Localized diacylglycerol drives the polarization of the microtubule-organizing center in T cells

Abstract

The reorientation of the T cell microtubule-organizing center (MTOC) toward the antigen-presenting cell enables the directional secretion of cytokines and lytic factors. By single-cell photoactivation of the T cell antigen receptor, we show that MTOC polarization is driven by localized accumulation of diacylglycerol (DAG). MTOC reorientation was closely preceded first by production of DAG and then by recruitment of the microtubule motor protein dynein. Blocking DAG production or disrupting the localization of DAG impaired MTOC recruitment. Localized DAG accumulation was also required for cytotoxic T cell-mediated killing. Furthermore, photoactivation of DAG itself was sufficient to induce transient polarization. Our data identify a DAG-dependent pathway that signals through dynein to control microtubule polarity in T cells.

Protein kinase D1/2 is involved in the maturation of multivesicular bodies and secretion of exosomes in T and B lymphocytes

“…[10][11][12][13][14][15] The discovery of exosome involvement in these responses increased interest in the regulation of exosome biogenesis and secretory traffic, with special attention to the contribution of lipids such as ceramide and DAG, as well as DAG-binding proteins. 14,[16][17][18][19][20][21] These studies suggest that positive and negative DAG regulators may control secretory traffic. By transforming DAG into phosphatidic acid (PA), diacylglycerol kinase α (DGKα) is essential for the negative control of DAG function in T lymphocytes.…”

“…23,24 The secretory vesicle pathway involves several DAGcontrolled checkpoints at which DGKα may act; these include vesicle formation and fission at the trans-Golgi network (TGN), MVB maturation, as well as their transport, docking and fusion to the plasma membrane. 9,[16][17][18][19][20] The molecular components that regulate some of these trafficking processes include protein kinase D (PKD) family members. 21 PKD1 activity, for instance, regulates fission of transport vesicles from TGN via direct interaction with the pre-existing DAG pool at this site.…”

High DGK-α and Disabled MAPK Pathways Cause Dysfunction of Human Tumor-Infiltrating CD8+ T Cells That Is Reversible by Pharmacologic Intervention

“…This results from DGK-a catabolizing DAG to PA thereby reducing DAG levels, which leads to termination of ras signaling and failure to activate downstream MAPK ERK. ERK activation has been linked to granule exocytosis (21,22), and DAG was found to be required for MTOC polarization (42) which is a required step for granule exocytosis. Thus, the high level of DGK-a observed in CD8-TILs could lead to a shortage in DAG causing the observed defects in activating the ras-MEK1/2-ERK pathway and impeding the degranulation and lytic response of CD8-TILs of RCC.…”

Cortical actin recovery at the immunological synapse leads to termination of lytic granule secretion in cytotoxic T lymphocytes

“…Furthermore, RAB27a-deficient CTLs, which do not secrete cytotoxic granules, failed to recover actin at the synapse, suggesting that RAB27a-mediated granule secretion is required for actin recovery. Finally, we show that both actin clearance and recovery correlated with synaptic phosphatidylinositol 4,5-bisphosphate (PIP 2 ) and that alterations in PIP 2 at the immunological synapse regulate cortical actin in CTLs, providing a potential mechanism through which CTLs control cortical actin density. Our work provides insight into actin-related mechanisms regulating CTL secretion that may facilitate serial killing during immune responses.…”