Regulation of T cell receptor-induced activation of the Ras-ERK pathway by diacylglycerol kinase zeta.
T cell development in the thymus and activation of mature T cells in the periphery depend on signals stimulated by engagement of the T cell antigen receptor (TCR). Among the second messenger cascades initiated by TCR ligation include the phosphatidylinositol pathway where the membrane phospholipid, phosphatidylinositol 4,5-bisphosphate, is hydrolyzed to inositol 1,4,5-trisphosphate and diacylglycerol (DAG). Inositol 1,4,5-trisphosphate signals a rise in intracellular free calcium, leading to translocation of nuclear factor of activated T cells into the nucleus. DAG activates RasGRP and protein kinase C theta. Because both RasGRP and protein kinase C theta are essential for thymocyte and T cell function, it is critical to understand how DAG is regulated. In this report, we demonstrate expression of DAG kinase zeta (DGKzeta, the enzyme that catalyzes the conversion of DAG to phosphatidic acid) in multiple lymphoid organs, with highest expression observed within the T cell compartment. Overexpression studies in Jurkat T cells indicate that DGKzeta interferes with TCR-induced Ras and ERK activation, AP-1 induction, and expression of the activation marker CD69. In contrast, TCR-stimulated calcium influx is not altered. Mutational analysis indicates that the kinase and DAG binding domains, but not the ankyrin repeats of DGKzeta, are required for its inhibitory effects. Collectively these studies demonstrate a potential role of DGKzeta to function as a selective negative regulator of DAG signaling on T cell activation and provide the first structure/function analysis of this enzyme in T cells.
Zhong
Xiao-Ping
XP
Signal Transduction Program, The Abramson Family Cancer Research Institute, Immunology Graduate Program, University of Pennsylvania School of Medicine, 421 Curie Boulevard, Philadelphia, PA 19104, USA.
Hainey
Ehmonie A
EA
Olenchock
Benjamin A
BA
Zhao
Haoran
H
Topham
Matthew K
MK
Koretzky
Gary A
GA
D015703:Antigens, CD / Q000032:analysis; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis; D002118:Calcium / Q000378:metabolism; D019852:Diacylglycerol Kinase / Q000235:genetics / Q000502:physiology*; D006801:Humans; D007527:Isoenzymes / Q000502:physiology; D019169:Jurkat Cells; D037181:Lectins, C-Type; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology*; D011948:Receptors, Antigen, T-Cell / Q000502:physiology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D018808:Transcription Factor AP-1 / Q000378:metabolism; D018631:ras Proteins / Q000502:physiology*; D000099192:CD69 Antigens
D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D002118:Calcium; D019852:Diacylglycerol Kinase; D007527:Isoenzymes; D037181:Lectins, C-Type; D020928:Mitogen-Activated Protein Kinases; D011948:Receptors, Antigen, T-Cell; D013755:Tetradecanoylphorbol Acetate; D018808:Transcription Factor AP-1; D018631:ras Proteins; D000099192:CD69 Antigens