The actin-based motor protein myosin II regulates MHC class II trafficking and BCR-driven antigen presentation.

Vascotto F., Lankar D., Faure-Andre G., Vargas P., Diaz J., Le Roux D., Yuseff M. I., Sibarita J. B., Boes M., Raposo G., Mougneau E., Glaichenhaus N., Bonnerot C., Manoury B. and Lennon-Dumenil A. M.
J Cell Biol 2007. 176: 1007-1019.

Antigen (Ag) capture and presentation onto major histocompatibility complex (MHC) class II molecules by B lymphocytes is mediated by their surface Ag receptor (B cell receptor [BCR]). Therefore, the transport of vesicles that carry MHC class II and BCR-Ag complexes must be coordinated for them to converge for processing. In this study, we identify the actin-associated motor protein myosin II as being essential for this process. Myosin II is activated upon BCR engagement and associates with MHC class II-invariant chain complexes. Myosin II inhibition or depletion compromises the convergence and concentration of MHC class II and BCR-Ag complexes into lysosomes devoted to Ag processing. Accordingly, the formation of MHC class II-peptides and subsequent CD4 T cell activation are impaired in cells lacking myosin II activity. Therefore, myosin II emerges as a key motor protein in BCR-driven Ag processing and presentation.

URL: http://www.ncbi.nlm.nih.gov/entrez/utils/fref.fcgi?PrId=3051&itool=AbstractPlus-def&uid=17389233&db=pubmed&url=http://www.jcb.org/cgi/pmidlookup?view=long&pmid=17389233

Pub Med: http://www.ncbi.nlm.nih.gov/pubmed/17389233

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