The present study assessed the ability of optogenetics techniques to provide a better understanding of the control of insulin secretion, particularly regarding pancreatic β-cell function in homeostasis and pathological conditions such as
diabetes mellitus (DM). We used optogenetics to investigate whether insulin secretion and
blood glucose homeostasis could be controlled by regulating intracellular
calcium ion concentrations ([Ca(2+)]i) in a mouse pancreatic β-cell line (MIN6) transfected with the optogenetic
protein channelrhodopsin-2 (ChR2). The ChR2-transfected MIN6 (ChR2-MIN6) cells secreted
insulin following irradiation with a
laser (470 nm). The increase in [Ca(2+)]i was accompanied by elevated levels of messenger RNAs that encode
calcium/calmodulin-dependent protein kinase II delta and
adenylate cyclase 1. ChR2-MIN6 cells suspended in
matrigel were inoculated into
streptozotocin-induced diabetic mice that were then subjected to a
glucose tolerance test.
Laser irradiation of these mice caused a significant decrease in
blood glucose, and the irradiated implanted cells expressed
insulin. These findings demonstrate the power of optogenetics to precisely and efficiently controlled insulin secretion by pancreatic β-cells 'on demand', in contrast to techniques using
growth factors or chemical inducers. Optogenetic technology shows great promise for understanding the mechanisms of
glucose homeostasis and for developing treatments for
metabolic diseases such as DM.