Orai, RyR, and IP3R channels cooperatively regulate calcium signaling in brain mid-capillary pericytes

Abstract Pericytes are multifunctional cells of the vasculature that are vital to brain homeostasis, yet many of their fundamental physiological properties, such as Ca 2+ signaling pathways, remain unexplored. We performed pharmacological and ion substitution experiments to investigate the mechanisms underlying pericyte Ca 2+ signaling in acute cortical brain slices of PDGFRβ-Cre::GCaMP6f mice. We report that mid-capillary pericyte Ca 2+ signalling differs from ensheathing type pericytes in that it is largely independent of L- and T-type voltage-gated calcium channels. Instead, Ca 2+ signals in mid-capillary pericytes were inhibited by multiple Orai channel blockers, which also inhibited Ca 2+ entry triggered by endoplasmic reticulum (ER) store depletion. An investigation into store release pathways indicated that Ca 2+ transients in mid-capillary pericytes occur through a combination of IP 3 R and RyR activation, and that Orai store-operated calcium entry (SOCE) is required to sustain and amplify intracellular Ca 2+ increases evoked by the GqGPCR agonist endothelin-1. These results suggest that Ca 2+ influx via Orai channels reciprocally regulates IP 3 R and RyR release pathways in the ER, which together generate spontaneous Ca 2+ transients and amplify Gq-coupled Ca 2+ elevations in mid-capillary pericytes. Thus, SOCE is a major regulator of pericyte Ca 2+ and a target for manipulating their function in health and disease.