Diacylglycerol kinase ? controls diacylglycerol metabolism at the immunological synapse.

ABSTRACT: Diacylglycerol (DAG) generation at the T cell immunological synapse (IS) determines the correct activation of antigen-specific immune responses. DAG kinases (DGKs) ? and ? act as negative regulators of DAG-mediated signals by catalyzing DAG conversion to phosphatidic acid (PA). Nonetheless, the specific input of each enzyme and their spatial regulation during IS formation remain uncharacterized. Here we report recruitment of endogenous DGK? and DGK? to the T cell receptor (TCR) complex following TCR/CD28 engagement. Specific DGK gene silencing shows that PA production at the activated complex depends mainly on DGK?, indicating functional differences between these proteins. DGK? kinase activity at the TCR is enhanced by phorbol-12-myristate-13-acetate cotreatment, suggesting DAG-mediated regulation of DGK? responsiveness. We used GFP-DGK? and -DGK? chimeras to assess translocation dynamics during IS formation. Only GFP-DGK? translocated rapidly to the plasma membrane at early stages of IS formation, independent of enzyme activity. Finally, use of a fluorescent DAG sensor confirmed rapid, sustained DAG accumulation at the IS and allowed us to directly correlate membrane translocation of active DGK? with DAG consumption at the IS. This study highlights a DGK?-specific function for local DAG metabolism at the IS and offers new clues to its mode of regulation.

SUBMITTER: Gharbi SI 

PROVIDER: S-EPMC3216665 | biostudies-literature | 2011 Nov

REPOSITORIES: biostudies-literature