Department of Endocrinology, The 1st Affiliated Hospital of Harbin Medical University, Harbin, 150001, China.
Department of Endocrinology, The 1st Affiliated Hospital of Harbin Medical University, Harbin, 150001, China.
Exp Cell Res. 2020 Nov 15;396(2):112291. doi: 10.1016/j.yexcr.2020.112291. Epub 2020 Sep 19.
Chronic oxidative stress resulting from hyperlipidemia is thought to be a key pathogenic driver of pancreatic β-cell dysfunction in leading to the onset of type 2 diabetes mellitus (T2DM). Long non-coding RNAs (lncRNAs) have been increasingly recognized to regulate dysfunction within pancreatic β-cells in the context of T2DM. In the present study, we sought to comprehensively analyze the roles of lncRNAs in dysfunctional β-cells and mouse islets. Analyses of INS-1E cells were performed by RNA-seq and qRT-PCR after treating with or without 0.5 mM palmitate for 4 days, leading us to identify the novel lncRNA Eif4g2 (lncEif4g2) as a functional regulator within these cells. When we overexpressed lncEif4g2 in INS-1E β-cells and mouse islets, this was sufficient for the reversal of palmitate-mediated reductions in cell viability, insulin production, ATP production by mitochondria, and creation of intracellular reactive oxygen species (ROS) and the dysfunction of mouse islets, with nuclear factor erythroid 2 related factor 2 (Nrf2) activation also being observed. In contrast, when lncEif4g2 was knocked down this led INS-1E cells and mouse islets to become more sensitive to palmitate-induced dysfunction, with reduced Nrf2 nuclear translocation also being detected. When antioxidants were used to treat INS-1E cells and mouse islets, however, these negative effects were reversed. Additional functional analyses revealed lncEif4g2 to be capable of directly binding to miR-3074-5p in β-cells, with the expression of lncEif4g2 and miR-3074-5p being negatively correlated with one another. We further found that cAMP-responsive element binding-protein (CREB) was a miR-3074-5p target gene in these cells, thus at least in part serving as a functional mediator of the lncEif4g2/miR-3074-5p axis within dysfunctional β-cells. In summary, our results thus reveal that lncEif4g2 is able to indirectly regulate the expression of CREB via targeting miR-3074-5p in INS-1E cells and mouse islets, thereby leading to enhanced Nrf2 activation.
慢性氧化应激是由高血脂引起的，被认为是导致 2 型糖尿病（T2DM）的胰腺β细胞功能障碍的关键致病驱动因素。长链非编码 RNA（lncRNA）已被越来越多地认识到可调节 T2DM 中胰腺β细胞的功能障碍。在本研究中，我们试图全面分析 lncRNA 在功能障碍的β细胞和小鼠胰岛中的作用。用 0.5 mM 软脂酸处理 INS-1E 细胞 4 天后，通过 RNA-seq 和 qRT-PCR 进行分析，导致我们鉴定出新型 lncRNA Eif4g2（lncEif4g2）作为这些细胞中的功能调节剂。当我们在 INS-1E β细胞和小鼠胰岛中转染 lncEif4g2 时，足以逆转软脂酸介导的细胞活力、胰岛素产生、线粒体产生的 ATP 和细胞内活性氧（ROS）的产生以及小鼠胰岛的功能障碍，同时观察到核因子红细胞 2 相关因子 2（Nrf2）的激活。相反，当敲低 lncEif4g2 时，INS-1E 细胞和小鼠胰岛对软脂酸诱导的功能障碍更加敏感，同时也检测到 Nrf2 核易位减少。然而，当抗氧化剂用于治疗 INS-1E 细胞和小鼠胰岛时，这些负面影响被逆转。额外的功能分析表明，lncEif4g2 能够在β细胞中直接与 miR-3074-5p 结合，lncEif4g2 和 miR-3074-5p 的表达呈负相关。我们还发现 cAMP 反应元件结合蛋白（CREB）是这些细胞中 miR-3074-5p 的靶基因，因此至少部分作为 lncEif4g2/miR-3074-5p 轴在功能障碍的β细胞中的功能调节剂。总之，我们的结果表明，lncEif4g2 能够通过靶向 INS-1E 细胞和小鼠胰岛中的 miR-3074-5p 间接调节 CREB 的表达，从而导致 Nrf2 激活增强。
