Journal Article

Synergistic activation of p53-dependent transcription by two cooperating damage recognition pathways

Hupp, Ted R, Wallace, Maura, Ball, H Mei-Ling, Gibbs, Neil K, Blaydes, Jeremy P, Craig, Ashley L, Traynor, Nicola J

2000

Overview

High level activation of p53-dependent transcription occurs following cellular exposure to genotoxic damaging agents such as UV-C, while ionizing radiation damage does not induce a similarly potent induction of p53-dependent gene expression. Reasoning that one of the major differences between UV-C and ionizing radiation damage is that the latter does not inhibit general transcription, we attempted to reconstitute p53-dependent gene expression in ionizing irradiated cells by co-treatment with selected transcription inhibitors that alone do not activate p53. p53-dependent transcription can be dramatically enhanced by the treatment of ionizing irradiated cells with low doses of DRB, which on its own does not induce p53 activity. The mechanism of ionizing radiation-dependent activation of p53-dependent transcription using DRB is more likely due to inhibition of gene transcription rather than prolonged DNA damage, as the non-genotoxic and general transcription inhibitor Roscovitine also synergistically activates p53 function in ionizing irradiated cells. These results identify two distinct signal transduction pathways that cooperate to fully activate p53-dependent gene expression: one responding to lesions induced by ionizing radiation and the second being a kinase pathway that regulates general RNA Polymerase II activity.

• Publisher: Nature Publishing,Nature Publishing Group
• Subject: Amino Acid Sequence / Apoptosis / Biological and medical sciences / Cancer research / Cancer therapies / Cell physiology / Cell transformation and carcinogenesis. Action of oncogenes and antioncogenes / Cooperation / Cyclin-Dependent Kinases - antagonists & inhibitors / Cyclin-Dependent Kinases - radiation effects / Dichlororibofuranosylbenzimidazole - pharmacology / DNA damage / DNA Damage - drug effects / DNA Damage - physiology / DNA Damage - radiation effects / DNA-directed RNA polymerase / Enzyme Inhibitors - pharmacology / Fundamental and applied biological sciences. Psychology / Gene expression / Gene Expression Regulation - radiation effects / Genotoxicity / Humans / Ionizing radiation / Kinases / Laboratories / Medical research / Melanoma / Molecular and cellular biology / Molecular Sequence Data / p53 Protein / Phosphorylation / Proteins / Purines - pharmacology / Radiation / Research centers / RNA polymerase / RNA Polymerase II - antagonists & inhibitors / RNA Polymerase II - genetics / Roscovitine / Senescence / Serine - metabolism / Signal Transduction / Transcription activation / Transcription factors / Transcription, Genetic / Tumor Cells, Cultured / Tumor Suppressor Protein p53 - genetics / Tumor Suppressor Protein p53 - metabolism / Tumor Suppressor Protein p53 - radiation effects / Ultraviolet Rays / X-Rays