Orai, RyR, and IP3R channels cooperatively regulate calcium signaling in brain mid-capillary pericytes
Braxton Phillips, Jenna Clark, Éric Martineau, Ravi L. Rungta
Abstract
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.