Analysis of the fibroblast transformation potential of GTPase-deficient gip2 oncogenes.
Expression of GTPase-deficient Gi2 alpha subunit (alpha i2) mutant polypeptides and overexpression of the wild-type alpha i2 polypeptide in Rat 1a, Swiss 3T3, and NIH 3T3 fibroblasts altered normal growth regulation and induced a loss of contact inhibition. In Rat 1a cells (but not in NIH 3T3 or Swiss 3T3 cells), expression of the GTPase-deficient alpha i2 mutant polypeptides allowed colony formation in soft agar, which correlated with a loss in anchorage dependence and a decreased serum requirement. The altered growth regulatory properties of Rat 1a cells induced by expression of alpha i2 mutant polypeptides was not significantly inhibited by cotransfection with a dominant negative Ha-ras mutant polypeptide (Asn-17rasH), indicating that the activated Gi2 membrane signal transduction protein is uniquely capable of altering the regulation of Rat 1a cell growth by a predominantly c-ras-independent mechanism. The results show that GTPase-deficient alpha i2 mutant polypeptides have the properties of an oncogene that can induce the phenotypic characteristics of transformation in Rat 1a cells but that only a subset of these changes is observed with NIH 3T3 and Swiss 3T3 cells.
Gupta
S K
SK
Division of Basic Sciences, National Jewish Center for Immunology and Respiratory Medicine, Denver, Colorado 80206.
Gallego
C
C
Lowndes
J M
JM
Pleiman
C M
CM
Sable
C
C
Eisfelder
B J
BJ
Johnson
G L
GL
D016475:3T3 Cells; D000818:Animals; D000906:Antibodies / Q000276:immunology; D002455:Cell Division; D002460:Cell Line; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D005347:Fibroblasts / Q000473:pathology*; D020558:GTP Phosphohydrolases / Q000235:genetics* / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D051379:Mice; D009154:Mutation; D009857:Oncogenes; D051381:Rats; D016211:Transforming Growth Factor alpha / Q000276:immunology
D000906:Antibodies; D016211:Transforming Growth Factor alpha; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins