Modest Interference with Actin Dynamics in Primary T Cell Activation by Antigen Presenting Cells Preferentially Affects Lamellal Signaling

Abstract

Dynamic subcellular distributions of signaling system components are critical regulators of cellular signal transduction through their control of molecular interactions. Understanding how signaling activity depends on such distributions and the cellular structures driving them is required for comprehensive insight into signal transduction. In the activation of primary murine T cells by antigen presenting cells (APC) signaling intermediates associate with various subcellular structures, prominently a transient, wide, and actin-associated lamellum extending from an interdigitated T cell:APC interface several micrometers into the T cell. While actin dynamics are well established as general regulators of cellular organization, their role in controlling signaling organization in primary T cell:APC couples and the specific cellular structures driving it is unresolved. Using modest interference with actin dynamics with a low concentration of Jasplakinolide as corroborated by costimulation blockade we show that T cell actin preferentially controls lamellal signaling localization and activity leading downstream to calcium signaling. Lamellal localization repeatedly related to efficient T cell function. This suggests that the transient lamellal actin matrix regulates T cell signaling associations that facilitate T cell activation.

PD-1 suppresses the maintenance of cell couples between cytotoxic T cells and tumor target cells within the tumor

“…To investigate whether impaired cell couple maintenance results in loss of cytolytic effector function, Clone 4 CTLs were treated with a low concentration (40nM) of Jasplakinolide. At this concentration cell coupling was not impaired (25, 26), but the percentage of CTLs displaying a peripheral F-actin ring was markedly reduced to levels similar to those achieved among Clone 4 TILs (Fig. 3C to E, fig.…”

“…3F). Treatment with a higher concentration (100nM) of Jasplakinolide impaired cell coupling (25) and further reduced killing (Fig. 3F).…”

Computational spatiotemporal analysis identifies WAVE2 and cofilin as joint regulators of costimulation-mediated T cell actin dynamics

“…Costimulation is the principal amplifier of T cell signaling, which is evident from the reduced recruitment, in the absence of co-receptor signaling, of numerous signaling intermediates to two principal cellular structures that mediate T cell activation: a large, highly cross-linked protein complex at the center of the immunological synapse and a large actin-based lamellum that selectively forms during the first five minutes of cell coupling and traps smaller signaling complexes (6, 31–33). To determine the importance of costimulation-controlled actin dynamics in driving such signaling organization, we asked whether the reduced localization of a prototypical element of T cell signaling upon costimulation blockade could be restored through the activation of WAVE2 and cofilin.…”

“…T cell activation stimulates the rapid and transient accumulation of T cell actin at the interface between the T cell and the APC (a region known as the immunological synapse) (1), which is coregulated by the TCR and CD28 (2). Genetic and pharmacological interference with T cell actin dynamics suggests that they are critical for many aspects of T cell function including APC coupling, spatiotemporal organization of T cell signaling, and regulation of transcription (2–6); however, the molecular mechanisms by which costimulation contributes to the regulation of T cell actin dynamics are unresolved.…”

ERM-Dependent Assembly of T-Cell Receptor Signaling and Co-stimulatory Molecules on Microvilli Prior to Activation

“…The role of the actin cytoskeleton in receptor clustering and in IS formation has been extensively studied (3,19,(46)(47)(48)(49)(50). In our own previous work, we found that the localization of TCRαβ molecules on microvilli is disturbed upon disruption of the actin cytoskeleton with latrunculin A (11).…”