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Amato E, Taroc EZM, Forni PE. Illuminating the terminal nerve: Uncovering the link between GnRH-1 neuron and olfactory development. J Comp Neurol 2024; 532:e25599. [PMID: 38488687 PMCID: PMC10958589 DOI: 10.1002/cne.25599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 01/11/2024] [Accepted: 02/19/2024] [Indexed: 03/18/2024]
Abstract
During embryonic development, the olfactory placode (OP) generates migratory neurons, including olfactory pioneer neurons, cells of the terminal nerve (TN), gonadotropin-releasing hormone-1 (GnRH-1) neurons, and other uncharacterized neurons. Pioneer neurons from the OP induce olfactory bulb (OB) morphogenesis. In mice, GnRH-1 neurons appear in the olfactory system around mid-gestation and migrate via the TN axons to different brain regions. The GnRH-1 neurons are crucial in controlling the hypothalamic-pituitary-gonadal axis. Kallmann syndrome is characterized by impaired olfactory system development, defective OBs, secretion of GnRH-1, and infertility. The precise mechanistic link between the olfactory system and GnRH-1 development remains unclear. Studies in humans and mice highlight the importance of the prokineticin-2/prokineticin-receptor-2 (Prokr2) signaling pathway in OB morphogenesis and GnRH-1 neuronal migration. Prokr2 loss-of-function mutations can cause Kallmann syndrome (KS), and hence the Prokr2 signaling pathway represents a unique model to decipher the olfactory/GnRH-1 connection. We discovered that Prokr2 is expressed in the TN neurons during the critical period of GnRH-1 neuron formation, migration, and induction of OB morphogenesis. Single-cell RNA sequencing identified that the TN is formed by neurons distinct from the olfactory neurons. The TN neurons express multiple genes associated with KS. Our study suggests that the aberrant development of pioneer/TN neurons might cause the KS spectrum.
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Affiliation(s)
- Enrico Amato
- Department of Biological Sciences, The Center for Neuroscience Research, The RNA Institute, University at Albany, State University of New York, Albany, NY 12222, USA
| | - Ed Zandro M. Taroc
- Department of Biological Sciences, The Center for Neuroscience Research, The RNA Institute, University at Albany, State University of New York, Albany, NY 12222, USA
| | - Paolo E. Forni
- Department of Biological Sciences, The Center for Neuroscience Research, The RNA Institute, University at Albany, State University of New York, Albany, NY 12222, USA
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Amato E, Taroc EZM, Forni PE. Illuminating the Terminal Nerve: Uncovering the Link between GnRH-1 and Olfactory Development. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.31.555770. [PMID: 37693459 PMCID: PMC10491181 DOI: 10.1101/2023.08.31.555770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
During embryonic development, the olfactory placode (OP) generates migratory neurons, including olfactory pioneer neurons, cells of the terminal nerve (TN), Gonadotropin-releasing hormone-1 (GnRH-1) neurons, and other uncharacterized neurons. Pioneer neurons from the olfactory placode induce olfactory bulb morphogenesis. In mice, GnRH-1 neurons appear in the olfactory system around mid-gestation and migrate via the terminal nerve axons to different brain regions. The GnRH-1 neurons are crucial in controlling the hypothalamic-pituitary-gonadal (HPG) axis. Kallmann syndrome is characterized by impaired olfactory system development, defective olfactory bulbs, defective secretion of GnRH-1, and infertility. The precise mechanistic link between the olfactory system and GnRH-1 development remains unclear. Studies in humans and mice highlight the importance of the Prokineticin-2/Prokineticin-Receptor-2 (Prokr2) signaling pathway in olfactory bulb morphogenesis and GnRH-1 neuronal migration. Prokr2 loss-of-function mutations can cause Kallmann syndrome, and hence the Prokr2 signaling pathway represents a unique model to decipher the olfactory/GnRH-1 connection. We discovered that Prokr2 is expressed in the TN neurons during the critical period of GnRH-1 neuron formation, migration, and induction of olfactory bulb morphogenesis. Single-cell RNA sequencing identified that the TN is formed by neurons that are distinct from the olfactory neurons. The TN neurons express multiple genes associated with KS. Our study suggests that the aberrant development of pioneer/TN neurons might cause the KS spectrum. Key Points 1) Pioneer or terminal nerve neurons play a crucial role in initiating the development of the olfactory bulbs. We found that the Prokineticin Receptor-2 gene, associated with Kallmann syndrome, is expressed by the olfactory pioneer/terminal nerve neurons.2) We genetically traced, isolated, and conducted Single-cell RNA sequencing on terminal nerve neurons of rodents. This analysis revealed a significant enrichment of gene expression related to Kallmann syndrome.3) Our study indicates that the investigation of Pioneer/terminal nerve neurons should be a pivotal focal point for comprehending developmental defects affecting olfactory and GnRH-1 systems.
