WNK4 kinase is a physiological intracellular chloride sensor
WNK4 kinase is a physiological intracellular chloride sensor
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DOI：
10.1073/pnas.1817220116
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发表时间：
2019-03-05
影响因子：
11.1
通讯作者：
Cheng, Chih-Jen
中科院分区：
文献类型：
--
作者：
Chen, Jen-Chi;Lo, Yi-Fen;Cheng, Chih-Jen
与非赖氨酸(WNK)激酶调节肾钠氯化物协同转运体(NCC)，以维持体内钠和钾的动态平衡。WNK1和WNK4在人类中的功能获得突变导致孟德尔高血压和高钾血症II型假性低醛固酮血症(PHAII)。X射线晶体结构和体外研究表明，氯离子(Cl-)结合在WNKS的激酶域内的疏水口袋上，从而抑制其活性。这一机制被认为是胞外钾对NCC进行生理调节的重要机制。为了验证WNK4生理上感知细胞内氯离子浓度的假设，我们产生了携带氯离子不敏感突变体WNK4的敲击小鼠。这些小鼠表现出高血压、高钾血症、过度活跃的NCC和其他特征，完全概括了由功能获得WNK4引起的人类和小鼠PHAII模型。通过饮食限钾降低血浆钾水平可以增加野生型小鼠的NCC活性，但不能增加敲击型小鼠的NCC活性。去甲肾上腺素是一种已知的NCC激活剂，它可以进一步增强敲门小鼠的NCC活性。野生型小鼠灌胃灭活NCC后1小时内灌胃血钾升高，但对敲击小鼠无作用。这些结果支持了WNK4是一种真正的生理细胞内氯离子感受器的观点，并且WNK4的氯离子调节是细胞外钾调节NCC的机制。
With-no-lysine (WNK) kinases regulate renal sodium-chloride cotransporter (NCC) to maintain body sodium and potassium homeostasis. Gain-of-function mutations of WNK1 and WNK4 in humans lead to a Mendelian hypertensive and hyperkalemic disease pseudohypoal-dosteronism type II (PHAII). X-ray crystal structure and in vitro studies reveal chloride ion (Cl-) binds to a hydrophobic pocket within the kinase domain of WNKs to inhibit its activity. The mechanism is thought to be important for physiological regulation of NCC by extracellular potassium. To test the hypothesis that WNK4 senses the intracellular concentration of Cl- physiologically, we generated knockin mice carrying Cl--insensitive mutant WNK4. These mice displayed hypertension, hyperkalemia, hyperactive NCC, and other features fully recapitulating human and mouse models of PHAII caused by gain-of-function WNK4. Lowering plasma potassium levels by dietary potassium restriction increased NCC activity in wild-type, but not in knockin, mice. NCC activity in knockin mice can be further enhanced by the administration of norepinephrine, a known activator of NCC. Raising plasma potassium by oral gavage of potassium inactivated NCC within 1 hour in wild-type mice, but had no effect in knockin mice. The results provide compelling support for the notion that WNK4 is a bona fide physiological intracellular Cl- sensor and that Cl- regulation of WNK4 underlies the mechanism of regulation of NCC by extracellular potassium.