RESUMO
Waardenburg syndrome (WS) is characterized by the association of sensorineural hearing loss and pigmentation abnormalities. Among the four types, WS Type 2 (WS2) is the only one without a remarkable distinguishing feature. Here, we report a patient initially diagnosed with WS2 who exhibits a 446 kb mosaic duplication in chromosome 22q13.1, encompassing SOX10, and detected using whole genome sequencing in a trio. The patient, a 46,XY boy, presents with profound bilateral sensorineural hearing loss, right heterochromia iridium, left bright blue iris, and skin-depigmented areas in the abdomen and limbs. Vestibular and imaging tests are normal, without inner ear or olfactory bulb malformations. Bilateral cochlear implantation did not prevent language and speech delays. Moderate congenital chronic constipation and neurodevelopmental difficulties were also present. Given the few genes included in this duplicated region (only one OMIM gene with dominant inheritance), this report provides further delineation of the phenotype related to duplications encompassing the entire SOX10 gene.
Assuntos
Perda Auditiva Neurossensorial , Vestíbulo do Labirinto , Síndrome de Waardenburg , Masculino , Humanos , Mosaicismo , Fenótipo , Perda Auditiva Neurossensorial/diagnóstico , Perda Auditiva Neurossensorial/genética , Síndrome de Waardenburg/diagnóstico , Síndrome de Waardenburg/genética , Fatores de Transcrição SOXE/genética , MutaçãoRESUMO
SOX10 belongs to a family of 20 SRY (sex-determining region Y)-related high mobility group box-containing (SOX) proteins, most of which contribute to cell type specification and differentiation of various lineages. The first clue that SOX10 is essential for development, especially in the neural crest, came with the discovery that heterozygous mutations occurring within and around SOX10 cause Waardenburg syndrome type 4. Since then, heterozygous mutations have been reported in Waardenburg syndrome type 2 (Waardenburg syndrome type without Hirschsprung disease), PCWH or PCW (peripheral demyelinating neuropathy, central dysmyelination, Waardenburg syndrome, with or without Hirschsprung disease), intestinal manifestations beyond Hirschsprung (ie, chronic intestinal pseudo-obstruction), Kallmann syndrome and cancer. All of these diseases are consistent with the regulatory role of SOX10 in various neural crest derivatives (melanocytes, the enteric nervous system, Schwann cells and olfactory ensheathing cells) and extraneural crest tissues (inner ear, oligodendrocytes). The recent evolution of medical practice in constitutional genetics has led to the identification of SOX10 variants in atypical contexts, such as isolated hearing loss or neurodevelopmental disorders, making them more difficult to classify in the absence of both a typical phenotype and specific expertise. Here, we report novel mutations and review those that have already been published and their functional consequences, along with current understanding of SOX10 function in the affected cell types identified through in vivo and in vitro models. We also discuss research options to increase our understanding of the origin of the observed phenotypic variability and improve the diagnosis and medical care of affected patients.
Assuntos
Desenvolvimento Embrionário/genética , Desenvolvimento Embrionário/fisiologia , Fatores de Transcrição SOXE/genética , Fatores de Transcrição SOXE/fisiologia , Animais , Sistema Nervoso Entérico/fisiologia , Regulação da Expressão Gênica no Desenvolvimento , Perda Auditiva/genética , Doença de Hirschsprung/genética , Humanos , Síndrome de Kallmann/genética , Melanócitos/fisiologia , Mutação , Neoplasias/genética , Crista Neural/embriologia , Crista Neural/fisiologia , Fenótipo , Síndrome de Waardenburg/genéticaRESUMO
The endothelin system is a vertebrate-specific innovation with important roles in regulating the cardiovascular system and renal and pulmonary processes, as well as the development of the vertebrate-specific neural crest cell population and its derivatives. This system is comprised of three structurally similar 21-amino acid peptides that bind and activate two G-protein coupled receptors. In 1994, knockouts of the Edn3 and Ednrb genes revealed their crucial function during development of the enteric nervous system and melanocytes, two neural-crest derivatives. Since then, human and mouse genetics, combined with cellular and developmental studies, have helped to unravel the role of this signaling pathway during development and adulthood. In this review, we will summarize the known functions of the EDN3/EDNRB pathway during neural crest development, with a specific focus on recent scientific advances, and the enteric nervous system in normal and pathological conditions.
