The role of SIRT1 in mediating renal cells apoptosis and its therapeutic perspective

氧化应激和/或tgf - β诱导的肾小球细胞凋亡是多种肾脏疾病发生的重要因素。确定调节这一过程的分子可能会导致预防肾脏疾病的新策略的发展。在这项研究中，我们评估了哺乳动物沉默信息调节因子2 （SIRT1）是否是氧化应激诱导的系膜细胞凋亡的关键调节因子，SIRT1最近被确定为对抗各种应激源的细胞生存因子。研究了过氧化氢（H_2O_2）和tgf - β作用下小鼠系膜细胞（MMC_s）凋亡细胞死亡（核凝聚）的形态学特征和促凋亡生化标志物（caspase-3和聚adp核糖聚合酶（PARP）的裂解）的表达。H_2O_2或tgf - β增加系膜细胞凋亡，主要通过乙酰化激活p53，这是p53激活的转录后修饰。在sirt1过表达的mmc中，H_2O、_2和tgf - β诱导的细胞凋亡明显减弱，而在sirt1敲低的mmc中，H_2O、_2和tgf - β诱导的细胞凋亡增强。我们还发现SIRT1直接与Smad7的n端相互作用。此外，SIRT1逆转了乙酰基转移酶（p300）介导的Smad7上两个赖氨酸残基（K64和K70）的乙酰化。在体内，Smad7蛋白表达水平通过sirt1过表达而降低，通过泛素蛋白酶体作用调节smurl介导的Smad7降解而下调sirt1表达水平而升高。我们的研究结果表明，SIRT1可以通过在系膜细胞中失活p53来阻止氧化应激诱导的细胞凋亡，而Smad7是SIRT1的一个新的靶分子，SIRT1通过加速Smad7的降解，在功能上减弱tgf β诱导的血管细胞凋亡。上调SIRT1可能为预防肾小球疾病提供新的策略。接下来，我们通过蛋白质芯片分析来研究具有诱导SIRT1能力的靶分子，并发现了24个针对卡路里限制的候选分子。少

Oxidative stress and/or TGF-beta-induced apoptosis of renal glomerular cells is an important factor for the development of various kidney diseases. Identification of molecules that modulate this process could lead to the development of new strategies for preventing kidney diseases. In this study, we evaluated whether mammalian silent information regulator 2 (SIRT1), which has been recently identified as a cell survival factor countering various stressors, is a key regulator of oxidative stress-induced mesangial cell apoptosis. Morphological features of apoptotic cell death (nuclear condensation) and the expression of biochemical pro-apoptotic markers [cleavages of caspase-3 and poly (ADP-ribose) polymerase (PARP)] were assessed in murine mesangial cells (MMC_s) exposed to hydrogen peroxide (H_2O_2) or TGF-beta. H_2O_2 or TGF-beta increased mesangial cell apoptosis, predominantly through p53 activation by acetylation, which is a post-transcriptional modification for p53 activation. H_2O … More _2 or TGF-beta-induced apoptosis was significantly attenuated in SIRT1-overexpressing MMCs, but enhanced in SIRT1-knockdown MMCs. We also find that SIRT1 directly interacts with the N-terminus of Smad7. Furthermore, SIRT1 reversed acetyl-transferase (p300)-mediated acetylation of two lysine residues (K64 and K70) on Smad7. In vivo, levels of Smad7 protein expression was reduced by SIRT1-overexpression and increased by SIRT 1-knockdown via modulating smurfl-mediated Smad7 degradation via ubiquitin proteasome action. Our results indicate that SIRT1 can prevent oxidative stress-induced apoptosis through p53 inactivation in mesangial cells and Smad7 is a new target molecule for SIRT1, and functionally SIRT1 attenuates TGFβ-induced vascular cell apoptosis through acceleration of Smad7 degradation. Up-regulation of SIRT1 may provide a new strategy for preventing kidney glomerular diseases. We next examine the target molecules which have the ability to induce SIRT1 by using a protein chip analysis and find that 24 candidates specific to calorie resariction. Less