Role of SGK2 in Sodium Transport in the Kidney

描述（由申请人提供）：本研究方案的总体目标是了解血清和糖皮质激素诱导的激酶2（sgk 2）的表达、调节和功能，以及其在钠（Na+）跨肾单位转运中的确切作用。醛固酮诱导的Na+在肾单位转运的分子基础尚未完全阐明。最近，sgk 1已被确定为早期醛固酮效应和上皮Na+通道介导的Na+转运之间的中央介质。甚至最近，发现了sgk的另外两种亚型sgk 2和sgk 3。将通过在大鼠中输注醛固酮和地塞米松进行sgk 2表达的定位和对血管紧张素介导的sgk 2调节的评估，随后通过原位杂交和免疫细胞化学进行sgk 2表达分析。将通过非洲爪蟾卵母细胞与sgk 2和肾单位片段特异性Na+共转运蛋白的共表达测定来鉴定sgk 2的下游效应子。最后，四环素诱导（Tet-On）的sgk 2表达系统在A6细胞将被构建分离的具体影响sgk 2对Na+转运的时间依赖性的方式。鉴于Na+处理不当可导致人体细胞外液体积膨胀和高血压，因此了解肾脏中介导醛固酮诱导的Na+转运的信号通路具有临床重要意义。

DESCRIPTION (provided by applicant): The overall goal of this research proposal is to understand the expression, regulation, and function of serum and glucocorticoid induced kinase 2 (sgk2) and the precise role it plays in sodium (Na+) transport across the nephron. The molecular basis underlying aldosterone-induced Na+ transport in the nephron has not been fully elucidated. Recently, sgk1 has been identified as a central mediator between early aldosterone effects and epithelial Na+ channel-mediated Na+ transport. Even more recently, two additional isoforms of sgk, sgk2 and sgk3, have been discovered. Localization of sgk2 expression and assessment of hormone-mediated sgk2 regulation will be performed through aldosterone and dexamethasone infusion in rats with subsequent sgk2 expression analyses by in situ hybridization and immunocytochemistry. Identification of downstream effectors of sgk2 will be performed through co-expression assays of Xenopus laevis oocytes with sgk2 and nephron segment-specific Na+ co-transporters. Finally, a tetracycline-inducible (Tet-On) sgk2 expression system in A6 cells will be constructed to isolate the specific effects of sgk2 on Na+ transport in a time-dependent manner. Given that inappropriate Na+ handling can result in extracellular fluid volume expansion and hypertension in humans, understanding the signaling pathways mediating aldosterone-induced Na+ transport in the kidney is clinically important.