Analisys of basal mutagenesis and UVA induced damages on Xeroderma Pigmentosum Variant patient cells

Abstract

DNA is constantly subject to the action of endogenous and exogenous agents that may cause numerous types of lesions in its molecule, interfering in the transcription and replication processes. Ultraviolet-light A (UVA), responsible for more than 90% of the solar ultraviolet radiation that reaches the Earth's surface, may cause direct and indirect DNA damage, inducing pyrimidine cyclobutane dimers (CPDs) and oxidized bases, respectively. Cells have several mechanisms capable of correcting these damages, such as Nucleotide Excision Repair (NER), as well as the Translesion Synthesis (TLS) pathway that bypasses CPDs and oxidized bases during replication. Deficiencies in the POLH/XPV gene, which codes for an important protein that acts on TLS, DNA polymerase · (pol eta), culminates in a rare, autosomal recessive syndrome, Xeroderma Pigmentosum Variant (XP-V). Thus, to better understand the role of endogenous oxidative stress in the mutation of XP-V patients, we intend to analyze the basal mutations in XP-V fibroblasts and compare them with the one complemented with pol eta. The project also proposes to analyze the mutagenic behavior of the same cell lines irradiated with UVA and treated with antioxidant agent (NAC) or by induction of the transcription factor Nrf2 (main responsible for the control of oxidative stress within the cells), as well as by transduction of photolyase that corrects specifically CPD damage. We will use a strategy developed by our group, where cells are cloned and then the exome of each clone is sequenced, to explore the mutagenic effects and identify mutation signatures in the absence of the pol eta more objectively, as well as the potentially protective effect of NAC, Nrf2 and photolyase. (AU)