Presbycusis is characterized by an age-related progressive decline of auditory function, and arises mainly from the degeneration of hair cells or spiral ganglion (SG) cells in the cochlea. Here we show that caloric restriction suppresses apoptotic cell death in the mouse cochlea and prevents late onset of presbycusis. Caloric restricted mice, which maintained body weight at the same level as that of young control (YC) mice, retained normal hearing and showed no cochlear degeneration. CR mice also showed significantly fewer TUNEL-positive staining cells and fewer cleaved caspase-3-positive staining cells relative to middle-age control (MC) mice. Microarray analysis revealed that CR down-regulated the expression of 28 proapoptotic genes, including Bak and Bim. Taken together, our findings suggest that loss of critical cells through apoptosis is an important mechanism of presbycusis in mammals, and that CR or staying lean can retard this process by suppressing apoptosis in the inner ear tissue.
Caloric restriction suppresses apoptotic cell death in the mammalian cochlea and leads to prevention of presbycusis.
Sex, Age, Specimen part
View SamplesWe investigated age-related changes in the transcriptional profile of skeletal muscle in 5 month old (young) and 25 month old (old) C57BL/6NHsd mice using high density oligonucleotide arrays (22,690 transcripts probed). We identified 712 transcripts that are differentially expressed in young (5 month old) and old (25-month old) mouse skeletal muscle. Caloric restriction (CR) completely or partially reversed 87% of the changes in expression. Examination of individual genes revealed a transcriptional profile indicative of increased p53 activity in the older muscle. To determine whether the increase in p53 activity is associated with transcriptional activation of apoptotic targets, we performed RT-PCR on four well known mediators of p53-induced apoptosis: puma, noxa, tnfrsf10b and bok. Expression levels for these proapoptotic genes increased significantly with age (P<0.05), while CR significantly lowered expression levels for these genes as compared to control fed old mice (P<0.05). Age-related induction of p53-related genes was observed in multiple tissues, but was not observed in SOD2+/- and GPX4+/- mice, suggesting that oxidative stress does not mediate the observed age-related increase in expression. Western blot analysis confirmed that protein levels for both p21 and GADD45a, two established transcriptional targets of p53, were higher in the older muscle tissue. These observations support a role for p53-mediated apoptotic activity in mammalian aging.
Gene expression profiling of aging reveals activation of a p53-mediated transcriptional program.
Age
View SamplesMitochondrial DNA (mtDNA) mutations may contribute to aging and age-related disorders. Previously, we created mice expressing a proofreading-deficient version of the mtDNA polymerase gamma (Polg) which accumulate age-related mtDNA mutations and display premature aging. Here we performed microarray gene expression profiling to identify mtDNA mutation-responsive genes in the cochlea of aged mitochondrial mutator mice. Age-related accumulation of mtDNA mutations was associated with transcriptional alternations consistent with reduced inner ear function, mitochondrial dysfunction, neurodegeneration, and reduced cell structural modulation. Hearing assessment and histopathological results confirmed that aged PolgD257A/D257A (D257A) mice exhibited moderate hearing loss and severe cochlear degenerations. Age-related accumulation of mtDNA mutations also resulted in alternations in gene expression consistent with induction of apoptosis, proteolysis, stress response, and reduced DNA repair. TUNEL (Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling) assay confirmed that the cochleae from aged D257A mice showed significantly more TUNEL positive cells compared to wild-type (WT) mice. The levels of cleaved caspase-3 were also found to increase in the cochleae of aged D257A mice. These observations provide evidence that age-related accumulation of mtDNA mutations is associated with apoptotic cell death in aged cochlea. Our results provide the first global view of molecular events associated with mtDNA mutations in postmitotic tissue, and suggest that apoptosis is the major mechanism of mtDNA mediated cell death in the development of age-related hearing disorder.
The role of mtDNA mutations in the pathogenesis of age-related hearing loss in mice carrying a mutator DNA polymerase gamma.
Sex, Age, Specimen part
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Identification of tissue-specific transcriptional markers of caloric restriction in the mouse and their use to evaluate caloric restriction mimetics.
Sex, Specimen part
View SamplesThe effect of a short-term calorie restricted diet was evaluated in heart in seven strains of mice
Identification of tissue-specific transcriptional markers of caloric restriction in the mouse and their use to evaluate caloric restriction mimetics.
Sex, Specimen part
View SamplesThe effect of a short-term calorie restricted diet was evaluated in gastrocnemius muscle (GASTROC) in seven strains of mice
Identification of tissue-specific transcriptional markers of caloric restriction in the mouse and their use to evaluate caloric restriction mimetics.
Sex, Specimen part
View SamplesThe effect of a short-term calorie restricted diet was evaluated in epididymal white adipose tissue (WAT) in seven strains of mice
Identification of tissue-specific transcriptional markers of caloric restriction in the mouse and their use to evaluate caloric restriction mimetics.
Sex, Specimen part
View SamplesThe effect of a short-term calorie restricted diet was evaluated in cerebral cortex in seven strains of mice
Identification of tissue-specific transcriptional markers of caloric restriction in the mouse and their use to evaluate caloric restriction mimetics.
Sex, Specimen part
View SamplesThe murine model of Lyme disease provides a unique opportunity to study the localized host response to similar stimulus, B. burgdorferi, in the joints of mice destined to develop severe arthritis (C3H) or mild disease (C57BL/6). Pathways associated with the response to infection and the development of Lyme arthritis were identified by global gene expression patterns using oligonucleotide microarrays. A robust induction of IFN responsive genes was observed in severely arthritic C3H mice at one week of infection, which was absent from mildly arthritic C57BL/6 mice. In contrast, infected C57BL/6 mice displayed a novel expression profile characterized by genes involved in epidermal differentiation and wound repair, which were decreased in the joints of C3H mice. These expression patterns were associated with disease state rather than inherent differences between C3H and C57BL/6 mice, as C57BL/6-IL10-/- mice infected with B. burgdorferi develop more severe arthritis that C57BL/6 mice and displayed an early gene expression profile similar to C3H mice. Gene expression profiles at two and four weeks post infection revealed a common response of all strains that was likely to be important for the host defense to B. burgdorferi and mediated by NF-kB-dependent signaling. The gene expression profiles identified in this study add to the current understanding of the host response to B. burgdorferi and identify two novel pathways that may be involved in regulating the severity of Lyme arthritis.
Gene expression profiling reveals unique pathways associated with differential severity of lyme arthritis.
No sample metadata fields
View SamplesGene expression profile of joint tissue from C3H and interval specific congenic mouse lines (ISCL) following infection with Borrelia burgdorferi
Interval-specific congenic lines reveal quantitative trait Loci with penetrant lyme arthritis phenotypes on chromosomes 5, 11, and 12.
Specimen part
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