posted on 2022-09-21, 03:44authored byAU Farooq, K Gembus, JJ Sandow, A Webb, Suresh MathivananSuresh Mathivanan, JA Manning, SS Shah, NJ Foot, S Kumar
Extracellular vesicles (EVs) are important mediators of intercellular communication. However, EV biogenesis remains poorly understood. We previously defined a role for Arrdc4 (Arrestin domain containing protein 4), an adaptor for Nedd4 family ubiquitin ligases, in the biogenesis of EVs. Here we report that ubiquitination of Arrdc4 is critical for its role in EV secretion. We identified five potential ubiquitinated lysine residues in Arrdc4 using mass spectrometry. By analysing Arrdc4 lysine mutants we discovered that lysine 270 (K270) is critical for Arrdc4 function in EV biogenesis. Arrdc4K270R mutation caused a decrease in the number of EVs released by cells compared to Arrdc4WT, and a reduction in trafficking of divalent metal transporter (DMT1) into EVs. Furthermore, we also observed a decrease in DMT1 activity and an increase in its intracellular degradation in the presence of Arrdc4K270R. K270 was found to be ubiquitinated with K-29 polyubiquitin chains by the ubiquitin ligase Nedd4-2. Thus, our results uncover a novel role of K-29 polyubiquitin chains in Arrdc4-mediated EV biogenesis and protein trafficking.
Funding
This work was supported by the National Health and Medical Research Council (NHMRC) project grant (GNT1122437) to S.K. and S.M., as well as a NHMRC project grant (GNT1099307), a NHMRC Senior Principal Research Fellowship (GNT1103006), a NHMRC Investigator Grant (GNT2007739) and a University of South Australia support package to S.K. A.F. was supported by an Australian Postgraduate Award. We thank the School of Pharmacy and Medical Sciences Instrument & Facilities for NanoSight and members of our laboratory for helpful suggestions.