A MUTATION IN THE EPITHELIAL SODIUM-CHANNEL CAUSING LIDDLE DISEASE INCREASES CHANNEL ACTIVITY IN THE XENOPUS-LAEVIS OOCYTE EXPRESSION SYSTEM
A MUTATION IN THE EPITHELIAL SODIUM-CHANNEL CAUSING LIDDLE DISEASE INCREASES CHANNEL ACTIVITY IN THE XENOPUS-LAEVIS OOCYTE EXPRESSION SYSTEM
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DOI：
10.1073/pnas.92.12.5699
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发表时间：
1995-06-06
影响因子：
11.1
通讯作者：
ROSSIER, BC
中科院分区：
文献类型：
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作者：
SCHILD, L;CANESSA, CM;ROSSIER, BC
我们已经研究了上皮性Na+通道突变的功能后果，该突变导致一种可遗传的盐敏感型高血压，即利德尔病。在利德尔描述的原始家族中发现的这种突变，在通道β亚基中引入了一个提前停止密码子，导致编码蛋白质的几乎所有C末端缺失。突变的β亚基与野生型α和伽马亚基在非洲爪哇卵母细胞中的共表达导致宏观阿米洛利敏感的NAF电流(I-Na)比野生型通道增加近3倍。I-Na的这种变化反映了整体通道活性的增加，其特征是膜片上活跃通道的数量更多。上皮性Na+通道β亚基截短突变不改变通道的生物物理和药理特性，包括单一电导、离子选择性或对阿米洛利阻断的敏感性。这些结果为利德尔病与细胞膜结构性通道过度活动有关提供了直接的生理学证据。大鼠上皮Na+通道β亚基和γ亚基C末端的缺失在功能上是相同的，提示γ亚基的胞质结构域可能是导致盐敏感型高血压的另一个分子靶点。
We have studied the functional consequences of a mutation in the epithelial Na+ channel that causes a heritable form of salt-sensitive hypertension, Liddle disease. This mutation, identified in the original kindred described by Liddle, introduces a premature stop codon in the channel beta subunit, resulting in a deletion of almost all of the C terminus of the encoded protein. Coexpression of the mutant beta subunit with wild-type alpha and gamma subunits in Xenopus laevis oocytes resulted in an approximate to 3-fold increase in the macroscopic amiloride-sensitive Naf current (I-Na) compared with the wild-type channel. This change in I-Na reflected an increase in the overall channel activity characterized by a higher number of active channels in membrane patches. The truncation mutation in the beta subunit of epithelial Na+ channel did not alter the biophysical and pharmacological properties of the channel-including unitary conductance, ion selectivity, or sensitivity to amiloride block These results provide direct physiological evidence that Liddle disease is related to constitutive channel hyperactivity in the cell membrane. Deletions of the C-terminal end of the beta and gamma subunits of rat epithelial Na+ channel were functionally equivalent in increasing I-Na, suggesting that the cytoplasmic domain of the gamma subunit might be another molecular target for mutations responsible for salt-sensitive forms of hypertension.