Canonical lymphocyte chemokine receptors CXCR3 and CXCR5 modulate neuronal autophagy.
Autophagy, a conserved cellular degradation process, plays a critical role in clearing toxic aggregate-prone proteins, which are characteristic pathological hallmarks of neurodegenerative diseases. As we previously found that microglia secreted factors impair neuronal autophagy and identified CCL3, CCL4 and CCL5 as causative chemokines, we screened the microglial secretome for soluble factors and neuronal cytokine receptors to identify candidates impacting autophagy in neuronal models. Against our expectations of identifying negative regulators, we found that two receptor-ligand pairs, CXCR3-CXCL10 and CXCR5-CXCL13, stimulated autophagy across several neuronal models, both in vitro (SH-SY5Y, i3Neurons) and in vivo. Mechanistically, CXCL10 and CXCL13 promoted autophagy through a shared mechanism: cognate receptor stimulation led to downstream activation of JNK, which in turn phosphorylates BCL-XL, promoting its disassociation from BECN1. The freed BECN1 interacts with VPS34 to form the autophagy initiation complex, enhancing autophagosome formation and flux. These findings reveal chemokine signalling as a targetable pathway for neuronal autophagy induction in neurodegeneration.