RESUMO
Neural tube defects (NTDs) are severe birth malformations that affect one in 1,000 live births. Recently, mutations in the planar cell polarity (PCP) pathway genes had been implicated in the pathogenesis of NTDs in both the mouse model and in human cohorts. Mouse models indicate that the homozygous disruption of Sec24b, which mediates the ER-to-Golgi transportation of the core PCP gene Vangl2 as a component of the COPII vesicle, will result in craniorachischisis. In this study, we found four rare missense heterozygous SEC24B mutations (p.Phe227Ser, p.Phe682Leu, p.Arg1248Gln, and p.Ala1251Gly) in NTDs cases that were absent in all controls. Among them, p.Phe227Ser and p.Phe682Leu affected its protein stability and physical interaction with VANGL2. Three variants (p.Phe227Ser, p.Arg1248Gln, and p.Ala1251Gly) were demonstrated to affect VANGL2 subcellular localization in cultured cells. Further functional analysis in the zebrafish including overexpression and dosage-dependent rescue study suggested that these four mutations all displayed loss-of-function effects compared with wild-type SEC24B. Our study demonstrated that functional mutations in SEC24B might contribute to the etiology of a subset of human NTDs and further expanded our knowledge of the role of PCP pathway-related genes in the pathogenesis of human NTDs.
Assuntos
Peptídeos e Proteínas de Sinalização Intracelular/química , Proteínas de Membrana/química , Mutação de Sentido Incorreto , Defeitos do Tubo Neural/genética , Proteínas de Transporte Vesicular/química , Proteínas de Transporte Vesicular/genética , Animais , Estudos de Casos e Controles , Polaridade Celular , Feminino , Expressão Gênica , Variação Genética , Células HEK293 , Células HeLa , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Masculino , Proteínas de Membrana/metabolismo , Camundongos , Defeitos do Tubo Neural/etiologia , Defeitos do Tubo Neural/patologia , Estabilidade Proteica , Estrutura Quaternária de Proteína , Análise de Sequência de DNA , Proteínas de Transporte Vesicular/metabolismo , Peixe-Zebra/embriologia , Peixe-Zebra/genéticaRESUMO
Neural tube defects (NTDs) constitute the second most frequent cause of human congenital abnormalities. Complex multigenetic causes have been suggested to contribute to NTDs. The planar cell polarity (PCP) pathway plays a critical role in neural tube closure in model organisms and in human. Knockout of Dact1 (Dapper, Frodo) leads to deregulated PCP signaling with defective neural tube in mice. Here, we report that five missense heterozygote mutations of the DACT1 gene are specifically identified in 167 stillborn or miscarried Han Chinese fetuses with neural tube defects. Our biochemical analyses revealed that among the five mutations, N356K and R45W show loss-of-function or reduced activities in inducing Dishevelled2 (DVL2) degradation and inhibiting jun-N-terminal kinase (JNK) phosphorylation, implicating mutated DACT1 as a risk factor for human NTDs. Our findings, together with early reports, suggest that rare mutations of the PCP-related genes may constitute a great contribution to human NTDs.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/genética , Mutação , Defeitos do Tubo Neural/genética , Proteínas Nucleares/genética , Animais , Povo Asiático , Polaridade Celular/genética , Embrião de Mamíferos/metabolismo , Humanos , Camundongos , Camundongos KnockoutAssuntos
Peptídeos e Proteínas de Sinalização Intracelular/genética , Proteínas de Membrana/genética , Mutação de Sentido Incorreto , Defeitos do Tubo Neural/genética , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , China , Proteínas Desgrenhadas , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Proteínas de Membrana/metabolismo , Fosfoproteínas/metabolismoRESUMO
OBJECTIVE: To determine the genetic cause of sex reversal in a Chinese family. METHODS: Two sisters aged 21 and 20 years old were referred for primary amenorrhoea and poor secondary sexual development. They were subjected to clinical, endocrinologic and ultrasonographic investigation, and molecular analysis including cytogenetics, array CGH, SRY and SF-1 mutation screening. RESULTS: A novel 15bp micro-duplication in the SF-1 gene in patients affected by 46,XY sex-reversal phenotype without dysgenesis. CONCLUSION: The novel 15bp duplication of SF-1 gene affecting 46,XY females with diverse phenotypic spectrum. This provides new information for genetic counselling of disorders of sex development.
Assuntos
Disgenesia Gonadal 46 XY/genética , Fator Esteroidogênico 1/genética , Povo Asiático , China , Análise Mutacional de DNA , Feminino , Duplicação Gênica , Disgenesia Gonadal 46 XY/diagnóstico , Humanos , Fenótipo , Adulto JovemRESUMO
Congenital contractural arachnodactyly (Beals syndrome) is a rare autosomal dominantly inherited connective tissue disorder characterized by flexion contractures, arachnodactyly, crumpled ears, and mild muscular hypoplasia. Here, a father and son with congenital contractural arachnodactyly features were identified. After sequencing 15 exons (22 to 36) of the FBN2 gene, a novel mutation (C1425Y) was found in exon 33. This de novo mutation presented first in the father and was transmitted to his son, but not in the other 14 unaffected family members and 365 normal people. The C1425Y mutation occurs at the 19th cbEGF domain. Cysteines in this cbEGF domain are rather conserved in species, from human down to ascidian. The cbEGF12-13 in human FBN1 was employed as the template to perform homology modeling of cbEGF18-19 of human FBN2 protein. The mutation has also been evaluated by further prediction tools, for example, SIFT, Blosum62, biochemical Yu's matrice, and UMD-Predictor tool. In all analysis, the mutation is predicted to be pathogenic. Thus, the structure destabilization by C1425Y might be the cause of the disorder.