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

Vascotto F, Lankar D, Faure-André G, Vargas P, Diaz J, Le Roux D, Yuseff MI, Sibarita JB, Boes M, Raposo G, Mougneau E, Glaichenhaus N, Bonnerot C, Manoury B, Lennon-Duménil AM.
J Cell Biol.. 2007 Mar 26; 176(7): 1007-19
DOI: jcb.200611147 [pii]10.1083/jcb.200611147

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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.

DOI: 10.1083/jcb.200611147
PMCID: PMC2064085
PMID: 17389233 [Indexed for MEDLINE]

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