Feedback control of the protein kinase TAK1 by SAPK2a/p38alpha.
TAB1, a subunit of the kinase TAK1, was phosphorylated by SAPK2a/p38alpha at Ser423, Thr431 and Ser438 in vitro. TAB1 became phosphorylated at all three sites when cells were exposed to cellular stresses, or stimulated with tumour necrosis factor-alpha (TNF-alpha), interleukin-1 (IL-1) or lipopolysaccharide (LPS). The phosphorylation of Ser423 and Thr431 was prevented if cells were pre-incubated with SB 203580, while the phosphorylation of Ser438 was partially inhibited by PD 184352. Ser423 is the first residue phosphorylated by SAPK2a/p38alpha that is not followed by proline. The activation of TAK1 was enhanced by SB 203580 in LPS-stimulated macrophages, and by proinflammatory cytokines or osmotic shock in epithelial KB cells or embryonic fibroblasts. The activation of TAK1 by TNF-alpha, IL-1 or osmotic shock was also enhanced in embryonic fibroblasts from SAPK2a/p38alpha-deficient mice, while incubation of these cells with SB 203580 had no effect. Our results suggest that TAB1 participates in a SAPK2a/p38alpha-mediated feedback control of TAK1, which not only limits the activation of SAPK2a/p38alpha but synchronizes its activity with other signalling pathways that lie downstream of TAK1 (JNK and IKK).
Cheung
Peter C F
PC
MRC Protein Phosphorylation Unit, School of Life Sciences, MSI/WTB Complex, Dow Street, University of Dundee, Dundee DD1 5EH, UK.
Campbell
David G
DG
Nebreda
Angel R
AR
Cohen
Philip
P
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001549:Benzamides / Q000494:pharmacology; D001665:Binding Sites; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism; D002460:Cell Line; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005246:Feedback; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins; D020930:MAP Kinase Kinase Kinases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008954:Models, Biological; D010766:Phosphorylation; D021122:Protein Subunits; D011725:Pyridines / Q000494:pharmacology; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D048051:p38 Mitogen-Activated Protein Kinases; D000099151:MAP Kinase Kinase Kinase 7
D048868:Adaptor Proteins, Signal Transducing; D001549:Benzamides; D002352:Carrier Proteins; D004791:Enzyme Inhibitors; D007093:Imidazoles; D047908:Intracellular Signaling Peptides and Proteins; D020930:MAP Kinase Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D021122:Protein Subunits; D011725:Pyridines; D011994:Recombinant Proteins; D048051:p38 Mitogen-Activated Protein Kinases; D000099151:MAP Kinase Kinase Kinase 7; C120227:2-(2-chloro-4-iodophenylamino)-N-cyclopropylmethoxy-3,4-difluorobenzamide; C099510:TAB1 protein, MAPKKK activator, vertebrate; C486300:TAB1 protein, human; C093642:SB 203580