Assuntos
Endotelina-3/fisiologia , Crista Neural/metabolismo , Receptor de Endotelina B/fisiologia , Animais , Evolução Biológica , Padronização Corporal/fisiologia , Diferenciação Celular/fisiologia , Movimento Celular/fisiologia , Endotelina-3/metabolismo , Endotelinas/metabolismo , Sistema Nervoso Entérico/embriologia , Sistema Nervoso Entérico/fisiologia , Humanos , Melanócitos/metabolismo , Crista Neural/embriologia , Crista Neural/fisiologia , Tubo Neural , Neurogênese , Receptores de Endotelina/genética , Receptores Acoplados a Proteínas G/metabolismo , Transdução de Sinais , Vertebrados/embriologiaRESUMO
BACKGROUND & AIMS: Maintenance and differentiation of progenitor cells in the developing enteric nervous system are controlled by molecules such as the signaling protein endothelin 3 (EDN3), its receptor (the endothelin receptor type B [EDNRB]), and the transcription factors SRY-box 10 (SOX10) and zinc finger E-box binding homeobox 2 (ZEB2). We used enteric progenitor cell (EPC) cultures and mice to study the roles of these proteins in enteric neurogenesis and their cross regulation. METHODS: We performed studies in mice with a Zeb2 loss-of-function mutation (Zeb2Δ) and mice carrying a spontaneous recessive mutation that prevents conversion of EDN3 to its active form (Edn3ls). EPC cultures issued from embryos that expressed only wild-type Zeb2 (Zeb2+/+ EPCs) or were heterozygous for the mutation (Zeb2Δ/+ EPCs) were exposed to EDN3; we analyzed the effects on cell differentiation using immunocytochemistry. In parallel, Edn3ls mice were crossed with Zeb2Δ/+mice; intestinal tissues were collected from embryos for immunohistochemical analyses. We investigated regulation of the EDNRB gene in transactivation and chromatin immunoprecipitation assays; results were validated in functional rescue experiments using transgenes expression in EPCs from retroviral vectors. RESULTS: Zeb2Δ/+ EPCs had increased neuronal differentiation compared to Zeb2+/+ cells. When exposed to EDN3, Zeb2+/+ EPCs continued expression of ZEB2 but did not undergo any neuronal differentiation. Incubation of Zeb2Δ/+ EPCs with EDN3, on the other hand, resulted in only partial inhibition of neuronal differentiation. This indicated that 2 copies of Zeb2 are required for EDN3 to prevent neuronal differentiation. Mice with combined mutations in Zeb2 and Edn3 (double mutants) had more severe enteric anomalies and increased neuronal differentiation compared to mice with mutations in either gene alone. The transcription factors SOX10 and ZEB2 directly activated the EDNRB promoter. Overexpression of EDNRB in Zeb2Δ/+ EPCs restored inhibition of neuronal differentiation, similar to incubation of Zeb2+/+ EPCs with EDN3. CONCLUSIONS: In studies of cultured EPCs and mice, we found that control of differentiation of mouse enteric nervous system progenitor cells by EDN3 requires regulation of Ednrb expression by SOX10 and ZEB2.
Assuntos
Diferenciação Celular/genética , Endotelina-3/genética , Sistema Nervoso Entérico/embriologia , Proteínas de Homeodomínio/genética , Células-Tronco Neurais/metabolismo , Neurogênese/genética , Receptor de Endotelina B/metabolismo , Proteínas Repressoras/genética , Fatores de Transcrição SOXE/metabolismo , Animais , Células Cultivadas , Imunoprecipitação da Cromatina , Endotelina-3/metabolismo , Sistema Nervoso Entérico/citologia , Sistema Nervoso Entérico/metabolismo , Citometria de Fluxo , Regulação da Expressão Gênica no Desenvolvimento , Heterozigoto , Doença de Hirschsprung , Proteínas de Homeodomínio/metabolismo , Imunoquímica , Camundongos , Mutação , Células-Tronco Neurais/citologia , Reação em Cadeia da Polimerase , Proteínas Repressoras/metabolismo , Células-Tronco , Homeobox 2 de Ligação a E-box com Dedos de ZincoRESUMO
Waardenburg syndrome (WS) is a genetic disorder characterized by sensorineural hearing loss and pigmentation anomalies. The clinical definition of four WS types is based on additional features due to defects in structures mostly arising from the neural crest, with type I and type II being the most frequent. While type I is tightly associated to PAX3 mutations, WS type II (WS2) remains partly enigmatic with mutations in known genes (MITF, SOX10) accounting for only 30% of the cases. We performed exome sequencing in a WS2 index case and identified a heterozygous missense variation in EDNRB. Interestingly, homozygous (and very rare heterozygous) EDNRB mutations are already described in type IV WS (i.e., in association with Hirschsprung disease [HD]) and heterozygous mutations in isolated HD. Screening of a WS2 cohort led to the identification of an overall of six heterozygous EDNRB variations. Clinical phenotypes, pedigrees and molecular segregation investigations unraveled a dominant mode of inheritance with incomplete penetrance. In parallel, cellular and functional studies showed that each of the mutations impairs the subcellular localization of the receptor or induces a defective downstream signaling pathway. Based on our results, we now estimate EDNRB mutations to be responsible for 5%-6% of WS2.
