WNK4 Enhances the Degradation of NCC through a Sortilin-Mediated Lysosomal Pathway
WNK4 Enhances the Degradation of NCC through a Sortilin-Mediated Lysosomal Pathway
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DOI：
10.1681/asn.2008121275
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发表时间：
2010-01-01
影响因子：
13.6
通讯作者：
Cai, Hui
中科院分区：
文献类型：
--
作者：
Zhou, Bo;Zhuang, Jieqiu;Cai, Hui
WNK 激酶是一种丝氨酸/苏氨酸激酶，在电解质稳态中发挥重要作用。 WNK4 通过溶酶体途径增强氯化钠协同转运蛋白 (NCC) 的降解，从而显着抑制氯化钠协同转运蛋白 (NCC) 的表面表达，但这种运输的机制尚不清楚。在这里，我们研究了溶酶体靶向受体分拣蛋白对 NCC 表达和降解的影响。在 Cos-7 细胞中，我们观察到 WNK4 的存在使 NCC 的稳态量减少了大约一半。与截短的分拣蛋白（显性失活突变体）共转染可防止 WNK4 诱导的 NCC 减少。 NCC 与野生型分拣蛋白和较小程度的截短分拣蛋白进行免疫沉淀。免疫染色显示，WNK4 增加了 NCC 与溶酶体标记物组织蛋白酶 D 的共定位，并且 NCC 与野生型分拣蛋白、截短分拣蛋白和 WNK4 在核周区域共定位。这些发现表明，WNK4 通过涉及分拣蛋白的机制促进 NCC 靶向溶酶体进行降解。
WNK kinase is a serine/threonine kinase that plays an important role in electrolyte homeostasis. WNK4 significantly inhibits the surface expression of the sodium chloride co-transporter (NCC) by enhancing the degradation of NCC through a lysosomal pathway, but the mechanisms underlying this trafficking are unknown. Here, we investigated the effect of the lysosomal targeting receptor sortilin on NCC expression and degradation. In Cos-7 cells, we observed that the presence of WNK4 reduced the steady-state amount of NCC by approximately half. Co-transfection with truncated sortilin (a dominant negative mutant) prevented this WNK4-induced reduction in NCC. NCC immunoprecipitated with both wild-type sortilin and, to a lesser extent, truncated sortilin. Immunostaining revealed that WNK4 increased the co-localization of NCC with the lysosomal marker cathepsin D, and NCC co-localized with wild-type sortilin, truncated sortilin, and WNK4 in the perinuclear region. These findings suggest that WNK4 promotes NCC targeting to the lysosome for degradation via a mechanism involving sortilin.