The multisubstrate adapter Gab1 regulates hepatocyte growth factor (scatter factor)-c-Met signaling for cell survival and DNA repair.
Hepatocyte growth factor (scatter factor) (HGF/SF) is a pleiotrophic mediator of epithelial cell motility, morphogenesis, angiogenesis, and tumorigenesis. HGF/SF protects cells against DNA damage by a pathway from its receptor c-Met to phosphatidylinositol 3-kinase (PI3K) to c-Akt, resulting in enhanced DNA repair and decreased apoptosis. We now show that protection against the DNA-damaging agent adriamycin (ADR; topoisomerase IIalpha inhibitor) requires the Grb2-binding site of c-Met, and overexpression of the Grb2-associated binder Gab1 (a multisubstrate adapter required for epithelial morphogenesis) inhibits the ability of HGF/SF to protect MDCK epithelial cells against ADR. In contrast to Gab1 and its homolog Gab2, overexpression of c-Cb1, another multisubstrate adapter that associates with c-Met, did not affect protection. Gab1 blocked the ability of HGF/SF to cause the sustained activation of c-Akt and c-Akt signaling (FKHR phosphorylation). The Gab1 inhibition of sustained c-Akt activation and of cell protection did not require the Gab1 pleckstrin homology or SHP2 phosphatase-binding domain but did require the PI3K-binding domain. HGF/SF protection of parental MDCK cells was blocked by wortmannin, expression of PTEN, and dominant negative mutants of p85 (regulatory subunit of PI3K), Akt, and Pak1; the protection of cells overexpressing Gab1 was restored by wild-type or activated mutants of p85, Akt, and Pak1. These findings suggest that the adapter Gab1 may redirect c-Met signaling through PI3K away from a c-Akt/Pak1 cell survival pathway.
Fan
S
S
Department of Radiation Oncology, Long Island Jewish Medical Center, The Long Island Campus for the Albert Einstein College of Medicine, New Hyde Park, New York 11040, USA.
Ma
Y X
YX
Gao
M
M
Yuan
R Q
RQ
Meng
Q
Q
Goldberg
I D
ID
Rosen
E M
EM
D048868:Adaptor Proteins, Signal Transducing; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis; D001665:Binding Sites; D015153:Blotting, Western; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism / Q000502:physiology; D002455:Cell Division; D002460:Cell Line; D002465:Cell Movement; D002470:Cell Survival; D004247:DNA / Q000378:metabolism; D004249:DNA Damage; D053938:DNA Fragmentation; D004260:DNA Repair; D004285:Dogs; D004317:Doxorubicin / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000378:metabolism; D051380:GRB2 Adaptor Protein; D005822:Genetic Vectors; D017228:Hepatocyte Growth Factor / Q000378:metabolism*; D006801:Humans; D008954:Models, Biological; D009154:Mutation; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism* / Q000502:physiology*; D010766:Phosphorylation; D011233:Precipitin Tests; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D019859:Proto-Oncogene Proteins c-met / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D015398:Signal Transduction; D013778:Tetrazolium Salts / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology; D013997:Time Factors; D014162:Transfection; D000077191:Wortmannin; D054462:p21-Activated Kinases
D048868:Adaptor Proteins, Signal Transducing; D000730:Androstadienes; D053148:Caspase 3; D020169:Caspases; D004247:DNA; D004317:Doxorubicin; D004791:Enzyme Inhibitors; D051380:GRB2 Adaptor Protein; D017228:Hepatocyte Growth Factor; D019869:Phosphatidylinositol 3-Kinases; D010750:Phosphoproteins; D017346:Protein Serine-Threonine Kinases; D011506:Proteins; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D019859:Proto-Oncogene Proteins c-met; D011994:Recombinant Proteins; D013778:Tetrazolium Salts; D013844:Thiazoles; D000077191:Wortmannin; D054462:p21-Activated Kinases; C098587:GAB1 protein, human; C490895:GAB2 protein, human; C495948:GRB2 protein, human; C494918:AKT1 protein, human; C515903:PAK1 protein, human; C505407:CASP3 protein, human; C022616:thiazolyl blue