Assuntos
Estudos de Associação Genética , Heterozigoto , Mutação , Receptor de Endotelina B/genética , Síndrome de Waardenburg/diagnóstico , Síndrome de Waardenburg/genética , Adolescente , Adulto , Substituição de Aminoácidos , Criança , Pré-Escolar , Biologia Computacional/métodos , Análise Mutacional de DNA , Exoma , Feminino , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Espaço Intracelular/metabolismo , Iris , Masculino , Taxa de Mutação , Linhagem , Fenótipo , Transporte Proteico , Sítios de Splice de RNA , Receptor de Endotelina B/metabolismo , Adulto JovemRESUMO
Hirschsprung disease (HSCR, intestinal aganglionosis) is a multigenic disorder with variable penetrance and severity that has a general population incidence of 1/5000 live births. Studies using animal models have contributed to our understanding of the developmental origins of HSCR and the genetic complexity of this disease. This review summarizes recent progress in understanding control of enteric nervous system (ENS) development through analyses in mouse models. An overview of signaling pathways that have long been known to control the migration, proliferation and differentiation of enteric neural progenitors into and along the developing gut is provided as a framework for the latest information on factors that influence enteric ganglia formation and maintenance. Newly identified genes and additional factors beyond discrete genes that contribute to ENS pathology including regulatory sequences, miRNAs and environmental factors are also introduced. Finally, because HSCR has become a paradigm for complex oligogenic diseases with non-Mendelian inheritance, the importance of gene interactions, modifier genes, and initial studies on genetic background effects are outlined.
Assuntos
Sistema Nervoso Entérico/patologia , Doença de Hirschsprung/genética , Doença de Hirschsprung/patologia , Crista Neural/embriologia , Animais , Diferenciação Celular/genética , Movimento Celular/genética , Proliferação de Células/genética , Modelos Animais de Doenças , Camundongos , Transdução de SinaisRESUMO
Over the last 20 years, there has been increasing focus on the development of novel stem cell based therapies for the treatment of disorders and diseases affecting the enteric nervous system (ENS) of the gastrointestinal tract (so-called enteric neuropathies). Here, the idea is that ENS progenitor/stem cells could be transplanted into the gut wall to replace the damaged or absent neurons and glia of the ENS. This White Paper sets out experts' views on the commonly used methods and approaches to identify, isolate, purify, expand and optimize ENS stem cells, transplant them into the bowel, and assess transplant success, including restoration of gut function. We also highlight obstacles that must be overcome in order to progress from successful preclinical studies in animal models to ENS stem cell therapies in the clinic.
Assuntos
Terapia Baseada em Transplante de Células e Tecidos/métodos , Sistema Nervoso Entérico/patologia , Trato Gastrointestinal/patologia , Doença de Hirschsprung/terapia , Pseudo-Obstrução Intestinal/terapia , Células-Tronco Neurais/transplante , Transplante de Células-Tronco , Animais , Modelos Animais de Doenças , Trato Gastrointestinal/inervação , Guias como Assunto , Doença de Hirschsprung/patologia , Humanos , Pseudo-Obstrução Intestinal/patologiaRESUMO
SOX10 is a transcription factor with well-known functions in neural crest and oligodendrocyte development. Mutations in SOX10 were first associated with Waardenburg-Hirschsprung disease (WS4; deafness, pigmentation defects and intestinal aganglionosis). However, variable phenotypes that extend beyond the WS4 definition are now reported. The neurological phenotypes associated with some truncating mutations are suggested to be the result of escape from the nonsense-mediated mRNA decay pathway; but, to date, no mechanism has been suggested for missense mutations, of which approximately 20 have now been reported, with about half of the latter shown to be redistributed to nuclear bodies of undetermined nature and function in vitro. Here, we report that p54NRB, which plays a crucial role in the regulation of gene expression during many cellular processes including differentiation, interacts synergistically with SOX10 to regulate several target genes. Interestingly, this paraspeckle protein, as well as two other members of the Drosophila behavior human splicing (DBHS) protein family, co-localize with SOX10 mutants in nuclear bodies, suggesting the possible paraspeckle nature of these foci or re-localization of the DBHS members to other subnuclear compartments. Remarkably, the co-transfection of wild-type and mutant SOX10 constructs led to the sequestration of wild-type protein in mutant-induced foci. In contrast to mutants presenting with additional cytoplasmic re-localization, those exclusively found in the nucleus alter synergistic activity between SOX10 and p54NRB. We propose that such a dominant negative effect may contribute to or be at the origin of the unique progressive and severe neurological phenotype observed in affected patients.
