E2F MEDIATED INDUCTION OF P19INK4D PLAYS AN IMPORTANT ROLE IN CELL CYCLE AND DNA DAMAGE RESPONSE

CARCAGNO, AL; SONZOGNI, SG; CERUTI, JM; GIONO, LE; CÁNEPA, ET

Villa Carlos Paz. Argentina

Congreso; XLIV Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2008

SAIB

E2F MEDIATED INDUCTION OF P19INK4D PLAYS AN IMPORTANT ROLE IN CELL CYCLE AND DNA DAMAGE RESPONSE p19INK4 is a member of the INK4 family of proteins that regulate G1/S cell cycle transition. INK4s inhibit pRb phosphorylation by CDK 4/6 and consequently reduce the transcriptional activity of E2F. p19 is expressed periodically during the cell cycle, showing the highest level at the G1/S phase. In silico analysis of the p19 promoter sequence revealed potential E2F binding sites. Moreover, the overexpression of E2F in asynchronic fibroblasts led to an increase in p19 mRNA at all cell cycle phases. However, the physiological significance of p19 regulation by E2F remained to be explored. The aim of this work was to study the role of E2F in two aspects of p19 expression: its periodic regulation during the cell cycle and its induction during the DNA damage response. To achieve this, we developed a strategy based on triple helix-forming oligonucleotides (TFOs) in order to prevent E2F binding to its response elements in the p19 promoter. Proof of principle experiments showed that TFOs were able to specifically prevent p19 induction by E2F during normal cell cycle as well as following DNA damage. In subsequent experiments, TFOs transfected cells showed alterations in their cell cycle kinetics, proliferation and ability to repair damaged DNA (clonogenicity). These results highlight the significance of the regulation of p19 by E2F in different physiological situations.