RESUMO
3-Aminobenzamide (3AB) is an inhibitor of poly (ADP-ribose) polymerase (PARP), an enzyme implicated in the maintenance of genomic integrity, which is activated in response to radiation-induced DNA strand breaks. cDNA macroarray membranes containing 1536 clones were used to characterize the gene expression profiles displayed by mouse BALB/3T3 fibroblasts (A31 cell line) in response to ionizing irradiation alone or in combination with 3AB. A31 cells in exponential growth were pre-treated with 3AB 4mM 1h before gamma-irradiation (4Gy), remaining in culture during 6h until harvesting time. A31 cells treated with 3AB alone presented a down-regulation in genes involved in protein processing and cell cycle control, while an up-regulation of genes involved in apoptosis and related to DNA/RNA synthesis and repair was verified. A31 cells irradiated with 4Gy displayed 41 genes differentially expressed, being detected a down-regulation of genes involved in protein processing and apoptosis, and genes controlling the cell cycle. Concomitantly, another set of genes for protein processing and related to DNA/RNA synthesis and repair were found to be up-regulated. A positive or negative interaction effect between 3AB and radiation was verified for 29 known genes. While the combined treatment induced a synergistic effect on the expression of LCK proto-oncogene and several genes related to protein synthesis/processing, a negative interaction effect was found for the expression of genes related to cytoskeleton and extracellular matrix assembly (SATB1 and Anexin III), cell cycle control (tyrosine kinase), and genes participating in DNA/RNA synthesis and repair (RNA helicase, FLAP endonuclease-1, DNA-3 glycosylase methyladenine, splicing factor SC35 and Soh1). The present data open the possibility to investigate the direct participation of specific genes, or gene products acting in concert in the mechanism underlying the cell response to radiation-induced DNA damage under the influence of PARP inhibitor.
Assuntos
Células 3T3/efeitos da radiação , Benzamidas/farmacologia , Inibidores Enzimáticos/farmacologia , Regulação da Expressão Gênica/efeitos da radiação , Ribonucleoproteínas , Células 3T3/efeitos dos fármacos , Células 3T3/fisiologia , Animais , Anexina A3/efeitos dos fármacos , Anexina A3/genética , Anexina A3/efeitos da radiação , Dano ao DNA/genética , Dano ao DNA/efeitos da radiação , Endodesoxirribonucleases/efeitos dos fármacos , Endodesoxirribonucleases/genética , Endodesoxirribonucleases/efeitos da radiação , Endonucleases Flap , Raios gama , Perfilação da Expressão Gênica , Regulação da Expressão Gênica/efeitos dos fármacos , Proteína Tirosina Quinase p56(lck) Linfócito-Específica/efeitos dos fármacos , Proteína Tirosina Quinase p56(lck) Linfócito-Específica/genética , Proteína Tirosina Quinase p56(lck) Linfócito-Específica/efeitos da radiação , Proteínas de Ligação à Região de Interação com a Matriz/efeitos dos fármacos , Proteínas de Ligação à Região de Interação com a Matriz/genética , Proteínas de Ligação à Região de Interação com a Matriz/efeitos da radiação , Camundongos , Proteínas Nucleares/efeitos dos fármacos , Proteínas Nucleares/genética , Proteínas Nucleares/efeitos da radiação , Análise de Sequência com Séries de Oligonucleotídeos , Inibidores de Poli(ADP-Ribose) Polimerases , Proto-Oncogene Mas , RNA/biossíntese , RNA/efeitos dos fármacos , RNA/efeitos da radiação , RNA Helicases/efeitos dos fármacos , RNA Helicases/genética , RNA Helicases/efeitos da radiação , Fatores de Processamento de Serina-ArgininaRESUMO
The induction of nicotinamide adenine dinucleotide phosphate-malic enzyme (NADP-ME) in etiolated maize (Zea mays) seedlings by UV-B and UV-A radiation, and different levels of photosynthetically active radiation (PAR, 400-700 nm) was investigated by measuring changes in activity, protein quantity and RNA levels as a function of intensity and duration of exposure to the different radiations. Under low levels of PAR, exposure to UV-B radiation but not UV-A radiation for 6 to 24 h caused a marked increase in the enzyme levels similar to that observed under high PAR in the absence of UV-B. UV-B treatment of green leaves following a 12-h dark period also caused an increase in NADP-ME expression. Exposure to UV-B radiation for only 5 min resulted in a rapid increase of the enzyme, followed by a more gradual rise with longer exposure up to 6 h. Low levels of red light for 5 min or 6 h were also effective in inducing NADP-ME activity equivalent to that obtained with UV-B radiation. A 5-min exposure to far-red light following UV-B or red light treatment reversed the induction of NADP-ME, and this effect could be eliminated by further treatment with UV-B or red light. These results indicate that physiological levels of UV-B radiation can have a positive effect on the induction of this photosynthetic enzyme. The reducing power and pyruvate generated by the activity of NADP-ME may be used for respiration, in cellular repair processes and as substrates for fatty acid synthesis required for membrane repair.
Assuntos
Malato Desidrogenase/efeitos da radiação , Fotossíntese/efeitos da radiação , Raios Ultravioleta , Zea mays/efeitos da radiação , Indução Enzimática , Malato Desidrogenase/metabolismo , RNA/metabolismo , RNA/efeitos da radiação , Fatores de Tempo , Zea mays/enzimologiaRESUMO
The interaction of ultraviolet radiation and virus particles of Western Equine Encephalomyelitis Virus (WEE) and Newcastle Disease Virus (NDV) which have respectively RNA of positive (RNA+) and negative (RNA-) polarity as genomes, was studied using purified particles. The purified virus preparations were irradiated at a range from 1,000 to 6,000 joules per m2 with posterior analysis of their propagation in primary cell cultures of chicken embryos. It could be observed that a radiation dose of to 4,500 joules per m2 could induce 10(9) TCID50 per ml as minimal loss of titer for WEE virus and NDV. The hemagglutination assay was used as a toll to evaluate the alterations caused by UV radiation on the molecular arrangement of virus proteins. Alterations of the virus hemagglutinating activity were only observe when radiation levels higher than 6,000 joules per m2 were used. The results from hemolysis assays showed the importance of the loss of the envelope integrity and the damages to nucleoprotein structures during the inactivation process, when we used radiation doses higher than 6,000 joules per m2. This model of study can increase our comprehension of the radiation effects on the cell physiology and biological components of the cell membranes.