In vivo Ca2+ imaging analysis of β-cells using an ultrasensitive Ca2+ indicator YC-Nano50

[Speaker] Kazunori Kanemaru:1,2
[Co-author] Isamu Taiko:2, Nami Kitajima:1, Hiroshi Sekiya:1, Masamitsu Iino:2
1:Department of Pharmacology, Graduate School of Medicine, The University of Tokyo, Japan, 2:Department of Cellular Molecular Pharmacology, Nihon University School of Medicine, Japan

Insulin secretion from pancreatic β-cells is regulated by intracellular Ca2+ signals, and plays a crucial role in the control of blood glucose levels. Although intracellular Ca2+ signals in β-cell have been analyzed in cell lines, isolated β-cells and pancreatic islets, Ca2+ signal patterns in β-cells in vivo may very well be more complex. Indeed, β-cells in living animals are under the influence of autonomic nervous system, and are continuously supplied with blood flow carrying various hormones, glucose, fatty acids and other substances that may affect the function of β-cells. Furthermore, previous reports suggest the existence of highly synchronized Ca2+ oscillations between β-cells and pancreatic islets in living animals, and the synchronization may be altered in diabetes mellitus. However, there is no direct evidence showing the intercellular synchronization of Ca2+ oscillations. Here, we report an in vivo β-cell Ca2+ imaging method using a transgenic mouse line expressing a genetically encoded Ca2+ indicator (YC-Nano50) in a β-cell specific manner. We succeeded in imaging Ca2+ concentrations in β-cells in laparotomized mice under anesthesia, and observed synchronized Ca2+ oscillations in β-cells within individual islets. The present in vivo β-cell Ca2+ imaging technique is expected to help us gain deeper insight into the regulation of insulin secretion and pathophysiology of diabetes mellitus.
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