By reverse transcription (RT)-PCR analyses, human gingival fibroblasts (HGFs) were demonstrated to express mRNAs for protease-activated receptor-1 (PAR-1) and PAR-3, although the expression of PAR-3 was much weaker than that of PAR-1. The mRNAs for PAR-2 and PAR-4 were not found by RT-PCR. Furthermore, PAR activation was studied by monitoring cytosolic Ca2+ concentration ([Ca2+]i) in cultured HGFs loaded with fura-2. At concentrations > 0.1 nM, α-thrombin caused a transient increase in [Ca2+]i in a concentration-dependent manner, and the maximum response was obtained with 10 nM α-thrombin. After the [Ca2+]i response, the HGFs were completely desensitized to the second stimulation with α-thrombin. The PAR-1 agonist peptide SFLLRN produced approximately the same transient [Ca2+]i response as α-thrombin. After stimulation with SFLLRN, the HGFs did not respond to α-thrombin, indicating that treatment with SFLLRN results in complete desensitization to α-thrombin. The PAR-2 and PAR-4 agonist peptides had no effect on [Ca2+]i in HGFs. These results suggest that α-thrombin-induced Ca2+ mobilization in HGFs is solely mediated by PAR-1.
- Ca signaling
- Gingival fibroblasts
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)
- Pharmacology, Toxicology and Pharmaceutics(all)