Division of Nephrology , Beth Israel Hospital , Harvard Medical School , Boston , Massachusetts 02215 , USA .
J Biol Chem 271 : 4251-5 ( 1996)
Abstract
Interaction of hepatocyte growth factor with its high affinity receptor c-met initiates a cascade of intracellular events leading to epithelial motility .
An 11-amino acid sequence from the c-met receptor has been found to cause cell transformation in transfected fibroblasts ( Ponzetto , C. , Bardelli , A. , Zhen , Z. , Maina , F. , Dalla , Z. P. , Giordano , S. , Graziani , A. , Panayotou , G. , and Comoglio , P. M.(1994 ) Cell 77 , -271 ) .
We inserted this sequence into a mutant platelet-derived growth factor receptor ( F5 ) to determine if this region of c-met can initiate cell motility and which signaling pathways it activates .
The platelet-derived growth factor ( PDGF ) receptor/c-met hybrid ( F5 met ) initiated PDGF-dependent chemotaxis in renal epithelial cells ( 8.0 +/- . 3 versus 70.5 +/- 4.8 cells/mm2 ) , while the parental construct , F5 , did not .
Addition of PDGF to cells expressing F5 met caused activation of the phosphatidylinositol ( PI ) 3-kinase ( control 2.0 +/- 0.8 , +PDGF . 1 +/- 5.1 , n = 3 , p < ; 0.05 ) and phospholipase C ( control 478.5 +/- 67 dpm/well , +PDGF 1049.3 +/- 93 , n = 4 , p = 0.003 ) , while neither pathway was activated in cells expressing F5 .
The chemotactic response of F5 met was inhibited by both the PI 3-kinase inhibitor wortmannin and the phospholipase C inhibitor U-71322 .
Selective activation of the PI -kinase utilizing a PDGF receptor mutant ( F3 ) containing the native high affinity PI 3-kinase binding site also resulted in PDGF stimulated chemotaxis , although less than that generated by the c-met sequence .
These findings demonstrate that the 11-amino acid sequence from c-met initiates epithelial motility via coincident activation of the PI -kinase and phospholipase C and that selective activation of the PI -kinase can initiate a partial chemotactic response .