Loss of Atoh8 Impairs Macroautophagy

The basic helix-loop-helix (bHLH) transcription factor ‘Atoh8’ is involved in the regulation of several developmental processes and pathologies. It regulates organogenesis, reprogramming, stem cell fate determination, and cancer development. However, the mechanisms underlying these observations remain unclear. Unlike many tissue-specific bHLH factors, Atoh8 is ubiquitously expressed during development as well as in adult tissues. In this study, we explored whether Atoh8 modulates basic cellular functions, which may reveal a common mechanism that could explain the diverse observations reported in the literature. Our findings demonstrate that the loss of Atoh8 impairs autophagy. In both primary myoblasts and mouse embryonic stem cells lacking Atoh8, we observed differential expression of LC3B-II, TFEB, and accumulation of p62, indicating impairment of autophagy. Furthermore, mass spectrometric analysis performed on C2C12 and Atoh8 overexpressing C2C12 myoblasts revealed significant alterations in the expression of proteins associated with mitochondrial and lysosomal functions. Finally, Cut&Tag sequencing performed in Atoh8 overexpressing C2C12 cells revealed that Atoh8 binds to multiple genes involved in autophagosome assembly. Overall, this study underscores that Atoh8 is a critical regulator of macroautophagy, and its reduction disrupts the autophagic process, whereas its overexpression results in increased autophagic flux.