Assuntos
Estudos de Associação Genética , Mutação de Sentido Incorreto , Proteínas Associadas à Matriz Nuclear/metabolismo , Fatores de Transcrição de Octâmero/metabolismo , Fenótipo , Proteínas de Ligação a RNA/metabolismo , Fatores de Transcrição SOXE/genética , Fatores de Transcrição SOXE/metabolismo , Linhagem Celular , Núcleo Celular/metabolismo , Proteínas de Ligação a DNA , Expressão Gênica , Humanos , Melanoma/genética , Melanoma/metabolismo , Proteínas Associadas à Matriz Nuclear/genética , Fatores de Transcrição de Octâmero/genética , Ligação Proteica , Transporte Proteico , Proteínas de Ligação a RNA/genética , Síndrome de Waardenburg/genética , Síndrome de Waardenburg/metabolismoRESUMO
Transcription factor SOX10 plays a role in the maintenance of progenitor cell multipotency, lineage specification, and cell differentiation and is a major actor in the development of the neural crest. It has been implicated in Waardenburg syndrome (WS), a rare disorder characterized by the association between pigmentation abnormalities and deafness, but SOX10 mutations cause a variable phenotype that spreads over the initial limits of the syndrome definition. On the basis of recent findings of olfactory-bulb agenesis in WS individuals, we suspected SOX10 was also involved in Kallmann syndrome (KS). KS is defined by the association between anosmia and hypogonadotropic hypogonadism due to incomplete migration of neuroendocrine gonadotropin-releasing hormone (GnRH) cells along the olfactory, vomeronasal, and terminal nerves. Mutations in any of the nine genes identified to date account for only 30% of the KS cases. KS can be either isolated or associated with a variety of other symptoms, including deafness. This study reports SOX10 loss-of-function mutations in approximately one-third of KS individuals with deafness, indicating a substantial involvement in this clinical condition. Study of SOX10-null mutant mice revealed a developmental role of SOX10 in a subpopulation of glial cells called olfactory ensheathing cells. These mice indeed showed an almost complete absence of these cells along the olfactory nerve pathway, as well as defasciculation and misrouting of the nerve fibers, impaired migration of GnRH cells, and disorganization of the olfactory nerve layer of the olfactory bulbs.
Assuntos
Surdez/genética , Predisposição Genética para Doença/genética , Síndrome de Kallmann/genética , Neuroglia/patologia , Condutos Olfatórios/patologia , Fatores de Transcrição SOXE/genética , Animais , Análise Mutacional de DNA , Surdez/patologia , Feminino , França , Galactosídeos , Células HeLa , Humanos , Indóis , Síndrome de Kallmann/patologia , Masculino , Camundongos , Mutação/genética , Plasmídeos/genéticaRESUMO
Mowat-Wilson syndrome (MWS) is a severe intellectual disability (ID)-distinctive facial gestalt-multiple congenital anomaly syndrome, commonly associating microcephaly, epilepsy, corpus callosum agenesis, conotruncal heart defects, urogenital malformations and Hirschsprung disease (HSCR). MWS is caused by de novo heterozygous mutations in the ZEB2 gene. The majority of mutations lead to haplo-insufficiency through premature stop codons or large gene deletions. Only three missense mutations have been reported so far; none of which resides in a known functional domain of ZEB2. In this study, we report and analyze the functional consequences of three novel missense mutations, p.Tyr1055Cys, p.Ser1071Pro and p.His1045Arg, identified in the highly conserved C-zinc-finger (C-ZF) domain of ZEB2. Patients' phenotype included the facial gestalt of MWS and moderate ID, but no microcephaly, heart defects or HSCR. In vitro studies showed that all the three mutations prevented binding and repression of the E-cadherin promoter, a characterized ZEB2 target gene. Taking advantage of the zebrafish morphant technology, we performed rescue experiments using wild-type (WT) and mutant human ZEB2 mRNAs. Variable, mutation-dependent, embryo rescue, correlating with the severity of patients' phenotype, was observed. Our data provide evidence that these missense mutations cause a partial loss of function of ZEB2, suggesting that its role is not restricted to repression of E-cadherin. Functional domains other than C-ZF may play a role in early embryonic development. Finally, these findings broaden the clinical spectrum of ZEB2 mutations, indicating that MWS ought to be considered in patients with lesser degrees of ID and a suggestive facial gestalt, even in the absence of congenital malformation.
