Institute of Anatomy, Ludwig-Maximilians-University Munich, Munich 80336 Germany.
J Biol Chem. 2012 Jul 27;287(31):25770-81. doi: 10.1074/jbc.M112.355420. Epub 2012 Jun 11.
Tendon overuse injuries and tendinitis are accompanied by catabolic processes and apoptosis of tenocytes. However, the precise molecular mechanisms of the destructive processes in tendon are not fully understood. Sirt-1, a nicotinamide adenine dinucleotide (NAD(+))-dependent deacetylase, has been linked to transcriptional silencing and appears to play a key role in inflammation. The purpose of this study was to examine whether down-regulation of Sirt-1 using antisense oligonucleotides (ASO) affects inflammatory and apoptotic signaling in tenocytes. Transient transfection of tenocytes with ASO against Sirt-1 induced expression of Bax and other proteins involved in apoptosis (cleaved caspase-3 and poly(ADP-ribose)polymerase), acetylation of tumor suppressor p53, and mitochondrial degradation. Interestingly, Sirt-1 was found to interact directly with p53. In contrast, Sirt-1 activator resveratrol inhibited interleukin-1β (IL-1β)- and nicotinamide-induced NF-κB activation and p65 acetylation and suppressed the activation of IκB-α kinase. Resveratrol also reversed the IL-1β- or nicotinamide-induced up-regulation of various gene products that mediate inflammation (cyclooxygenase-2) and matrix degradation (matrix metalloproteinase-9) that are known to be regulated by NF-κB. Knockdown of Sirt-1 by using ASO abolished the inhibitory effects of resveratrol on inflammatory and apoptotic signaling including Akt activation and SCAX suppression. Down-regulation of histone deacetylase Sirt-1 by mRNA interference abrogated the effect of resveratrol on NF-κB suppression, thus highlighting the crucial homeostatic role of this enzyme. Overall, these results suggest for the first time that Sirt-1 can regulate p53 and NF-κB signaling via deacetylation, demonstrating a novel role for resveratrol in the treatment of tendinitis/tendinopathy.
肌腱过度使用损伤和肌腱炎伴随着分解代谢过程和腱细胞凋亡。然而，肌腱破坏性过程的确切分子机制尚未完全理解。Sirt-1 是一种烟酰胺腺嘌呤二核苷酸（NAD(+)）依赖性去乙酰化酶，与转录沉默有关，似乎在炎症中发挥关键作用。本研究旨在研究使用反义寡核苷酸（ASO）下调 Sirt-1 是否会影响腱细胞中的炎症和凋亡信号。用针对 Sirt-1 的 ASO 瞬时转染腱细胞，诱导 Bax 和其他参与凋亡的蛋白质（切割的 caspase-3 和多聚（ADP-核糖）聚合酶）、肿瘤抑制因子 p53 的乙酰化和线粒体降解的表达。有趣的是，发现 Sirt-1 与 p53 直接相互作用。相比之下，Sirt-1 激活剂白藜芦醇抑制白细胞介素-1β（IL-1β）和烟酰胺诱导的 NF-κB 激活和 p65 乙酰化，并抑制 IκB-α 激酶的激活。白藜芦醇还逆转了 IL-1β 或烟酰胺诱导的各种基因产物的上调，这些基因产物介导炎症（环加氧酶-2）和基质降解（基质金属蛋白酶-9），这些基因产物已知受 NF-κB 调节。使用 ASO 敲低 Sirt-1 可消除白藜芦醇对炎症和凋亡信号的抑制作用，包括 Akt 激活和 SCAX 抑制。通过 mRNA 干扰下调组蛋白去乙酰化酶 Sirt-1 可消除白藜芦醇对 NF-κB 抑制的作用，从而突出了该酶的重要稳态作用。总的来说，这些结果首次表明 Sirt-1 可以通过去乙酰化调节 p53 和 NF-κB 信号，从而证明白藜芦醇在治疗肌腱炎/腱病中的新作用。
