Proteomic profiling of human plasma exosomes identifies PPARγ as an exosome-associated protein

Abstract

Exosomes are nanovesicles that are released from cells as a mechanism of cell-free intercellular communication. Only a limited number of proteins have been identified from the plasma exosome proteome. Here, we developed a multi-step fractionation scheme incorporating gel exclusion chromatography, rate zonal centrifugation through continuous sucrose gradients, and high-speed centrifugation to purify exosomes from human plasma. Exosome-associated proteins were separated by SDS-PAGE and 66 proteins were identified by LC-MS/MS, which included both cellular and extracellular proteins. Furthermore, we identified and characterized peroxisome proliferatoractivated receptor-γ (PPARγ), a nuclear receptor that regulates adipocyte differentiation and proliferation, as well as immune and inflammatory cell functions, as a novel component of plasmaderived exosomes. Given the important role of exosomes as intercellular messengers, the discovery of PPARγ as a component of human plasma exosomes identifies a potential new pathway for the paracrine transfer of nuclear receptors.

Exosome Adherence and Internalization by Hepatic Stellate Cells Triggers Sphingosine 1-Phosphate-dependent Migration

“…To examine whether other ECM proteins could be responsible for integrin activation by exosomes, we blotted lysed exosomes for collagen I, which was not detected in our serum-derived exosomes. This result was consistent with plasma exosome proteomic profiling reports, in which FN is the predominant ECM protein expressed on exosomes that could contribute to FN-integrin interactions (46,47). CD29 or RGD, both of which block integrin-FN binding, decreased the cell surface binding of exosomes (Fig.…”

Exosomes account for vesicle-mediated transcellular transport of activatable phospholipases and prostaglandins

“…6D). Exosomes could also supply the 15d-PGJ 2 already bound to its receptor, as a recent report indicates the presence of the PPAR ␥ receptor among proteins found in exosomes isolated from human serum ( 71 ). Interestingly, the exosome FABP we report in Table1 could bind the AA present in exosomes ( Fig.…”

Exosomes

“…33 Interestingly, the tumor necrosis factor receptor has also been identified in plasma exosomes. 34 Other molecules important in the cardiovascular system identified in exosomes include proliferator activated receptor-γ, 35 phosphatase and tensin homolog, 36 annexins, 4 dipeptidyl peptidase-4, 4 epidermal growth factor receptor, 37 and a host of metabolic enzymes. 4 The p22 and gp91 subunits of phagocyte-like NADPH oxidase as well as NADPH oxidase activity have been detected in exosomes derived from platelets of septic individuals, although the significance of this is not known.…”