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

Pericytes are multifunctional cells of the vasculature that are vital to brain homeostasis, yet many of their fundamental physiological properties, such as Ca2+ signaling pathways, remain unexplored. We performed pharmacological and ion substitution experiments to investigate the mechanisms underlying pericyte Ca2+ signaling in acute cortical brain slices of PDGFR beta-Cre::GCaMP6f mice. We report that mid-capillary pericyte Ca2+ signalling differs from ensheathing type pericytes in that it is largely independent of L- and T-type voltage-gated calcium channels. Instead, Ca2+ signals in mid-capillary pericytes were inhibited by multiple Orai channel blockers, which also inhibited Ca2+ entry triggered by endoplasmic reticulum (ER) store depletion. An investigation into store release pathways indicated that Ca2+ transients in mid-capillary pericytes occur through a combination of IP3R and RyR activation, and that Orai store-operated calcium entry (SOCE) is required to sustain and amplify intracellular Ca2+ increases evoked by the GqGPCR agonist endothelin-1. These results suggest that Ca2+ influx via Orai channels reciprocally regulates IP3R and RyR release pathways in the ER, which together generate spontaneous Ca2+ transients and amplify Gq-coupled Ca2+ elevations in mid-capillary pericytes. Thus, SOCE is a major regulator of pericyte Ca2+ and a target for manipulating their function in health and disease. Pharmacology and imaging of pericytes expressing GCaMP6f uncovers the basis of Ca2+ signaling in mid-capillary brain pericytes.

Automated summary

We investigated the mechanisms underlying pericyte Ca2+ signaling in the acute cortical brain slices of mice. Our findings suggest that mid-capillary pericytes exhibit different Ca2+ signaling compared to ensheathing type pericytes. We discovered that Orai channels play a significant role in regulating Ca2+ entry in mid-capillary pericytes, and that store-operated calcium entry (SOCE) is required to sustain and amplify intracellular Ca2+ increases. This study provides insights into the regulation of pericyte function and highlights the potential of targeting SOCE for therapeutic intervention in brain-related conditions.