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

氧化应激和/或转化生长因子-β诱导的肾小球细胞凋亡是多种肾脏疾病发生发展的重要因素。识别调节这一过程的分子可能会导致开发预防肾脏疾病的新策略。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。观察过氧化氢(H_2O_2)和转化生长因子-β对小鼠肾小球系膜细胞(MMC_S)的细胞凋亡(核固缩)和促凋亡生化标志物[caspase-3和多聚腺苷二磷酸核糖聚合酶(PARP)的裂解]表达的影响。H_2O_2或转化生长因子-β促进系膜细胞凋亡，主要是通过乙酰化激活P53，这是对P53激活的转录后修饰。H_2O…在高表达SIRT1的MMCs中，More_2或TGF-β诱导的细胞凋亡显著减少，而在SIRT1基因敲除的MMCs中，More_2或转化生长因子-β诱导的MMCs的凋亡明显增强。我们还发现SIRT1直接与Smad7的N末端相互作用。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，SIRT1过表达可降低Smad7蛋白的表达水平，而SIRT1可通过泛素蛋白酶体作用调节Smad7的降解，从而使SIRT1基因敲除后Smad7蛋白表达增加。我们的结果表明，SIRT1可以通过失活P53来阻止氧化应激诱导的系膜细胞凋亡，Smad7是SIRT1的一个新的靶分子，并且SIRT1通过加速Smad7的降解而在功能上减弱转化生长因子β诱导的血管细胞凋亡。SIRT1的上调可能为预防肾小球疾病提供新的策略。接下来，我们使用蛋白质芯片分析来检查有能力诱导SIRT1的目标分子，发现24个候选分子特定于卡路里再分配。较少

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