Cyclin-G-associated kinase GAK/dAux regulates autophagy initiation via ULK1/Atg1 in glia

Abstract

Autophagy is a major means for the elimination of protein inclusions in neurons in neurodegenerative diseases such as Parkinsons disease (PD). Yet, the mechanism of autophagy in the other brain cell type, glia, is less well characterized and remains largely unknown. Here we present evidence that the PD risk factor Cyclin G-associated kinase (GAK)/dAuxilin (dAux) is a new component in glial autophagy. GAK/dAux directly interacts with ULK1/Atg1 via its uncoating domain. Lack of GAK/dAux increases the autophagosome number and size in adult fly glia and mouse microglia, and generally upregulates levels of components in the initiation and PI3K class III complexes including ULK1/Atg1, demonstrating that GAK/dAux regulates the onset of glial autophagy. Consistently, lack of GAK/dAux enhances Atg1 and Atg9 trafficking to autophagosomes, promoting autophagy initiation. On the other hand, lack of GAK/dAux impairs the autophagic flux and blocks substrate degradation, suggesting that GAK/dAux might play additional roles in glial autophagy. Our findings identify a new autophagy factor in glia; considering the pivotal role of glia under pathological conditions, targeting glial autophagy is potentially a therapeutic strategy for PD.