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MHC class II‐associated proteins in B‐cell exosomes and potential functional implications for exosome biogenesis
Author(s) -
Buschow Sonja I,
Balkom Bas W M,
Aalberts Marian,
Heck Albert J R,
Wauben Marca,
Stoorvogel Willem
Publication year - 2010
Publication title -
immunology and cell biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.999
H-Index - 104
eISSN - 1440-1711
pISSN - 0818-9641
DOI - 10.1038/icb.2010.64
Subject(s) - microvesicles , exosome , major histocompatibility complex , mhc class i , microbiology and biotechnology , biology , mhc class ii , antigen , chemistry , biochemistry , immunology , microrna , gene
Professional antigen‐presenting cells secrete major histocompatibility complex class II (MHC II) carrying exosomes with unclear physiological function(s). Exosomes are first generated as the intraluminal vesicles (ILVs) of a specific type of multivesicular body, and are then secreted by fusion of this compartment with the plasma membrane. We have previously shown that in contrast to the sorting of MHC II at lysosomally targeted multivesicular bodies, sorting of MHC II into exosomes does not rely on MHC II ubiquitination. In search for proteins that drive the incorporation of MHC II into exosomes or functionally discriminate exosomal from plasma membrane MHC II, we first analyzed the total proteome of highly purified B cell‐derived exosomes using sensitive and accurate mass spectrometry (MS), and identified 539 proteins, including known and not previously identified constituents. Using quantitative MS, we then identified a small subset of proteins that were specifically co‐immunoprecipitated with MHC II from detergent‐solubilized exosomes. These include HSC71, HSP90, 14‐3‐3ε, CD20 and pyruvate kinase type M2 (PKM2), and we speculate on the functionality of their interaction with exosomal MHC II.