H89, an inhibitor of PKA and MSK, inhibits cyclic-AMP response element binding protein-mediated MAPK phosphatase-1 induction by lipopolysaccharide.
OBJECTIVE
Lipopolysaccharide (LPS) stimulates the production of inflammatory cytokines and the amplification of immune responses via MAPK pathways. MAPK phosphatases (MKPs) feedback-regulate the activities of MAPKs to prevent excessive immunological functions. H89 has been used as an inhibitor of the protein kinase A (PKA) and mitogen- and stress-activated protein kinase (MSK) pathways. In view of the potential roles of PKA and MSK for MKP-1 induction and the ability of H89 to inhibit these kinases, this study examined the effect of H89 on MKP-1 induction by LPS and the role of cyclic-AMP response element binding protein (CREB) in the MKP-1 induction.


RESULTS
H89 treatment inhibited increases in MKP-1 protein and mRNA levels, and gene transcription by LPS in Raw264.7 cells. Immunoblot, gel-shift, and chromatin-immunoprecipitation assays showed the activation of CREB by LPS, and the ability of H89 to inhibit it, suggesting that H89's inhibition of CREB may affect MKP-1 induction. In addition, H89 prevented the ability of LPS to induce other MKP genes (Dusp-2, 4, 8, and 16). Experiments using MAPK inhibitors showed that MAPKs are involved in CREB phosphorylation and MKP-1 induction, suggesting that CREB-mediated MKP-1 induction serves in part as a feedback-inhibitory loop of MAPKs.


CONCLUSIONS
Our results demonstrate that H89 inhibits the activation of CREB and the CREB-mediated MKP-1 induction by LPS, which may result from its inhibition of PKA and MSK.
Cho
Il Je
IJ
Seoul National University, Sillim-dong, Kwanak-gu, Korea.
Woo
Na Ri
NR
Shin
In Chul
IC
Kim
Sang Geon
SG
D000818:Animals; D001483:Base Sequence; D002460:Cell Line / Q000187:drug effects; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D054638:Dual Specificity Phosphatase 1 / Q000235:genetics / Q000378:metabolism*; D004790:Enzyme Induction; D017930:Genes, Reporter; D007546:Isoquinolines / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000276:immunology / Q000494:pharmacology*; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D038744:Ribosomal Protein S6 Kinases, 90-kDa / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D013449:Sulfonamides / Q000494:pharmacology*
D017362:Cyclic AMP Response Element-Binding Protein; D007546:Isoquinolines; D008070:Lipopolysaccharides; D047428:Protein Kinase Inhibitors; D013449:Sulfonamides; D038744:Ribosomal Protein S6 Kinases, 90-kDa; C116919:mitogen and stress-activated protein kinase 1; D017868:Cyclic AMP-Dependent Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D054638:Dual Specificity Phosphatase 1; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide