title: Formin-generated actomyosin arcs propel T cell receptor microcluster movement at the immune synapse.
abstract: Actin assembly and inward flow in the plane of the immunological synapse (IS) drives the centralization of T cell receptor microclusters (TCR MCs) and the integrin leukocyte functional antigen 1 (LFA-1). Using structured-illumination microscopy (SIM), we show that actin arcs populating the medial, lamella-like region of the IS arise from linear actin filaments generated by one or more formins present at the IS distal edge. After traversing the outer, Arp2/3-generated, lamellipodia-like region of the IS, these linear filaments are organized by myosin II into antiparallel concentric arcs. Three-dimensional SIM shows that active LFA-1 often aligns with arcs, whereas TCR MCs commonly reside between arcs, and total internal reflection fluorescence SIM shows TCR MCs being swept inward by arcs. Consistently, disrupting actin arc formation via formin inhibition results in less centralized TCR MCs, missegregated integrin clusters, decreased T-B cell adhesion, and diminished TCR signaling. Together, our results define the origin, organization, and functional significance of a major actomyosin contractile structure at the IS that directly propels TCR MC transport.
authors: Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892.
authors: Sricharan
authors: http://orcid.org/0000-0003-3045-3513
authors: S
authors: Murugesan
authors: Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892.
authors: Jinsung
authors: J
authors: Hong
authors: Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892.
authors: Jason
authors: http://orcid.org/0000-0001-5131-6767
authors: J
authors: Yi
authors: Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147.|National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, People's Republic of China.
authors: Dong
authors: http://orcid.org/0000-0002-2961-0676
authors: D
authors: Li
authors: Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892.
authors: Jordan R
authors: http://orcid.org/0000-0003-0427-7501
authors: JR
authors: Beach
authors: Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147.
authors: Lin
authors: L
authors: Shao
authors: Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892.
authors: John
authors: J
authors: Meinhardt
authors: Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892.
authors: Grey
authors: http://orcid.org/0000-0002-7193-9352
authors: G
authors: Madison
authors: Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892.
authors: Xufeng
authors: http://orcid.org/0000-0002-9723-7965
authors: X
authors: Wu
authors: Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147.
authors: Eric
authors: E
authors: Betzig
authors: Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892 hammerj@nhlbi.nih.gov.
authors: John A
authors: http://orcid.org/0000-0002-2496-5179
authors: JA
authors: Hammer
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D051376:Actin-Related Protein 2-3 Complex / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D000205:Actomyosin / Q000378:metabolism*; D000818:Animals; D000938:Antigen-Presenting Cells / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000378:metabolism; D002449:Cell Aggregation; D002465:Cell Movement; D005326:Fetal Proteins; D005453:Fluorescence; D000080865:Formins; D006801:Humans; D054992:Immunological Synapses / Q000378:metabolism*; D019169:Jurkat Cells; D016169:Lymphocyte Function-Associated Antigen-1 / Q000378:metabolism; D051379:Mice; D008840:Microfilament Proteins; D008853:Microscopy; D024462:Myosin Type II / Q000378:metabolism; D009687:Nuclear Proteins; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism*; D013601:T-Lymphocytes / Q000378:metabolism
chemical_list: D051376:Actin-Related Protein 2-3 Complex; D000199:Actins; D005326:Fetal Proteins; D000080865:Formins; D016169:Lymphocyte Function-Associated Antigen-1; D008840:Microfilament Proteins; D009687:Nuclear Proteins; D011948:Receptors, Antigen, T-Cell; D000205:Actomyosin; D024462:Myosin Type II