Assuntos
Alelos , Doença de Hirschsprung/genética , Proteínas de Homeodomínio/genética , Deficiência Intelectual/genética , Microcefalia/genética , Mutação de Sentido Incorreto , Proteínas Repressoras/genética , Sequência de Aminoácidos , Animais , Linhagem Celular , DNA/metabolismo , Modelos Animais de Doenças , Fácies , Feminino , Ordem dos Genes , Proteínas de Homeodomínio/química , Proteínas de Homeodomínio/metabolismo , Humanos , Masculino , Dados de Sequência Molecular , Fenótipo , Ligação Proteica , Proteínas Repressoras/química , Proteínas Repressoras/metabolismo , Transcrição Gênica , Peixe-Zebra , Homeobox 2 de Ligação a E-box com Dedos de Zinco , Dedos de Zinco/genéticaRESUMO
A deletion encompassing several SOX10 enhancers was recently identified in a patient presenting with Waardenburg syndrome type 4 (WS4), which is defined as a combination of Hirschsprung disease (HSCR, intestinal aganglionosis) and WS (deafness and pigmentation defects). The expression patterns of some of the known SOX10 enhancers in animal models led to the speculation that endophenotypes of WS4 may be linked to mutations within some of these sequences. The present study investigated deletions and point mutations within four SOX10 enhancers in 144 unexplained isolated HSCR cases. One deletion and two point mutations affecting binding sites for known neural crest transcription factors were identified. In vitro functional analysis revealed that the first point mutation disrupts autoregulation by SOX10, whereas the second affects AP2a and SOX10 synergistic activity. The present findings suggest that the mutations within SOX10 enhancers contribute to isolated HSCR.
Assuntos
Sequências Reguladoras de Ácido Nucleico , Fatores de Transcrição SOXE/genética , Síndrome de Waardenburg/genética , Sequência de Bases , Feminino , Doença de Hirschsprung , Humanos , Lactente , Masculino , Dados de Sequência Molecular , Mutação Puntual , Deleção de Sequência , Fatores de Transcrição/genéticaRESUMO
The SOX10 transcription factor is a characteristic marker for migratory multipotent neural crest (NC) progenitors as well as several of their differentiated derivatives. The involvement of SOX10 in Waardenburg-Hirschsprung disease (pigmentation defects, deafness and intestinal aganglionosis) and studies of mutant animal models have contributed significantly to the understanding of its function in neural crest cells (NCC) in general and in the melanocytes and enteric nervous system (ENS) in particular. Cell-based studies have further demonstrated the important roles of this transcription factor in maintaining the NC progenitor cell number and in determining glial cell fate. Phenotypic variability observed among patients presenting with SOX10 mutations is in agreement with molecular genetics and animal model studies, which revealed that SOX10 cooperates with different partner factors; a number of genetic modifiers of SOX10 have been identified. This study reviews the expression, regulation, and function of SOX10 in normal development of the ENS and in disease conditions, as well as the genetic and molecular interactions of SOX10 with other ENS genes/factors. We also discuss future research areas. Further understanding of SOX10 function will benefit from genomic and cell biological studies that integrate the cell-intrinsic molecular mechanisms and the interactions of the enteric NCC with the niche environment.
