Nuclear protein kinase activities during the cell cycle of HeLa S3 cells

Nuclear proteins associated with gene expression in mouse plasmacytoma cell lines

Nucleoplasmic and non-histone chromatin proteins from two unrelated and four related mouse plasmacytoma cell lines have been analysed by biosynthetic labelling with [35S]-methionine followed by one- and two-dimensional polyacrylamide gel electrophoresis. We have attempted to find a relationship between the patterns of nuclear proteins and gene expression in mutant plasmacytoma cell lines. The majority of nuclear proteins are common to all of the cell lines studied as would be expected if the majority of nuclear proteins are concerned with functions common to all plasma cells. There are, however, both qualitative and quantitative differences in the nuclear protein patterns of mutant and parent cell lines which appear to correlate with differences in gene expression. The turnover of nuclear proteins in two of the cell lines, MOPC 315.40 (IgA producer) and MOPC 315.32 (lambda 2 chain producer) was studied using pulse-chase techniques.

On the mechanism of reductive activation in the mode of action of some anticancer drugs

Bioactivation of a number of DNA-specific antitumor drugs depends on oxidoreduction. Bleomycin, neocarzinostatin and anthracycline glycosides are the best known among such drugs in terms of reductive activation processes. Their reduction results in short-lived radical or electrophilic intermediates attacking DNA stereospecifically. The physico-chemical properties of these drugs and the nature of DNA damage are reviewed. Models for DNA-intercalation, electron-donor systems involved in drug metabolisation, and the role of oxygen in radical reactions, are discussed in the light of recent reports.

Induction by phenobarbital of the mRNA for a specific variant of rat liver microsomal cytochrome P-450

The treatment of rats for 4 days with phenobarbital causes an apparent 3-fold increase in the amount of total liver cytochrome P-450. By sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, metyrapone binding and immunoprecipitation, this increase was found to be due to a much larger increase in a restricted number of specific cytochrome P-450 variants. A radioimmunoassay technique demonstrated that the major phenobarbital-inducible variant, of molecular weight 52 000, is induced 24-fold by phenobarbital. Immunoprecipitation analysis of products of translation in vitro with an antibody specific to the 52 000-mol.wt. cytochrome P-450 showed that phenobarbital induces the mRNA in polyribosomes for this variant 20-fold. Evidence is presented for the action of phenobarbital at the transcriptional and translational levels.

Polyamine-activated protein kinase reaction from nuclei and nucleoli of Physarum polycephalum which phosphorylates a unique Mr 70 000 nonhistone protein

Methods are described for the detection and purification of a protein kinase from nuclei and nucleoli of Physarum polycephalum which catalyzed transfer of phosphate from [gamma-32P]ATP to a unique nonhistone protein of Mr 70 000 in a reaction that was polyamine dependent. Enzymatic phosphorylation of the nonhistone protein by the purified protein kinase was stimulated greatly, at times more than 60-fold, by the polyamines spermidine and spermine. This unique polyamine-dependent reaction was localized on the rDNA minichromosome of the nucleolus. The polyamine-dependent protein kinase, which was first partially purified with the acidic nonhistone protein fraction from isolated nucleoli, was resolved from at least six other protein kinases by phosphocellulose chromatography into a catalytic component of Mr 26 000 and a complex comprised of the catalytic component associated with a phosphate acceptor protein of Mr 70 000. The complex also catalyzed polyamine-dependent phosphorylation of the endogenous Mr 70 000 component. The resolved catalytic component catalyzed polyamine-dependent phosphorylation of a dephosphorylated Mr 70 000 nonhistone protein that had been independently isolated from nucleoli and previously demonstrated to have properties concordant with a specific regulatory role in rRNA gene transcription [Keuhn, G. D., Affolter, H. U., Atmar, V. J., Seebeck, T., Gubler, U., & Braun, R. (1979) Proc. Natl. Acad. Sci. U.S.A. 76, 2541-2545]. These studies indicate one way that the polyamines may regulate rRNA gene transcription through the mediation of a highly specific nonhistone protein kinase.