Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.6 (RNA polymerase)
 34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have previously suggested that the inhibition of RNA polymerase II-mediated transcription after exposure to UV light promotes the accumulation of p53 and the induction of apoptosis (Oncogene 13, 823-831). However, it was not clear whether p53 induction was contributing to apoptosis. Here we report that apoptosis is triggered at lower UV doses in p53-deficient Li-Fraumeni syndrome (LFS) and human papillomavirus (HPV) E6 expressing fibroblasts than in normal cells, suggesting that p53 can be protective against UV-induced apoptosis. There is no significant difference in the effect of UV-irradiation on the cell cycle distribution of normal and primary LFS fibroblasts. Importantly, the recovery of nascent mRNA synthesis in all p53-deficient fibroblasts is significantly impaired compared with control cells after exposure to relevant doses of UV light. Taken together, our results suggest that wild-type p53 can protect cells against UV-induced apoptosis by facilitating the recovery of transcription. Furthermore, we suggest that the capacity of cells to recover transcription after genotoxic damage is an important determinant of sensitivity to apoptosis.
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PMID:Role for p53 in the recovery of transcription and protection against apoptosis induced by ultraviolet light. 1093 82

RNA polymerase (pol) III synthesizes essential small RNAs, including tRNA and 5S rRNA. Wild-type p53 can repress pol III transcription both in vitro and in vivo. Many tumours carry substitutions in p53 which have selective effects on its functions. We identify tumour-derived mutations that compromise the ability of p53 to regulate pol III transcription. Furthermore, substitution R175H, the most common mutation in cancers, converts p53 from a repressor to an activator of pol III. Oncoproteins neutralize p53 in some tumours; we show that human papillomavirus E6 and cellular hdm2 can both release pol III from repression by p53. These data suggest that the restraining influence of p53 on pol III will be lost in many tumours. In addition to these features of sporadic cancers, some individuals inherit mutant forms of p53 and consequently suffer from Li-Fraumeni syndrome, showing genetic predisposition to certain malignancies. We find that pol III transcriptional activity is often highly elevated in primary fibroblasts from Li-Fraumeni patients, especially if the germline p53 mutation is followed by loss of the remaining allele. Our data suggest that p53 status can have a profound effect upon pol III transcription and hence on the biosynthetic capacity of cells.
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PMID:RNA polymerase III transcription can be derepressed by oncogenes or mutations that compromise p53 function in tumours and Li-Fraumeni syndrome. 1208 26