title: Functional analysis of a nonsyndromic hearing loss-associated mutation in the transmembrane II domain of the GJC3 gene.
abstract: In a previous study, we identified a novel missense mutation, p.W77S, in theGJC3gene encoding connexin30.2/connexin31.3 (CX30.2/CX31.3) from patients with hearing loss. The functional alteration of CX30.2/CX31.3 caused by the p.W77S mutant ofGJC3gene, however, remains unclear. In the current study, our result indicated that the p.W77 is localized at the second membrane-spanning segments (TM2) and near border of the E1 domain of the CX30.2/CX31.3 protein and highly conserved (Conseq score = 8~9) in all species. The p.W77S missense mutation proteins in the intracellular distribution are different CX30.2/CX31.3WT and an accumulation of the mutant protein in the endoplasmic reticulum (ER) of the HeLa cell. Furthermore, co-expression of WT and p.W77S mutant chimerae proteins showed that the heteromeric connexon accumulated in the cytoplasm, thereby impairing the WT proteins' expression in the cell membranes. In addition, we found that CX30.2/CX31.3W77S missense mutant proteins were degraded by lysosomes and proteosomes in the transfected HeLa cell. Based on these findings, we suggest that p.W77S mutant has a dominant negative effect on the formation and function of the gap junction. These results give a novel molecular elucidation for the mutation ofGJC3in the development of hearing loss.
authors.affiliation: Department of BioMedical Sciences, Chung Shan Medical University, Taichung, Taiwan;; Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan.
authors.forename: Swee-Hee
authors.initials: SH
authors.lastname: Wong
authors.affiliation: Department of Otolaryngology, Cathay General Hospital, Taipei, Taiwan.
authors.forename: Wen-Hung
authors.initials: WH
authors.lastname: Wang
authors.affiliation: Department of BioMedical Sciences, Chung Shan Medical University, Taichung, Taiwan.
authors.forename: Pin-Hua
authors.initials: PH
authors.lastname: Chen
authors.affiliation: Department of BioMedical Sciences, Chung Shan Medical University, Taichung, Taiwan;; Department of Medical Research, Chung Shan Medical University Hospital, Taichung, Taiwan.
authors.forename: Shuan-Yow
authors.initials: SY
authors.lastname: Li
authors.affiliation: Department of BioMedical Sciences, Chung Shan Medical University, Taichung, Taiwan;; Department of Medical Research, Chung Shan Medical University Hospital, Taichung, Taiwan.
authors.forename: Jiann-Jou
authors.initials: JJ
authors.lastname: Yang
mesh_terms: D017630:Connexins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D003638:Deafness / Q000235:genetics* / Q000473:pathology; D004721:Endoplasmic Reticulum / Q000737:chemistry / Q000235:genetics; D017629:Gap Junctions / Q000235:genetics / Q000473:pathology; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006801:Humans; D008247:Lysosomes / Q000235:genetics; D020125:Mutation, Missense; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D000072417:Protein Domains; D059748:Proteolysis; D013329:Structure-Activity Relationship
chemical_list: D017630:Connexins; C464674:GJC3 protein, human; D009419:Nerve Tissue Proteins
keywords: CX30.2/CX31.3; GJC3; hearing loss.; mutation