PP2A and CDK16 antagonistically regulate WIPI2B phosphorylation and neuronal autophagosome biogenesis

Autophagy is a recycling pathway that clears cellular constituents, supporting homeostasis. In primary murine neurons, autophagosome biogenesis declines during aging. Importantly, this decline can be restored by the ectopic expression of key autophagy component WIPI2B. The phosphorylation state of WIPI2B serine 395 is critical for this restoration, suggesting that WIPI2B S395 phosphorylation regulates autophagosome biogenesis. Here, we identified protein phosphatase 2A (PP2A) and CDK16 as regulators of WIPI2B S395 phosphorylation and neuronal autophagy. Using <i>Caenorhabditis elegans</i> , we showed that PP2A and CDK16 regulate neuronal autophagy through the same genetic pathway as WIPI2B <i>in vivo</i> . Further, purified mammalian PP2A and CDK16 directly modified WIPI2B S395 phosphorylation <i>in vitro.</i> In primary murine neurons, PP2A and CDK16 colocalized with WIPI2B at autophagosomes, and manipulation of PP2A and CDK16 expression altered WIPI2B puncta formation and rates of autophagosome biogenesis. Altogether, our data support the conclusion that PP2A and CDK16 regulate WIPI2B S395 phosphorylation, modulating autophagosome biogenesis in neurons.