Figure 3.

Aging-associated alterations in mitochondrial gene transcripts. (A) Hierarchical clustering and heat map of genes coding for proteins regulating mitochondrial energetics from adult (A1–A10) and aged patients (O1–O10). Green indicates downregulation; red, upregulation; and black, no change in the level of expression of genes. (B) Volcano plot illustrating the relative changes in expression of genes coding for mitochondrial proteins from aged and adult patients (p(Corr) < .05). There were 101 genes coding for mitochondrial proteins that were significantly different in the aged group compared with the adult group (blue dots). (C) Number of significantly downregulated (87 genes, green bar) and upregulated (14 genes, red bar) genes in the aged atrias compared with adults and their distribution according to their molecular function with 49% of the altered genes coded for proteins regulating mitochondrial energetic pathways (30% for substrate metabolism, 13% for oxidative phosphorylation (OXPHOS), and 6% for tricarboxylic acid cycle (TCA), and the remaining 51% for other mitochondrial functions including apoptosis (Apopt) and detoxification (Detox). (D) Expression values for selected genes coding for subunits of mitochondrial proteins regulating energetics from right atrial appendages of adult (n = 10, white dots) and aged (n = 10, black dots) patients are shown as dot-plots highlighting the clustering of gene expression within each age group with the statistical significance of age-related changes between the two groups shown with their p-values, n = 10 for adults and n = 10 for aged.