Sirtuin1 Maintains Actin Cytoskeleton by Deacetylation of Cortactin in Injured Podocytes
Sirtuin1 Maintains Actin Cytoskeleton by Deacetylation of Cortactin in Injured Podocytes
复制标题
DOI：
10.1681/asn.2014030289
复制
发表时间：
2015-08-01
影响因子：
13.6
通讯作者：
Inagi, Reiko
中科院分区：
文献类型：
--
作者：
Motonishi, Shuta;Nangaku, Masaomi;Inagi, Reiko
最近的研究强调了Sirtuin1(SIRT1)的肾脏保护作用，SIRT1是一种有助于细胞调节的脱乙酰酶。然而，SIRT1在足细胞中的病理生理作用尚不清楚。在这里，我们研究了SIRT1在足细胞中的功能。我们首先建立了足细胞特异性Sirt1基因敲除(SIRT1(pod-/-))小鼠。然后通过注射肾毒性血清诱导肾小球疾病。SIRT1(pod-/-)小鼠的尿白蛋白排泄量和BUN的增加以及肾小球损伤的严重程度均显著高于野生型小鼠。Western印迹分析和免疫荧光显示SIRT1(pod-/-)小鼠足细胞特异性蛋白显著减少，电子显微镜显示与野生型小鼠相比，SIRT1(pod-/-)小鼠足细胞损伤明显加重，包括肌动蛋白细胞骨架紊乱。硫酸鱼精蛋白诱导的足细胞损伤也因足细胞特异性SIRT1缺乏而加剧。在体外，当细胞被SIRT1抑制剂预处理时，过氧化氢处理的足细胞中肌动蛋白细胞骨架的紊乱变得更加明显。相反，这种由H_2O_2引起的排列紊乱可被SIRT1激活所改善。此外，SIRT1的激活去乙酰化了细胞核中的肌动蛋白结合和聚合蛋白Cortactin，促进了去乙酰化的Cortactin在细胞质中的定位。Cortactin下调或抑制Cortactin的核输出导致肌动蛋白细胞骨架的错乱和解离，提示细胞质Cortactin对维持肌动蛋白细胞骨架是必要的。综上所述，这些发现表明，SIRT1通过去乙酰化皮质蛋白从而维持肌动蛋白细胞骨架的完整性来保护足细胞和防止肾小球损伤。
Recent studies have highlighted the renoprotective effect of sirtuin1 (SIRT1), a deacetylase that contributes to cellular regulation. However, the pathophysiologic role of SIRT1 in podocytes remains unclear. Here, we investigated the function of SIRT1 in podocytes. We first established podocyte-specific Sirt1 knockout (SIRT1(pod-/-)) mice. We then induced glomerular disease by nephrotoxic serum injection. The increase in urinary albumin excretion and BUN and the severity of glomerular injury were all significantly greater in SIRT1(pod-/-) mice than in wild-type mice. Western blot analysis and immunofluorescence showed a significant decrease in podocyte-specific proteins in SIRT1(pod-/-) mice, and electron microscopy showed marked exacerbation of podocyte injury, including actin cytoskeleton derangement in SIRT1(pod-/-) mice compared with wild-type mice. Protamine sulfate-induced podocyte injury was also exacerbated by podocyte-specific SIRT1 deficiency. In vitro, actin cytoskeleton derangement in H2O2-treated podocytes became prominent when the cells were pretreated with SIRT1 inhibitors. Conversely, this H2O2-induced derangement was ameliorated by SIRT1 activation. Furthermore, SIRT1 activation deacetylated the actin-binding and -polymerizing protein cortactin in the nucleus and facilitated deacetylated cortactin localization in the cytoplasm. Cortactin knockdown or inhibition of the nuclear export of cortactin induced actin cytoskeleton derangement and dissociation of cortactin from F-actin, suggesting the necessity of cytoplasmic cortactin for maintenance of the actin cytoskeleton. Taken together, these findings indicate that SIRT1 protects podocytes and prevents glomerular injury by deacetylating cortactin and thereby, maintaining actin cytoskeleton integrity.