Department of Endocrinology and Metabolism, The Second Affiliated Hospital of Chongqing Medical University, 76, Linjiang Road, Yuzhong District, Chongqing 400010, China.
Department of Gastroenterology, The Second Affiliated Hospital of Chongqing Medical University, 76, Linjiang Road, Yuzhong District, Chongqing 400010, China.
Life Sci. 2020 Jul 1;252:117648. doi: 10.1016/j.lfs.2020.117648. Epub 2020 Apr 8.
This study was conducted to determine the relationship between mesencephalic astrocyte-derived neurotrophic factor (MANF), autophagy and endoplasmic reticulum (ER) stress, and whether liraglutide (LRG) can protect β cells, promote autophagy and alleviate ER stress by regulating MANF expression.
Human serum samples were collected from healthy controls (NC), simple hyperlipidemia (HLD), and newly diagnosed type 2 diabetes (T2D). The MANF levels were detected using ELISA. In vitro, after the mouse islet MIN6 cells were treated with glucose (GLU), palmitate (PA), thapsigargin (TG), LRG, and chloroquine (CQ), cell proliferation was detected using cell counting kit-8 (CCK-8), apoptosis-related protein cleaved caspase 3 (C-cas-3), ER stress, and autophagy-related proteins were detected by Western blotting, MANF, insulin, and C-cas-3 proteins were detected via immunofluorescence. Subcellular structures and autophagosomes were examined using electron microscopy.
Compared with the NC group, the MANF levels in the HLD and T2D groups increased significantly. After ER stress induced by GLU, PA, and TG, cell viability decreased, while MANF, c-cas3, ERS, and autophagy-related proteins increased, which was related to the concentration of GLU, PA, and TG. Compared with the BSA group, the number of mitochondria and autophagosomes in the PA group increased and the mitochondria were damaged. In the PA and TG plus CQ groups, the effect was further exaggerated. But after co-treatment with LRG, the effects of GLU, PA, and TG were attenuated.
LRG protects islet β cells from ER stress by upregulating MANF to promote autophagy turnover.
本研究旨在探讨中脑神经胶质细胞衍生神经营养因子（MANF）、自噬和内质网（ER）应激之间的关系，以及利拉鲁肽（LRG）是否可以通过调节 MANF 表达来保护β细胞、促进自噬和减轻 ER 应激。
收集健康对照（NC）、单纯高脂血症（HLD）和新诊断的 2 型糖尿病（T2D）患者的血清样本，采用 ELISA 检测 MANF 水平。体外培养小鼠胰岛 MIN6 细胞，用葡萄糖（GLU）、棕榈酸（PA）、他普西龙（TG）、LRG 和氯喹（CQ）处理后，通过细胞计数试剂盒-8（CCK-8）检测细胞增殖，通过 Western blot 检测凋亡相关蛋白 cleaved caspase 3（C-cas-3）、ER 应激和自噬相关蛋白，通过免疫荧光检测 MANF、胰岛素和 C-cas-3 蛋白，通过电子显微镜观察亚细胞结构和自噬体。
与 NC 组相比，HLD 和 T2D 组 MANF 水平明显升高。GLU、PA 和 TG 诱导 ER 应激后，细胞活力下降，而 MANF、C-cas3、ERS 和自噬相关蛋白增加，与 GLU、PA 和 TG 的浓度有关。与 BSA 组相比，PA 组的线粒体和自噬体数量增加，线粒体受损。在 PA 和 TG 加 CQ 组中，这种作用进一步被夸大。但与 LRG 共同处理后，GLU、PA 和 TG 的作用减弱。
LRG 通过上调 MANF 促进自噬周转来保护胰岛β细胞免受 ER 应激。
