Bukhari Ashfaq-Ahmad-Shah, Zhang Xue, Li Min, Zhao Anran, Dong Hao, Liang Xiubin
Department of Pathophysiology.
Department of Pathophysiology;Department of Nephrology, the Affiliated Sir Run Run Hospital of Nanjing Medical University, Nanjing, Jiangsu 211166, China.
J Biomed Res. 2020 Jul 30;34(5):351-360. doi: 10.7555/JBR.34.20190155.
Renal epithelial sodium channel (ENaC) plays a crucial role in maintaining homeostasis and sodium absorption. While insulin participates in controlling sodium transport across the renal epithelium, the underlying molecular mechanism remain unclear. In this study, we found that insulin increased the expression and function of alpha-epithelial sodium channel (α-ENaC) as well as phosphorylation of cofilin, a family of actin-binding proteins which disassembles actin filaments, in mouse cortical collecting duct (mpkCCD) cells. The wild-type (WT) cofilin and its constitutively phosphorylated form (S3D), but not its constitutively non-phosphorylable form (S3A), contributed to the elevated expression on α-ENaC. Overexpression of 14-3-3ε, β, or γ increased the expression of α-ENaC and cofilin phosphorylation, which was blunted by knockdown of 14-3-3ε, β, or γ. Moreover, it was found that insulin increased the interaction between cofilin and 14-3-3 isoforms, which indicated relevance of 14-3-3 isoforms with cofilin. Furthermore, LIMK1/SSH1 pathway was involved in regulation of cofilin and α-ENaC expression by insulin. The results from this work indicate that cofilin participates in the regulation of α-ENaC by interaction with 14-3-3 isoforms.
肾上皮钠通道（ENaC）在维持体内平衡和钠吸收中起关键作用。虽然胰岛素参与控制钠跨肾上皮的转运，但其潜在的分子机制仍不清楚。在本研究中，我们发现胰岛素增加了小鼠皮质集合管（mpkCCD）细胞中α-上皮钠通道（α-ENaC）的表达和功能以及丝切蛋白（一种可分解肌动蛋白丝的肌动蛋白结合蛋白家族）的磷酸化。野生型（WT）丝切蛋白及其组成型磷酸化形式（S3D），而非其组成型不可磷酸化形式（S3A），促成了α-ENaC表达的升高。14-3-3ε、β或γ的过表达增加了α-ENaC的表达和丝切蛋白磷酸化，而14-3-3ε、β或γ的敲低则使其减弱。此外，发现胰岛素增加了丝切蛋白与14-3-3异构体之间的相互作用，这表明14-3-3异构体与丝切蛋白相关。此外，LIMK1/SSH1通路参与胰岛素对丝切蛋白和α-ENaC表达的调节。这项工作的结果表明，丝切蛋白通过与14-3-3异构体相互作用参与α-ENaC的调节。
