Differentially altered Ca2+ regulation and Ca2+ permeability in Cx26 hemichannels formed by the A40V and G45E mutations that cause keratitis ichthyosis deafness syndrome.
Differentially altered Ca2+ regulation and Ca2+ permeability in Cx26 hemichannels formed by the A40V and G45E mutations that cause keratitis ichthyosis deafness syndrome.
复制标题
DOI：
10.1085/jgp.201010433
复制
发表时间：
2010-07
期刊：
影响因子：
--
通讯作者：
Verselis VK
中科院分区：
文献类型：
--
作者：
Sánchez HA;Mese G;Srinivas M;White TW;Verselis VK
编码 Cx26 的 GJB2 突变是人类遗传性耳聋的最常见原因之一。已发现 100 多个突变分散在 Cx26 蛋白中，其中大多数会导致非综合征性感音神经性耳聋。在一部分突变中，耳聋伴有角化过度皮肤病，这种疾病通常很严重，有时甚至致命。许多综合征性耳聋突变定位于氨基末端和第一细胞外环 (E1) 结构域。在这里，我们检查了两个这样的突变，A40V 和 G45E，它们位于 TM1/E1 边界附近，与角膜炎鱼鳞病耳聋 (KID) 综合征相关。据报道，这两种突变体都会形成异常打开的半通道，导致细胞膜“渗漏”。在这里，我们量化了 Ca2+ 敏感性，并在宏观和单通道水平上检查了这些突变体的生物物理特性。我们发现 A40V 半通道显示出细胞外 Ca2+ 的调节显着受损，增加了先前建议的异常半通道开放的可能性。然而，G45E 半通道仅表现出对 Ca2+ 调节的适度损害，相反表现出对 Ca2+ 的渗透性的显着增加。通过半胱氨酸取代并检查硫醇修饰试剂的可及性，我们证明 G45 而不是 A40 是孔衬里残基。两种突变体都充当细胞-细胞通道。数据表明，G45E 和 A40V 是半通道功能获得突变体，它们产生相似的表型，但潜在机制不同。 A40V 产生渗漏的半通道，而 G45E 则提供了 Ca2+ 过量进入的途径。这些异常特性，单独或组合起来，会严重损害细胞完整性并导致细胞死亡增加。
Mutations in GJB2, which encodes Cx26, are one of the most common causes of inherited deafness in humans. More than 100 mutations have been identified scattered throughout the Cx26 protein, most of which cause nonsyndromic sensorineural deafness. In a subset of mutations, deafness is accompanied by hyperkeratotic skin disorders, which are typically severe and sometimes fatal. Many of these syndromic deafness mutations localize to the amino-terminal and first extracellular loop (E1) domains. Here, we examined two such mutations, A40V and G45E, which are positioned near the TM1/E1 boundary and are associated with keratitis ichthyosis deafness (KID) syndrome. Both of these mutants have been reported to form hemichannels that open aberrantly, leading to “leaky” cell membranes. Here, we quantified the Ca2+ sensitivities and examined the biophysical properties of these mutants at macroscopic and single-channel levels. We find that A40V hemichannels show significantly impaired regulation by extracellular Ca2+, increasing the likelihood of aberrant hemichannel opening as previously suggested. However, G45E hemichannels show only modest impairment in regulation by Ca2+ and instead exhibit a substantial increase in permeability to Ca2+. Using cysteine substitution and examination of accessibility to thiol-modifying reagents, we demonstrate that G45, but not A40, is a pore-lining residue. Both mutants function as cell–cell channels. The data suggest that G45E and A40V are hemichannel gain-of-function mutants that produce similar phenotypes, but by different underlying mechanisms. A40V produces leaky hemichannels, whereas G45E provides a route for excessive entry of Ca2+. These aberrant properties, alone or in combination, can severely compromise cell integrity and lead to increased cell death.
登录
查看更多内容
DOI：
10.1038/jid.2008.335
发表时间：
2009-04
期刊：
The Journal of investigative dermatology
影响因子：
--
作者：
Lee JR;Derosa AM;White TW
通讯作者：
White TW
影响因子：
--
作者：
Kronengold, J;Trexler, EB;Verselis, VK
通讯作者：
Verselis, VK
影响因子：
4.8
作者：
Gonzalez, Daniel;Gomez-Hernandez, Juan M.;Barrio, Luis C.
通讯作者：
Barrio, Luis C.
DOI：
10.1085/jgp.200308861
发表时间：
2003-10
期刊：
The Journal of general physiology
影响因子：
--
作者：
Kronengold J;Trexler EB;Bukauskas FF;Bargiello TA;Verselis VK
通讯作者：
Verselis VK
影响因子：
2.9
作者：
Hoang Dinh E;Ahmad S;Chang Q;Tang W;Stong B;Lin X
通讯作者：
Lin X