EVALUATION OF THE RELATIVE CONTRIBUTION OF ALTERNATIVE DNA POLYMERASES TO THE DNA DMAGAE RESPONSE (DDR)

AGOSTINA P. BERTOLIN CO-AUTHOR; SABRINA F. MANSILLA CO-AUTHOR; PAOLA CAMPODÓNICO; NICOLAS CALZETTA; MARIA BELEN DE LA VEGA; VANESA GOTTIFREDI

Ciudad de Buenos Aires

Congreso; REUNIÓN CONJUNTA DE SOCIEDADES DE BIOCIENCIAS; 2017

SAIB, SAIC, SAI, SAA, SAB, SAFE, SAFIS, SAH, SAP.

The DNA damage response (DDR) is a multifaceted network of signals which is activated by structural and chemical alterations of the DNA. The DDR involves DNA repair, DNA damage tolerance and checkpoint pathways which act in coordination to overcome the genotoxic stress. The level of crosstalk between DDR pathways has been partially revealed. For instance, it is accepted that DNA damage tolerance by alternative DNA polymerases facilitates DNA replication across DNA lesions hence preventing structural changes at replication forks known to trigger checkpoint activation. It is unclear if all alternative DNA polymerases (Alt. Pols) have complete overlapped functions in DDR. By using siRNA technology we depleted the expression of 6 different alternative DNA polymerases, either individually or in combination, and evaluated their relevant contribution to DDR after the exposure to DNA damaging agents. We analysed the induction of known replication stress markers such as the phosphorylation of H2AX (γH2A X) and the recruitment of 53BP1 to foci. From all of the alt. Pols evaluated, only Alt. DNA polymerase iota (Pol ι) contributed differently to the induction of replication stress markers, meaning that the amount of γH2AX and the recruitment of 53BP1 to foci were reduced in the absence of Pol ι. In the DNA damage tolerance pathway Alt. Pols play a crucial role in promoting the elongation of ongoing replication forks, implying that their expression is needed to prevent accumulation of replication stress markers. Our results suggest that this might not be true to all the polymerases implicated in the DNA damage tolerance pathway, as we observed that the expression of at least one alternative polymerase is needed to promote the accumulation of replication stress markers. We aim to evaluate how the cell responds to DNA damaging agents in the absence of Pol ι, whereas replication stress seems to be diminished, by analysing cell death and genomic instability.