Combined spatial and enzymatic regulation of Csk by cAMP and protein kinase a inhibits T cell receptor signaling.
Raft-associated Csk controls signaling through the T cell receptor (TCR) and was mainly anchored to Cbp/PAG (phosphoprotein associated with glycosphingolipid-enriched membrane domains). Treatment of cells with the cAMP-elevating agent prostaglandin E(2) (PGE(2)) augmented the level of Cbp/PAG phosphorylation with a concomitant increase in amounts of Csk bound to Cbp/PAG. While TCR-triggering resulted in transient dissociation of Csk from Cbp/PAG/rafts allowing TCR-induced tyrosine phosphorylation to occur, pretreatment with PGE(2) reduced Csk dissociation upon TCR triggering. This correlated with lowered TCR-induced phosphorylation of CD3 zeta-chain and linker for activation of T cells. Moreover, competition of endogenous Csk from lipid rafts abolished PGE(2)-mediated inhibition of TCR-induced zeta-chain phosphorylation and activation of the nuclear factor of activated T cells (NFAT) activator protein 1 (AP-1). Finally, raft-associated Csk already activated via Cbp/PAG binding, gained additional increase in phosphotransferase activity upon protein kinase A-mediated phosphorylation of Csk. We propose that cAMP regulates Csk via both spatial and enzymatic mechanisms, thereby inhibiting signaling through the TCR.
Vang
Torkel
T
Department of Medical Biochemistry, Institute of Basic Medical Sciences, University of Oslo, Box 1112, Blindern, N-0317 Oslo, Norway.
Abrahamsen
Hilde
H
Myklebust
Sondre
S
Horejsí
Václav
V
Taskén
Kjetil
K
D017252:CD3 Complex / Q000378:metabolism; D000081247:CSK Tyrosine-Protein Kinase; D002455:Cell Division; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D015232:Dinoprostone / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007376:Interleukin-2 / Q000235:genetics; D021962:Membrane Microdomains / Q000378:metabolism; D010455:Peptides / Q000737:chemistry; D010766:Phosphorylation; D010770:Phosphotransferases / Q000378:metabolism; D011233:Precipitin Tests; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D015398:Signal Transduction; D013997:Time Factors; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism; D018909:src Homology Domains; D019061:src-Family Kinases
D017252:CD3 Complex; C121704:CD3 antigen, zeta chain; D007376:Interleukin-2; D010455:Peptides; D011948:Receptors, Antigen, T-Cell; D011994:Recombinant Proteins; D018808:Transcription Factor AP-1; D014443:Tyrosine; D000242:Cyclic AMP; D010770:Phosphotransferases; D011505:Protein-Tyrosine Kinases; D000081247:CSK Tyrosine-Protein Kinase; D019061:src-Family Kinases; C000631346:CSK protein, human; D017868:Cyclic AMP-Dependent Protein Kinases; D015232:Dinoprostone