Mechanisms of WNK1 and WNK4 interaction in the regulation of thiazide-sensitive NaCl cotransport
Mechanisms of WNK1 and WNK4 interaction in the regulation of thiazide-sensitive NaCl cotransport
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DOI：
10.1172/jci200522452
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发表时间：
2005-05-01
影响因子：
15.9
通讯作者：
Ellison, DH
中科院分区：
文献类型：
--
作者：
Yang, CL;Zhu, XM;Ellison, DH
无赖氨酸（WNK）激酶在哺乳动物远端肾单位沿着高度表达。WNK 1或WNK 4中的突变导致家族性高钾血症性高血压（FHHt），这表明蛋白质产物会聚在最终的共同途径上。我们以前表明，WNK 4下调噻嗪敏感的NaCl协同转运蛋白（NCC）的活性，WNK 1抑制的效果。在这里，我们研究了WNK 1和WNK 4相互作用调节离子转运的机制。我们报告说，WNK 1抑制WNK 4对NCC活性的影响，并与WNK 4在涉及激酶结构域的蛋白质复合物中结合。尽管激酶死亡的WNK 1也与WNK 4相关，但它不能抑制WNK 4介导的NCC抑制;然而，单独的WNK 1激酶结构域不足以阻断WNK 4的作用。WNK 4的羧基末端222个氨基酸足以抑制NCC，但该片段不被WNK 1阻断。相反，WNK 1抑制需要完整的WNK 4激酶结构域，即与WNK 1结合的区域。总之，这些数据表明：（a）WNK 4羧基末端介导NCC抑制，（B）WNK 1激酶结构域与WNK 4激酶结构域相互作用，和（c）WNK 1对WNK 4的抑制依赖于WNK 1催化活性和完整的WNK 1蛋白。这些发现为WNK 1和WNK 4之间复杂的相互关系提供了深入了解，并为FHHt提供了分子基础。
With-no-lysine (WNK) kinases are highly expressed along the mammalian distal nephron. Mutations in either WNK1 or WNK4 cause familial hyperkalemic hypertension (FHHt), suggesting that the protein products converge on a final common pathway. We showed previously that WNK4 downregulates thiazide-sensitive NaCl cotransporter (NCC) activity, an effect suppressed by WNK1. Here we investigated the mechanisms by which WNK1 and WNK4 interact to regulate ion transport. We report that WNK1 suppresses the WNK4 effect on NCC activity and associates with WNK4 in a protein complex involving the kinase domains. Although a kinase-dead WNK1 also associates with WNK4, it fails to suppress WNK4-mediated NCC inhibition; the WNK1 kinase domain alone, however, is not sufficient to block the WNK4 effect. The carboxyterminal 222 amino acids of WNK4 are sufficient to inhibit NCC, but this fragment is not blocked by WNK1. Instead, WNK1 inhibition requires an intact WNK4 kinase domain, the region that binds to WNK1. In summary, these data show that: (a) the WNK4 carboxyl terminus mediates NCC suppression, (b) the WNK1 kinase domain interacts with the WNK4 kinase domain, and (c) WNK1 inhibition of WNK4 is dependent on WNK1 catalytic activity and an intact WNK1 protein. These findings provide insight into the complex interrelationships between WNK1 and WNK4 and provide a molecular basis for FHHt.