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SPAK kinase is a substrate and target of PKCθ in T‐cell receptor‐induced AP‐1 activation pathway
Author(s) -
Li Yingqiu,
Hu Junru,
Vita Randi,
Sun Binggang,
Tabata Hiroki,
Altman Am
Publication year - 2004
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7600125
Subject(s) - biology , protein kinase c , kinase , microbiology and biotechnology , protein serine threonine kinases , signal transduction , receptor , substrate (aquarium) , enzyme activator , biophysics , biochemistry , protein kinase a , ecology
Protein kinase C‐θ (PKCθ) plays an important role in T‐cell activation via stimulation of AP‐1 and NF‐κB. Here we report the isolation of SPAK, a Ste20‐related upstream mitogen‐activated protein kinase (MAPK), as a PKCθ‐interacting kinase. SPAK interacted with PKCθ (but not with PKCα) via its 99 COOH‐terminal residues. TCR/CD28 costimulation enhanced this association and stimulated the catalytic activity of SPAK. Recombinant SPAK was phosphorylated on Ser‐311 in its kinase domain by PKCθ, but not by PKCα. The magnitude and duration of TCR/CD28‐induced endogenous SPAK activation were markedly impaired in PKCθ‐deficient T cells. Transfected SPAK synergized with constitutively active PKCθ to activate AP‐1, but not NF‐κB. This synergistic activity, as well as the receptor‐induced SPAK activation, required the PKCθ‐interacting region of SPAK, and Ser‐311 mutation greatly reduced these activities of SPAK. Conversely, a SPAK‐specific RNAi or a dominant‐negative SPAK mutant inhibited PKCθ‐ and TCR/CD28‐induced AP‐1, but not NF‐κB, activation. These results define SPAK as a substrate and target of PKCθ in a TCR/CD28‐induced signaling pathway leading selectively to AP‐1 (but not NF‐κB) activation.