title: TGF-beta1 enhances the expression of alpha-smooth muscle actin in cultured human pulpal fibroblasts: immunochemical and ultrastructural analyses.
abstract: Transforming growth factor-beta 1 (TGF-beta1) has been related to induce the expression of alpha-smooth muscle actin (alpha-SMA) in fibroblasts during repair. Because pulpal fibroblasts seem to be somewhat different from other fibroblasts, the present study investigated in vitro whether TGF-beta1 enhances the expression of alpha-SMA in human pulpal fibroblasts. TGF-beta1 was added in doses between 5-10 ng/mL to cultures of both dental pulp and gingival human fibroblasts. The expression of alpha-SMA was analyzed by immunofluorescence and Western blotting, whereas the ultrastructure was evaluated by electron microscopy. In addition, the expression of tenascin, osteonectin, and vimentin was also investigated. Both cell types were immunoreactive for alpha-SMA even without TGF-beta1. When TGF-beta1 was added to cell cultures, the expression of alpha-SMA increased dramatically in pulpal fibroblasts, independent of the concentration used. It was confirmed by the Western blotting analysis. Ultrastructure revealed myofilaments and indented nuclei in both fibroblasts treated with TGF-beta1. Tenascin and osteonectin were only immunolabeled in pulpal fibroblasts treated or not with TGF-beta1. Both fibroblast types were positive for vimentin. The present findings showed that TGF-beta1 up-regulated the expression of alpha-SMA, thus inducing pulpal fibroblasts to acquire the myofibroblast phenotype.
authors.affiliation: Laboratory of Mineralized Tissue Biology, Department of Cell and Developmental Biology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil.
authors.forename: Elizabeth F
authors.initials: EF
authors.lastname: Martinez
authors.forename: Vera C
authors.initials: VC
authors.lastname: Araújo
authors.forename: Suzana O M
authors.initials: SO
authors.lastname: Sousa
authors.forename: Victor E
authors.initials: VE
authors.lastname: Arana-Chavez
mesh_terms: D000199:Actins / Q000096:biosynthesis*; D015153:Blotting, Western; D002478:Cells, Cultured; D003782:Dental Pulp / Q000166:cytology / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D005881:Gingiva / Q000166:cytology; D006801:Humans; D046529:Microscopy, Electron, Transmission; D032390:Myoblasts, Smooth Muscle / Q000378:metabolism; D015676:Osteonectin / Q000096:biosynthesis; D010641:Phenotype; D019063:Tenascin / Q000096:biosynthesis; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology* / Q000502:physiology; D014746:Vimentin / Q000096:biosynthesis
chemical_list: D000199:Actins; D015676:Osteonectin; D019063:Tenascin; D053773:Transforming Growth Factor beta1; D014746:Vimentin