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Studies of DNA repair and its biological consequences


This project aims to study different aspects of DNA repair, as well as its consequences to the cell, mainly cell death and mutagenesis. These studies include research in mammalian cells, plants and bacteria, which are presented as subprojects. In mammalian tissue culture we are developing viral vectors for expression control of DNA repair genes, taking XPA gene as a model. We are trying to inactivate it employing ribozymes, creating new cell lines which are defective for this gene. The endpoints are the identification of phenotypic alterations, such as sensitivity to genotoxic agents, as UV light. Moreover, the XPA gene is being inserted in several vectors under the control of conditional promoters, and these are being transfected in XPA cells, with the goal of obtaining a conditional mutant for this gene. These cell lines are under construction and together with cells already available in this laboratory will be employed to investigate the mechanisms of apoptosis induced by UV irradiation. Initial results with rat kangaroo cells indicated that UV-induced cell death is an active process involving apoptosis, independently of DNA replication (MIYAJI e MENCK, 1995,1996). In fact, the starting signal for apoptosis can be reverted by photo reactivation, allowing the investigation of the sequence of events that result in cell death (MIYAJI e MENCK, 1996,1998). However, these studies are limited because most of the genes related to apoptosis are not known in marsupial cells. Thus, we are constructing new human cell lines expressing the photolysis gene from marsupial cells, in order to use the photo reactivation tool in human cells. Another line of investigation is the development of episomal shuttle vectors, containing different mutations in the marker supF gene, which will be used for genetic recombination studies. It is our interest to employ this system to identify how genetic defects related to DNA repair are involved in the process of DNA recombination in mammalian cells. Arabidopsis thaliana is being used as a model to investigate DNA repair in plants. Although the number of studies of DNA repair in plants is small, the high expositions of these organisms to environmental aggression that result in DNA damage justify the important interest of this work… (AU)

Scientific publications
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
CHIGANÇAS‚ V.; MIYAJI‚ E.N.; MUOTRI‚ A.R.; JACYSYN‚ J.F.; AMARANTE-MENDES‚ G.P.; YASUI‚ A.; MENCK‚ C.F.M. Photorepair prevents ultraviolet-induced apoptosis in human cells expressing the marsupial photolyase gene. Cancer Research, v. 60, n. 9, p. 2458, 2000.

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