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Inoue K, Bostan H, Browne MR, Bevis OF, Bortner CD, Moore SA, Stence AA, Martin NP, Chen SH, Burkholder AB, Li JL, Shaw ND. DUX4 double whammy: The transcription factor that causes a rare muscular dystrophy also kills the precursors of the human nose. SCIENCE ADVANCES 2023; 9:eabq7744. [PMID: 36800423 PMCID: PMC9937577 DOI: 10.1126/sciadv.abq7744] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 01/12/2023] [Indexed: 05/19/2023]
Abstract
SMCHD1 mutations cause congenital arhinia (absent nose) and a muscular dystrophy called FSHD2. In FSHD2, loss of SMCHD1 repressive activity causes expression of double homeobox 4 (DUX4) in muscle tissue, where it is toxic. Studies of arhinia patients suggest a primary defect in nasal placode cells (human nose progenitors). Here, we show that upon SMCHD1 ablation, DUX4 becomes derepressed in H9 human embryonic stem cells (hESCs) as they differentiate toward a placode cell fate, triggering cell death. Arhinia and FSHD2 patient-derived induced pluripotent stem cells (iPSCs) express DUX4 when converted to placode cells and demonstrate variable degrees of cell death, suggesting an environmental disease modifier. HSV-1 may be one such modifier as herpesvirus infection amplifies DUX4 expression in SMCHD1 KO hESC and patient iPSC. These studies suggest that arhinia, like FSHD2, is due to compromised SMCHD1 repressive activity in a cell-specific context and provide evidence for an environmental modifier.
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Affiliation(s)
- Kaoru Inoue
- Pediatric Neuroendocrinology Group, Clinical Research Branch, National Institute of Environmental Health Sciences (NIEHS), Research Triangle Park, NC, USA
| | - Hamed Bostan
- Integrative Bioinformatics, NIEHS, Research Triangle Park, NC, USA
| | - MaKenna R. Browne
- Pediatric Neuroendocrinology Group, Clinical Research Branch, National Institute of Environmental Health Sciences (NIEHS), Research Triangle Park, NC, USA
| | - Owen F. Bevis
- Pediatric Neuroendocrinology Group, Clinical Research Branch, National Institute of Environmental Health Sciences (NIEHS), Research Triangle Park, NC, USA
| | - Carl D. Bortner
- Signal Transduction Laboratory, NIEHS, Research Triangle Park, NC, USA
| | - Steven A. Moore
- Department of Pathology, University of Iowa Carver College of Medicine and Senator Paul D. Wellstone Muscular Dystrophy Specialized Research Center, Iowa City, IA, USA
| | - Aaron A. Stence
- University of Iowa Hospitals and Clinics, Iowa City, IA, USA
| | | | - Shih-Heng Chen
- Viral Vector Core, NIEHS, Research Triangle Park, NC, USA
| | | | - Jian-Liang Li
- Integrative Bioinformatics, NIEHS, Research Triangle Park, NC, USA
| | - Natalie D. Shaw
- Pediatric Neuroendocrinology Group, Clinical Research Branch, National Institute of Environmental Health Sciences (NIEHS), Research Triangle Park, NC, USA
