Thrombin induces c-fos expression in cultured human endothelial cells by a Ca2(+)-dependent mechanism.
The proto-oncogene c-fos has been implicated in the modulation of various cell functions. We have found that thrombin, a pleiotropic activator of endothelial cells, induced c-fos mRNA in human umbilical vein endothelial cells (HEC). This effect was dose-related (0.05 to 1.0 U/mL) and transient (maximal after 1 hour and negligible within 4 hours). Since thrombin activates phosphoinositide (PI) turnover through a pertussis toxin (PT)-sensitive guanosine triphosphate-binding regulatory protein(s) (G-protein) with subsequent stimulation of protein kinase C (PKC) and Ca2+ movements, we investigated whether these intracellular pathways are also responsible for c-fos induction. PT inhibited thrombin's effect on c-fos expression, but had no effect on c-fos expression by phorbol myristate acetate (PMA). Down regulation of PKC by prolonged exposure to PMA had no effect on thrombin and ionomycin stimulation of c-fos, but inhibited PMA activation of this gene. Quenching of the Ca1(2+) increase in response to quin2 loading in the absence of external Ca2+ suppressed thrombin activity on c-fos transcription. Under the same conditions PMA activity was not inhibited or only partially inhibited. Interleukin-1 beta (IL-1 beta) and basic fibroblast growth factor (bFGF) stimulation of c-fos mRNA level were not inhibited by quin2; on the contrary, ionomycin effect was blocked by this agent. These results indicate that thrombin-induced c-fos expression in HEC does not require a fully active PKC but is dependent on normal intracellular Ca2+ availability.
Lampugnani
M G
MG
Istituto di Ricerche Farmacologische Mario Negri, Milan, Italy.
Colotta
F
F
Polentarutti
N
N
Pedenovi
M
M
Mantovani
A
A
Dejana
E
E
D002118:Calcium / Q000494:pharmacology / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D004730:Endothelium, Vascular / Q000166:cytology* / Q000378:metabolism / Q000502:physiology; D005786:Gene Expression Regulation / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D037342:Pertussis Toxin; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos; D013917:Thrombin / Q000494:pharmacology*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D016760:Proto-Oncogene Proteins c-fos; D010566:Virulence Factors, Bordetella; D037342:Pertussis Toxin; D011493:Protein Kinase C; D013917:Thrombin; D002118:Calcium