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

VALLERGA MB, FEDERICO MB, MANSILLA SF, HABIF M, SPERONI J, GOTTIFREDI V.

Montevideo

Workshop; XVII ALEXANDER HOLLAENDER COURSE, ?Environmental Genetics, Epigenetics and Genomic Instability?; 2012

The participation of the Fanconi Anemia Pathway in the replication of UV-damaged DNA María Belén Vallerga, María Belén Federico,Sabrina Mansilla, Juliana Speroni, Martín Habif and Vanesa Gottifredi Cell Cycle and Genomics Estability Laboratory, Fundación Instituto Leloir, CONICET, UBA, Buenos Aires, Argentina Maintenance of genomic stability is highly dependent on DNA repair and DNA tolerance mechanisms which aid DNA replication avoid fork collapse at DNA lesions. When DNA replication is challenged by UV a specialized DNA polymerase, pol eta, maintains fork processivity at DNA lesions, therefore protecting cell viability. Intriguingly, Pol eta lost in human cells does not steeply increase UV sensitivity, suggesting compensatory tolerance mechanisms promote cell survival. Using human pol eta defective cells or transiently downregulating pol eta with siRNA technology we found increased and sustained FANCD2 ubiquitination and focal formation after UVC, consistent with activation of the FANCONI ANEMIA (FA) pathway which is linked to recruitment of homologous recombination (HR) markers. To determine the contribution of FANDC2-dependent HR at collapsed replication forks we are currently analyzing general markers of damage H2AX phosphorylation), markers of HR activation (Rad51), markers of double strand breaks accumulation (53BP1), setting up viability assays and cytogenetic analysis. Together this information will allow us to predict if FANCD2 can trigger HR after UV and if this contributes to cell viability when pol eta is absent. Moreover, this knowledge might be of use when designing novel therapies that combine chemotoxins and genetic therapy.