Mitogen-stimulated events in nuclei of Swiss 3T3 cells Evidence for a direct link between changes of inositol lipids, protein kinase C requirement and the onset of DNA synthesis

• Published in: FEBS letters 1991-06, Vol.283 (2), p.243-246
• Main Authors: Martelli, A.M., Gilmour, R.S., Neri, L.M., Manzoli, L., Corps, A.N., Cocco, L.
• Format: Article
• Language: English
• Subjects: 1,2-dioleyl-racglycerol; 5-bromodeoxyuridine; Adenosine Triphosphate - metabolism; adenosine trisphosphate; Animals; ATP; Bombesin - pharmacology; BrdU; Cell Line; Cell Nucleus - drug effects; Cell Nucleus - physiology; DAG; DNA Replication - drug effects; DNA synthesis; EGTA; ethylene glycol-bis(β-aminoethyl ether) N,N,N′,N′-tetraacetic acid; IGF-I; inositol 1,4,5-trisphosphate; Inositol lipid; insulin-like growth factor I; Insulin-Like Growth Factor I - pharmacology; IP3; Kinetics; Mice; Mitogen; Mitogens; Nucleus; phosphatidic acid; Phosphatidic Acids - metabolism; phosphatidyl-serine; Phosphatidylinositol 4,5-Diphosphate; phosphatidylinositol 4-phosphate; Phosphatidylinositol Phosphates; Phosphatidylinositols - metabolism; PIP; PIP2; PKC; Protein kinase C; Protein Kinases - metabolism; SPH; sphingosine; Swiss 3T3 cell
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/0014-5793(91)80598-W

Two different clones of Swiss 3T3 cells belonging to the same original cell line have been obtained, one of which was unresponsive to mitogenic stimulation (e.g. insulin-like growth factor-I, bombesin, insulin-like growth factor-I + bombesin), while the other clone showed a very high rate of DNA synthesis under identical conditions as demonstrated by 5-bromodeoxyuridine incorporation. Both types of cells expressed the IGF-I receptor and showed high contact inhibition. When highly purified nuclei from responsive cells, treated for a short time with bombesin and insulin-like growth factor-I or insulin-like growth factor-I alone, were incubated with [γ-32P]adenosine triphosphate, the labelling of phosphatidylinositol-mono- und diphosphate decreased when compared to controls, while this transient effect did not appear in the nuclei from unresponsive cells. Similarly nuclear protein kinase C is activated only in responsive cells. Therefore, it seems that a direct link exists between polyphosphoinositide metabolism, protein kinase C activation and the early events leading to cell division, since the rapid changes in the labelling of both phosphatidylinositol mono- and di-phosphate occur only in nuclei from Swiss 3T3 cells, which respond to the mitogenic stimulus determined by insulin-like growth factor-I on its own, or in combination with bombesin.