Autocrine regulation of single pancreatic β-cell survival

Function and survival of cells depend in part on the presence of growth factors. We explored the autocrine regulation of insulin and nerve growth factor (NGF) on single adult rat pancreatic β-cell survival and hormone secretion. When NGF or insulin signaling were blocked in culture media, cell survival decreased compared with control cells, with apoptosis being the main mechanism of cell death. To further explore the role of glucose in β-cell survival, we cultured the cells for 16 h in 2.6 mmol/l glucose and observed that nearly 17% of the cells developed apoptosis; this effect was partially prevented by NGF and almost completely inhibited by insulin treatment. A high [K.sup.+] concentration had the same effect, suggesting that insulin and NGF secretion by the cells was responsible for the survival effects and not glucose per se. Blocking NGF signaling with an NGF antibody or with K252a reduced insulin biosynthesis and secretion in the cells that survived the treatment. Moreover, the functional β-cell subpopulation with a higher insulin secretion rate is more susceptible to K252a. These results further indicate that NGF and insulin play important autoregulatory roles in pancreatic β-cell survival and function and strongly suggest the need to explore new focuses in diabetes treatment.
Inadequate β-cell mass is a crucial factor in diabetes. Immune destruction of β-cells is the main defect in type 1 diabetes (1), whereas in type 2 diabetes, β-cell mass is [...]