Protein kinase C (PKC)-mediated phosphorylation of PACSIN2 triggers the removal of caveolae from the plasma membrane

PACSIN2, a membrane-sculpting BAR domain protein, localizes to caveolae. Here, we found that PKC phosphorylates PACSIN2 at serine 313, thereby decreasing its membrane binding and tubulation capacities. Concomitantly, phosphorylation decreased the time span for which caveolae could be tracked at the plasma membrane (the 'tracking-duration'). Analyses of the phospho-mimetic S313E mutant suggested that PACSIN2 phosphorylation is sufficient to reduce caveolar tracking-durations. Both hypotonic treatment and isotonic drug-induced PKC activation increased PACSIN2 phosphorylation at serine 313 and shortened caveolar tracking-durations. Caveolar tracking-durations were also reduced upon the expression of other membrane-binding deficient PACSIN2 mutants or RNAi-mediated PACSIN2 depletion, pointing to a role of PACSIN2 levels for the lifetime of caveolae. Interestingly, the decrease in membrane-bound PACSIN2 was inversely correlated with the recruitment and activity of dynamin 2, a GTPase mediating membrane scission. Furthermore, expression of EHD2, which stabilizes caveolae and binds to PACSIN2, restored the tracking-durations of cells with reduced PACSIN2 levels. These findings suggest that the PACSIN2 phosphorylation decreases its membrane-binding activity, thereby decreasing its stabilizing effect on caveolae and triggering dynamin-mediated removal of caveolae.