The chemotactic response to PDGF-BB: evidence of a role for Ras.
The PDGF receptor-beta mediates both mitogenic and chemotactic responses to PDGF-BB. Although the role of Ras in tyrosine kinase-mediated mitogenesis has been characterized extensively, its role in PDGF-stimulated chemotaxis has not been defined. Using cells expressing a dominant-negative ras, we find that Ras inhibition suppresses migration toward PDGF-BB. Overexpression of either Ras-GTPase activating protein (Ras-GAP) or a Ras guanine releasing factor (GRF) also inhibited PDGF-stimulated chemotaxis. In addition, cells producing excess constitutively active Ras failed to migrate toward PDGF-BB, consistent with the observation that either excess ligand or excess signaling intermediate can suppress the chemotactic response. These results suggest that Ras can function in normal cells to support chemotaxis toward PDGF-BB and that either too little or too much Ras activity can abrogate the chemotactic response. In contrast to Ras overexpression, cells producing excess constitutively active Raf, a downstream effector of Ras, did migrate toward PDGF-BB. Cells expressing dominant-negative Ras were able to migrate toward soluble fibronectin demonstrating that these cells retained the ability to migrate. These results suggest that Ras is an intermediate in PDGF-stimulated chemotaxis but may not be required for fibronectin-stimulated cell motility.
Kundra
V
V
Department of Cell Biology, Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
Anand-Apte
B
B
Feig
L A
LA
Zetter
B R
BR
D016475:3T3 Cells; D000818:Animals; D000077214:Becaplermin; D015153:Blotting, Western; D002633:Chemotaxis / Q000502:physiology*; D005353:Fibronectins / Q000494:pharmacology; D020690:GTPase-Activating Proteins; D020662:Guanine Nucleotide Exchange Factors; D008246:Lysophospholipids / Q000494:pharmacology; D051379:Mice; D015689:Oncogene Protein p21(ras) / Q000235:genetics / Q000378:metabolism; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D019908:Proto-Oncogene Proteins c-raf; D020574:Proto-Oncogene Proteins c-sis; D020796:Receptor, Platelet-Derived Growth Factor alpha; D017479:Receptors, Platelet-Derived Growth Factor / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D020703:ras GTPase-Activating Proteins; D020663:ras Guanine Nucleotide Exchange Factors; D018631:ras Proteins / Q000378:metabolism*; D020666:ras-GRF1
D005353:Fibronectins; D020690:GTPase-Activating Proteins; D020662:Guanine Nucleotide Exchange Factors; D008246:Lysophospholipids; D010982:Platelet-Derived Growth Factor; D011506:Proteins; D011518:Proto-Oncogene Proteins; D020574:Proto-Oncogene Proteins c-sis; D011994:Recombinant Proteins; D020703:ras GTPase-Activating Proteins; D020663:ras Guanine Nucleotide Exchange Factors; D020666:ras-GRF1; D000077214:Becaplermin; D020796:Receptor, Platelet-Derived Growth Factor alpha; D017479:Receptors, Platelet-Derived Growth Factor; D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf; D015689:Oncogene Protein p21(ras); D018631:ras Proteins