B cells extract antigens using Arp2/3-generated actin foci interspersed with linear filaments [article]

Sophie I Roper, Laabiah Wasim, Dessislava Malinova, Michael Way, Susan Cox, Pavel Tolar
2019 bioRxiv   pre-print
Antibody production depends on B cell internalization and presentation of antigens to helper T cells. To acquire antigens displayed by antigen-presenting cells, B cells form immune synapses and extract antigens by the mechanical activity of the acto-myosin cytoskeleton. While cytoskeleton organization driving the initial formation of the B cell synapse has been studied, how the cytoskeleton supports antigen extraction remains poorly understood. Here we show that after initial cell spreading,
more » ... cell spreading, F-actin in B cell synapses forms a highly dynamic pattern composed of actin foci interspersed with linear filaments and myosin IIa. The foci are generated by Arp2/3-mediated branched-actin polymerization and stochastically associate with antigen clusters to mediate internalization. However, antigen extraction also requires the activity of formins, which reside near the foci and produce the interspersed filaments. Thus, a cooperation of branched-actin foci supported by linear filaments underlies B cell mechanics during antigen extraction.
doi:10.1101/792481 fatcat:3ge5d5cch5fxvptu6ulw2c247i