Specific regulation of cytokine-dependent p38 MAP kinase activation by p62/SQSTM1.
We have previously shown that p62/SQSTM1 binds to p38. In this study, we identified two association domains of p62 to p38 by conducting co-immunoprecipitation experiments. One domain comprises the amino acids 173-182, named N-terminal p38 interaction (NPI) domain, and the other domain comprises the amino acids 335-344, named C-terminal p38 interaction (CPI) domain. An aspartic acid tripeptide located at 335-337 was required for their association. However, the direct interaction was only observed between the recombinant p38 and the peptide of the NPI domain, but not that of the CPI domain in the surface plasmon resonance analyses. These results suggest that the CPI domain may serve to form a certain conformation suitable for the association with p38. Furthermore, we showed that knockdown of p62 expression by siRNA led to impaired p38 phosphorylation only when HeLa cells were stimulated by cytokine. The critical role of p62 in cytokine-dependent p38 signalling pathway was further confirmed by measuring IL-8 mRNA. Cytokine mRNA is often stabilized via p38 pathway. In the absence of p62, IL-8 mRNA induced by IL-1beta became more fragile. These data show that p62 specifically regulates cytokine-dependent p38 signalling pathway.
Kawai
Kayoko
K
Antibiotics Laboratory and Bioarchitect Research Group, DRI, RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.
Saito
Akiko
A
Sudo
Tatsuhiko
T
Osada
Hiroyuki
H
D048868:Adaptor Proteins, Signal Transducing / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006801:Humans; D047468:Immunoprecipitation; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism*; D008156:Luciferases / Q000378:metabolism; D010446:Peptide Fragments / Q000494:pharmacology; D010766:Phosphorylation; D010957:Plasmids; D011485:Protein Binding; D020871:RNA Stability; D012333:RNA, Messenger; D034741:RNA, Small Interfering / Q000494:pharmacology; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000071456:Sequestosome-1 Protein; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*
D048868:Adaptor Proteins, Signal Transducing; D016209:Interleukin-8; D010446:Peptide Fragments; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D011994:Recombinant Proteins; C099718:SQSTM1 protein, human; D000071456:Sequestosome-1 Protein; D008156:Luciferases; D048051:p38 Mitogen-Activated Protein Kinases