The proteoglycan syndecan 4 regulates transient receptor potential canonical 6 channels via RhoA/Rho-associated protein kinase signaling.
The proteoglycan syndecan 4 regulates transient receptor potential canonical 6 channels via RhoA/Rho-associated protein kinase signaling.
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DOI：
10.1161/atvbaha.111.241018
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发表时间：
2012-02
期刊：
影响因子：
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通讯作者：
Tepel M
中科院分区：
文献类型：
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作者：
Liu Y;Echtermeyer F;Thilo F;Theilmeier G;Schmidt A;Schülein R;Jensen BL;Loddenkemper C;Jankowski V;Marcussen N;Gollasch M;Arendshorst WJ;Tepel M
Syndecan 4 (Sdc4) 调节信号转导并调节蛋白质通道的活性。 Sdc4 对于细胞通透性的调节至关重要。我们假设 Sdc4 可能以 RhoA/Rho 相关蛋白激酶依赖性方式调节瞬时受体电位规范 6 (TRPC6) 通道（肾小球通透性的决定因素）。 Sdc4 敲除 (Sdc4−/−) 小鼠在基线条件下和牛血清白蛋白超负荷后表现出肾小球滤过率增加和白蛋白尿改善（每个 P<0.05）。使用逆转录聚合酶链反应和免疫印迹，Sdc4−/− 小鼠的 TRPC6 mRNA 减少了 79%，TRPC6 蛋白减少了 82%（每个 P<0.05）。 Sdc4−/− 小鼠的 RhoA 活性增加了 87%，肾小球中埃兹蛋白的磷酸化增加了 48%（每个 P<0.05）。培养的足细胞中 Sdc4 敲低会降低 TRPC6 基因表达，并减少 TRPC6 与质膜以及 TRPC6 介导的钙内流和电流的关联。 Sdc4敲低使负调节蛋白Rho GTPase激活蛋白失活33%，同时RhoA活性增加41%，并且ezrin磷酸化增加（P<0.05）。相反，Sdc4的过度表达降低了RhoA活性并增加了TRPC6蛋白和TRPC6介导的钙内流和电流。我们的结果建立了 Sdc4 以前未知的 TRPC6 通道调节功能，并支持 Sdc4 在肾小球通透性调节中的作用。
Syndecan 4 (Sdc4) modulates signal transduction and regulates activity of protein channels. Sdc4 is essential for the regulation of cellular permeability. We hypothesized that Sdc4 may regulate transient receptor potential canonical 6 (TRPC6) channels, a determinant of glomerular permeability, in a RhoA/Rho-associated protein kinase-dependent manner. Sdc4 knockout (Sdc4−/−) mice showed increased glomerular filtration rate and ameliorated albuminuria under baseline conditions and after bovine serum albumin overload (each P<0.05). Using reverse transcription–polymerase chain reaction and immunoblotting, Sdc4−/− mice showed reduced TRPC6 mRNA by 79% and TRPC6 protein by 82% (each P<0.05). Sdc4−/− mice showed an increased RhoA activity by 87% and increased phosphorylation of ezrin in glomeruli by 48% (each P<0.05). Sdc4 knockdown in cultured podocytes reduced TRPC6 gene expression and reduced the association of TRPC6 with plasma membrane and TRPC6-mediated calcium influx and currents. Sdc4 knockdown inactivated negative regulatory protein Rho GTPase activating protein by 33%, accompanied by a 41% increase in RhoA activity and increased phosphorylation of ezrin (P<0.05). Conversely, overexpression of Sdc4 reduced RhoA activity and increased TRPC6 protein and TRPC6-mediated calcium influx and currents. Our results establish a previously unknown function of Sdc4 for regulation of TRPC6 channels and support the role of Sdc4 for the regulation of glomerular permeability.