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

抄録

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.