Abstract
Mitochondrial dynamics regulates several characteristics of mitochondria such as architecture, activity, transport, interaction with other organelles, inheritance and degradation. Important defects in mitochondrial dynamics typical of aging, for example in the autophagic pathway, result in the accumulation of damaged mitochondria and development of pathologies in mice and humans. This is especially relevant for postmitotic tissues with elevated metabolism and mitochondrial turnover, such as the liver. As a consequence, hepatic mitochondria accumulate damage and mutations in mitochondrial DNA (mtDNA) with aging. Some hypotheses have already been elaborated in an attempt to explain this phenotype, but still lack evidence. In this sense, the main goal of this project is to evaluate the role of autophagy in the accumulation of mutant mtDNA in the liver. For this, heteroplasmic mice containing mtDNA of two mouse lineages, C57BL/6 (B6) and NZB/BINJ (NZB) will be used. It is known that mtDNA NZB results in mitochondrial dysfunction, and when present in heteroplasmy it causes cognitive and behavioral disorders. In addition, the level of mtDNA NZB increases in the liver with age. To investigate the role of autophagy in NZB mtDNA accumulation, we will perform a knock out of the Atg7 gene, which regulates a fundamental stage of autophagic activation. Due to the perinatal lethality of Atg7 deletion, we will carry out the conditional knockout of this gene in the liver by use of floxed Atg7 mice and cre recombinase expression regulated by the Alb (albumin) gene promoter. Hepatic levels of mtDNA NZB from animals with 35-37 and 100-102 days of age, from the wild type and the knockout groups, will be compared to the NZB mtDNA levels in the tail (10-12 days of age). With this, we expect to investigate the hypothesis that autophagy regulates the accumulation of mutant mtDNA in the liver.
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