Investigation of the role of Alkyladenine DNA glycosylase (AAG) in the repair of alkylated bases in the mitochondrial DNA of mice

Abstract

Living organisms are in constant exposure to agents that can damage their DNA, so they have developed DNA repair mechanisms to maintain the integrity of their genome. As the nuclear DNA, mitochondrial DNA is also subject to damage and may even accumulate more lesions than nuclear because of its location close to the electron transport chain, generating reactive oxygen species. In these organelles, the main pathway of repair is the base excision repair (BER), which repairs simple strand breaks and modified bases such as oxidized and alkylated bases, the beginning of this path is given by the recognition of modified bases by a DNA glycosylase. Alkylated bases, like 3-methyladenine, a toxic lesion to the cell, are recognized and repaired by the alkyladenine DNA glycosylase (AAG). Currently, AAG is known to be located in human mitochondria and nuclei, but its location in the mitochondria against exposure to alkylating agents has not yet been detected in mice. Since DNA repair pathways are targets for the study of human diseases and therapeutic trials, and that AAG activity can modulate the efficiency of various chemotherapeutic agents in use, it is necessary to study the DNA repair by AAG in murine mitochondria and to verify the difference of this repair in comparison to human mitochondria. Thus, the present work will investigate the role of AAG in the mitochondrial DNA repair in mouse (C2C12) and human (HeLa) cells (for comparison) expressing normal or reduced AAG levels, exposed to the alkylating agent methyl methanesulfonate (MMS), as well as the evaluation of cellular survival and mitochondrial bioenergetics of these cells in these situations. (AU)