Pathogenetic role of the deafness-related M34T mutation of Cx26
Pathogenetic role of the deafness-related M34T mutation of Cx26
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DOI：
10.1093/hmg/ddl184
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发表时间：
2006-09-01
影响因子：
3.5
通讯作者：
Mammano, Fabio
中科院分区：
文献类型：
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作者：
Bicego, Massimiliano;Beltramello, Martina;Mammano, Fabio
编码差距连接蛋白连接蛋白26（Cx 26）的GJB 2基因突变是遗传性非综合征性听力损失的主要原因。等位基因变异M34 T在导致遗传性耳聋中的作用仍然存在争议。通过结合遗传、临床、生化、电生理和结构建模研究，我们重新评估了M34 T突变的致病作用。遗传和听力学数据表明，大多数杂合子携带者和所有五个复合杂合子表现出受损的听觉功能。瞬时转染HeLa细胞中的功能表达表明，虽然M34 T被正确地合成并靶向质膜，但它不能有效地形成显示异常电行为的细胞间通道，并且仅保留野生型蛋白（HCx 26 wt）的单位电导的11%。此外，M34 T通道未能支持荧光黄的细胞间扩散和机械诱导的细胞间Ca 2+波的传播。当与HCx 26 wt共表达时，M34 T对细胞-细胞偶联产生显性负效应。我们的研究结果是一致的结构模型，预测突变导致收缩的通道孔。这些数据支持M34 T是与听力障碍相关的Cx 26的病理变异的观点。
Mutations in the GJB2 gene, which encodes the gap junction protein connexin26 (Cx26), are the major cause of genetic non-syndromic hearing loss. The role of the allelic variant M34T in causing hereditary deafness remains controversial. By combining genetic, clinical, biochemical, electrophysiological and structural modeling studies, we have re-assessed the pathogenetic role of the M34T mutation. Genetic and audiological data indicate that the majority of heterozygous carriers and all five compound heterozygotes exhibited an impaired auditory function. Functional expression in transiently transfected HeLa cells showed that, although M34T was correctly synthesized and targeted to the plasma membrane, it inefficiently formed intercellular channels that displayed an abnormal electrical behavior and retained only 11% of the unitary conductance of the wild-type protein (HCx26wt). Moreover, M34T channels failed to support the intercellular diffusion of Lucifer Yellow and the spreading of mechanically induced intercellular Ca2+ waves. When co-expressed together with HCx26wt, M34T exerted dominant-negative effects on cell-cell coupling. Our findings are consistent with a structural model, predicting that the mutation leads to a constriction of the channel pore. These data support the view that M34T is a pathological variant of Cx26 associated with hearing impairment.