Digenic inheritance of non-syndromic deafness caused by mutations at the gap junction proteins Cx26 and Cx31.
Mutations in the genes coding for connexin 26 (Cx26) and connexin 31 (Cx31) cause non-syndromic deafness. Here, we provide evidence that mutations at these two connexin genes can interact to cause hearing loss in digenic heterozygotes in humans. We have screened 108 GJB2 heterozygous Chinese patients for mutations in GJB3 by sequencing. We have excluded the possibility that mutations in exon 1 of GJB2 and the deletion of GJB6 are the second mutant allele in these Chinese heterozygous probands. Two different GJB3 mutations (N166S and A194T) occurring in compound heterozygosity with the 235delC and 299delAT of GJB2 were identified in three unrelated families (235delC/N166S, 235delC/A194T and 299delAT/A194T). Neither of these mutations in Cx31 was detected in DNA from 200 unrelated Chinese controls. Direct physical interaction of Cx26 with Cx31 is supported by data showing that Cx26 and Cx31 have overlapping expression patterns in the cochlea. In addition, by coimmunoprecipitation of mouse cochlear membrane proteins, we identified the presence of heteromeric Cx26/Cx31 connexons. Furthermore, by cotransfection of mCherry-tagged Cx26 and GFP-tagged Cx31 in human embryonic kidney (HEK)-293 cells, we demonstrated that the two connexins were able to co-assemble in vitro in the same junction plaque. Together, our data indicate that a genetic interaction between these two connexin genes can lead to hearing loss.
Liu
Xue-Zhong
XZ
Department of Otolaryngology (D-48), University of Miami, 1666 NW 12th Avenue, Miami, FL 33136, USA. xliu@med.miami.edu
Yuan
Yongyi
Y
Yan
Denise
D
Ding
Emilie Hong
EH
Ouyang
Xiao Mei
XM
Fei
Yu
Y
Tang
Wenxue
W
Yuan
Huijun
H
Chang
Qing
Q
Du
Li Lin
LL
Zhang
Xin
X
Wang
Guojian
G
Ahmad
Shoeb
S
Kang
Dong Yang
DY
Lin
Xi
X
Dai
Pu
P
D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D003051:Cochlea / Q000378:metabolism; D000072259:Connexin 26; D017630:Connexins / Q000235:genetics* / Q000378:metabolism; D003638:Deafness / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009154:Mutation; D010375:Pedigree; D025941:Protein Interaction Mapping
D017630:Connexins; C000607042:GJB2 protein, human; C000607043:Gjb2 protein, mouse; D000072259:Connexin 26; C068044:GJB3 protein, human