Expression and role of serum and glucocorticoid-regulated kinase 2 in the regulation of Na+/H+ exchanger 3 in the mammalian kidney
Expression and role of serum and glucocorticoid-regulated kinase 2 in the regulation of Na+/H+ exchanger 3 in the mammalian kidney
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DOI：
10.1152/ajprenal.00075.2010
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发表时间：
2010-12-01
影响因子：
4.2
通讯作者：
Pearce, David
中科院分区：
文献类型：
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作者：
Pao, Alan C.;Bhargava, Aditi;Pearce, David
[10] Pao AC，Bhargava A，Di Sole F，Quigley R，Shao X，Wang J，托马斯S，Zhang J，Shi M，Funder JW，莫伊OW，皮尔斯D.血清和糖皮质激素调节激酶2在哺乳动物肾脏Na+/H+交换器3调节中的表达和作用美国肾脏生理学杂志299：F1496-F1506，2010年。首次发表于2010年10月6日; doi：10.1152/ajprenal.00075.2010.-血清和糖皮质激素调节激酶2（sgk 2）与sgk 1的激酶结构域80%相同，sgk 1是肾脏远端肾单位盐皮质激素调节钠（Na+）转运的重要介质。sgk 2的表达模式和在肾功能中的作用实际上是未知的。啮齿动物肾脏的原位杂交和免疫组织化学结合显微切割的大鼠肾小管的实时RT-PCR显示，近端直小管和Henle袢的粗升支中有强大的sgk 2表达。Sgk 2表达在远端小管细胞与水通道蛋白-2免疫染色是最小的，但显着的近端小管细胞与Na+/H+交换器3（NHE 3）免疫染色。为了确定盐皮质激素是否以类似于sgk 1的方式调节sgk 2的表达，我们研究了用生理剂量的醛固酮和糖皮质激素受体拮抗剂RU 486治疗的肾上腺切除大鼠肾脏中sgk 2 mRNA的表达。北方印迹分析和原位杂交显示，与sgk 1不同，sgk 2在肾脏中的表达不受醛固酮治疗的影响。基于sgk 2在也表达NHE 3的近端小管细胞中表达的观察，我们询问sgk 2是否调节NHE 3活性。我们在负鼠肾（OKP）细胞中异源表达sgk 2，并通过Na+依赖性细胞pH恢复来测量Na+/H+交换活性。组成型活性sgk 2而非sgk 1刺激Na+/H+交换活性> 30%。此外，sgk 2介导的Na+/H+交换活性的增加与NHE 3的细胞表面表达的增加相关。总之，这些结果表明，模式的表达，调节和哺乳动物肾脏内的sgk 2的作用是不同的sgk 1和sgk 2可能发挥以前未被认识到的作用，在近端小管通过NHE 3的跨管Na+转运的控制。
Pao AC, Bhargava A, Di Sole F, Quigley R, Shao X, Wang J, Thomas S, Zhang J, Shi M, Funder JW, Moe OW, Pearce D. Expression and role of serum and glucocorticoid-regulated kinase 2 in the regulation of Na+/H+ exchanger 3 in the mammalian kidney. Am J Physiol Renal Physiol 299: F1496-F1506, 2010. First published October 6, 2010; doi: 10.1152/ajprenal.00075.2010.-Serum and glucocorticoid-regulated kinase 2 (sgk2) is 80% identical to the kinase domain of sgk1, an important mediator of mineralocorticoid-regulated sodium (Na+) transport in the distal nephron of the kidney. The expression pattern and role in renal function of sgk2 are virtually uncharacterized. In situ hybridization and immunohistochemistry of rodent kidney coupled with real-time RT-PCR of microdissected rat kidney tubules showed robust sgk2 expression in the proximal straight tubule and thick ascending limb of the loop of Henle. Sgk2 expression was minimal in distal tubule cells with aquaporin-2 immunostaining but significant in proximal tubule cells with Na+/H+ exchanger 3 (NHE3) immunostaining. To ascertain whether mineralocorticoids regulate expression of sgk2 in a manner similar to sgk1, we examined sgk2 mRNA expression in the kidneys of adrenalectomized rats treated with physiological doses of aldosterone together with the glucocorticoid receptor antagonist RU486. Northern blot analysis and in situ hybridization showed that, unlike sgk1, sgk2 expression in the kidney was not altered by aldosterone treatment. Based on the observation that sgk2 is expressed in proximal tubule cells that also express NHE3, we asked whether sgk2 regulates NHE3 activity. We heterologously expressed sgk2 in opossum kidney (OKP) cells and measured Na+/H+ exchange activity by Na+ -dependent cell pH recovery. Constitutively active sgk2, but not sgk1, stimulated Na+/H+ exchange activity by >30%. Moreover, the sgk2-mediated increase in Na+/H+ exchange activity correlated with an increase in cell surface expression of NHE3. Together, these results suggest that the pattern of expression, regulation, and role of sgk2 within the mammalian kidney are distinct from sgk1 and that sgk2 may play a previously unrecognized role in the control of transtubular Na+ transport through NHE3 in the proximal tubule.