From the Department of Endocrinology and Metabolism, Baskent University Faculty of Medicine, Ankara, Turkey.
Exp Clin Transplant. 2022 Jun;20(6):585-594. doi: 10.6002/ect.2022.0027.
Lipotoxicity and glucolipotoxicity are among the mostimportanttriggers of beta-cell failure in patients with type 2 and posttransplant diabetes. Because the Golgi apparatus is a vital organelle in secretory cells like beta cells, its behavior under stress conditions determines the cell's functional capacity.
To mimic lipotoxicity and glucolipotoxicity as metabolic stresses for beta-cell failure, rat insulinoma INS-1E cells were treated with palmitic acid, glucose, or both. Cells were cultured in the presence of 5.0, 16.7, or 33 mM glucose with or without 0.5 mM palmitic acid for 8, 16, 24, and 48 hours. Incubation in the presence of any of the 3 concentrations of glucose with 0.5 mM palmitic acid provided glucolipotoxicity. In addition to the endoplasmic reticulum stress marker (Hspa5), we evaluated changes in Golgi function under experimental metabolic stresses. In doing this, we measured expression levels of the genes coding Golgi structural proteins (Acbd3,Golga2, and Arf1), Golgi glycosylation enzymes sialyltransferaz10 and sialyltransferase 1 (St3gal1), and Golgi stress mediators (Creb3 and Arf4).
Golgi responded to lipotoxicity and glucolipotoxicity by increasing the expression of St3gal1 (P = .05 in both conditions) and Creb3 (P = .022 and P = .01, respectively). The Arf4 gene transcript also increased in glucolipotoxic media (P = .03). Glucotoxicity alone did not induce a change in the transcript levels of Creb3 and Arf4. Lipotoxicity and glucolipotoxicity induced Creb3 and Arf4 expression, which are important Golgi stress response mediators leading to apoptosis.
This preliminary study showed that the Golgi stress response is important in lipotoxic and glucolipotoxic conditions in terms of beta-cell failure. Solving the mystery of intracellular molecular mechanisms leading to beta-cell dysfunction is crucial to understanding the pathophysiology of posttransplant diabetes and most probably the failure of intraportal islet transplants in the long term.
脂毒性和糖脂毒性是 2 型糖尿病和移植后糖尿病患者β细胞衰竭的最重要触发因素之一。由于高尔基体是β细胞等分泌细胞中的重要细胞器，因此其在应激条件下的行为决定了细胞的功能能力。
为了模拟脂毒性和糖脂毒性作为β细胞衰竭的代谢应激，用棕榈酸、葡萄糖或两者同时处理大鼠胰岛素瘤 INS-1E 细胞。将细胞在 5.0、16.7 或 33 mM 葡萄糖存在下培养，有或没有 0.5 mM 棕榈酸，分别孵育 8、16、24 和 48 小时。在任何 3 种葡萄糖浓度下孵育时加入 0.5 mM 棕榈酸可提供糖脂毒性。除内质网应激标志物（Hspa5）外，我们还评估了实验代谢应激下高尔基体功能的变化。为此，我们测量了编码高尔基体结构蛋白（Acbd3、Golga2 和 Arf1）、高尔基体糖基化酶唾液酸转移酶 10 和唾液酸转移酶 1（St3gal1）以及高尔基体应激介质（Creb3 和 Arf4）的基因表达水平。
高尔基体通过增加 St3gal1 的表达对脂毒性和糖脂毒性作出反应（在两种情况下 P =.05）和 Creb3（分别为 P =.022 和 P =.01）。Arf4 基因转录物在糖脂毒性培养基中也增加（P =.03）。单纯的葡萄糖毒性不会引起 Creb3 和 Arf4 转录水平的变化。脂毒性和糖脂毒性诱导了 Creb3 和 Arf4 的表达，这是导致细胞凋亡的重要高尔基体应激反应介质。
这项初步研究表明，高尔基体应激反应在β细胞衰竭的脂毒性和糖脂毒性条件下很重要。解决导致β细胞功能障碍的细胞内分子机制的奥秘对于理解移植后糖尿病的病理生理学以及在长期内门静脉胰岛移植的失败至关重要。
