title: MKP-7, a negative regulator of JNK, regulates VCAM-1 expression through IRF-1.
abstract: Cell adhesion molecules (CAMs) are involved in a variety of pathologies including cancer, inflammation, pathogenic infections and autoimmune disease. In particular, VCAM-1, rather than ICAM-1, plays a major role in the initiation of atherosclerosis and tumor progression. Therefore, we attempted to elucidate differential mechanisms that regulate VCAM-1 and ICAM-1 expressions. Down-regulation of JNK by a specific inhibitor (SP600125) or dominant negative (DN) JNK1 plasmid enhanced TNF-α-induced VCAM-1 but not ICAM-1 expression. Moreover, transfection with a JNK1-overexpressing vector resulted in the inhibition of VCAM-1 expression stimulated by TNF-α in HUVECs, suggesting that JNK negatively regulates TNF-α-induced VCAM-1 expression in endothelial cells (ECs). Next, we investigated whether JNK signaling affects IRF-1 and/or GATA6, which are transcription factors that mediate TNF-α induction of VCAM-1 but not ICAM-1. The DN-JNK1 plasmid-transfected cells enhanced TNF-α up-regulation of IRF-1 whereas JNK1-overexpressing cells displayed down-regulation; however, neither DN-JNK1 transfection nor JNK1 overexpression affected GATA6 protein levels in the nuclear fraction. Chromatin immunoprecipitation (ChIP) assay confirmed that the inhibition of JNK by DN-JNK1 transfection increases the binding of IRF-1 to the VCAM-1 promoter whereas the overexpression of JNK1 inhibits IRF-1 binding to the VCAM-1 promoter. However, neither DN-JNK1 nor JNK1 overexpression altered GATA6 affinity for the VCAM-1 promoter region. We also examined whether MKP-7 affects ICAM-1 or VCAM-1 by regulating JNK. TNF-α-induced phosphor-JNK levels increased after 5min, peaked at 10 min, and decreased after 30 min. Interestingly, MKP-7 protein levels increased after 30 min, when phosphor-JNK induction by TNF-α was decreased. In addition, silencing MKP-7 with specific siRNA resulted in an increase in phosphor-JNK and inhibited the expression of VCAM-1 but not ICAM-1. Moreover, silencing MKP-7 caused the down-regulation of IRF-1 protein levels and binding to the VCAM-1 promoter. Thus, we suggest that MKP-7, a negative regulator of JNK, regulates VCAM-1 expression in activated endothelial cells through IRF-1 but not GATA6.
authors.affiliation: Department of Pharmacology, School of Medicine, Institute of Health Sciences, Gyeongsang National University, Jinju, Republic of Korea.
authors.forename: Irina Tsoy
authors.initials: IT
authors.lastname: Nizamutdinova
authors.forename: Young Min
authors.initials: YM
authors.lastname: Kim
authors.forename: Jae Heun
authors.initials: JH
authors.lastname: Lee
authors.forename: Ki Churl
authors.initials: KC
authors.lastname: Chang
authors.forename: Hye Jung
authors.initials: HJ
authors.lastname: Kim
mesh_terms: D047369:Chromatin Immunoprecipitation; D054637:Dual-Specificity Phosphatases / Q000235:genetics / Q000378:metabolism*; D050993:GATA6 Transcription Factor / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D050856:Interferon Regulatory Factor-1 / Q000235:genetics / Q000378:metabolism; D008156:Luciferases; D048670:MAP Kinase Kinase 4 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D054639:Mitogen-Activated Protein Kinase Phosphatases / Q000235:genetics / Q000378:metabolism*; D010957:Plasmids; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D015398:Signal Transduction / Q000235:genetics*; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism; D019010:Vascular Cell Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism*
chemical_list: D050993:GATA6 Transcription Factor; C494759:GATA6 protein, human; D050856:Interferon Regulatory Factor-1; D047428:Protein Kinase Inhibitors; D014409:Tumor Necrosis Factor-alpha; D019010:Vascular Cell Adhesion Molecule-1; D008156:Luciferases; D048670:MAP Kinase Kinase 4; D054639:Mitogen-Activated Protein Kinase Phosphatases; C439065:DUSP16 protein, human; D054637:Dual-Specificity Phosphatases