1. Optogenetic control of insulin secretion in intact pancreatic islets with β-cell-specific expression of Channelrhodopsin-2
- Author
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Inês G. Mollet, Annika S. Axelsson, Anders Rosengren, Fatemeh Safi, and Thomas Reinbothe
- Subjects
insulin secretion ,medicine.medical_specialty ,Endocrinology, Diabetes and Metabolism ,medicine.medical_treatment ,Mice, Transgenic ,Stimulation ,Biology ,Glucagon ,Mice ,Endocrinology ,Bacterial Proteins ,Channelrhodopsins ,Insulin-Secreting Cells ,Diabetes mellitus ,Internal medicine ,medicine ,Animals ,Insulin ,Secretion ,Transgenes ,Promoter Regions, Genetic ,Cells, Cultured ,islets ,geography ,geography.geographical_feature_category ,diabetes ,Pancreatic islets ,Islet ,medicine.disease ,Insulin oscillation ,Optogenetics ,Luminescent Proteins ,medicine.anatomical_structure ,Cell Tracking ,Organ Specificity ,beta-cells ,Channelrhodopsin-2 ,Research Paper - Abstract
Insulin is secreted from the pancreatic β-cells in response to elevated glucose. In intact islets the capacity for insulin release is determined by a complex interplay between different cell types. This has made it difficult to specifically assess the role of β-cell defects to the insulin secretory impairment in type 2 diabetes. Here we describe a new approach, based on optogenetics, that enables specific investigation of β-cells in intact islets. We used transgenic mice expressing the light-sensitive cation channel Channelrhodopsin-2 (ChR2) under control of the insulin promoter. Glucose tolerance in vivo was assessed using intraperitoneal glucose tolerance tests, and glucose-induced insulin release was measured from static batch incubations. ChR2 localization was determined by fluorescence confocal microscopy. The effect of ChR2 stimulation with blue LED light was assessed using Ca(2+) imaging and static islet incubations. Light stimulation of islets from transgenic ChR2 mice triggered prompt increases in intracellular Ca(2+). Moreover, light stimulation enhanced insulin secretion in batch-incubated islets at low and intermediate but not at high glucose concentrations. Glucagon release was not affected. Beta-cells from mice rendered diabetic on a high-fat diet exhibited a 3.5-fold increase in light-induced Ca(2+) influx compared with mice on a control diet. Furthermore, light enhanced insulin release also at high glucose in these mice, suggesting that high-fat feeding leads to a compensatory potentiation of the Ca(2+) response in β-cells. The results demonstrate the usefulness and versatility of optogenetics for studying mechanisms of perturbed hormone secretion in diabetes with high time-resolution and cell-specificity.
- Published
- 2014