Organellar calcium signalling mechanisms in Drosophila epithelial function.

Calcium signalling and calcium homeostasis are essential for life. Studies of calcium signalling thus constitute a major proportion of research in the life sciences, although the majority of these studies are based in cell lines or isolated cells. Epithelial cells and tissues are essential in the regulation of critical physiological processes, including fluid transport; and so the modulation of such processes in vivo by cell-specific calcium signalling is thus of interest. In this review, we describe the approaches to measuring intracellular calcium in the genetically tractable fluid-transporting tissue, the Drosophila Malpighian tubule by targeting cell-specific protein-based calcium reporters to defined regions, cells and intracellular compartments of the intact Malpighian tubule. We also discuss recent findings on the roles of plasma membrane and intracellular calcium channels; and on organellar stores - including mitochondria, Golgi and peroxisomes - in Malpighian tubule function.