ERK1/2 controls Na,K-ATPase activity and transepithelial sodium transport in the principal cell of the cortical collecting duct of the mouse kidney
ERK1/2 controls Na,K-ATPase activity and transepithelial sodium transport in the principal cell of the cortical collecting duct of the mouse kidney
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DOI：
10.1074/jbc.m405674200
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发表时间：
2004-12-03
影响因子：
4.8
通讯作者：
Firsov, D
中科院分区：
文献类型：
--
作者：
Michlig, S;Mercier, A;Firsov, D
磷酸化活性ERK 1/2（pERK 1/2）的免疫染色显示正常肾集合管具有明显的MEK 1/2-ERK 1/2通路活性。MEK 1/2-ERK 1/2通路控制着近端和远端肾单位中多种不同的离子转运，这引起了一个问题，即该通路是否参与了皮质集合管（CCD）主细胞的基底和/或基底膜依赖性跨上皮钠重吸收，这是一个由顶端上皮钠通道和基底外侧钠泵（Na，K-ATP酶）介导的过程。为了回答这个问题，我们使用了来自正常小鼠肾脏的离体显微切割CCD或体外培养的mpkCCD（cl 4）主细胞。在离体和体外观察到显著的pERK 1/2基础水平。醛固酮和加压素，已知上调钠重吸收的CCD，没有改变ERK 1/2的活性无论是在体外或体外。MEK 1/2抑制剂PD 98059下调基础和醛固酮或加压素刺激的钠转运，与pERK 1/2在体外的减少平行。MEK 1/2抑制剂可抑制未受刺激和经醛固酮或加压素刺激的CCD的Na，K-ATP酶活性，但不抑制上皮钠通道活性。细胞表面生物素化显示，Na，K-ATP酶的内在活性，而不是细胞表面表达的pERK 1/2控制。PD 98059对Na，K-ATP酶活性也有明显的抑制作用。我们的数据表明，ERK 1/2途径控制Na，K-ATP酶的活性和跨上皮钠转运的主细胞，并表明，ERK 1/2途径的基础组成活性是这种控制的关键组成部分。
The collecting duct of normal kidney exhibits significant activity of the MEK1/2-ERK1/2 pathway as shown in vivo by immunostaining of phosphorylated active ERK1/2 (pERK1/2). The MEK1/2-ERK1/2 pathway controls many different ion transports both in proximal and distal nephron, raising the question of whether this pathway is involved in the basal and/or hormone-dependent transepithelial sodium reabsorption in the principal cell of the cortical collecting duct (CCD), a process mediated by the apical epithelial sodium channel and the basolateral sodium pump (Na, K-ATPase). To answer this question we used ex vivo microdissected CCDs from normal mouse kidney or in vitro cultured mpkCCD(cl4) principal cells. Significant basal levels of pERK1/2 were observed ex vivo and in vitro. Aldosterone and vasopressin, known to up-regulate sodium reabsorption in CCDs, did not change ERK1/2 activity either ex vivo or in vitro. Basal and aldosterone- or vasopressin-stimulated sodium transport was down-regulated by the MEK1/2 inhibitor PD98059, in parallel with a decrease in pERK1/2 in vitro. The activity of Na, K-ATPase but not that of epithelial sodium channel was inhibited by MEK1/2 inhibitors in both unstimulated and aldosteroneor vasopressin-stimulated CCDs in vitro. Cell surface biotinylation showed that intrinsic activity rather than cell surface expression of Na, K-ATPase was controlled by pERK1/2. PD98059 also significantly inhibited the activity of Na, K-ATPase ex vivo. Our data demonstrate that the ERK1/2 pathway controls Na, K-ATPase activity and transepithelial sodium transport in the principal cell and indicate that basal constitutive activity of the ERK1/2 pathway is a critical component of this control.