Effects of thiol antioxidants on hepatocyte growth factor signaling in cardiac myocytes.
We describe here novel antioxidant-sensitive events in which activation kinetics are delayed, leading to inhibition of cell signaling. Hepatocyte growth factor (HGF) transiently phosphorylated p44/42 mitogen-activated protein kinase (MAPK) with a peak at 3-5 min in HL-1 adult cardiac myocytes. Pretreatment of cells with thiol antioxidants, N-acetylcysteine or alpha-lipoic acid attenuated MAPK phosphorylation induced by a 3-min incubation with HGF. However, kinetic analysis revealed that the apparent inhibition of HGF signaling was due to a delay in the activation because HGF phosphorylated MAPK with a peak at 5-7 min in cells treated with thiol antioxidants. This 2-min delay in HGF activation of MAPK resulted in >5-min delay in phosphorylation of MAPK targets such as p90RSK and GATA-4. Hydrogen peroxide did not mimic HGF signaling, and HGF did not induce reactive oxygen species production. Thus, in cardiac myocytes, thiol antioxidants delay HGF-mediated MAPK activation and suppress subsequent signaling eventsvia reactive oxygen species-independent mechanism.
Kitta
K
K
Antioxidants Research Laboratory and Cell and Molecular Nutrition Program, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA 02111, USA.
Day
R M
RM
Remeika
J
J
Blumberg
J B
JB
Suzuki
Y J
YJ
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D015153:Blotting, Western; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism; D050991:GATA4 Transcription Factor; D006321:Heart / Q000187:drug effects; D017228:Hepatocyte Growth Factor / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007700:Kinetics; D020935:MAP Kinase Signaling System; D051379:Mice; D008954:Models, Biological; D009206:Myocardium / Q000166:cytology* / Q000378:metabolism; D010766:Phosphorylation; D019893:Ribosomal Protein S6 Kinases / Q000378:metabolism; D015398:Signal Transduction; D013438:Sulfhydryl Compounds / Q000494:pharmacology*; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism
D000975:Antioxidants; D004268:DNA-Binding Proteins; D050991:GATA4 Transcription Factor; D013438:Sulfhydryl Compounds; D014157:Transcription Factors; D017228:Hepatocyte Growth Factor; D006861:Hydrogen Peroxide; D019893:Ribosomal Protein S6 Kinases