Assuntos
Sistema Nervoso Entérico/embriologia , Sistema Nervoso Entérico/metabolismo , Fatores de Transcrição SOXE/metabolismo , Animais , Sequência de Bases , Regulação da Expressão Gênica no Desenvolvimento , Humanos , Modelos Animais , Dados de Sequência Molecular , Mutação/genética , Crista Neural/citologia , Fatores de Transcrição SOXE/química , Fatores de Transcrição SOXE/genéticaRESUMO
SOX10 involvement in syndromic form of Hirschsprung disease (intestinal aganglionosis, HSCR) in humans as well as developmental defects in animal models highlight the importance of this transcription factor in control of the pool of enteric progenitors and their differentiation. Here, we characterized the role of SOX10 in cell migration and its interactions with ß1-integrins. To this end, we crossed the Sox10(lacZ/+) mice with the conditional Ht-PA::Cre; beta1(neo/+) and beta1(fl/fl) mice and compared the phenotype of embryos of different genotypes during enteric nervous system (ENS) development. The Sox10(lacZ/+); Ht-PA::Cre; beta1(neo/fl) double mutant embryos presented with increased intestinal aganglionosis length and more severe neuronal network disorganization compared to single mutants. These defects, detected by E11.5, are not compensated after birth, showing that a coordinated and balanced interaction between these two genes is required for normal ENS development. Use of video-microscopy revealed that defects observed result from reduced migration speed and altered directionality of enteric neural crest cells. Expression of ß1-integrins upon SOX10 overexpression or in Sox10(lacZ/+) mice was also analyzed. The modulation of SOX10 expression altered ß1-integrins, suggesting that SOX10 levels are critical for proper expression and function of this adhesion molecule. Together with previous studies, our results strongly indicate that SOX10 mediates ENCC adhesion and migration, and contribute to the understanding of the molecular and cellular basis of ENS defects observed both in mutant mouse models and in patients carrying SOX10 mutations.
Assuntos
Movimento Celular , Integrina beta1/metabolismo , Crista Neural/metabolismo , Fatores de Transcrição SOXE/metabolismo , Animais , Adesão Celular , Linhagem Celular Tumoral , Cruzamentos Genéticos , Modelos Animais de Doenças , Embrião de Mamíferos/metabolismo , Sistema Nervoso Entérico/embriologia , Sistema Nervoso Entérico/metabolismo , Sistema Nervoso Entérico/patologia , Regulação da Expressão Gênica no Desenvolvimento , Haploinsuficiência , Doença de Hirschsprung/embriologia , Doença de Hirschsprung/metabolismo , Doença de Hirschsprung/patologia , Integrina beta1/genética , Camundongos , Crista Neural/citologia , Crista Neural/patologia , Fenótipo , Mapeamento de Interação de Proteínas , Fatores de Transcrição SOXE/genéticaRESUMO
Waardenburg syndrome (WS) is characterized by an association of pigmentation abnormalities and sensorineural hearing loss. Four types, defined on clinical grounds, have been delineated, but this phenotypic classification correlates imperfectly with known molecular anomalies. SOX10 mutations have been found in patients with type II and type IV WS (i.e., with Hirschsprung disease), more complex syndromes, and partial forms of the disease. The phenotype induced by SOX10 mutations is highly variable and, except for the neurological forms of the disease, no genotype-phenotype correlation has been characterized to date. There is no mutation hotspot in SOX10 and most cases are sporadic, making it particularly difficult to correlate the phenotypic and genetic variability. This study reports on three independent families with SOX10 mutations predicted to result in the same missense mutation at the protein level (p.Met112Ile), offering a rare opportunity to improve our understanding of the mechanisms underlying phenotypic variability. The pigmentation defects of these patients are very similar, and the neurological symptoms showed a somewhat similar evolution over time, indicating a potential partial genotype-phenotype correlation. However, variability in gastrointestinal symptoms suggests that other genetic factors contribute to the expression of these phenotypes. No correlation between the rs2435357 polymorphism of RET and the expression of Hirschsprung disease was found. In addition, one of the patients has esophageal achalasia, which has rarely been described in WS.
Assuntos
Mutação/genética , Polimorfismo de Nucleotídeo Único/genética , Fatores de Transcrição SOXE/genética , Síndrome de Waardenburg/genética , Síndrome de Waardenburg/patologia , Adolescente , Adulto , Criança , Pré-Escolar , Família , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Linhagem , Fenótipo , Proto-Oncogene MasRESUMO
Adar null mutant mouse embryos die with aberrant double-stranded RNA (dsRNA)-driven interferon induction, and Adar Mavs double mutants, in which interferon induction is prevented, die soon after birth. Protein kinase R (Pkr) is aberrantly activated in Adar Mavs mouse pup intestines before death, intestinal crypt cells die, and intestinal villi are lost. Adar Mavs Eifak2 (Pkr) triple mutant mice rescue all defects and have long-term survival. Adenosine deaminase acting on RNA 1 (ADAR1) and PKR co-immunoprecipitate from cells, suggesting PKR inhibition by direct interaction. AlphaFold studies on an inhibitory PKR dsRNA binding domain (dsRBD)-kinase domain interaction before dsRNA binding and on an inhibitory ADAR1 dsRBD3-PKR kinase domain interaction on dsRNA provide a testable model of the inhibition. Wild-type or editing-inactive human ADAR1 expressed in A549 cells inhibits activation of endogenous PKR. ADAR1 dsRNA binding is required for, but is not sufficient for, PKR inhibition. Mutating the ADAR1 dsRBD3-PKR contact prevents co-immunoprecipitation, ADAR1 inhibition of PKR activity, and co-localization of ADAR1 and PKR in cells.
