title: FGF-10 prevents mechanical stretch-induced alveolar epithelial cell DNA damage via MAPK activation.
abstract: Cyclic stretch of alveolar epithelial cells (AEC) can alter normal lung barrier function. Fibroblast growth factor-10 (FGF-10), an alveolar type II cell mitogen that is critical for lung development, may have a role in promoting AEC repair. We studied whether cyclic stretch induces AEC DNA damage and whether FGF-10 would be protective. Cyclic stretch (30 min of 30% strain amplitude and 30 cycles/min) caused AEC DNA strand break formation, as assessed by alkaline unwinding technique and DNA nucleosomal fragmentation. Pretreatment of AEC with FGF-10 (10 ng/ml) blocked stretch-induced DNA strand break formation and DNA fragmentation. FGF-10 activated AEC mitogen-activated protein kinase (MAPK), and MAPK inhibitors prevented FGF-10-induced AEC MAPK activation and abolished the protective effects of FGF-10 against stretch-induced DNA damage. In addition, a Grb2-SOS inhibitor (SH(3)b-p peptide), a RAS inhibitor (farnesyl transferase inhibitor 277), and a RAF-1 inhibitor (forskolin) each prevented FGF-10-induced extracellular signal-regulated kinase (ERK) 1/2 phosphorylation in AEC. Moreover, N17-A549 cells that express a RAS dominant/negative protein prevented the FGF-10-induced ERK1/2 phosphorylation and RAS activation in AEC. We conclude that cyclic stretch causes AEC DNA damage and that FGF-10 attenuates these effects by mechanisms involving MAPK activation via the Grb2-SOS/Ras/RAF-1/ERK1/2 pathway.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, 303 East Chicago Avenue, Tarry 14-707, Chicago, IL 60611, USA. upadhyayd@pol.net
authors.forename: Daya
authors.initials: D
authors.lastname: Upadhyay
authors.forename: Eduardo
authors.initials: E
authors.lastname: Correa-Meyer
authors.forename: Jacob I
authors.initials: JI
authors.lastname: Sznajder
authors.forename: David W
authors.initials: DW
authors.lastname: Kamp
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D017209:Apoptosis / Q000502:physiology; D002460:Cell Line; D004249:DNA Damage / Q000187:drug effects*; D004789:Enzyme Activation / Q000502:physiology; D004847:Epithelial Cells / Q000187:drug effects / Q000502:physiology; D051526:Fibroblast Growth Factor 10; D005346:Fibroblast Growth Factors / Q000502:physiology*; D051380:GRB2 Adaptor Protein; D006801:Humans; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D018384:Oxidative Stress / Q000502:physiology; D011506:Proteins / Q000502:physiology; D019908:Proto-Oncogene Proteins c-raf / Q000502:physiology; D011650:Pulmonary Alveoli / Q000187:drug effects* / Q000502:physiology*; D020664:Son of Sevenless Proteins / Q000502:physiology; D013314:Stress, Mechanical; D018631:ras Proteins / Q000502:physiology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C496463:FGF10 protein, human; D051526:Fibroblast Growth Factor 10; D051380:GRB2 Adaptor Protein; C495948:GRB2 protein, human; D011506:Proteins; D020664:Son of Sevenless Proteins; D005346:Fibroblast Growth Factors; D019908:Proto-Oncogene Proteins c-raf; D020928:Mitogen-Activated Protein Kinases; D018631:ras Proteins