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Mohassel P, Chang N, Inoue K, Delaney A, Hu Y, Donkervoort S, Saade D, Billioux BJ, Meader B, Volochayev R, Konersman CG, Kaindl AM, Cho CH, Russell B, Rodriguez A, Foster KW, Foley AR, Moore SA, Jones PL, Bonnemann CG, Jones T, Shaw ND. Cross-sectional, Neuromuscular Phenotyping Study of Arhinia Patients With SMCHD1 Variants. Neurology 2022; 98:e1384-e1396. [PMID: 35121673 PMCID: PMC8967428 DOI: 10.1212/wnl.0000000000200032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 12/30/2021] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND AND OBJECTIVES Facioscapulohumeral muscular dystrophy type 2 (FSHD2) and arhinia are two distinct disorders caused by pathogenic variants in the same gene, SMCHD1. The mechanism underlying this phenotypic divergence remains unclear. In this study, we characterize the neuromuscular phenotype of individuals with arhinia caused by SMCHD1 variants and analyze their complex genetic and epigenetic criteria to assess their risk for FSHD2. METHODS Eleven individuals with congenital nasal anomalies, including arhinia, nasal hypoplasia, or anosmia, underwent a neuromuscular exam, genetic testing, muscle ultrasound, and muscle MRI. Risk for FSHD2 was determined by combined genetic and epigenetic analysis of 4q35 haplotype, D4Z4 repeat length and methylation profile. We also compared expression levels of pathogenic DUX4 mRNA in primary myoblasts or dermal fibroblasts (upon myogenic differentiation or epigenetic transdifferentiation, respectively) in these individuals to those with confirmed FSHD2. RESULTS Among the eleven individuals with rare, pathogenic, heterozygous missense variants in exons 3-11 of SMCHD1, only a subset (n=3/11; 1 male, 2 females; age 25-51 years) met the strict genetic and epigenetic criteria for FSHD2 (D4Z4 repeat unit length <21 in cis with a 4qA haplotype, and D4Z4 methylation <30%). None of the 3 individuals had typical clinical manifestations or muscle imaging findings consistent with FSHD2. However, the arhinia patients meeting the permissive genetic and epigenetic criteria for FSHD2 displayed some DUX4 expression in dermal fibroblasts under the epigenetic de-repression by drug treatment and in the primary myoblasts undergoing myogenic differentiation. DISCUSSION In this cross-sectional study, we identified arhinia patients who meet the full genetic and epigenetic criteria for FSHD2 and display the molecular hallmark of FSHD, that is DUX4 de-repression and expression in vitro, but who do not manifest with the typical clinicopathologic phenotype of FSHD2. The distinct dichotomy between FSHD2 and arhinia phenotypes despite an otherwise poised DUX4 locus implies the presence of novel disease-modifying factors that seem to operate as a "switch", resulting in one phenotype and not the other. Identification and further understanding of these disease-modifying factors will likely provide valuable insight with therapeutic implications for both diseases.
