DHHC7-mediated palmitoylation of the accessory protein barttin critically regulates the functions of ClC-K chloride channels
DHHC7-mediated palmitoylation of the accessory protein barttin critically regulates the functions of ClC-K chloride channels
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DOI：
10.1074/jbc.ra119.011049
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发表时间：
2020-05-01
影响因子：
4.8
通讯作者：
Ponimaskin, Evgeni
中科院分区：
文献类型：
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作者：
Gorinski, Nataliya;Wojciechowski, Daniel;Ponimaskin, Evgeni
巴丁蛋白是人类ClC-K氯离子通道的辅助亚基，在肾脏和内耳均有表达。巴丁促进它与ClC-K形成的复合物运输到质膜，并参与激活该通道。巴丁蛋白经历翻译后棕榈酰化，这对其功能至关重要，但催化这种翻译后修饰的酶是未知的。本研究发现锌指DHHC-type containing 7 （DHHC7）蛋白是一种重要的巴丁棕榈酰酰基转移酶，其缺失影响巴丁棕榈酰化和clc - k -巴丁通道的激活。我们研究了巴丁棕榈酰化在Zdhhc7（?/?）小鼠体内的功能作用。虽然Zdhhc7（?/?）动物肾脏中巴丁棕榈酰化显著降低，但在生理条件下并未对肾脏结构和功能产生病理改变。然而，当Zdhhc7（?/?）小鼠被喂食低盐饮食时，它们出现了低钠血症和轻度代谢性碱中毒，这是人类巴特氏综合征（BS） IV型的特征症状。值得注意的是，我们还观察到与人类BS IV型相关的致病R8L巴丁酮变体的棕榈酰化降低。我们的结果表明，dhhc7介导的巴丁酮酰化失调似乎在某些BS变体的氯通道功能障碍中起重要作用。这表明靶向DHHC7活性可能为降低高血压提供一种潜在的治疗策略。
Barttin is the accessory subunit of the human ClC-K chloride channels, which are expressed in both the kidney and inner ear. Barttin promotes trafficking of the complex it forms with ClC-K to the plasma membrane and is involved in activating this channel. Barttin undergoes post-translational palmitoylation that is essential for its functions, but the enzyme(s) catalyzing this post-translational modification is unknown. Here, we identified zinc finger DHHC-type containing 7 (DHHC7) protein as an important barttin palmitoyl acyltransferase, whose depletion affected barttin palmitoylation and ClC-K-barttin channel activation. We investigated the functional role of barttin palmitoylation in vivo in Zdhhc7(?/?) mice. Although palmitoylation of barttin in kidneys of Zdhhc7(?/?) animals was significantly decreased, it did not pathologically alter kidney structure and functions under physiological conditions. However, when Zdhhc7(?/?) mice were fed a low-salt diet, they developed hyponatremia and mild metabolic alkalosis, symptoms characteristic of human Bartter syndrome (BS) type IV. Of note, we also observed decreased palmitoylation of the disease-causing R8L barttin variant associated with human BS type IV. Our results indicate that dysregulated DHHC7-mediated barttin palmitoylation appears to play an important role in chloride channel dysfunction in certain BS variants, suggesting that targeting DHHC7 activity may offer a potential therapeutic strategy for reducing hypertension.