Importance of Ca2+ in Gastric Epithelial Restitution – new views revealed by real-time in vivo measurements

摘要

It has been a few decades since Ca²⁺ was identified as one of the important factors that can accelerate gastric wound repair as well as contribute to epithelial homeostasis and regulation of gastric secretions. The mechanistic basis has remained largely unexplored in vivo because it was not possible to track in real time either intracellular Ca²⁺ mobilization or wound repair in living tissues. Recent advances in technology, such as combining high resolution light microscopy and genetically encoded Ca²⁺ reporters in mice, now allow the monitoring of Ca²⁺ mobilization during gastric epithelial cell restitution. Ca²⁺ is a ubiquitous second messenger that influences numerous cellular processes, including gastric acid/bicarbonate secretion, mucus secretion, and cell migration. We have demonstrated that cytosolic Ca²⁺ mobilization within the restituting gastric epithelial cells is a central signal driving small wound repair. However, extracellular Ca²⁺ is also mobilized in the juxtamucosal luminal space above a wound, and evidence suggests extracellular Ca²⁺ is a third messenger that also promotes gastric epithelial restitution. Interplay between intracellular and extracellular Ca²⁺ is necessary for efficient gastric epithelial restitution.