Formin-generated actomyosin arcs propel T cell receptor microcluster movement at the immune synapse

Murugesan, Sricharan; Hong, Jinsung; Yi, Jason; Dong, Li; Beach, Jordan R.; Shao, Lin; Meinhardt, John; Madison, Grey; Wu, Xufeng; Betzig, Eric; Hammer, John A.

doi:10.1083/jcb.201603080

Cited by 187 publications

(335 citation statements)

References 62 publications

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“…The polarized filopodia structures formed after GML treatment are phenotypically similar to structures found in Arp2- and Arp3-deficient T cells or T cells treated with Arp2/3 inhibitors (8, 9). To determine whether GML induced filopodia formation by inhibiting Arp2/3 complex activity, we used the small molecule inhibitor CK-666, which stabilizes the inactive state of the Arp2/3 complex by preventing the Arp2 and Arp3 subunits from moving into the activated filament-like conformation (47).…”

Section: Resultssupporting

confidence: 52%

“…Formins bind to the barbed edge of actin filaments and prevent the association of actin with actin-capping proteins (7). Formins regulate the assembly of structures in the pSMAC and are critical for the retrograde flow of signaling clusters into the cSMAC (8, 9). In contrast, the activated Arp2/3 complex mediates the branching of actin filaments that ultimately drives the formation of the dense lamellipodia structures in the dSMAC (8, 10).…”

Section: Introductionmentioning

confidence: 99%

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Glycerol monolaurate induces filopodia formation by disrupting the association between LAT and SLP-76 microclusters

et al. 2018

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Glycerol monolaurate (GML) is a monoglyceride with potent antimicrobial properties that suppresses T cell receptor (TCR)-induced signaling and T cell effector function. Actin rearrangement is needed for the interaction of T cells with antigen presenting cells and for migration to sites of infection. Because of the critical role actin rearrangement plays in T cell effector function, we analyzed the effect of GML on the rearrangement of the actin cytoskeleton after TCR activation. We found that GML-treated human T cells were less adherent than untreated T cells and did not form actin ring structures, but instead developed numerous inappropriate actin-mediated filopodia. The formation of these filopodia was not due to disruption of TCR-proximal regulators of actin or microtubule polymerization. Instead, total internal reflection fluorescence microscopy demonstrated mislocalization of actin nucleation protein Arp2 microclusters, but not those containing the adaptor proteins SLP-76 and WASp, or the actin nucleation protein ARPC3, which are necessary for TCR-induced actin rearrangement. Additionally, SLP-76 microclusters colocalized with WASp and WAVE microclusters, but not LAT. Together, our data suggest that GML alters actin cytoskeletal rearrangements and identify diverse functions for GML as a T cell-suppressive agent.

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Section: Resultssupporting

confidence: 52%

Section: Introductionmentioning

confidence: 99%

Glycerol monolaurate induces filopodia formation by disrupting the association between LAT and SLP-76 microclusters

et al. 2018

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“…Furthermore, recent in vitro studies have shown that formins bind to MTs through their FH2 domain, which suppresses the actin polymerization function of formins (48,49), although the formin mDia1 was also reported to polymerize actin filament by recruitment to MT tips (50). In addition, a recent study showed that NMII-rich actin arcs in the IS are derived from formin-mediated actin polymerization primarily in the lamellipodia (51). To test whether the activation of ROCK and formin mediates MT-actin interactions at the T-cell contact zone, we activated EB3-EGFP-and TagRFP-Tactin-expressing Jurkat cells on anti-CD3-coated coverslips in the presence of Y-27632 or the formin inhibitor SMIFH2 (15 μM) (52).…”

Section: Mt Network Forms a Radially Emanating Dynamic Array During Tmentioning

confidence: 99%

Dynamic microtubules regulate cellular contractility during T-cell activation

Hui

Upadhyaya

2017

Proc. Natl. Acad. Sci. U.S.A.

