TFEB coordinates autophagosome biogenesis and ribophagy during starvation via SQSTM1.

Abstract

(Macro)autophagy is a conserved cellular degradation pathway that delivers substrates to lysosomes via autophagosomes. Among various physiological stimuli, nutrient starvation is the most potent inducer of autophagy. In response to starvation, transcription factor EB (TFEB) is activated and up-regulates a broad set of autophagy-related genes. However, the mechanisms by which TFEB promotes autophagosome biogenesis remain incompletely understood. Here, we demonstrate that TFEB-mediated transcriptional induction of <i>sequestosome 1</i> (SQSTM1; p62) triggers the formation of SQSTM1-positive bodies that recruit essential autophagy factors, thereby initiating autophagosome biogenesis. Genetic disruption of TFEB-dependent SQSTM1 regulation markedly impairs starvation-induced autophagy, underscoring the critical role of the TFEB-SQSTM1 axis in the autophagic response to nutrient stress. Furthermore, we show that these SQSTM1 bodies contain ubiquitinated ribosomal proteins and that TFEB promotes ribosomal protein ubiquitination by inducing the E3 ubiquitin ligase ZNF598. Collectively, our findings uncover a transcriptionally coordinated mechanism that regulates both autophagosome biogenesis and substrate ubiquitination, facilitating efficient cargo clearance during starvation-induced autophagy.