majority of GnRH neurons but no kisspeptin neurons. Together, these studies highlight the complexity of the brain kisspeptin neuronal system and indicate that both ARN and RP3V kisspeptin neurons participate in a variety of limbic functions. In relation to the GnRH neuronal network, these investigations demonstrate that, alongside the RP3V kisspeptin cells, rostral ARN kisspeptin neurons may also project to GnRH neuron cell bodies. However, no kisspeptin neurons innervate GnRH nerve terminals in the external layer of the median eminence. These studies provide a neuroanatomical framework for the further elucidation of the functions of the ARN and RP3V kisspeptin neuron populations.

scholarly journals A recessive PRDM13 mutation results in congenital hypogonadotropic hypogonadism and cerebellar hypoplasia

2021 ◽  
Author(s):  
Danielle Emma Whittaker ◽  
Roberto Oleari ◽  
Louise Gregory ◽  
Polona Le Quesne-Stabej ◽  
Hywel Williams ◽  
...  
Keyword(s):  
Cell Fate ◽  
Neuronal Development ◽  
Ventricular Zone ◽  
Hypogonadotropic Hypogonadism ◽  
Ectopic Expression ◽  
Mechanistic Explanation ◽  
Delayed Puberty ◽  
Cerebellar Hypoplasia ◽  
Neuron Development ◽  
Congenital Hypogonadotropic Hypogonadism

PRDM13 (PR Domain containing 13) is a putative chromatin modifier and transcriptional regulator that functions downstream of the transcription factor PTF1A, which in turn controls GABAergic fate in the spinal cord and neuronal development in the hypothalamus. Here, we report a novel, recessive syndrome associated with PRDM13 mutation. Patients exhibited intellectual disability, ataxia with cerebellar hypoplasia, scoliosis and delayed puberty with congenital hypogonadotropic hypogonadism (CHH). Expression studies revealed Prdm13/PRDM13 transcripts in the developing hypothalamus and cerebellum in mouse and human. We investigated the development of hypothalamic neurons and the cerebellum in mice homozygous for a Prdm13 mutant allele. A significant reduction in the number of Kisspeptin (Kiss1) neurons in the hypothalamus and PAX2+ progenitors emerging from the cerebellar ventricular zone were observed. The latter was accompanied by ectopic expression of the glutamatergic lineage marker TLX3. Phenotypically, mice lacking PRDM13 displayed cerebellar hypoplasia, normal gonadal structure, but delayed pubertal onset. Together, these findings identify PRDM13 as a critical regulator of GABAergic cell fate in the cerebellum and of kisspeptin neuron development in the hypothalamus, providing a mechanistic explanation for the co-occurrence of CHH and cerebellar hypoplasia in this syndrome. To our knowledge, this is the first evidence linking disrupted PRDM13-mediated regulation of Kiss1 neurons to CHH in humans.

scholarly journals Semaphorin Signaling in GnRH Neurons: From Development to Disease

2018 ◽  
Vol 109 (3) ◽  
pp. 193-199 ◽  
Author(s):  
Roberto Oleari ◽  
Antonella Lettieri ◽  
Alyssa Paganoni ◽  
Luca Zanieri ◽  
Anna Cariboni
Keyword(s):  
Embryonic Development ◽  
Mouse Models ◽  
Neuronal Development ◽  
Large Family ◽  
Gonadotropin Releasing Hormone ◽  
Final Position ◽  
Gnrh Neuron ◽  
Neuron Development ◽  
Hypothalamic Neurons ◽  
Gnrh Neurons

In mammals, fertility critically depends on the pulsatile secretion of gonadotropin-releasing hormone (GnRH) by scattered hypothalamic neurons (GnRH neurons). During development, GnRH neurons originate in the nasal placode and migrate first into the nasal compartment and then through the nasal/forebrain junction, before they reach their final position in the hypothalamus. This neurodevelopmental process, which has been extensively studied in mouse models, is regulated by a plethora of factors that might control GnRH neuron migration or survival as well as the fasciculation/targeting of the olfactory/vomeronasal axons along which the GnRH neurons migrate. Defects in GnRH neuron development or release can lead to isolated GnRH deficiency, with the underlying genetic causes still being partially unknown. Recently, semaphorins and their receptors neuropilins and plexins, a large family of molecules implicated in neuronal development and plasticity, are emerging as key regulators of GnRH neuron biology and deficiency. Specifically, semaphorins have been shown to play different roles in GnRH neuron biology by regulating migration and survival during embryonic development as well as secretion in adulthood.

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