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

AGUSTINA PAOLA BERTOLIN; SABRINA FLORENCIA MANSILLA; PAOLA CAMPODÓNICO; NICOLÁS CALZETTA,; MARÍA BELÉN DE LA VEGA; VANESA GOTTIFREDI

Buenos Aires

Congreso; Reunión Conjunta de Biociencias; 2017

Sociedades de Biociencias

The DNA damage response (DDR) is a multifaceted network ofsignals which is activated by structural and chemical alterations ofthe DNA. One key aspect of DDR is DNA damage tolerance by alternative DNA polymerases which facilitates DNA replication acrossDNA lesions. 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 alternativeDNA polymerases, either individually or in combination, and evaluated their relevant contribution to the accumulation of DDR markersafter the exposure to DNA damaging agents such as cisplatin. Weanalysed the induction of known replication stress markers such asthe phosphorylation of H2AX (γH2AX) and the formation of 53BP1foci. As expected, the loss of most Alt. Pols caused the accumulationof increased levels of such DDR markers, as a consequence of asuboptimal response of cells depleted from Alt. pols to cisplatin. Incontrast to other Alt. Pols, the loss of polymerase iota (Pol ι) causeda reduction in the induction of γH2AX and the formation of 53BP1foci. Hence, the function of Pol ι might not be restricted to the DNAsynthesis across DNA lesions as reported for the rest of the Alt pols.By means of studying DNA replication parameters such as originfiring and the rate of nascent DNA elongation we will present evidence suggesting that, in fact, the contribution of pol ι to DNA replicationis different from that of other Alt. pols. We will also present evidencedemonstrating that the contribution to DDR of pol ι is relevant forthe survival and the genomic stability of cells. Together our data demonstrates that pol ι has a contribution to DDR that is not shared byother Alt. pols hence suggesting that the loss of its function may bemore difficult to compensate in cancer cells.