Lin Ning, Niu Yixin, Zhang Weiwei, Li Xiaoyong, Yang Zhen, Su Qing
Department of Endocrinology, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University Shanghai, China.
Int J Clin Exp Pathol. 2017 Nov 1;10(11):11300-11307. eCollection 2017.
Free fatty acid (FFA)-induced pancreatic β-cell loss is implicated in the pathogenesis of type 2 diabetes mellitus (T2DM). It has been documented that circulating microRNA (miR)-802 levels are significantly greater in T2DM patients than in healthy subjects. However, the role of miR-802 in FFA-induced damage to β cells is still unclear. In the present study, we measured the expression of miR-802 in the INS-1 rat insulinoma cell line after palmitate treatment for 48 h. Gain- and loss-of-function studies were conducted to determine the function of miR-802 in palmitate-induced apoptosis and reactive oxygen species (ROS) production. The target gene(s) of miR-802 was functionally characterized. Compared to control cells, palmitate treatment caused a time- and concentration-dependent induction of miR-802 in INS-1 cells. Knockdown of miR-802 significantly blocked palmitate-induced apoptosis and attenuated ROS formation. Moreover, miR-802 downregulation prevented the reduction of prosurvival proteins Mcl-1 and Bcl-xL by palmitate. In contrast, ectopic expression of miR-802 stimulated apoptosis and ROS generation in INS-1 cells. Sirtuin 6 (SIRT6) was identified to be a direct target gene of miR-802. Overexpression of miR-802 suppressed the expression of SIRT6. Enforced expression of SIRT6 abolished the induction of apoptosis and ROS production by miR-802. Taken together, miR-802 is required for palmitate-induced damage to β cells by targeting SIRT6 and represents a potential therapeutic target for T2DM.
游离脂肪酸（FFA）诱导的胰腺β细胞丢失与2型糖尿病（T2DM）的发病机制有关。已有文献记载，T2DM患者循环中的微小RNA（miR）-802水平显著高于健康受试者。然而，miR-802在FFA诱导的β细胞损伤中的作用仍不清楚。在本研究中，我们检测了棕榈酸处理48小时后INS-1大鼠胰岛素瘤细胞系中miR-802的表达。进行了功能获得和功能缺失研究，以确定miR-802在棕榈酸诱导的细胞凋亡和活性氧（ROS）产生中的作用。对miR-802的靶基因进行了功能鉴定。与对照细胞相比，棕榈酸处理导致INS-1细胞中miR-802呈时间和浓度依赖性诱导。敲低miR-802可显著阻断棕榈酸诱导的细胞凋亡并减弱ROS形成。此外，miR-802下调可防止棕榈酸导致的促生存蛋白Mcl-1和Bcl-xL减少。相反，miR-802的异位表达刺激了INS-1细胞的凋亡和ROS生成。沉默调节蛋白6（SIRT6）被确定为miR-802的直接靶基因。miR-802的过表达抑制了SIRT6的表达。SIRT6的强制表达消除了miR-802诱导的细胞凋亡和ROS产生。综上所述，miR-802通过靶向SIRT6参与棕榈酸诱导的β细胞损伤，是T2DM的一个潜在治疗靶点。
