A novel variant in the GJB6 gene in a large Chinese family with a unique phenotype of Clouston syndrome / 医学前沿

Clouston syndrome (OMIM #129500), also known as hidrotic ectodermal dysplasia type 2, is a rare autosomal dominant skin disorder. To date, four mutations in the GJB6 gene, G11R, V37E, A88V, and D50N, have been confirmed to cause this condition. In previous studies, the focus has been mainly on gene sequencing, and there has been a lack of research on clinical manifestations and pathogenesis. To confirm the diagnosis of this pedigree at the molecular level and summarize and analyse the clinical phenotype of patients and to provide a basis for further study of the pathogenesis of the disease, we performed whole-exome and Sanger sequencing on a large Chinese Clouston syndrome pedigree. Detailed clinical examination included histopathology, hair microscopy, and scanning electron microscopy. We found a novel heterozygous missense variant (c.134G>C:p.G45A) for Clouston syndrome. We identified a new clinical phenotype involving all nail needling pain in all patients and found a special honeycomb hole structure in the patients' hair under scanning electron microscopy. Our data reveal that a novel variant (c.134G>C:p.G45A) plays a likely pathogenic role in this pedigree and highlight that genetic testing is necessary for the diagnosis of Clouston syndrome.

Mechanistic effect of the human GJB6 gene and its mutations in HaCaT cell proliferation and apoptosis

We constructed lentiviral vectors containing the human wild-type GJB6 gene and the mutant variants A88V and G11R. The three proteins were stably expressed by the Tet-on system in the HaCaT cell line and used to study the functional effect of the variants. The CCK-8 assay and flow cytometric analyses were used to determine the levels of cell proliferation and apoptosis. Western blot analyses were performed to analyze the relevant clinical indicators of hidrotic ectodermal dysplasia and markers of apoptosis in transfected HaCaT cells. The CCK8 assay and the flow cytometry results showed a significant increase (P<0.05) in the apoptosis of HaCaT cells expressing the A88V and G11R mutants. In addition, we demonstrated that the A88V and G11R mutants induced the apoptosis of transfected HaCaT cells via the activation of caspase-3, -8, -9, and PARA. No change was observed in the activity of BAX compared with the control. This study provides further clarification on the mechanisms underlying the effect of the mutant variants A88V and G11R of the GJB6 gene on the induction of HaCaT cell apoptosis.

Construction of HaCaT cell lines stably expressing the human GJB6 gene by using a Tet-On lentiviral vector and their identification / 中华皮肤科杂志

Objective To construct HaCaT cell lines stably expressing the wild type human GJB6 gene or its mutant by using a Tet-On lentiviral vector, and to lay an experimental foundation for studies on pathogenesis of hidrotic ectodermal dysplasia. Methods The wild-type human GJB6 gene and its mutant (A88V)were amplified by PCR, and then inserted into the Tet-on lentivirus plasmid to construct recombinant lentivirus vectors. The recombinants were identified by gene sequencing and enzymatic digestion. Cultured HaCaT cells were classified into three groups to be transfected with a negative control lentiviral vector (NC group), the lentivirus vector expressing the wild-type human GJB6 gene (WT group), or the lentivirus vector expressing the mutant human GJB6 gene (MU group). Puromycin was used to select HaCaT cell clones stably expressing the GJB6 gene which encodes the connexin 30 (Cx30)protein. The selected HaCaT cell clones were cultured with or without tetracycline for 48 hours, thereafter, real-time PCR(RT-PCR) was performed to detect GJB6 gene mRNA expression, Western-blot analysis to measure expressions of Cx30 and FLAG-tag proteins, and cell counting kit 8 (CCK8)assay to evaluate cellular proliferative activity. Results Enzymatic digestion and gene sequencing showed that recombinant lentivirus plasmids were successfully constructed. RT-PCR showed evidently increased mRNA expression of the GJB6 gene in stably transfected HaCaT cells. Moreover, the expression abundance of the GJB6 gene was 112.369 times higher in the WT group induced by tetracycline than in that without tetracycline treatment (P 0.05). Conclusion HaCaT cell lines which stably express the wild-type GJB6 gene or its mutant(A88V)are successfully constructed.