Thrombin activates Ras-CREB/ATF-1 signaling and stimulates c-fos, c-jun, and c-myc expression in human gingival fibroblasts.
BACKGROUND
Protease-activated receptors (PARs) can be stimulated by thrombin and other proteases generated by periodontal pathogens. Activation of PARs in gingival fibroblasts (GFs) can modulate wound healing and inflammatory responses in gingival tissues.


METHODS
The mRNA expression of PARs and early responsive genes in GFs and other oral cells was studied by reverse transcription-polymerase chain reaction. Western blotting was used to study the activation of p38 and cAMP responsive element binding protein (CREB)/activating transcription factor (ATF)-1 as well as Ras.


RESULTS
GFs, dental pulp cells, and buccal mucosal fibroblasts expressed PAR-1 and -3 receptors, whereas gingival keratinocytes expressed PAR-1 and -2 receptors. Stimulation of GFs by thrombin rapidly activated Ras signaling and the phosphorylation of CREB/ATF-1 and p38. Thrombin also stimulated the expression of c-fos in GFs within 1 hour of exposure. Stimulation of c-jun mRNA expression showed biphasic responses with two peaks after 1 and 8 hours of exposure. Elevated c-myc expression in GFs by thrombin was noted after 2 hours of exposure. Moreover, the stimulation of c-fos and c-myc mRNA expression by thrombin can be attenuated by D-Phe-Pro-ArgCH(2)Cl, a serine-proteinase inhibitor.


CONCLUSIONS
PAR activation during gingival wounding or inflammation may stimulate Ras-CREB/ATF-1 signaling and c-fos, c-jun, and c-myc expression. This might be due to the proteinase activity of thrombin. These signaling events are important for wound healing and inflammatory responses in gingival tissues.
Chan
Chiu-Po
CP
Department of Dentistry, Chang-Gung Memorial Hospital, Taipei, Taiwan.
Chang
Mei-Chi
MC
Wang
Ying-Jan
YJ
Chen
Lin-I
LI
Tsai
Yi-Ling
YL
Lee
Jang-Jaer
JJ
Jia
Hsi-Wei
HW
Jeng
Jiiang-Huei
JH
D051697:Activating Transcription Factor 1 / Q000187:drug effects*; D015153:Blotting, Western; D050882:CREB-Binding Protein / Q000187:drug effects*; D002478:Cells, Cultured; D003782:Dental Pulp / Q000166:cytology / Q000187:drug effects; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects*; D005881:Gingiva / Q000166:cytology / Q000187:drug effects*; D006801:Humans; D015603:Keratinocytes / Q000187:drug effects; D009061:Mouth Mucosa / Q000166:cytology / Q000187:drug effects; D009842:Oligopeptides / Q000494:pharmacology; D016760:Proto-Oncogene Proteins c-fos / Q000187:drug effects*; D016755:Proto-Oncogene Proteins c-jun / Q000187:drug effects*; D016271:Proto-Oncogene Proteins c-myc / Q000187:drug effects*; D016283:Proto-Oncogene Proteins p21(ras) / Q000187:drug effects*; D044463:Receptor, PAR-1 / Q000187:drug effects; D044464:Receptor, PAR-2 / Q000187:drug effects; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects*; D013917:Thrombin / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D013997:Time Factors; D048051:p38 Mitogen-Activated Protein Kinases / Q000187:drug effects
C531110:ATF1 protein, human; D051697:Activating Transcription Factor 1; C489427:MYC protein, human; D009842:Oligopeptides; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D016271:Proto-Oncogene Proteins c-myc; D044463:Receptor, PAR-1; D044464:Receptor, PAR-2; D015842:Serine Proteinase Inhibitors; C020924:phenylalanyl-prolyl-arginine methyl chloride; D050882:CREB-Binding Protein; C494363:CREBBP protein, human; D048051:p38 Mitogen-Activated Protein Kinases; D013917:Thrombin; D016283:Proto-Oncogene Proteins p21(ras)