Studies on the cell-cycle dependency of the actions of insulin-like growth factor-I in Balb/c 3T3 cells.
The present study was conducted to determine the cell-cycle dependency of various actions of IGF-I in Balb/c 3T3 cells. When autophosphorylation of the IGF-I receptor was determined in [32P]-labelled cells, IGF-I increased radioactivity in a 100 K-Da phosphoprotein, presumably beta-subunit of the IGF-I receptor, both in quiescent and in primed competent cells. Likewise, IGF-I stimulated uptake of [3H]deoxyglucose independent of the cell cycle. In contrast, IGF-I increased calcium entry, radioactivity in [3H]diacylglycerol, and [3H]thymidine incorporation in primed competent cells while these reactions were not induced by IGF-I in quiescent cells. The latter three reactions were attenuated when cells were pretreated with pertussis toxin. These results indicate that some, but not all, of the actions of IGF-I are dependent on the cell cycle in Balb/c 3T3 cells. They also suggest that a pertussis-toxin-sensitive G protein may be involved in the cell-cycle-dependent actions of IGF-I.
Kojima
I
I
Fourth Department of Internal Medicine, University of Tokyo School of Medicine, Japan.
Kitaoka
M
M
Ogata
E
E
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis; D004075:Diglycerides / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D005947:Glucose / Q000378:metabolism / Q000493:pharmacokinetics; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology* / Q000502:physiology; D051379:Mice; D008807:Mice, Inbred BALB C; D037342:Pertussis Toxin; D010766:Phosphorylation; D011956:Receptors, Cell Surface / Q000378:metabolism; D017451:Receptors, Somatomedin; D013002:Somatomedins / Q000494:pharmacology*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D004075:Diglycerides; D011956:Receptors, Cell Surface; D017451:Receptors, Somatomedin; D013002:Somatomedins; D010566:Virulence Factors, Bordetella; D007334:Insulin-Like Growth Factor I; D004247:DNA; D037342:Pertussis Toxin; D005947:Glucose; D002118:Calcium