Three common GJB2 mutations causing nonsyndromic hearing loss in Chinese populations are retained in the endoplasmic reticulum.
CONCLUSIONS
The three most common GJB2 mutations found in the Chinese populations, c.235delC, c.299-300delAT, and c.176-191de1 (16) bp, cannot form gap junctons (GJs) in the plasma membrane. These mutant proteins were retained in the endoplasmic reticulum (ER), suggesting that ER stress (ERS) and subsequent ERS-induced cell death may be responsible for hearing loss caused by these GJB2 truncation mutations.


OBJECTIVE
The objective of this study was to investigate the subcellular location of the protein products of three GJB2 mutants (c.235de1C, c.299-300delAT, and c.176-191de1 (16) bp) and to explore the deafness mechanism caused by these GJB2 truncation mutations.


METHODS
Mutant-eGFP fusion protein vectors were constructed by PCR and TA cloning. HEK293 cells were transfected by a liposome-mediated method. Transfected cells were incubated with ER-Tracker and observed under a confocal microscope.


RESULTS
Cells transfected with wild type gave characteristic punctuate patterns of GJs in the cell membrane. In contrast, c.235de1C, c.299-300delAT, and c.176-191de1 (16) bp mutant proteins were found to be trapped in the ER, and were therefore unable to form GJs in the plasma membrane.
Zhang
Yanping
Y
Department of Otolaryngology, Hospital of Chinese PLA, Beijing, China. yanping309@yahoo.com <yanping309@yahoo.com>
Wang
Ju
J
Li
Lina
L
Sun
Yurui
Y
Feng
Bo
B
D015153:Blotting, Western; D002681:China; D000072259:Connexin 26; D017630:Connexins / Q000235:genetics / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D006319:Hearing Loss, Sensorineural / Q000235:genetics*; D006801:Humans; D018613:Microscopy, Confocal; D050505:Mutant Proteins / Q000378:metabolism; D009154:Mutation; D014162:Transfection
D017630:Connexins; C000607042:GJB2 protein, human; D050505:Mutant Proteins; D000072259:Connexin 26