The SH2-domian-containing inositol 5-phosphatase (SHIP)-2 binds to c-Met directly via tyrosine residue 1356 and involves hepatocyte growth factor (HGF)-induced lamellipodium formation, cell scattering and cell spreading.
Recently, evidence has been accumulating that inositol and phosphatidylinositol polyphosphate play important roles in a variety of signal transduction systems including membrane traffic, actin cytoskeleton rearrangement and cell motility. In this paper, we show for the first time that the SH2-domain-containing inositol 5-phosphatase (SHIP)-2 binds directly to the hepatocyte growth factor (HGF/SF) receptor, c-Met, via phosphotyrosine 1356. HGF induces the breakdown of cell junctions and the dispersion of colonies of epithelial cells including MDCK cells. Whereas only few lamellipodia are observed in MDCK cells 2 min after stimulation with HGF, both SHIP-2- and SHIP-1-overexpressing cells form large, broad lamellipodia. The number of lamellipodia is 2-4-fold greater than that of mock-transfected MDCK cells in the same time period and SHIP is found to colocalize with actin at the leading edge. Furthermore, overexpression of a catalytic inactive mutant of SHIP-2 suppresses HGF-potentiated cell scattering and cell spreading, although these mutant-expressing cells form enhanced number of lamellipodia 2 min after HGF stimulation. Interestingly, cells expressing a mutant lacking the proline-rich domain of SHIP-2 at the C-terminal form few lamellipodia, but still spread and scatter upon stimulation with HGF at a reduced rate. These data suggest that phosphatase activity is required for HGF-mediated cell spreading and scattering but not for alteration of lamellipodium formation, while the proline-rich region influences lamellipodium formation. Furthermore, treatment with 10 microM of phosphatidylinositol 3 (PI3) kinase inhibitor, LY294002, abrogates HGF-induced cell scattering of SHIP-2-overexpressing cells but not parental HEK293 cells, suggesting that a balance between PI3 kinase and SHIP is important for cell motility.
Koch
Alexandra
A
Institut für Biochemie, Medizinische Hochschule Hannover, OE 4310, Carl-Neuberg-Str. 1, Hannover D-30623, Germany.
Mancini
Annalisa
A
El Bounkari
Omar
O
Tamura
Teruko
T
D000818:Animals; D018929:Cell Culture Techniques; D002465:Cell Movement / Q000235:genetics*; D004285:Dogs; D017228:Hepatocyte Growth Factor / Q000494:pharmacology*; D006801:Humans; D007668:Kidney / Q000166:cytology; D019869:Phosphatidylinositol 3-Kinases / Q000494:pharmacology; D000072183:Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics* / Q000378:metabolism; D019859:Proto-Oncogene Proteins c-met / Q000378:metabolism* / Q000494:pharmacology; D011554:Pseudopodia / Q000235:genetics; D015398:Signal Transduction; D014443:Tyrosine / Q000378:metabolism
D014443:Tyrosine; D017228:Hepatocyte Growth Factor; D019869:Phosphatidylinositol 3-Kinases; D019859:Proto-Oncogene Proteins c-met; D010744:Phosphoric Monoester Hydrolases; C098706:INPPL1 protein, human; D000072183:Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases