Figure 1.
Immunohistochemical validation of genes identified in microarray experiments.
A representative ETS abnormal skeletal muscle fiber is shown A. Prohibitin 2, B. Mitochondrial DNA Polymerase Gamma, C. P53 Up-regulated Mediator of Apoptosis, D. Cytochrome C Oxidase activity, E. Succinate Dehydrogenase activity.
Figure 2.
Immunohistochemical validation of signal transduction/transcriptional activation identified by gene expression profiling.
Activation of AMP kinase and peroxisome proliferator activated receptor pathways in response to deletion mutation accumulation. A. CD36/Fatty acid Translocase, a pparα regulated gene, B. No Primary antibody control, C. Peroxisome proliferator-activated receptor gamma co-activator 1, D. Activated AMP Kinase, E. Inhibited Acetyl-CoA Carboxylase F. Peroxisome proliferator-activated receptor alpha.
Figure 3.
Effect of β-GPA administration on mitochondrial DNA abundance in vivo.
A. Mitochondrial genome content of the Vastus medialis muscle following β-GPA treatment was measured using real-time PCR. B. Electron transport system abnormalities are more abundant in rats treated with the AMP kinase activator β-guanidinopropionic acid. Each Vastus lateralis skeletal muscle was stained for cytochrome C oxidase and succinate dehydrogenase every 60 microns for one millimeter. Regions of skeletal muscle fibers lacking COX activity and hyper-reactive for SDH (the ETS abnormal phenotype) were counted.
Figure 4.
Model of positive feedback loop in ETS abnormal fibers.
Signal transduction pathways detect mitochondrial dysfunction and drive transcriptional activation leading to up-regulation of mitochondrial DNA replication and subsequent deletion mutation accumulation. Genes in green were up-regulated in ETS abnormal fibers. Proteins in blue were found to be up-regulated by immunohistochemistry in ETS abnormal fibers. Proteins in purple were detected by both assays. wt: wild-type mitochondrial genomes, Δ deletion mutation containing mitochondrial genomes.