Structural changes in endocrine pancreas of male Wistar rats due to chronic cola drink consumption. Role of PDX-1

Nickel Sulfate-Induced GSIS Injury in MIN6 Cells by Activating the JNK Pathway Through Oxidative Stress

Nickel has an impact on human health, especially in the context of the new energy industries. Nickel's influence on glycemia remains controversial, and the effects and mechanisms of nickel on islet function still need further exploration. MIN6 cells were treated with different concentrations of nickel sulfate (NiSO4) (0, 75, 150, and 300 µg/mL) for different durations (0, 12, 24, and 48 h). The study measured cell cycle progression, apoptosis, reactive oxygen species (ROS) production, oxidative stress-related indexes (T-SOD, TBARS, 8-OHdG, and GSH), glucose-induced insulin secretion (GSIS), and the expression of JNK pathway-related proteins, pancreaticoduodenal homeobox-1 (PDX-1), glucose transporter 2 (GLUT2), and forkhead box protein O1 (FOXO1). NiSO4 damaged MIN6 cells in a time- and dose-dependent manner. NiSO4 blocked the cell cycle, induced apoptosis, and reduced insulin secretion in the GSIS experiment. NiSO4 also induced ROS production, increased oxidative stress-related indexes (TRABS and 8-OHdG), and decreased antioxidant stress-related indexes (GSH and T-SOD). In addition, NiSO4 activated the JNK pathway, upregulated FOXO1 protein expression, and inhibited PDX-1 and GLUT2 protein expression, affecting insulin release during GSIS. NiSO4 inhibited the proliferation of MIN6 cells through oxidative stress, aggravated apoptosis, caused functional impairment, upregulated the expression of FOXO1 by activating the JNK pathway, inhibited the expression of PDX-1 and GLUT2 proteins, and impaired the GSIS function of islets.

Molecular Mechanism of Pancreatic β-Cell Failure in Type 2 Diabetes Mellitus

Various important transcription factors in the pancreas are involved in the process of pancreas development, the differentiation of endocrine progenitor cells into mature insulin-producing pancreatic β-cells and the preservation of mature β-cell function. However, when β-cells are continuously exposed to a high glucose concentration for a long period of time, the expression levels of several insulin gene transcription factors are substantially suppressed, which finally leads to pancreatic β-cell failure found in type 2 diabetes mellitus. Here we show the possible underlying pathway for β-cell failure. It is likely that reduced expression levels of MafA and PDX-1 and/or incretin receptor in β-cells are closely associated with β-cell failure in type 2 diabetes mellitus. Additionally, since incretin receptor expression is reduced in the advanced stage of diabetes mellitus, incretin-based medicines show more favorable effects against β-cell failure, especially in the early stage of diabetes mellitus compared to the advanced stage. On the other hand, many subjects have recently suffered from life-threatening coronavirus infection, and coronavirus infection has brought about a new and persistent pandemic. Additionally, the spread of coronavirus infection has led to various limitations on the activities of daily life and has restricted economic development worldwide. It has been reported recently that SARS-CoV-2 directly infects β-cells through neuropilin-1, leading to apoptotic β-cell death and a reduction in insulin secretion. In this review article, we feature a possible molecular mechanism for pancreatic β-cell failure, which is often observed in type 2 diabetes mellitus. Finally, we are hopeful that coronavirus infection will decline and normal daily life will soon resume all over the world.