Project description:Cardiomyopathy (CM) is an intrinsic weakening of the myocardium with contractile dysfunction and congestive heart failure (CHF). CHF has been postulated to result from decreased mitochondrial energy production and oxidative stress. The effects of decreased mitochondrial oxygen consumption can also accelerate with aging, with the mitochondrial theory of aging forming the basis of this knowledge. We previously showed DNA methylation changes in human hearts with CM. This was associated with mitochondrial DNA depletion, being another molecular marker of CM. We examined the relationship between mitochondrial dysfunction and cardiac epigenetic DNA methylation changes in both young and old mice. We used genetically engineered C57Bl/6 mice transgenic for a cardiac-specific mutant of the mitochondrial polymerase (termed Y955C). Y955C mice undergo left ventricular hypertrophy (LVH) at a young age (~94 days old), and LVH decompensated to CHF at old age (~255 days old). In Y955C hearts, 95 differentially expressed genes were found, while 4,452 genes were differentially expressed in aged hearts. Moreover, cardiac DNA methylation patterns differed between Y955C (4,506 peaks with 68.5% hypomethylation) and aged hearts (73,286 peaks with 80.2% hypomethylated). Correlatively, of the 95 Y955C-dependent differentially expressed genes, 30 genes (31.6%) also displayed differential DNA methylation; in the 4,452 age dependent differentially expressed genes, 342 gene (7.7%) displayed associated DNA methylation changes. Both Y955C and aging demonstrated significant enrichment of CACGTG-associated E-box motifs in differentially methylated regions. Cardiac mitochondrial polymerase dysfunction alters nuclear DNA methylation. Furthermore, aging causes a robust change in cardiac DNA methylation that is partially associated with mitochondrial polymerase dysfunction. This study addresses how Y955C-mutated mitochondrial DNA polymerase g and aging affect cardiac (left ventricle) gene expression and epigenetic nuclear DNA methylation.

Project description:We performed a microarray analysis of auditory midbrain (inferior colliculus, IC) mRNA from young adult CBA mice (controls) with good hearing, middle aged (MA) with good hearing, and old mild (MP) and severe (SP) presbycusic CBA mice. Fold Change data derived from RMA normalization revealed that the overall GABA receptor alpha 6 expression profiles for MA, MP and SP were down-regulated relative to young adult controls with good hearing. Relative real-time PCR for five GABA receptors confirmed this age-related down regulation quantitatively. Functional hearing data: Auditory Brainstem Responses (ABR) enriched the analysis to select the probe-sets that changed with age and hearing loss by the linear regression best-fit line model technique. GABA receptor genotype-phenotype correlations with auditory functional data indicated that GABA-receptor subtypes are under expressed in SP mice. Hierarchical clustering (HC) analyses yielded statistical significance of normalized GeneChip data Real-time PCR showed that Gabra6, GABA B receptor 1 (Gabbr1), and Gaba transporter protein Slc32a1 may be involved in physiological changes that occur in age-related hearing loss. Presbycusis – age-related hearing loss – is the number one communicative disorder of our aged population. In this study we analyzed gene expression for a set of GABA receptors in the inferior colliculus of aging CBA mice using the Affymetrix GeneChip MOE430A. Functional phenotypic hearing changes from RMA normalized microarray data (39 replicates) in four age-groups, Young Controls and Middle aged mice with good hearing, mild and sever e presbycusis from old mice. Fold change gene expression derived from RMA normalized data were first subjected to one-way ANOVA, and then linear regression was performed. The selected gene expression changes were confirmed by relative real-time relative to young adult controls with good hearing. Statistically significant and real time PCR confirmed GABA receptor genes; Gabra6, GABA B receptor 1 (Gabbr1), and Gaba transporter protein Slc32a1, may be involved in physiological changes that occur in age-related hearing loss. Lastly, gene expression measures of each age group were correlated with pathway/network relationships relevant to the inferior colliculus using Pathway Architect, to identify key pathways consistent with the gene expression changes observed

Project description:We performed a microarray analysis of auditory midbrain (inferior colliculus, IC) mRNA from young adult CBA mice (controls) with good hearing, middle aged (MA) with good hearing, and old mild (MP) and severe (SP) presbycusic CBA mice. Fold Change data derived from RMA normalization revealed that the overall GABA receptor alpha 6 expression profiles for MA, MP and SP were down-regulated relative to young adult controls with good hearing. Relative real-time PCR for five GABA receptors confirmed this age-related down regulation quantitatively. Functional hearing data: Auditory Brainstem Responses (ABR) enriched the analysis to select the probe-sets that changed with age and hearing loss by the linear regression best-fit line model technique. GABA receptor genotype-phenotype correlations with auditory functional data indicated that GABA-receptor subtypes are under expressed in SP mice. Hierarchical clustering (HC) analyses yielded statistical significance of normalized GeneChip data Real-time PCR showed that Gabra6, GABA B receptor 1 (Gabbr1), and Gaba transporter protein Slc32a1 may be involved in physiological changes that occur in age-related hearing loss. Presbycusis – age-related hearing loss – is the number one communicative disorder of our aged population. In this study we analyzed gene expression for a set of GABA receptors in the inferior colliculus of aging CBA mice using the Affymetrix GeneChip MOE430A. Functional phenotypic hearing changes from RMA normalized microarray data (39 replicates) in four age-groups, Young Controls and Middle aged mice with good hearing, mild and sever e presbycusis from old mice. Fold change gene expression derived from RMA normalized data were first subjected to one-way ANOVA, and then linear regression was performed. The selected gene expression changes were confirmed by relative real-time relative to young adult controls with good hearing. Statistically significant and real time PCR confirmed GABA receptor genes; Gabra6, GABA B receptor 1 (Gabbr1), and Gaba transporter protein Slc32a1, may be involved in physiological changes that occur in age-related hearing loss. Lastly, gene expression measures of each age group were correlated with pathway/network relationships relevant to the inferior colliculus using Pathway Architect, to identify key pathways consistent with the gene expression changes observed In the study of Expression changes in IC GABA receptors in the Auditory Midbrain of young adult and aging presbycusis mice total of thirty nine chips were used. The normal aging mice were in Four groups Young adults Controls with good hearing (8 mice, 8 MOE430A GeneChips), Middle aged group with good hearing ( 17 mice, 17 MOE430A GeneChips), Mild Presbycusis with limited hearing loss (9 mice, 9 MOE430A GeneChips) and Severe Presbycusis (5 mice, 5 MOE430A GeneChips).

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Transcriptomic analysis of cardiac gene expression associated to RAGE deletion and aging

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