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T-cell receptor (TCR) triggering and subsequent T-cell activation are essential for the adaptive immune response. Recently, multiple lines of evidence have shown that force transduction across the TCR complex is involved during TCR triggering, and that the T cell might use its force-generation machinery to probe the mechanical properties of the opposing antigen-presenting cell, giving rise to different signaling and physiological responses. Mechanistically, actin polymerization and turnover have been shown to be essential for force generation by T cells, but how these actin dynamics are regulated spatiotemporally remains poorly understood. Here, we report that traction forces generated by T cells are regulated by dynamic microtubules (MTs) at the interface. These MTs suppress Rho activation, nonmuscle myosin II bipolar filament assembly, and actin retrograde flow at the T-cell-substrate interface. Our results suggest a novel role of the MT cytoskeleton in regulating force generation during T-cell activation.T lymphocytes, central players in the adaptive immune response, are activated when T-cell receptors (TCRs) on their surface recognize cognate peptide-major histocompatibility complex (pMHC) expressed on the surface of antigen-presenting cells (APCs). A burst of actin polymerization is triggered upon TCR stimulation (1), leading to an enhancement of the cell/APC contact area as the T cell spreads over the surface of the APC (2) and the formation of a macromolecular protein assembly known as the immunological synapse (IS) (3, 4). Accompanying IS formation, T cells also undergo a rapid polarization of the microtubule (MT) cytoskeleton, within 1-2 min after initial contact, that facilitates directional secretion of cytokines and cytolytic factors toward the APC (5-7). Therefore, the contact zone between T cells and APCs is a site at which the MT and actin cytoskeletons could potentially interact to regulate signaling.Recent studies have established that T cells generate significant traction stresses at the cell-cell interface, albeit relatively weak compared with adherent cells (8-11). These forces, which peak 5-10 min after stimulation, facilitate T-cell activation, in part, by inducing conformational changes in the TCR-CD3 complex (12-15). Although actin polymerization/depolymerization dynamics are essential for T cells to maintain dynamic traction stresses and to drive calcium influx and integrin affinity maturation (9, 16, 17), the regulatory pathways that control these cytoskeletal forces are not completely understood. In particular, whether and how the polarized MT cytoskeleton interacts with the actin cytoskeleton and regulates force generation at the T-cell-APC contact remain open questions.MTs in the cell exist in two populations: dynamic/tyrosinated MTs and stable MTs that have undergone posttranslational modifications, including detyrosination and acetylation (18). Previous studies of T-cell activation have elucidated that microtubuleorganizing center (MTOC) translocation is associated with the formati...

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“…Actin polymerization and myosin contraction induced by TCR engagement results in retrograde flow of actomyosin at the cell periphery which serves as a primary force-generating element at the cell-substrate interface. The advent of super-resolution imaging and novel fluorescent probes has revealed a diversity of actin structures at the T cell/substrate interface [56]. On planar substrates (and conjugates), within 2–3 minutes of stimulation, the actin network forms an annular ring at the lamellipodium and is composed of the characteristic Arp2/3 mediated branched networks as well as formin-mediated linear bundles.…”

Section: Cytoskeletal Dynamics During Immune Cell Activationmentioning

confidence: 99%

Mechanosensing in the immune response

Upadhyaya

2017

Seminars in Cell & Developmental Biology

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Cells have a remarkable ability to sense and respond to the mechanical properties of their environment. Mechanosensing is essential for many phenomena from cell movements and tissue rearrangements to cell differentiation and the immune response. Cells of the immune system get activated when membrane receptors bind to cognate antigen on the surface of antigen presenting cells. Both T and B lymphocyte signaling has been shown to be responsive to physical forces and mechanical cues. Cytoskeletal forces exerted by cells likely mediate this mechanical modulation. Here we discuss recent advances in the field of immune cell mechanobiology at the molecular and cellular scale.

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Formin-generated actomyosin arcs propel T cell receptor microcluster movement at the immune synapse

Abstract: Murugesan et al. report that actomyosin arcs at the T cell synapse are formin-generated structures that directly propel T cell receptor cluster movement. The authors reveal the origin, organization, and functions of a major cytoskeletal network during synapse maturation.

Cited by 187 publications

References 62 publications

Glycerol monolaurate induces filopodia formation by disrupting the association between LAT and SLP-76 microclusters

Glycerol monolaurate induces filopodia formation by disrupting the association between LAT and SLP-76 microclusters

Dynamic microtubules regulate cellular contractility during T-cell activation

Mechanosensing in the immune response

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