RhoA/Rho-associated kinase pathway selectively regulates thrombin-induced intercellular adhesion molecule-1 expression in endothelial cells via activation of I kappa B kinase beta and phosphorylation of RelA/p65.
We investigated the involvement of the RhoA/Rho-associated kinase (ROCK) pathway in regulating ICAM-1 expression in endothelial cells by the procoagulant, thrombin. Exposure of HUVECs to C3 exoenzyme, a selective inhibitor of Rho, markedly reduced thrombin-induced ICAM-1 expression. Inhibition of ROCK, the downstream effector of Rho, also prevented thrombin-induced ICAM-1 expression. Blockade of thrombin-induced ICAM-1 expression was secondary to inhibition of NF-kappaB activity, the key regulator of ICAM-1 expression in endothelial cells. In parallel studies we observed that inhibition of the RhoA/ROCK pathway by the same pharmacological and genetic approaches failed to inhibit TNF-alpha-induced NF-kappaB activation and ICAM-1 expression. The effect of RhoA/ROCK inhibition on thrombin-induced NF-kappaB activation was secondary to inhibition of IkappaB kinase activation and subsequent IkappaBalpha degradation and nuclear uptake and the DNA binding of NF-kappaB. Inhibition of the RhoA/ROCK pathway also prevented phosphorylation of Ser(536) within the transactivation domain 1 of NF-kappaB p65/RelA, a critical event conferring transcriptional competency to the bound NF-kappaB. Thus, the RhoA/ROCK pathway signals thrombin-induced ICAM-1 expression through the activation of IkappaB kinase, which promotes NF-kappaB binding to ICAM-1 promoter and phosphorylation of RelA/p65, thus mediating the transcriptional activation of bound NF-kappaB.
Anwar
Khandaker N
KN
Department of Pediatrics, University of Rochester School of Medicine, Rochester, NY 14642, USA.
Fazal
Fabeha
F
Malik
Asrar B
AB
Rahman
Arshad
A
D002460:Cell Line; D004730:Endothelium, Vascular / Q000166:cytology / Q000201:enzymology* / Q000378:metabolism; D004789:Enzyme Activation; D006801:Humans; D051550:I-kappa B Kinase; D018799:Intercellular Adhesion Molecule-1 / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D047908:Intracellular Signaling Peptides and Proteins; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology*; D012333:RNA, Messenger / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D015398:Signal Transduction / Q000502:physiology*; D013917:Thrombin / Q000037:antagonists & inhibitors / Q000502:physiology*; D051996:Transcription Factor RelA; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein / Q000037:antagonists & inhibitors / Q000502:physiology*
D047908:Intracellular Signaling Peptides and Proteins; D016328:NF-kappa B; D012333:RNA, Messenger; D051996:Transcription Factor RelA; D018799:Intercellular Adhesion Molecule-1; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; C496559:CHUK protein, human; D051550:I-kappa B Kinase; C496560:IKBKB protein, human; C496565:IKBKE protein, human; D013917:Thrombin; D020742:rhoA GTP-Binding Protein