Scotin, a novel p53-inducible proapoptotic protein located in the ER and the nuclear membrane.

p53 is a transcription factor that induces growth arrest or apoptosis in response to cellular stress. To identify new p53-inducible proapoptotic genes, we compared, by differential display, the expression of genes in spleen or thymus of normal and p53 nullizygote mice after gamma-irradiation of whole animals. We report the identification and characterization of human and mouse Scotin homologues, a novel gene directly transactivated by p53.

Immortalisation of a human diploid fibroblast cell strain: a DT-diaphorase paradox.

Transfection of a normal human diploid fibroblast cell strain, GM38, with a simian virus 40 (SV40) large T antigen containing plasmid, yielded an immortal cell line, G38-8X, which had a similar sensitivity as the parental cell strain to the quinone-containing chemotherapeutic agent mitomycin C (MMC), under both aerobic and hypoxic exposure conditions. The activity level of DT-diaphorase was similar in both the parental GM38 and G38-8X cells. Although DT-diaphorase could be detected by Western blot analysis, using two mouse anti-human monoclonal antibodies, in GM38 cells, it was not detected in the G38-8X cells.

Oxidative stress is involved in the UV activation of p53.

In many vertebrate cells exposure to ultraviolet light lead to a dramatic increase in the cellular levels of the tumour suppressor protein p53, followed by a biological response of either growth arrest or programmed cell death. Ultraviolet light can be absorbed directly by cellular macromolecules, leading to photochemical modification of DNA and proteins. Additionally, it also causes free radical formation, resulting in oxidative stress.

p53-dependent growth arrest following calcium phosphate-mediated transfection of murine fibroblasts.

A variety of genotoxic agents can induce an accumulation of p53 protein in the nuclei of mammalian cells and lead to either growth arrest or apoptosis in a p53-dependent manner. Recently, the induction of the p53 pathway has also been reported for non-genotoxic agents such as heat shock and hypoxia, rendering it likely that p53 activity might be triggered by a wider range of cellular stress factors. Here we report the effect of calcium phosphate-mediated transfection, a technique commonly used in studies of transient gene expression in mammalian cells, on fibroblasts containing wild-type p53.

Effects of TGF-betas and bFGF on Astroglial Cell Growth and Gene Expression in Vitro.

Transforming growth factor-betas (TGF-betas) 2 and 3 are expressed in murine embryonic astrocytes in vivo, but their cellular functions are not known. Primary cultures of rat neonatal astroglial cells express mRNA transcripts for TGF-betas 1, 2, and 3, as well as basic fibroblast growth factor (bFGF) and secrete TGF-beta1 and TGF-beta2 protein. TGF-beta3 protein levels cannot be determined at present.