Store-Operated Ca²⁺ Channels Mediate Microdomain Ca²⁺ Signals and Amplify Gq-Coupled Ca²⁺ Elevations in Capillary Pericytes

Abstract

Pericytes are multifunctional cells of the vasculature that are vital to brain homeostasis, yet many of their fundamental physiological properties remain unexplored. Ca2+ is a ubiquitous second messenger across cell-types, where it mediates diverse functions such as contractility and gene transcription. It is therefore important to understand the cellular mechanisms underlying Ca2+ signalling in capillary pericytes. Here, we performed pharmacological and ion substitution experiments to investigate the mechanisms underlying pericyte Ca2+ signaling in acute cortical brain slices of PDGFRβ-GCaMP6f mice. We report that in mid-capillary bed pericytes (≥ 4th branch order), spontaneous microdomain Ca2+ signals are dependent on extracellular Ca2+, but largely independent of depolarization, L- and T-type voltage-gated calcium channels (VGCCs), and TRPC3/6 channels. In contrast, these microdomain signals were inhibited by multiple Orai channel blockers, including the specific antagonist GSK-7975A. Furthermore, capillary pericytes exhibited classical store operated calcium entry (SOCE) following store depletion that was sensitive to GSK-7975A and required for amplification of intracellular Ca2+ increases evoked by the vasoconstrictor endothelin-1. These results suggest that Orai SOCE mediates microdomain Ca2+ signals at rest and amplifies Gq-GPCR coupled Ca2+ elevations in capillary pericytes. Thus, SOCE is a major regulator of pericyte Ca2+ and a target for manipulating their function in health and disease.

TRP channels: a provocative rationalization for local Ca2+ control in arterial tone development

“…Although observations are limited, brain studies have noted that precapillary arterioles can operate in a sphincter-like manner as they branch from the penetrating arteriole. The mural cells embedded in these segments are intriguing in many aspects ( Phillips et al, 2022 ), perhaps most notably herein, the robust expression of TRPC3 and TRPC6 ( He et al, 2018 ; Vanlandewijck et al, 2018 ) ( Figure 2 ). Vasomotor heterogeneity is also observable across the length of a penetrating arterioles, a behavior consistent although not definitive for, focal zones of enhanced TRPC channel expression and pharmacomechanical control ( Institoris et al, 2015 ; Chow et al, 2020 ).…”