Thrombin inhibits Bim (Bcl-2-interacting mediator of cell death) expression and prevents serum-withdrawal-induced apoptosis via protease-activated receptor 1.
To investigate the role of thrombin in regulating apoptosis, we have used CCl39 cells, a fibroblast cell line in which thrombin-induced cell proliferation has been extensively studied. Withdrawal of serum from CCl39 cells resulted in a rapid apoptotic response that was completely prevented by the inclusion of thrombin. The protective effect of thrombin was reversed by pertussis toxin, suggesting that cell-survival signalling pathways are activated via a G(i) or G(o) heterotrimeric GTPase. Serum-withdrawal-induced death required de novo gene expression and was preceded by the rapid de novo expression of the pro-apoptotic 'BH3-only' protein Bim (Bcl-2-interacting mediator of cell death). Thrombin strongly inhibited the up-regulation of both Bim protein and Bim mRNA. The ability of thrombin to repress Bim expression, and to protect cells from apoptosis, was reversed by U0126, a MEK1/2 [MAPK (mitogen-activated protein kinase) or ERK (extracellular-signal-regulated kinase) 1/2] inhibitor, or LY294002, a phosphoinositide 3'-kinase (PI3K) inhibitor, suggesting that both the Raf-->MEK-->ERK1/2 and PI3K pathways co-operate to repress Bim and promote cell survival. A PAR1p (protease-activated receptor 1 agonist peptide) was also able to protect cells from serum-withdrawal-induced apoptosis, suggesting that thrombin acts via PAR1 to prevent apoptosis.
Chalmers
Claire J
CJ
Signalling Programme, The Babraham Institute, Babraham Hall, Cambridge CB2 4AT, UK.
Balmanno
Kathryn
K
Hadfield
Kathryn
K
Ley
Rebecca
R
Cook
Simon J
SJ
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins; D000072224:Bcl-2-Like Protein 11; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002470:Cell Survival; D016895:Culture Media, Serum-Free; D005047:Etoposide / Q000633:toxicity; D005786:Gene Expression Regulation; D008565:Membrane Proteins; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D037342:Pertussis Toxin / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D014176:Protein Biosynthesis; D011493:Protein Kinase C / Q000378:metabolism; D011518:Proto-Oncogene Proteins; D044463:Receptor, PAR-1; D018179:Receptors, Thrombin / Q000378:metabolism*; D015398:Signal Transduction; D013917:Thrombin / Q000037:antagonists & inhibitors / Q000494:pharmacology*
D051017:Apoptosis Regulatory Proteins; D000072224:Bcl-2-Like Protein 11; D002352:Carrier Proteins; D016895:Culture Media, Serum-Free; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D044463:Receptor, PAR-1; D018179:Receptors, Thrombin; D005047:Etoposide; D037342:Pertussis Toxin; D019869:Phosphatidylinositol 3-Kinases; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases; D013917:Thrombin