Podoplanin is a component of extracellular vesicles that reprograms cell-derived exosomal proteins and modulates lymphatic vessel formation
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Patricia Carrasco-Ramírez1,*, David W. Greening2,*, Germán Andrés3, Shashi K. Gopal2, Ester Martín-Villar1, Jaime Renart1, Richard J. Simpson2, Miguel Quintanilla1
1Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas (CSIC) – Universidad Autónoma de Madrid (UAM), Madrid, Spain
2Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, Australia
3Electron Microscopy Unit, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas (CSIC) – Universidad Autónoma de Madrid (UAM), Madrid, Spain
*These authors have contributed equally to this work
Miguel Quintanilla, e-mail: email@example.com
Keywords: podoplanin, microvesicles, exosomes, tumor progression, lymphangiogenesis
Recevied: September 17, 2015 Accepted: February 10, 2016 Published: February 17, 2016
Podoplanin (PDPN) is a transmembrane glycoprotein that plays crucial roles in embryonic development, the immune response, and malignant progression. Here, we report that cells ectopically or endogenously expressing PDPN release extracellular vesicles (EVs) that contain PDPN mRNA and protein. PDPN incorporates into membrane shed microvesicles (MVs) and endosomal-derived exosomes (EXOs), where it was found to colocalize with the canonical EV marker CD63 by immunoelectron microscopy. We have previously found that expression of PDPN in MDCK cells induces an epithelial-mesenchymal transition (EMT). Proteomic profiling of MDCK-PDPN cells compared to control cells shows that PDPN-induced EMT is associated with upregulation of oncogenic proteins and diminished expression of tumor suppressors. Proteomic analysis of exosomes reveals that MDCK-PDPN EXOs were enriched in protein cargos involved in cell adhesion, cytoskeletal remodeling, signal transduction and, importantly, intracellular trafficking and EV biogenesis. Indeed, expression of PDPN in MDCK cells stimulated both EXO and MV production, while knockdown of endogenous PDPN in human HN5 squamous carcinoma cells reduced EXO production and inhibited tumorigenesis. EXOs released from MDCK-PDPN and control cells both stimulated in vitro angiogenesis, but only EXOs containing PDPN were shown to promote lymphatic vessel formation. This effect was mediated by PDPN on the surface of EXOs, as demonstrated by a neutralizing specific monoclonal antibody. These results contribute to our understanding of PDPN-induced EMT in association to tumor progression, and suggest an important role for PDPN in EV biogenesis and/or release and for PDPN-EXOs in modulating lymphangiogenesis.
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