A STR IPAK complex mediates axonal transport of autophagosomes and dense core vesicles through PP2A regulation

Abstract

Autophagy plays an essential role in the cellular homeostasis of neurons, facilitating the clearance of cellular debris. This clearance process is orchestrated through the assembly, transport, and fusion of autophagosomes with lysosomes for degradation. The motor protein dynein drives autophagosome motility from distal sites of assembly to sites of lysosomal fusion. In this study, we identify the scaffold protein CKA (connector of kinase to AP-1) as essential for autophagosome transport in neurons. Together with other core components of the striatin-interacting phosphatase and kinase (STR IPAK) complex, we show that CKA associates with dynein and directly binds Atg8a, an autophagosomal protein. CKA is a regulatory subunit of PP2A, a component of the STR IPAK complex. We propose that the STR IPAK complex modulates dynein activity. Consistent with this hypothesis, we provide evidence that CKA facilitates axonal transport of dense core vesicles and autophagosomes in a PP2A-dependent fashion. In addition, CKA-deficient flies exhibit PP2A-dependent motor coordination defects. CKA function within the STR IPAK complex is crucial to prevent transport defects that may contribute to neurodegeneration.