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Affiliation(s)
- Payam Mohassel
- Neuromuscular and Neurogenetic Disorders of Childhood Section, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
| | - Ning Chang
- Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno, Nevada, USA
| | - Kaoru Inoue
- Pediatric Neuroendocrinology Group, Clinical Research Branch, National Institute of Environmental Health Sciences, National Institutes of Health, RTP, NC
| | - Angela Delaney
- National Institute of Child Health and Development, National Institutes of Health, Bethesda, MD
| | - Ying Hu
- Neuromuscular and Neurogenetic Disorders of Childhood Section, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
| | - Sandra Donkervoort
- Neuromuscular and Neurogenetic Disorders of Childhood Section, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
| | - Dimah Saade
- Neuromuscular and Neurogenetic Disorders of Childhood Section, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
| | - B Jeanne Billioux
- International Neuroinfectious Diseases Unit, Division of Neuroimmunology and Neurovirology, National institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
| | - Brooke Meader
- National Institute of Child Health and Development, National Institutes of Health, Bethesda, MD
| | - Rita Volochayev
- Environmental Autoimmunity Group, Clinical Research Branch, National Institute of Environmental Health Sciences, National Institutes of Health, Bethesda, MD
| | | | - Angela M Kaindl
- Charitè-Universitätsmedizin Berlin, Department of Pediatric Neurology, Center for Chronically Sick Children and Institute of Cell Biology and Neurobiology, Berlin, Germany
| | - Chie-Hee Cho
- Institute for diagnostic and interventional Radiology, University Clinic, Jena, Germany
| | - Bianca Russell
- Division of Pediatric Genetics, Department of Pediatrics, University of California, Los Angeles, Los Angeles, CA
| | | | - K Wade Foster
- Florida Dermatology and Skin Cancer Centers, Winter Haven, FL
| | - A Reghan Foley
- Neuromuscular and Neurogenetic Disorders of Childhood Section, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
| | - Steven A Moore
- Department of Pathology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Peter L Jones
- Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno, Nevada, USA
| | - Carsten G Bonnemann
- Neuromuscular and Neurogenetic Disorders of Childhood Section, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
| | - Takako Jones
- Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno, Nevada, USA
| | - Natalie D Shaw
- Pediatric Neuroendocrinology Group, Clinical Research Branch, National Institute of Environmental Health Sciences, National Institutes of Health, RTP, NC
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Oleari R, Massa V, Cariboni A, Lettieri A. The Differential Roles for Neurodevelopmental and Neuroendocrine Genes in Shaping GnRH Neuron Physiology and Deficiency. Int J Mol Sci 2021; 22:9425. [PMID: 34502334 PMCID: PMC8431607 DOI: 10.3390/ijms22179425] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 08/27/2021] [Accepted: 08/28/2021] [Indexed: 01/19/2023] Open
Abstract
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.
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Affiliation(s)
- Roberto Oleari
- Department of Pharmacological and Biomolecular Sciences, University of Milan, 20133 Milano, Italy;
| | - Valentina Massa
- Department of Health Sciences, University of Milan, 20142 Milano, Italy;
- CRC Aldo Ravelli for Neurotechnology and Experimental Brain Therapeutics, Department of Health Sciences, University of Milan, 20142 Milano, Italy
| | - Anna Cariboni
- Department of Pharmacological and Biomolecular Sciences, University of Milan, 20133 Milano, Italy;
| | - Antonella Lettieri
- Department of Health Sciences, University of Milan, 20142 Milano, Italy;
- CRC Aldo Ravelli for Neurotechnology and Experimental Brain Therapeutics, Department of Health Sciences, University of Milan, 20142 Milano, Italy
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Abstract
Many of the recent advances in our understanding of human reproductive biology and its genetic basis have arisen directly via the genetic investigation of patients with Kallmann syndrome and their families. The disease is characterised by the association of an isolated defect in the secretion (or, less commonly, action) of gonadotropin-releasing hormone (GnRH) and consequent infertility, with anosmia and potentially other associated non-reproductive features. GnRH-producing neurons are located in the hypothalamic brain region after a peculiar migration during embryonic life. To date, different genes affecting GnRH neuron development/migration have so far been implicated in Kallmann syndrome, but our knowledge of the genetic basis of the syndrome remains incomplete. From a clinical point of view, the disease has suffered from a lack of definitive diagnosis and treatment, and although progress has been made in terms of timely diagnosis and evidence-based treatment of patients, implementation remains inconsistent. These aspects will be discussed in this review, which examines new strategies for arriving at more evidence-based and patient-centred medical practice in Kallmann syndrome.
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Affiliation(s)
- Du Soon Swee
- Department of Endocrinology, Singapore General Hospital, Singapore
| | - Richard Quinton
- Department of Endocrinology, Diabetes & Metabolism, Royal Victoria Infirmary, Newcastle-Upon-Tyne Hospitals, Newcastle-upon-Tyne, UK
- Translational & Clinical Research Institute, University of Newcastle-upon-Tyne, Newcastle-Upon-Tyne, UK
| | - Roberto Maggi
- Department of Pharmaceutical Sciences, Università degli Studi di Milano, Milan, MI, Italy
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