SGK-1在人近端肾小管细胞中血管紧张素II介导的钠重吸收中的作用。

The role of SGK-1 in angiotensin II-mediated sodium reabsorption in human proximal tubular cells.

作者信息

Stevens Veronica A, Saad Sonia, Poronnik Philip, Fenton-Lee Carol A, Polhill Tania S, Pollock Carol A

机构信息

Department of Medicine, University of Sydney, Renal Research Group, Kolling Institute, Royal North Shore Hospital, St Leonards, NSW 2065, Australia .

出版信息

Nephrol Dial Transplant. 2008 Jun;23(6):1834-43. doi: 10.1093/ndt/gfm923. Epub 2008 Jan 31.

DOI:10.1093/ndt/gfm923

PMID:18238849

Abstract

BACKGROUND

The role of angiotensin II (Ang II) in mediating excessive sodium reabsorption in diabetic nephropathy is recognized. Serine-glucocorticoid kinase-1 (SGK-1) increases sodium-hydrogen exchanger-3 (NHE3) expression and is known to be upregulated in in vitro and in vivo models of diabetic nephropathy. However, a link between Ang II and SGK-1 in diabetic nephropathy has not been established.

METHODS

Ang II production in cultured human proximal tubular cells was measured under normal (5 mM) and high (25 mM) glucose conditions. The Ang II type 1 receptor was identified by RT-PCR. SGK-1 and NHE3 mRNA and protein expression was measured in proximal tubule cells (PTCs) exposed to Ang II. EIPA inhibitable changes in cell sodium uptake were undertaken to confirm that alterations in NHE3 mRNA and protein were reflected in transport activity. SGK-1 was silenced in the PTCs using small interfering RNA to determine the role of SGK-1 in mediating Ang II-induced increases in NHE3-mediated sodium uptake.

RESULTS

Ang II production by PTCs was significantly increased by exposure to high glucose (P < 0.02). Ang II increased NHE3 and SGK-1 mRNA expression to 275 +/- 30% (P < 0.02) and 130 +/- 10% (P < 0.05) respectively. Silencing of SGK-1 reduced Ang II-stimulated NHE3 protein expression to 49.8 +/- 6.1% (P < 0.05) of control levels. SGK-1 silencing abolished increases in (22)Na(+) uptake seen in Ang II-treated cells to 86.7 +/- 1.6% of control values.

CONCLUSION

These data suggest that increased sodium reabsorption in renal proximal tubular cells considered to be due to Ang II in diabetes mellitus is mediated through SGK-1 expression.

摘要

背景

血管紧张素II（Ang II）在介导糖尿病肾病中过度的钠重吸收方面的作用已得到认可。丝氨酸-糖皮质激素激酶-1（SGK-1）可增加钠-氢交换体-3（NHE3）的表达，并且已知在糖尿病肾病的体外和体内模型中其表达上调。然而，糖尿病肾病中Ang II与SGK-1之间的联系尚未确立。

方法

在正常（5 mM）和高（25 mM）葡萄糖条件下，测量培养的人近端肾小管细胞中Ang II的产生。通过逆转录聚合酶链反应（RT-PCR）鉴定血管紧张素II 1型受体。在暴露于Ang II的近端小管细胞（PTCs）中测量SGK-1和NHE3的mRNA和蛋白表达。进行EIPA可抑制的细胞钠摄取变化，以确认NHE3 mRNA和蛋白的改变反映在转运活性中。使用小干扰RNA使PTCs中的SGK-1沉默，以确定SGK-1在介导Ang II诱导的NHE3介导的钠摄取增加中的作用。

结果

暴露于高葡萄糖时，PTCs产生的Ang II显著增加（P < 0.02）。Ang II分别将NHE3和SGK-1的mRNA表达增加至275±30%（P < 0.02）和130±10%（P < 0.05）。SGK-1沉默使Ang II刺激的NHE3蛋白表达降低至对照水平的49.8±6.1%（P < 0.05）。SGK-1沉默消除了Ang II处理细胞中（22）Na（+）摄取增加至对照值的86.7±1.6%。