Identification of organelle-specific autophagy regulators from tandem CRISPR screens.

Autophagy is a conserved degradative process that promotes cellular homeostasis under stress conditions. Under nutrient starvation, autophagy is nonselective, promoting indiscriminate breakdown of cytosolic components. Conversely, selective autophagy is responsible for the specific turnover of damaged organelles. We hypothesized that selective autophagy may be regulated by signaling pathways distinct from those controlling starvation-induced autophagy, thereby promoting organelle turnover. To address this question, we conducted kinome-wide CRISPR screens to identify distinct signaling pathways responsible for the regulation of basal autophagy, starvation-induced autophagy, and two types of selective autophagy, ER-phagy and pexophagy. These parallel screens identified both known and novel autophagy regulators, some common to all conditions and others specific to selective autophagy. More specifically, CDK11A and NME3 were further characterized to be selective ER-phagy regulators. Meanwhile, PAN3 and CDC42BPG were identified as an activator and inhibitor of pexophagy, respectively. Collectively, these datasets provide the first comparative description of the kinase signaling that defines the regulation of selective autophagy and bulk autophagy.