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Updated: Jul 16, 2026

Visualizing the Actin and Microtubule Cytoskeletons at the B-cell Immune Synapse Using Stimulated Emission Depletion (STED) Microscopy
Published on: April 9, 2018
The actin-based motor protein myosin II regulates MHC class II trafficking and BCR-driven antigen presentation
Fulvia Vascotto1, Danielle Lankar, Gabrielle Faure-André
1Institut National de la Santé et de la Recherche Medicale Unité 653, Unité Mixte de Recherche 144 Institut Curie, 75005 Paris, France.
Abstract:
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.
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