RESUMO
Waardenburg syndrome (WS) is a rare disorder characterized by pigmentation defects and sensorineural deafness, classified into four clinical subtypes, WS1-S4. Whereas the absence of additional features characterizes WS2, association with Hirschsprung disease defines WS4. WS is genetically heterogeneous, with six genes already identified, including SOX10. About 50 heterozygous SOX10 mutations have been described in patients presenting with WS2 or WS4, with or without myelination defects of the peripheral and central nervous system (PCWH, Peripheral demyelinating neuropathy-Central dysmyelinating leukodystrophy-Waardenburg syndrome-Hirschsprung disease, or PCW, PCWH without HD). The majority are truncating mutations that most often remove the main functional domains of the protein. Only three missense mutations have been thus far reported. In the present study, novel SOX10 missense mutations were found in 11 patients and were examined for effects on SOX10 characteristics and functions. The mutations were associated with various phenotypes, ranging from WS2 to PCWH. All tested mutations were found to be deleterious. Some mutants presented with partial cytoplasmic redistribution, some lost their DNA-binding and/or transactivation capabilities on various tissue-specific target genes. Intriguingly, several mutants were redistributed in nuclear foci. Whether this phenomenon is a cause or a consequence of mutation-associated pathogenicity remains to be determined, but this observation could help to identify new SOX10 modes of action.
Assuntos
Mutação de Sentido Incorreto , Fatores de Transcrição SOXE/genética , Síndrome de Waardenburg/genética , Síndrome de Waardenburg/patologia , Adolescente , Adulto , Linhagem Celular , Criança , Pré-Escolar , Feminino , Células HeLa , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Fenótipo , Fatores de Transcrição SOXE/metabolismo , Síndrome de Waardenburg/classificação , Adulto JovemRESUMO
The involvement of SOX10 and ZFHX1B in Waardenburg-Hirschsprung disease (hypopigmentation, deafness, and absence of enteric ganglia) and Mowat-Wilson syndrome (mental retardation, facial dysmorphy and variable congenital malformations including Hirschsprung disease) respectively, highlighted the importance of both transcription factors during enteric nervous system (ENS) development. The expression and function of SOX10 are now well established, but those of ZFHX1B remain elusive. Here we describe the expression profile of Zfhx1b and its genetic interactions with Sox10 during mouse ENS development. Through phenotype analysis of Sox10;Zfhx1b double mutants, we show that a coordinated and balanced interaction between these two genes is required for normal ENS development. Double mutants present with more severe ENS defects due to decreased proliferation of enteric progenitors and increased neuronal differentiation from E11.5 onwards. Thus, joint activity between these two transcription factors is crucial for proper ENS development and our results contribute to the understanding of the molecular basis of ENS defects observed both in mutant mouse models and in patients carrying SOX10 and ZFHX1B mutations.
Assuntos
Sistema Nervoso Entérico/embriologia , Proteínas de Homeodomínio/metabolismo , Proteínas Repressoras/metabolismo , Fatores de Transcrição SOXE/metabolismo , Animais , Cruzamentos Genéticos , Embrião de Mamíferos/metabolismo , Sistema Nervoso Entérico/citologia , Sistema Nervoso Entérico/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Doença de Hirschsprung/metabolismo , Proteínas de Homeodomínio/genética , Humanos , Camundongos , Camundongos Endogâmicos C3H , Camundongos Knockout , Mutação , Neuroglia/metabolismo , Proteínas Repressoras/genética , Fatores de Transcrição SOXE/genética , Células-Tronco/metabolismo , Homeobox 2 de Ligação a E-box com Dedos de ZincoRESUMO
Hirschsprung disease (HSCR) is the most frequent developmental anomaly of the enteric nervous system, with an incidence of 1 in 5000 live births. Chronic intestinal pseudo-obstruction (CIPO) is less frequent and classified as neurogenic or myogenic. Isolated HSCR has an oligogenic inheritance with RET as the major disease-causing gene, while CIPO is genetically heterogeneous, caused by mutations in smooth muscle-specific genes. Here, we describe a series of patients with developmental disorders including gastrointestinal dysmotility, and investigate the underlying molecular bases. Trio-exome sequencing led to the identification of biallelic variants in ERBB3 and ERBB2 in 8 individuals variably associating HSCR, CIPO, peripheral neuropathy, and arthrogryposis. Thorough gut histology revealed aganglionosis, hypoganglionosis, and intestinal smooth muscle abnormalities. The cell type-specific ErbB3 and ErbB2 function was further analyzed in mouse single-cell RNA sequencing data and in a conditional ErbB3-deficient mouse model, revealing a primary role for ERBB3 in enteric progenitors. The consequences of the identified variants were evaluated using quantitative real-time PCR (RT-qPCR) on patient-derived fibroblasts or immunoblot assays on Neuro-2a cells overexpressing WT or mutant proteins, revealing either decreased expression or altered phosphorylation of the mutant receptors. Our results demonstrate that dysregulation of ERBB3 or ERBB2 leads to a broad spectrum of developmental anomalies, including intestinal dysmotility.
