P110α and P110δ catalytic subunits of PI3 kinase regulate lysophosphatidylcholine-induced TRPC6 externalization

Lipid oxidation products, including lysophosphatidylcholine (lysoPC) inhibit endothelial cell (EC) migration in vitro and impair EC healing of arterial injuries in vivo, in part by activating phosphatidylinositol 3-kinase (PI3K), which increases the externalization of canonical transient receptor potential 6 (TRPC6) channels and the subsequent increase in intracellular calcium. Inhibition of PI3K is a potential method to decrease TRPC6 activation and restore migration, but PI3K is involved in multiple intracellular signaling pathways and has multiple downstream effectors. The goal of this study is to identify the specific p110 catalytic subunit isoforms responsible for lysoPC-induced TRPC6 externalization to identify a target for intervention while minimizing impact on alternative signaling pathways. Down-regulation of the p110α and p110δ isoforms, but not the p110β or p110γ isoforms, with small interfering RNA significantly decreased phosphatidylinositol (3,4,5)-trisphosphate production and TRPC6 externalization, and significantly improved EC migration in the presence of lysoPC. These results identify an additional role of p110α in EC and reveal for the first time a specific role of p110δ in EC, providing a foundation for subsequent in vivo studies to investigate the impact of p110 isoform inhibition on arterial healing after injury.