Tumor necrosis factor-alpha induces early-onset endothelial adhesivity by protein kinase Czeta-dependent activation of intercellular adhesion molecule-1.
We tested the hypothesis that TNF-alpha induces early-onset endothelial adhesivity toward PMN by activating the constitutive endothelial cell surface ICAM-1, the beta2-integrin (CD11/CD18) counter-receptor. Stimulation of human pulmonary artery endothelial cells with TNF-alpha resulted in phosphorylation of ICAM-1 within 1 minute, a response that was sustained up to 15 minutes after TNF-alpha challenge. We observed that TNF-alpha induced 10-fold increase in PMN adhesion to endothelial cells in an ICAM-1-dependent manner and that this response paralleled the rapid time course of ICAM-1 phosphorylation. We also observed that the early-onset TNF-alpha-induced endothelial adhesivity was protein synthesis-independent and associated with cell surface ICAM-1 clustering. Pretreatment of cells with the pan-PKC inhibitor, chelerythrine, prevented the activation of endothelial adhesivity. As PKCzeta, an atypical PKC isoform abundantly expressed in endothelial cells, is implicated in signaling TNF-alpha-induced ICAM-1 gene transcription, we determined the possibility that PKCzeta was involved in mediating endothelial adhesivity through ICAM-1 expression. We observed that TNF-alpha stimulation of endothelial cells induced PKCzeta activation and its association with ICAM-1. Inhibition of PKCzeta by pharmacological and genetic approaches prevented the TNF-alpha-induced phosphorylation and the clustering of the cell surface ICAM-1 as well as activation of endothelial adhesivity. Thus, TNF-alpha induces early-onset, protein synthesis-independent expression of endothelial adhesivity by PKCzeta-dependent phosphorylation of cell surface ICAM-1 that precedes the de novo ICAM-1 synthesis. The rapid ICAM-1 expression represents a novel mechanism for promoting the stable adhesion of PMN to endothelial cells that is needed to facilitate the early-onset transendothelial migration of PMN.
Javaid
Kamran
K
Department of Pharmacology, University of Illinois College of Medicine, 835 S Wolcott Ave, Chicago, Ill 60612, USA.
Rahman
Arshad
A
Anwar
Khandaker N
KN
Frey
Randall S
RS
Minshall
Richard D
RD
Malik
Asrar B
AB
D000911:Antibodies, Monoclonal / Q000494:pharmacology; D018821:CD18 Antigens / Q000276:immunology / Q000378:metabolism; D002448:Cell Adhesion / Q000187:drug effects; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D009504:Neutrophils / Q000502:physiology; D010766:Phosphorylation / Q000187:drug effects; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011651:Pulmonary Artery / Q000166:cytology; D011940:Receptor Aggregation / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D000099221:Protein Kinase C zeta
D000911:Antibodies, Monoclonal; D018821:CD18 Antigens; D004791:Enzyme Inhibitors; D018799:Intercellular Adhesion Molecule-1; D011493:Protein Kinase C; D011500:Protein Synthesis Inhibitors; D014409:Tumor Necrosis Factor-alpha; D000099221:Protein Kinase C zeta