Assuntos
Deficiências do Desenvolvimento/genética , Pseudo-Obstrução Intestinal/genética , Mutação , Neuregulina-1/genética , Receptor ErbB-2/genética , Receptor ErbB-3/genética , Adolescente , Animais , Pré-Escolar , Deficiências do Desenvolvimento/patologia , Modelos Animais de Doenças , Feminino , Motilidade Gastrointestinal/genética , Doença de Hirschsprung/genética , Doença de Hirschsprung/patologia , Humanos , Recém-Nascido , Pseudo-Obstrução Intestinal/patologia , Masculino , Camundongos , Modelos Moleculares , Linhagem , Fenótipo , Gravidez , Receptor ErbB-2/química , Receptor ErbB-3/química , Receptor ErbB-3/deficiênciaRESUMO
Waardenburg syndrome (WS) is characterized by the association of pigmentation abnormalities, including depigmented patches of the skin and hair, vivid blue eyes or heterochromia irides, and sensorineural hearing loss. However, other features such as dystopia canthorum, musculoskeletal abnormalities of the limbs, Hirschsprung disease, or neurological defects are found in subsets of patients and used for the clinical classification of WS. Six genes are involved in this syndrome: PAX3 (encoding the paired box 3 transcription factor), MITF (microphthalmia-associated transcription factor), EDN3 (endothelin 3), EDNRB (endothelin receptor type B), SOX10 (encoding the Sry bOX10 transcription factor), and SNAI2 (snail homolog 2), with different frequencies. In this review we provide an update on all WS genes and set up mutation databases, summarize molecular and functional data available for each of them, and discuss the applications in diagnostics and genetic counseling.
Assuntos
Mutação/genética , Síndrome de Waardenburg/genética , Humanos , Fatores de Transcrição/genética , Síndrome de Waardenburg/classificação , Síndrome de Waardenburg/diagnóstico , Síndrome de Waardenburg/patologiaRESUMO
Waardenburg syndrome (WS) is an auditory-pigmentary disorder that exhibits varying combinations of sensorineural hearing loss and abnormal pigmentation of the hair and skin. Depending on additional symptoms, WS is classified into four subtypes, WS1-WS4. Absence of additional features characterizes WS2. The association of facial dysmorphic features defines WS1 and WS3, whereas the association with Hirschsprung disease (aganglionic megacolon) characterizes WS4, also called "Waardenburg-Hirschsprung disease." Mutations within the genes MITF and SNAI2 have been identified in WS2, whereas mutations of EDN3, EDNRB, and SOX10 have been observed in patients with WS4. However, not all cases are explained at the molecular level, which raises the possibility that other genes are involved or that some mutations within the known genes are not detected by commonly used genotyping methods. We used a combination of semiquantitative fluorescent multiplex polymerase chain reaction and fluorescent in situ hybridization to search for SOX10 heterozygous deletions. We describe the first characterization of SOX10 deletions in patients presenting with WS4. We also found SOX10 deletions in WS2 cases, making SOX10 a new gene of WS2. Interestingly, neurological phenotypes reminiscent of that observed in WS4 (PCWH syndrome [peripheral demyelinating neuropathy, central dysmyelinating leukodystrophy, WS, and Hirschsprung disease]) were observed in some WS2-affected patients with SOX10 deletions. This study further characterizes the molecular complexity and the close relationship that links the different subtypes of WS.