Analysis of Arrdc4 ubiquitination and its function in extracellular vesicle biogenesis

Thesis (PhD(Medical Sciences)--University of South Australia, 2021. Includes bibliographical references (pages 140-153) This thesis examines the role of ubiquitination of Arrdc4 protein, an adaptor for Nedd4 family of ubiquitin ligases, in the release of extracellular vesicles (EV). As EVs play crucial functions in inter-cellular communication, it is important to understand how they are generated by the cells. Studies here report that Arrdc4, that has been previously shown to be involved in EV biogenesis, undergoes ubiquitination at several Lys (K) residues. Among these, ubiquitination at K270, involving K29-linked ubiquitin chains, is crucial for the function of Arrdc4 in EV biogenesis. The study also revealed the importance of Arrdc4-dependent EV release in reticulocyte maturation and identified potential interacting partners for Arrdc4. Overall, this study contributes novel findings towards ubiquitination-dependent regulation of EV biogenesis and provides new directions for further studies.