In vivo monitoring of intracellular Ca2+ dynamics in the pancreatic β-cells of zebrafish embryos

Reka Lorincz, Christopher H. Emfinger, Andrea Walcher, Michael Giolai, Claudia Krautgasser, Maria S. Remedi, Colin G. Nichols & Dirk Meyer. Islets, Volume 10, Issue 6, 2 November 2018, Pages 221-238 Read More

Abstract

Assessing 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 vivo and ex vivo analyses of [Ca2+]i demonstrate 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 vivo imaging 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+]i responses, while intravenous glucose injections cause immediate and islet-wide synchronized [Ca2+]i fluctuations. Finally, we demonstrate that embryos with disrupted mutation of the CaV1.2 channel gene cacna1c are hyperglycemic and that this phenotype is associated with glucose-independent [Ca2+]i fluctuation in β-cells. The data reveal a novel central role of cacna1c in β-cell specific stimulus-secretion coupling in zebrafish and demonstrate that the novel approach we propose–to monitor the [Ca2+]i dynamics in embryonic β-cells in vivo–will help to expand the understanding of β-cell physiological functions in healthy and diseased states. © 2018, © 2018 The Authors. Published with license by Tayloy & Francis.

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Posted on December 27, 2018
Posted in: Neurogenetics & Transcriptomics, Neurovascular Injury & Repair, Publications Authors: ,