Department of Biochemistry & Molecular Biology, School of Basic Medicine, Anhui Medical University, Hefei 230032, China.
Department of General Surgery, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui 230022, China.
Cell Signal. 2018 Dec;52:155-162. doi: 10.1016/j.cellsig.2018.09.008. Epub 2018 Sep 14.
RING finger 186 (RNF186) is involved in the process of endoplasmic reticulum (ER)-stress-mediated apoptosis and inflammation of different cell types, such as HeLa cells and colon epithelial cells. However, the physiological and functional roles of RNF186 in peripheral tissues remain largely unknown. In the current study, we investigate the physiological function of RNF186 in the regulation of ER stress with respect to its biological roles in regulating insulin sensitivity in mouse primary hepatocytes. RNF186 expression is induced in the livers of diabetic, obese and diet-induced obese (DIO) mice. Mouse primary hepatocytes were isolated and treated with Ad-RNF186 or Ad-GFP. The results suggest that overexpression of RNF186 increases the protein levels of the ER stress sensors inositol requiring kinase 1 (IRE1) and C/EBP homologous protein (CHOP) protein, as well as the phosphorylation level of eukaryotic initiation factor 2α (eIF2α), in mouse primary hepatocytes. This effect impedes the action of insulin through c-Jun N-terminal kinase (JNK)-mediated phosphorylation of insulin receptor substrate 1 (IRS1). Furthermore, overexpression of RNF186 also significantly increases the levels of proinflammatory cytokines, including TNFα, IL-6 and MCP1. In addition, tauroursodeoxycholic acid (TUDCA), an ER stress inhibitor, alleviates the expression of ER stress markers induced by RNF186 overexpression. Taken together, the results of the present study show that overexpression of RNF186 induces ER stress and impairs insulin signalling in mouse primary hepatocytes, suggesting that RNF186 merits further investigation as a potential therapeutic target for treatment of insulin-resistance-associated metabolic diseases.
环指蛋白 186（RNF186）参与内质网（ER）应激介导的不同细胞类型的凋亡和炎症反应，如 HeLa 细胞和结肠上皮细胞。然而，RNF186 在周围组织中的生理和功能作用在很大程度上仍然未知。在本研究中，我们研究了 RNF186 在调节内质网应激方面的生理功能，以及其在调节小鼠原代肝细胞胰岛素敏感性方面的生物学作用。糖尿病、肥胖和饮食诱导肥胖（DIO）小鼠的肝脏中诱导表达 RNF186。分离并培养小鼠原代肝细胞，用 Ad-RNF186 或 Ad-GFP 处理。结果表明，RNF186 的过表达增加了 ER 应激传感器肌醇需求激酶 1（IRE1）和 C/EBP 同源蛋白（CHOP）蛋白的蛋白质水平，以及真核起始因子 2α（eIF2α）的磷酸化水平，在小鼠原代肝细胞中。这种作用通过 c-Jun N 末端激酶（JNK）介导的胰岛素受体底物 1（IRS1）磷酸化来阻碍胰岛素的作用。此外，RNF186 的过表达也显著增加了促炎细胞因子的水平，包括 TNFα、IL-6 和 MCP1。此外，内质网应激抑制剂牛磺熊脱氧胆酸（TUDCA）减轻了 RNF186 过表达诱导的 ER 应激标志物的表达。总之，本研究结果表明，RNF186 的过表达诱导 ER 应激并损害小鼠原代肝细胞中的胰岛素信号转导，表明 RNF186 作为治疗与胰岛素抵抗相关的代谢性疾病的潜在治疗靶点值得进一步研究。
