Affiliation:
1. Department of Human Genetics, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium
2. Équipe Labellisée Ligue 2018, Aix Marseille Université, INSERM 1068, CNRS 7258, Institut Paoli Calmettes, Centre de Recherche en Cancérologie de Marseille, 13009 Marseille, France
3. NanoView Biosciences, Boston, MA 02135
Abstract
Extracellular vesicles (EVs) are membrane-limited organelles mediating cell-to-cell communication in health and disease. EVs are of high medical interest, but their rational use for diagnostics or therapies is restricted by our limited understanding of the molecular mechanisms governing EV biology. Here, we tested whether PDZ proteins, molecular scaffolds that support the formation, transport, and function of signal transduction complexes and that coevolved with multicellularity, may represent important EV regulators. We reveal that the PDZ proteome (
ca.
150 proteins in human) establishes a discrete number of direct interactions with the tetraspanins CD9, CD63, and CD81, well-known EV constituents. Strikingly, PDZ proteins interact more extensively with syndecans (SDCs), ubiquitous membrane proteins for which we previously demonstrated an important role in EV biogenesis, loading, and turnover. Nine PDZ proteins were tested in loss-of-function studies. We document that these PDZ proteins regulate both tetraspanins and SDCs, differentially affecting their steady-state levels, subcellular localizations, metabolism, endosomal budding, and accumulations in EVs. Importantly, we also show that PDZ proteins control the levels of heparan sulfate at the cell surface that functions in EV capture. In conclusion, our study establishes that the extensive networking of SDCs, tetraspanins, and PDZ proteins contributes to EV heterogeneity and turnover, highlighting an important piece of the molecular framework governing intracellular trafficking and intercellular communication.
Funder
Agence Nationale de la Recherche
Fonds Wetenschappelijk Onderzoek
KU Leuven
CONACYT | Sistema Nacional de Investigadores
Publisher
Proceedings of the National Academy of Sciences