Autophagy regulates neuronal differentiation by controlling WNT/DVL signal pathway

Development of human embryonic stem cells (hESCs) technology provides a powerful tool to understand the mechanism of various diseases, as well as a model for human developmental study in vitro. In this study, we generated neurons from hESCs with previously established protocol and we observed that autophagy-related genes were upregulated at neuroepithelial/NPC stage. To check the importance of autophagy activation, bafilomycin was treated at a specific time point. We found that inhibition of autophagy at NPC stage delayed neuronal differentiation, as indicated by the downregulation of neuronal marker TUJ1 and upregulation of NPC marker NESTIN. Further investigation revealed that WNT signaling might be involved as part of the underlying mechanisms. Autophagy negatively regulates WNT signaling by promoting Disheveled-2 (DVL-2) degradation. Disruption of autophagy might lead to failure in the downregulation of WNT signaling and consequently, delaying neuronal differentiation. Dysregulation of autophagy has been associated with a variety of neurological diseases, including Vici syndrome. Here, we developed cerebral organoids culture to model Vici syndrome by introducing loss of function mutation in EPG5 gene. Mutation in EPG5 gene disturbed autophagy process, subsequently induced defect in progenitor cells migration and cortical layer generation in organoids. The results showed how damaged autophagy leads to smaller organoids, recapitulating Vici syndrome-associated microcephaly, and therefore validating the disease relevance of our study.