Abstract
Immunological synapse (IS) formation between a T cell and an antigen-presenting cell is accompanied by the reorientation of the T cell centrosome toward the interface. This polarization response is thought to enhance the specificity of T cell effector function by enabling the directional secretion of cytokines and cytotoxic factors toward the antigen-presenting cell. Centrosome reorientation is controlled by polarized signaling through diacylglycerol (DAG) and protein kinase C (PKC). This drives the recruitment of the motor protein dynein to the IS, where it pulls on microtubules to reorient the centrosome. Here, we used T cell receptor photoactivation and imaging methodology to investigate the mechanisms controlling dynein accumulation at the synapse. Our results revealed a remarkable spatiotemporal correlation between dynein recruitment to the synaptic membrane and the depletion of cortical filamentous actin (F-actin) from the same region, suggesting that the two events were causally related. Consistent with this hypothesis, we found that pharmacological disruption of F-actin dynamics in T cells impaired both dynein accumulation and centrosome reorientation. DAG and PKC signaling were necessary for synaptic F-actin clearance and dynein accumulation, while calcium signaling and microtubules were dispensable for both responses. Taken together, these data provide mechanistic insight into the polarization of cytoskeletal regulators and highlight the close coordination between microtubule and F-actin architecture at the IS.
Highlights
Antigen recognition by the T cell receptor (TCR) induces the formation of a stereotyped interface between the T cell and the antigen-presenting cell known as the immunological synapse (IS) [1]
Actin clearance promotes polarized dynein accumulation at the immunological synapse irradiation is used to generate a micron-sized region of cognate peptide-MHC beneath an individual T cell, inducing localized TCR signaling responses and cytoskeletal remodeling events that can be monitored by epifluorescence or total internal reflection fluorescence (TIRF) microscopy
Cortical filamentous actin (F-actin) clearance within the IS plays a well-established role in the directional secretion of cytotoxic molecules toward the target cell [25, 26], and it has been linked to the reorientation of the centrosome [13, 21]
Summary
Antigen recognition by the T cell receptor (TCR) induces the formation of a stereotyped interface between the T cell and the antigen-presenting cell known as the immunological synapse (IS) [1]. Critical to IS assembly is the reorientation of the T cell centrosome ( called the microtubule organizing center, or MTOC) to the center of the interface [2, 3]. The centrosome polarizes to the IS within minutes of initial TCR stimulation, carrying with it the Golgi apparatus, endosomal compartment, and, in cytotoxic T cells, lytic granules. Actin clearance promotes polarized dynein accumulation at the immunological synapse containing perforin and granzyme. This is though to promote the directional secretion of cytokines and cytotoxic factors toward the APC, thereby enhancing the specificity of these critical effector responses
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
