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Proliferation of dental pulp fibroblasts in response to thrombin involves mitogen‐activated protein kinase signalling
Author(s) -
Gruber R.,
Jindra C.,
Kandler B.,
Watzak G.,
Fischer M. B.,
Watzek G.
Publication year - 2004
Publication title -
international endodontic journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.988
H-Index - 119
eISSN - 1365-2591
pISSN - 0143-2885
DOI - 10.1111/j.0143-2885.2004.00777.x
Subject(s) - thrombin , mapk/erk pathway , kinase , p38 mitogen activated protein kinases , mitogen activated protein kinase , microbiology and biotechnology , phosphorylation , protein kinase a , chemistry , biology , immunology , platelet
Aim To examine the involvement of mitogen‐activated protein kinases (MAPK) signalling on thrombin‐stimulated human dental pulp fibroblasts (DPF). Methodology Dental pulp fibroblasts were isolated from dental pulp connective tissue of third molars and expanded in vitro . Expression of thrombin receptors was analysed by RT‐PCR, and cell proliferation was measured by 3 [H]‐thymidine incorporation assay. Phosphorylation levels of MAPK were determined by Western blot analysis, and alkaline phosphatase activity was measured to serve as a marker for odontogenic differentiation. Statistical analysis was performed by Student's t ‐test. Results Dental pulp fibroblasts express the thrombin receptors protease‐activated receptor‐1 (PAR‐1), PAR‐3 and PAR‐4. Measurement of 3 [H]‐thymidine incorporation revealed a dose‐dependent increase of DNA synthesis in response to thrombin treatment. The thrombin‐induced mitogenic activity was decreased by the extracellular signal‐regulated protein kinase (ERK) signalling inhibitor PD98059 ( P < 0.05), and by SB203580 ( P < 0.05), a p38 MAPK inhibitor. Western blot analysis demonstrated increased phosphorylation of ERK in DPF following stimulation with thrombin, while p38 MAPK and c‐Jun NH 2 ‐terminal kinase (JNK) were not activated. Alkaline phosphatase activity of DPF remained unchanged upon incubation with thrombin. Conclusions These results suggest that signalling via MAPK mediates the mitogenic activity of thrombin on DPF and may thus play a role during the early stages of pulp repair.