Synthesis of polyphosphoinositides in nuclei of Friend cells. Evidence for polyphosphoinositide metabolism inside the nucleus which changes with cell differentiation

• Published in: Biochemical journal Vol. 248; no. 3; pp. 765 - 770
• Main Authors: Cocco, L, Gilmour, R S, Ognibene, A, Letcher, A J, Manzoli, F A, Irvine, R F
• Format: Journal Article
• Language: English
• Published: England 15.12.1987
• Subjects: Animals; Cell Nucleus - metabolism; Cell Nucleus - ultrastructure; Cell Transformation, Viral; Cells, Cultured; Chromatography, Thin Layer; Friend murine leukemia virus; Leukemia, Erythroblastic, Acute - metabolism; Leukemia, Erythroblastic, Acute - ultrastructure; Leukemia, Experimental - metabolism; Lipids - biosynthesis; Mice; Microscopy, Electron; Phosphatidylinositol Phosphates; Phosphatidylinositols - biosynthesis
• ISSN: 0264-6021; 1470-8728
• DOI: 10.1042/bj2480765

Previous work demonstrated the existence of phosphatidylinositol kinase and phosphatidylinositol phosphate kinase in rat liver nuclei, with the suggestion that these activities are in the nuclear membrane [Smith & Wells (1983) J. Biol. Chem. 258, 9368-9373]. Here we show that highly purified nuclei from Friend cells, washed free of nuclear membrane by Triton, can incorporate radiolabel from [gamma-32P]ATP into phosphatidic acid, phosphatidylinositol phosphate and phosphatidylinositol 4,5-bisphosphate. The degree of radiolabelling of phosphatidylinositol bisphosphate is highly dependent on the state of differentiation of the cells, being barely detectable in growing cells and much greater after dimethyl sulphoxide-induced differentiation; this difference is mostly due to different amounts of phosphatidylinositol phosphate in the isolated nuclei. We suggest that polyphosphoinositides are made inside the nucleus and that they have a role in chromatin function; either the phospholipids themselves play a role, or there is a possibility of intranuclear signalling by inositide-derived molecules.