RNA-seq of mouse heart that is both heart SOD2 knockout and deficient for mitochondrial DNA repair

To study whether increase in mitochondrial oxidative stress (SOD2 removal) and decrease in mitochondrial DNA repair (Ogg1 dMTS) results into increase in mutations in mitochondrial RNA (mtRNA). Oxidative stress has been suggested to induce mutations in mtDNA and as DNA is used as a template in transcription, mutations or 8-oxo-dG on DNA can induce GC>TA transversion accumulation in mtRNA. To verify this, we extracted and sequenced (Illumina) total RNA from heart Sod2 knockout mice alone and mice that were also deficient for mitochondrial base-excision repair. The repair deficiency was induced by removing the genomic region encoding for the predicted mitochondrial targeting sequence from endogenous OGG1 (L2 to W23) called Ogg1 dMTS mice, thus excluding the protein from mitochondria. OGG1 is a DNA glycosylase that recognizes and repairs 8-oxo-dG damage from DNA. Oxidative stress can induce 8-oxo-dG lesions, thus we removed the mitochondrial matrix localized superoxide dismutase (SOD2) from these mice to increase the level of oxidative stress. 8-oxo-dG lesion can be mutagenic because some DNA repair polymerases are known to erroneously incorporate adenosine opposite to 8-oxo-dG during replication leading to GC>TA transversion mutations.