The ras-binding domain of ral GDS-like protein-2 as a ras inhibitor in smooth muscle cells.
This study was undertaken to determine whether the response of smooth muscle cells to mitogens can be inhibited by inactivating ras with the ral GDS like protein-2 ras-binding domain (RGL2-RBD). RGL2 is a member of the ral GDS family of proteins that contains a carboxy terminal ras-binding domain which binds the GTP ligated form of ras and rap and a CDC25 homology domain with the structural features of a guanine nucleotide exchange factor. The effect of ras signaling on the smooth muscle cell growth factor response was studied using rat aortic A10 smooth muscle cells transfected with a plasmid that encoded the RGL2-RBD. RGL2-RBD transfection resulted in a 12-fold reduction in the number of clonal colonies that were obtained after selection, and dramatically slowed cell cycle progression. RGBL2-RBD reduced DNA synthesis and inhibited platelet derived growth factor (PDGF)-mediated activation of the MAPK pathway. These findings indicated that interfering with ras signaling inhibits smooth muscle cell proliferation and raise the possibility that ras signaling inhibition might be used therapeutically to control smooth muscle proliferation after vascular injury.
Fischer
Thomas H
TH
Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA. tfischer@med.unc.edu
Brittain
Julie
J
Trabalzini
Lorenza
L
Banes
Albert J
AJ
White
Gilbert C
GC
Smith
Carr J
CJ
Nichols
Timothy C
TC
D000818:Animals; D001665:Binding Sites; D002455:Cell Division; D002478:Cells, Cultured; D020662:Guanine Nucleotide Exchange Factors; D020935:MAP Kinase Signaling System; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D017434:Protein Structure, Tertiary; D016283:Proto-Oncogene Proteins p21(ras) / Q000037:antagonists & inhibitors* / Q000378:metabolism; D051381:Rats; D020691:rab GTP-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*
D020662:Guanine Nucleotide Exchange Factors; D010982:Platelet-Derived Growth Factor; C102739:RGL2 protein, human; D020928:Mitogen-Activated Protein Kinases; D016283:Proto-Oncogene Proteins p21(ras); D020691:rab GTP-Binding Proteins