Impaired membrane targeting and aberrant cellular localization of human Cx26 mutants associated with inherited recessive hearing loss

Abstract

Conclusion: This study demonstrated that five Cx26 mutations (R32H, S199F, 572delT, 631-632delGT, and Y155X) affect gap junction (GJ) functions by causing impaired membrane targeting and aberrant cellular localization, and one mutation (R165W) leads to a constriction of the channel pore with no dye coupling. Objective: To investigate the pathogenetic roles of six recessive Cx26 mutations (p.R32H, p.R165W, p.S199F, c.572delT, c.631-632delGT, and p.Y155X), which have not been functionally analyzed in vitro. Methods: The six mutants and wild-type Cx26 (wtCx26) were cloned into the EcoRI and SalI sites of pEGFP-N1 vector. We transfected the seven constructs into HeLa cells, followed by analysis of their protein expression using the western blot method, study of the protein localizations and gap junction-plaques on the cytomembrane under confocal microscopy, and assessment of the dye coupling of the mutated GJ channels by intercellular dye transfer experiment. Results: p.R165W targeted the cytomembrane and formed GJ-like structures in adjacent HeLa cells, causing null dye coupling. The mutants (p.R32H, p.S199F, c.572delT, c.631-632delGT, and p.Y155X) failed to reach the cell surface, and perfectly co-localized with endoplasmic reticulum (ER) throughout the cells.

Keywords::

• Mutant
• HeLa cell
• functional study

Acknowledgments

This project was supported by the National Nature Science Foundation of China (grant nos 30000094 and 30070807) and the Postdoctoral Science Foundation of Central South University, China.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.