Studies on the cell-cycle dependency of the actions of insulin-like growth factor-I in Balb/c 3T3 cells

✍ Scribed by Itaru Kojima; Masafumi Kitaoka; Etsuro Ogata

• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: English
• Weight: 466 KB
• Volume: 143
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/jcp.1041430318

✦ Synopsis

I 12, lapan

The present study was conducted to determine the cell-cycle dependency of various actions of IGF-I in Balbk 3T3 cells. When autophosphorylation of the IGF-I receptor was determined in [ '2P]-labelled cells, IGF-I increased radioactivity in a 100 K-Da phosphoprotein, presumably p-subunit of the IGF-I receptor, both in quiesent 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 [ 'H]diacylglycerol, and I3H]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 cellcycle-dependent actions of IGF-I.

Insulin-like growth factor-I (IGF-I) is a potent mitogen which regulates mammalian somatic growth in vivo (1). TGF-I also stimulates cell proliferation in various types of cells in tissue culture. The mechanism by which IGF-I promotes cell growth is of great interest but still remains largely uncertain. The mode of action