부산대학교 도서관

ABSTRACTAssessing the response of pancreatic islet cells to glucose stimulation is important for understanding β-cell function. Zebrafish are a promising model for studies of metabolism in general, including stimulus-secretion coupling in the pancreas. We used transgenic zebrafish embryos expressing a genetically-encoded Ca2+sensor in pancreatic β-cells to monitor a key step in glucose induced insulin secretion; the elevations of intracellular [Ca2+]i. In vivoand ex vivoanalyses of [Ca2+]idemonstrate that β-cell responsiveness to glucose is well established in late embryogenesis and that embryonic β-cells also respond to free fatty acid and amino acid challenges. In vivoimaging of whole embryos further shows that indirect glucose administration, for example by yolk injection, results in a slow and asynchronous induction of β-cell [Ca2+]iresponses, while intravenous glucose injections cause immediate and islet-wide synchronized [Ca2+]ifluctuations. Finally, we demonstrate that embryos with disrupted mutation of the CaV1.2channel gene cacna1care hyperglycemic and that this phenotype is associated with glucose-independent [Ca2+]ifluctuation in β-cells. The data reveal a novel central role of cacna1cin β-cell specific stimulus-secretion coupling in zebrafish and demonstrate that the novel approach we propose – to monitor the [Ca2+]idynamics in embryonic β-cells in vivo– will help to expand the understanding of β-cell physiological functions in healthy and diseased states.