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Expression of a catalytically inactive form of diacylglycerol kinase α induces sustained signaling through RasGRP
Author(s) -
Jones David R.,
Sanjuán Miguel Angel,
Stone James C.,
Mérida Isabel
Publication year - 2002
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fj.01-0762fje
Subject(s) - diacylglycerol kinase , microbiology and biotechnology , signal transduction , second messenger system , protein kinase c , mapk/erk pathway , agonist , stimulation , intracellular , biology , protein kinase a , kinase , receptor , chemistry , biochemistry , endocrinology
ABSTRACT Regulating the generation and clearance of lipid second messengers, such as diacylglycerol (DAG), is critical for the correct propagation of intracellular signaling pathways. DAGK type α acts as a negative modulator of the DAG levels generated during T cell activation, which is initiated by triggering of the endogenous T cell receptor (TCR), as well as by stimulation of an ectopically expressed human muscarinic type 1 receptor. Here we show that stimulation of either of these receptors causes rapid, transient membrane translocation of the recently discovered Ras guanyl nucleotide release protein (RasGRP), followed by activation of mitogen‐activated protein kinase (MAPK). When cells expressing a catalytically inactive form of DAGKα were analyzed, however, similar agonist stimulation resulted in sustained signaling through RasGRP and MAPK. Biochemical analysis showed that expression of kinase‐dead diacylglycerol kinase α (DGKα) led to a greater, more sustained, DAG accumulation following receptor stimulation. These results suggest that, in T cells, agonist‐stimulated DAG generation is the key factor controlling activation of the Ras/MAPK signaling pathway through membrane translocation of RasGRP. Moreover, we demonstrate that through the modulation of the intracellular level of agonist‐stimulated DAG, DGKα alters Ras activation and downstream signaling dramatically, a process of utmost importance for sound immunological function.