Keronninn Moreno de Lima Bessa
From DNA Repair Lab
I undergraduated in Biology at the Federal University of Rio Grande do Norte. In 2006, I got my PhD in Biotechnology at the University of Sao Paulo, Brazil. Nowadays, I am supported by a Postdoctoral Fellowship from FAPESP.
Research projectUltraviolet light (UV) generates DNA lesions, cyclobutante pyrimidine dimers (CPDs) and 6-4 pyrimidine-pyrimidone photoproducts being the most frequent ones. These DNA lesions can be removed from the genome by two different DNA repair processes: photoreactivation and nucleotide excision repair (NER). Photoreactivation envolves enzymes named photolyases, which contain chromophores that capture blue photons and use them to repair the UV photoproducts. Interestingly, these enzymes present a high specificity to the target lesion, being classified as CPD-photolyases and 6-4PP-photolyases. Even though photoreactivation has been found widespread in the nature, these enzymes are absent in placental mammals, including humans. In these organisms, repair of UV-induced DNA lesions is performed by NER. Our research work is interested in investigating the effects of CPDs and 6-4PPs on the induction of cellular responses upon UV irradiation. For this purpose, we have constructed adenoviral vectors carrying the marsupial CPD-photolyase and plant 6-4PP-photolyase. So far, we have been able to demonstrate that both CPDs and 6-4PPs play important roles in cell death pathways in NER-deficient human fibroblasts, while CPDs are the major signals that lead NER-proficient human cells to death. At this time, we have been employing these recombinant adenoviral vectors for studying the effects of CPDs and 6-4PPs in cellular processes such as DNA replication and RNA transcription, which are inhibited by UV irradiation. Publications1. LIMA-BESSA KM, Chiganças V, Stary A, Kannouche P, Sarasin A, Armelini MG, Jacysyn JF, Amarante-Mendes, GP, Cordeiro-Stone M, Cleaver JE, Menck CF. Adenovirus mediated transduction of the human DNA polymerase eta cDNA. DNA Repair, v. 5, p. 925-934, 2006. |