Caveolin‐1 Supports the P2Y2 Receptor Signaling

Abstract

Damage to the CNS cells’ can cause a differential spatiotemporal release of multiple factors into the extracellular space. Among such factors, nucleotides, and their interaction with the P2Y2 nucleotide receptors (P2Y2Rs) have gained prominence as putative modulators of gliotic responses after CNS injury. Yet, the molecular mechanisms underlying these interactions and responses remain to be explored. Discontinuous sucrose density gradient separation of 1321N1 cells (expressing recombinant hP2Y2R) homogenates revealed co‐fractionation of P2Y2Rs in cav‐1 (+) membrane‐raft fractions. Likewise, confocal microscopy revealed that a significant percent of P2Y2Rs co‐localized with cav‐1 in its sub‐cellular distribution. Blocking cav‐1 expression in hP2Y2‐1321N1 cells elicited abnormal intracellular Ca2+ mobilization responses and uncharacteristic patterns of AKT, ERK1/2 and p38 phosphorylation levels when stimulated with nucleotide agonists, as determined by microfluorometric calcium imaging analyses and immunoblotting, respectively. Our findings suggest that P2Y2Rs reside in membrane caveolae of non‐stimulated 1321N1 cells and that this sub‐cellular compartment may couple its downstream signaling machinery. We hypothesize that P2Y2Rs’ signaling cascades are linked to their expression in cav‐1 (+) micro‐domains. NAM is supported by the NIGMS‐NIH award number R25GM061838 at the UPR‐MSC.