G{beta}{gamma} is a direct regulator of endogenous p101/p110{gamma} and p84/p110{gamma} PI3K{gamma} complexes in mouse neutrophils

The PI3K isoform is activated by Gi-coupled GPCRs in myeloid cells, but the extent to which the two endogenous complexes of PI3K, p101/p110 and p84/p110, receive direct regulation through Gβ or indirect regulation through RAS and the sufficiency of those inputs is controversial or unclear. We generated mice with point mutations that prevent Gβ binding to p110 (RK552DD) or to p101 (VVKR777AAAA) and investigated the effects of these mutations in primary neutrophils and in mouse models of neutrophilic inflammation. Loss of Gβ binding to p110 substantially reduced the activation of both p101/p110 and p84/p110 in neutrophils by various GPCR agonists. Loss of Gβ binding to p101 caused more variable effects, depending on both the agonist and cellular response, with the biggest reductions seen in PIP3 production by primary neutrophils in response to LTB4 and MIP-2 and in the migration of neutrophils during thioglycolate-induced peritonitis or MIP2-induced ear pouch inflammation. We also observed that p101VVKR777AAAA neutrophils showed enhanced p84-dependent ROS responses to fMLP and C5a, suggesting that competition may exist between p101/p110 and p84/p110 for Gβ subunits downstream of GPCR activation. GPCRs did not activate p110 in neutrophils from mice lacking both the p101 and p84 regulatory subunits, indicating that RAS binding to p110 is insufficient to support GPCR activation in this cell type. These findings define a direct role for Gβ subunits in ...
Source: Signal Transduction Knowledge Environment - Category: Science Authors: Tags: STKE Research Articles Source Type: news