Transcriptional regulation of E2F factors in DNA damage response

CASTILLO D; OGARA MF; CÁNEPA ET; PREGI N

San Miguel de Tucumán

Congreso; XLV REUNIÓN ANUAL DE LA SOCIEDAD ARGENTINA DE INVESTIGACIÓN EN BIOQUÍMICA Y BIOLOGÍA MOLECULAR (SAIB); 2009

SOCIEDAD ARGENTINA DE INVESTIGACIÓN EN BIOQUÍMICA Y BIOLOGÍA MOLECULAR (SAIB)

Following genotoxic stress, the E2F1 transcription factor has been shown to undergo post-translational modifications that correlate with a stabilization and increase in its protein levels. The aim of this work is to examine whether this increase in protein levels is only due to its gained stability or is also a result of enhanced transcription of the E2F1 gene. This study also includes the other family members, E2F2 to E2F5. We subjected HEK293 and HN9 cells to genotoxic stress -such as UV, H O and neocarzinostatin- and allowed them to trigger a DNA repair response and recover for different time periods. Northern Blot analyses were carried out using E2F1 to E2F5 probes. Quantifications revealed that E2F1 mRNA levels were induced between 4 to 8 hours following genotoxic exposition in both cell lines for all types of stress, reaching a 3 to 4.5-fold increase in HEK293 and a 2 to 3.5-fold increase in HN9 cells. Surprisingly, E2F2 transcription was enhanced 2.5 to 4-fold from 4 to 12 hours of recovery only in neuronal HN9 cells after every stress. E2F3, E2F4 and E2F5 mRNA levels remained unchanged. Preliminary results suggest that MAPK and ATM/ATR pathways are involved in this response. Our results reveal a new mechanism in which E2F1 and E2F2 respond to genotoxic stress by increasing their transcript levels.