he participation of the Fanconi Anemia Pathway in the replication of UV-damaged DNA

FEDERICO MB, VALLERGA MB, MANSILLA S, SPERONI J, HABIF M, DALESSIO C AND GOTTIFREDI V.

San Luis

Congreso; XLVII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular.; 2011

The participation of the Fanconi Anemia Pathway in the replication of UV-damaged DNA MB Federico, MB Vallerga, S Mansilla, J Speroni, M Habif, C D’ Alessio and V Gottifredi Cell Cycle and Genomic Stability Laboratory, Fundación Instituto Leloir, CONICET, UBA, BA, Argentina When cells are challenged with genotoxic agents, replicating cells must use damaged DNA as templates. In this way, active replication forks do not collapse and cell viability is protected. After UV irradiation a specialized DNA polymerase pol eta uses UV-damaged DNA as template.  Intriguingly, Pol eta lost in human cells does not steeply increase UV sensitivity. This suggests that compensatory mechanisms promote cell survival when pol eta is absent. We have found an increase and sustained FANCD2 ubiquitination and focal formation after UV irradiation when pol eta is lost. FANCD2 is a key marker of the activation of the FANCONI ANEMIA (FA) pathway. While there is limited information regarding a role of the FA pathway after UV irradiation, it is well established that FANCD2 ubiquitination is linked to the recruitment of homologous recombination (HR) specific markers to other lesions. We therefore thought that cell viability in the absence of pol eta might result from the activation of FANDC2-dependent HR at collapsed replication forks.  We are currently analyzing markers of damage such as gH2AX phosphorylation, markers of HR such as Rad51, markers of double strand breaks accumulation such as 53BP1 and setting up viability assays. This information might allow us to predict if FANCD2 can trigger HR after UV and if this contributes to cell viability when pol eta is absent.