脳毛細血管内皮細胞におけるGタンパク質共役受容体とPiezo1チャネルのクロストーク：PIP2による調節機構とその神経血管連関への影響

Brain capillaries are sensors of neural activity. When a brain region is active, capillary endothelial cells (ECs) sense neuron-derived mediators and elicit a local increase in blood flow (functional hyperemia) to support the rise in metabolic needs. This hyperemic response involves a rapid electrical component and a slower chemical component that involves Gαq PCR (G_qPCR) activation by agonists released from neurons. The intravascular forces associated with hyperemia engage mechanosensitive Piezo1-mediated signaling that serves a mechano-feedback control function to facilitate the return of elevated blood flow to basal levels. Whether G_qPCR activity influences Piezo1 mechanosensitive signaling has not been explored, despite the potential significant implications of such crosstalk. Using patch-clamp electrophysiology and freshly isolated brain capillary ECs, we demonstrate that prostanoid or muscarinic G_qPCR activation facilitates Piezo1 activity. Pharmacological studies revealed the involvement of Gαq and phospholipase C stimulation, as well as downstream phosphatidylinositol-4,5-bisphosphate (PIP₂) hydrolysis in Piezo1 activation, but not signaling triggered by metabolites of PIP₂ hydrolysis. Exogenous application of nanomolar-to-micromolar PIP₂ suppressed Piezo1 open probability. Brain capillary ECs from mouse models of Alzheimer's disease, cerebral small vessel disease, or Piezo1 gain-of-function mutation exhibited higher Piezo1 activity, that was corrected by exogenous ex vivo PIP₂ application. We finally tested in vivo the hypothesis that systemic PIP₂ administration restores functional hyperemia in EC-specific Piezo1 gain-of-function mutant mice suffering impaired blood flow. Our findings provide insights into Piezo1 channel regulation and how it affects neurovascular coupling and cerebral blood flow.