SIRT1调节的组蛋白H3表观遗传修饰在糖尿病视网膜病变代谢记忆中的作用

Previous studies demonstrated that epigenetic histone (H) modifications may be involved in metabolic memory in diabetic retinopathy (DR), but the underlying mechanisms are still incompletely understood. Recently, we found that a class III H deacetylase Sirtuin 1 (SIRT1) inhibits the metabolic memory, however, it is unclear whether there is a correlation between the inhibitory effects and epigenetic H modifications mediated by SIRT1. Therefore, this study is designed to, firstly, investigate that SIRT1 may modulate H3 acetylation and H3 methylation by ChIP assays, which play a role in the pathogenesis of the metabolic memory in DR; then, clarify the effects of SIRT1-mediated H3 methylation may be associated with the up-regulation of H methyltransferase SUV39H1 by gene recombination; further, reveal that the inhibitory effects of SIRT1 on the metabolic memory in DR could attribute to the epigenetic H modifications mediated by it in vivo and in vitro. As far as we know, it is no report for the action of SIRT1 in the pathogenesis of the metabolic memory in DR, and the novel findings would highlight the potential role of SIRT1 in the pathogenesis of epigenetic H modifications-related diseases. In a word, these results may provide scientific basis for the prevention and treatment of the metabolic memory in DR.

既往研究发现，糖尿病视网膜病变（DR）代谢记忆的发生与组蛋白（H）表观遗传修饰有关，但其具体作用不明；最近，本课题组研究发现，H去乙酰化酶SIRT1可抑制糖尿病鼠视网膜代谢记忆的发生，然而SIRT1调节的H表观遗传修饰是否在DR代谢记忆中发挥作用，目前尚不清晰。为此，本课题首先应用染色质免疫共沉淀技术，探讨SIRT1可调节H3乙酰化和甲基化，且在糖尿病鼠视网膜组织细胞代谢记忆中发挥重要作用；其次运用基因重组技术，阐明SIRT1调节H3甲基化可能与组蛋白甲基转移酶SUV39H1上调有关；进一步以SIRT1为靶点进行体内外干预，揭示SIRT1对代谢记忆的抑制作用与其调节H3表观遗传修饰有关联性。这些研究目前在国际上尚属空白，其预期的研究结果将可能丰富人们对SIRT1调控的H3表观遗传修饰异常相关疾病如DR等发病机制的认识，为DR代谢记忆临床防治等提供理论和实验依据，具有重要的理论和现实意义。

表观遗传作用在许多代谢性疾病如糖尿病发病中发挥着重要作用，因此，开发一类表观遗传调节药物，从而激活复杂的基因转录重排过程，治疗前景十分乐观。我们的研究表明，在糖尿病代谢记忆状态下，二甲双胍通过人脐静脉内皮细胞和牛视网膜毛细血管内皮细胞的组蛋白H3K9 低乙酰化及超甲基化抑制炎症及凋亡相关基因如NF-κB/P65，TNF-α 及 p53 ，并通过调控H3K9乙酰化激活甲基转移酶SUV39H1，从而增加H3K9甲基化。进一步研究发现，在二甲双胍治疗过程中，SIRT1在H3K9超甲基化及低乙酰化过程中发挥重要作用。更为重要的是，类似的结果已经在糖尿病鼠的视网膜中得到证实。总之，二甲双胍作为一类表观遗传药物，通过SIRT1调节组蛋白H3K9表观遗传改变，从而抑制糖尿病的代谢记忆作用。