The role of interleukin-1β and extracellular signal-regulated kinase 1/2 in glucose-stimulated insulin secretion

Abstract

Glucose-stimulated insulin secretion (GSIS) is one of the important physiological characteristics of islet β cells, and extracellular-regulated protein kinase 1/2 (ERK1/2) is an important member of the mitogen-activated protein kinase family that regulates this process. The inflammatory cytokine interleukin (IL)-1β can inhibit the insulin secretion of pancreatic β cells, but the exact mechanism is unclear. This study was designed to investigate the inhibitory effect of IL-1β on GSIS in βTC-6 cells and its relation with the ERK1/2 signal transduction pathway. β-TC6 cells were cultured and stimulated with 0mM, 1.38mM, or 5.5mM glucose. In addition, GSIS in β-TC6 cells was blocked by IL-1β at concentrations of 0.15 ng/mL, 1.5 ng/mL, and 15 ng/mL. After glucose stimulation and IL-1β intervention, the insulin level in the cell supernatant was detected by radioimmunoassay, and the phosphorylation level of ERK1/2 was detected by western blotting assay. The insulin level in the 1.38mM glucose group was 108.52 ± 5.94 uIU/mL, which was significantly higher than the 0mM and 5.5mM glucose groups (p < 0.05). Compared with the 0mM glucose group, the level of ERK1/2 phosphorylation was increased in the 1.38mM and 5.5mM glucose groups. After intervention by 0.15 ng/mL, 1.5 ng/mL, and 15 ng/mL IL-1β, the level of ERK1/2 phosphorylation induced by 1.38mM glucose stimulation decreased in a dose-dependent manner, and the insulin level correspondingly decreased. IL-1β can inhibit GSIS in βTC-6 cells, which is related to its inhibition of the phosphorylation of ERK1/2.

Keywords

• β-TC6
• Diabetes
• ERK1/2
• IL-1β
• Insulin