title: Stretch-induced cell proliferation is mediated by FAK-MAPK pathway.
abstract: Previously we reported that a uni-axial cyclic stretch treatment of rat 3Y1 fibroblasts induced focal adhesion kinase (FAK) tyrosine phosphorylation followed by mitogen-activated protein kinase (MAPK) activation (Wang et al., 2001) [Wang, J.G., Miyazu, M., Matsushita, E., Sokabe, M., Naruse, K., 2001. Uni-axial cyclic stretch induces focal adhesion kinase (FAK) tyrosine phosphorylation followed by mitogen-activated protein kinase (MAPK) activation. Biochem. Biophys. Res. Comm. 288, 356-361]. In the present study, we investigated whether stretch-induced MAPK activation leads to proliferation of fibroblasts. 3Y1 fibroblasts were subjected to a uni-axial cyclic stretch treatment (1 Hz, 120% in length) and the bromodeoxyuridine (BrdU) incorporation was measured to access cell proliferation. BrdU incorporation increased in a time-dependent manner and became significant within 6 hours. To investigate the involvement of FAK, we transiently expressed FAK mutants that lacked tyrosine phosphorylation site (s) (F397Y, F925Y, F397/925Y). Transient expression of wild-type FAK or mock vector did not inhibit the stretch-induced BrdU incorporation, however, the FAK mutants significantly blocked BrdU incorporation. Treatment of the cells with MAPK inhibitors, PD98059 or SB203580, blocked extracellular signal-regulated kinase (ERK) phosphorylation and p38 MAPK phosphorylation, respectively, and also blocked stretch-induced BrdU incorporation. These results suggest that the stretch-induced FAK activation followed by MAPK activation plays an important role in the stretch-induced proliferation of 3Y1 fibroblasts.
authors.affiliation: Research Center of Stem Cells Biology and Tissue Engineering, Sun Yat-Sen University, 74 Zhong Shan Road 2, Guang Zhou 510080, China. Juguangw@hotmail.com
authors.forename: Ju Guang
authors.initials: JG
authors.lastname: Wang
authors.forename: Motoi
authors.initials: M
authors.lastname: Miyazu
authors.forename: Peng
authors.initials: P
authors.lastname: Xiang
authors.forename: Shu Nong
authors.initials: SN
authors.lastname: Li
authors.forename: Masahiro
authors.initials: M
authors.lastname: Sokabe
authors.forename: Keiji
authors.initials: K
authors.lastname: Naruse
mesh_terms: D000818:Animals; D001973:Bromodeoxyuridine / Q000378:metabolism; D049109:Cell Proliferation; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D005419:Flavonoids / Q000494:pharmacology; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D007093:Imidazoles / Q000494:pharmacology; D015151:Immunoblotting; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D015398:Signal Transduction / Q000502:physiology*; D013314:Stress, Mechanical; D014443:Tyrosine / Q000378:metabolism
chemical_list: D005419:Flavonoids; D007093:Imidazoles; D011725:Pyridines; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496052:Ptk2 protein, rat; D020928:Mitogen-Activated Protein Kinases; D001973:Bromodeoxyuridine; C093642:SB 203580; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one