The actin-disassembly protein glia maturation factor γ enhances actin remodeling and B cell antigen receptor signaling at the immune synapse Deretic, Nikola Bolger-Munro, Madison ; https://orcid.org/0000-0002-8176-4824 Choi, Kate Abraham, Libin Gold, Michael R. Cell Biology Developmental Biology ddc:570 Signaling by the B cell antigen receptor (BCR) initiates actin remodeling. The assembly of branched actin networks that are nucleated by the Arp2/3 complex exert outward force on the plasma membrane, allowing B cells to form membrane protrusions that can scan the surface of antigen-presenting cells (APCs). The resulting Arp2/3 complex-dependent actin retrograde flow promotes the centripetal movement and progressive coalescence of BCR microclusters, which amplifies BCR signaling. Glia maturation factor γ (GMFγ) is an actin disassembly-protein that releases Arp2/3 complex-nucleated actin filaments from actin networks. By doing so, GMFγ could either oppose the actions of the Arp2/3 complex or support Arp2/3 complex-nucleated actin polymerization by contributing to the recycling of actin monomers and Arp2/3 complexes. We now show that reducing the levels of GMFγ in human B cell lines via transfection with a specific siRNA impairs the ability of B cells to spread on antigen-coated surfaces, decreases the velocity of actin retrograde flow, diminishes the coalescence of BCR microclusters into a central cluster at the B cell-APC contact site, and decreases APC-induced BCR signaling. These effects of depleting GMFγ are similar to what occurs when the Arp2/3 complex is inhibited. This suggests that GMFγ cooperates with the Arp2/3 complex to support BCR-induced actin remodeling and amplify BCR signaling at the immune synapse. Frontiers Media 2021 info:eu-repo/semantics/article doc-type:article text http://purl.org/coar/resource_type/c_2df8fbb1 https://research-explorer.ista.ac.at/record/15264 https://research-explorer.ista.ac.at/download/15264/15291 Deretic N, Bolger-Munro M, Choi K, Abraham L, Gold MR. The actin-disassembly protein glia maturation factor γ enhances actin remodeling and B cell antigen receptor signaling at the immune synapse. <i>Frontiers in Cell and Developmental Biology</i>. 2021;9. doi:<a href="https://doi.org/10.3389/fcell.2021.647063">10.3389/fcell.2021.647063</a> eng info:eu-repo/semantics/altIdentifier/doi/10.3389/fcell.2021.647063 info:eu-repo/semantics/altIdentifier/issn/2296-634X info:eu-repo/semantics/altIdentifier/pmid/34336818 https://creativecommons.org/licenses/by/4.0/ info:eu-repo/semantics/openAccess