The autophagy-related gene Atg101 in Drosophila regulates both neuron and midgut homeostasis

Atg101 is an autophagy-related gene identified in worms, flies, mice, and mammals, which encodes a protein that functions in autophagosome formation by associating with the ULK1-Atg13-Fip200 complex. In the last few years, the critical role of Atg101 in autophagy has been well-established through biochemical studies and the determination of its protein structure. However, Atg101's physiological role, both during development and in adulthood, remains less understood. Here, we describe the generation and characterization of an Atg101 loss-of-function mutant in Drosophila and report on the roles of Atg101 in maintaining tissue homeostasis in both adult brains and midguts. We observed that homozygous or hemizygous Atg101 mutants were semi-lethal, with only some of them surviving into adulthood. Both developmental and starvation-induced autophagy processes were defective in the Atg101 mutant animals, and Atg101 mutant adult flies had a significantly shorter lifespan and displayed a mobility defect. Moreover, we observed the accumulation of ubiquitin-positive aggregates in Atg101 mutant brains, indicating a neuronal defect. Interestingly, Atg101 mutant adult midguts were shorter and thicker and exhibited abnormal morphology with enlarged enterocytes. Detailed analysis also revealed that the differentiation from intestinal stem cells to enterocytes was impaired in these midguts. Cell type-specific rescue experiments disclosed that Atg101 had a function in enterocytes and limited their growth. In summary, the results of our study indicate that Drosophila Atg101 is essential for tissue homeostasis in both adult brains and midguts. We propose that Atg101 may have a role in age-related processes.