LAMTOR1 ubiquitination restricts its interaction with the vacuolar-type H+-ATPase, promotes autophagy and is controlled by USP32

ABSTRACTAmong the various signals governing autophagy, ubiquitination plays a critical role both by controlling the stability of upstream regulators or components of macroautophagy/autophagy pathways and by facilitating the recruitment of cargo to autophagy receptors. As such, modulators of ubiquitin signaling can influence autophagic substrate degradation. Recently, we identified a non-proteolytic ubiquitin signal at the Ragulator complex subunit LAMTOR1 that is reversed by the deubiquitinase USP32. Loss of USP32 promotes ubiquitination within the unstructured N-terminal region of LAMTOR1 and prevents its efficient interaction with the vacuolar-type H+-ATPase, a prerequisite for full activation of MTORC1 at lysosomes. Consequently, MTORC1 activity is decreased and autophagy is upregulated in USP32 knockout cells. This phenotype is conserved in Caenorhabditis elegans. Depletion of USP32 homolog CYK-3 in worms results in LET-363/MTOR inhibition and autophagy induction. Based on our data, we propose an additional control layer of the MTORC1 activation cascade at lysosomes via USP32-regulated LAMTOR1 ubiquitination.KEYWORDS: ATPaseautophagydeubiquitinase (DUB)LAMTOR1ragulator complexubiquitinUSP32V-MTORC1 AcknowledgmentsWe would like to thank the other co-authors who contributed to the original manuscript: Ludovico Martins Alves, Henrik Dutz, Georg Tascher, Florian Bonn, Manuel Kaulich, Ivan Dikic and Florian Steinberg.Disclosure statementNo potential conflict of interest was reported by the author(s).Additional informationFundingThis work was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – Project ID 323732846 and Project ID 25913077-SFB 1177.