Sendon 2019 Abstract IOC139
|Sendon PM, Simard ML, Stewart J (2019) Development and characterization of a novel mouse model carrying specific mitochondrial DNA mutations. Mitochondr Physiol Network 24.01.
Mutations of the mitochondrial DNA (mtDNA) have long been of interest in the study of ageing and human diseases. These genetic mutations disrupt mitochondrial gene expression, leading to mitochondrial dysfunction. Unfortunately, it is still not possible to transgenically manipulate animal mtDNA so relevant animal models with mtDNA mutations are not abundant. To circumvent this, heterozygous female mutator mice, containing a proofreading-deficient form of mtDNA polymerase-gamma, were used in this study to transmit mtDNA mutations to the offspring. Lineages of nuclear-wild type mice transmitting acquired mtDNA mutations were then developed through series of breeding and screening. Histochemical analyses and sequencing were used to identify specific alleles that might play a role in mitochondrial dysfunction. Three SNPs were identified: a mutation in the mt-tRNAAla gene, a synonymous mutation in mt-cytb, and a mutation within the TFAM binding site of the mitochondrial control region. The mutations in mt-tRNAAla and mt-cytb do not have pathogenic effects, however, the mutation in the control region may affect mtDNA replication and transcription. Quantitative PCR results showed that mtDNA copy number in heart tissue of mutant mice was significantly lower compared to the WT; in the skeletal muscle, however, there was no significant difference. These results suggest that mtDNA replication is affected by the mutation in a tissue-specific manner. Steady state mt-mRNA levels in the heavy strand of heart tissue were lower in the mutant than the WT but no significant difference was observed in the light strand. To check for heteroplasmy, mutation levels between mothers and offspring were measured. At present, the highest mutation level is at 88% and the lowest is at 20%. Mutation levels across tissues were also measured, with high variability in colon and liver. Cardiomyopathy was observed in ageing mutant mice (61 to 90-week-old). Other experiments will be carried out, such as, in vitro replication and transcription assays, histochemical staining of other tissues, and comparison of mitochondrial respiration between WT and mutant mice to further molecularly characterize this new mouse model.
• Bioblast editor: Plangger M
Labels: MiParea: mtDNA;mt-genetics
- Max Planck Inst Biol Ageing, Cologne, Germany