The BPAN and intellectual disability disease proteins WDR45 and WDR45B modulate autophagosome-lysosome fusion.

WDR45 and WDR45B are β-propeller proteins belonging to the WIPI (WD repeat domain, phosphoinositide interacting) family. Mutations in and are genetically linked with beta-propeller protein-associated neurodegeneration (BPAN) and intellectual disability (ID), respectively. WDR45 and WDR45B are homologs of yeast Atg18. Atg18 forms a complex with Atg2 for autophagosome biogenesis, probably by transferring lipids from the ER to phagophores. We revealed that WDR45 and WDR45B are critical for autophagosome-lysosome fusion in neural cells. WDR45 and WDR45B, but not their disease-related mutants, bind to the tether protein EPG5 and facilitate its targeting to late endosomes/lysosomes. In -deficient cells, the formation of tether-SNARE fusion machinery is compromised. The macroautophagy/autophagy deficiency in DKO cells is ameliorated by suppression of -GlcNAcylation, which promotes autophagosome maturation. Thus, our results provide insights into the pathogenesis of and -related neurological diseases.