Project description:Age-related hearing loss is a multifactorial and progressive process, which negatively impacts quality of life in many senior adults as the number one chronic neurodegenerative condition. This study was done to examine gene expression changes occurring in mouse auditory nerve and cochlear lateral wall tissues that may contribute to age-related hearing loss. In addition to conducting general differential expression analysis, a focused analysis of genes linked to neural cells was done.
Project description:Age-related hearing loss (AHL) is the progressive loss of auditory function with aging. The DBA/2J (DBA) mice have been used as a model of AHL and undergoes progressive, age-related hearing loss by 12 weeks of age. Here we analyzed cochlear gene expression of 7-week-old and 36-week-old DBA mice using microarrays. Auditory brainstem response (ABR) analysis confrimed that severe age-related hearing loss occured in 36-week-old mice, whereas moderate hearing loss occured in 7-week-old mice. Comprehensive gene expression analysis identified genes correlated with AHL and revealeed that 15 mitochondrial process categories, including â??mitochondrial electron transport chainâ??, â??oxidative phosphorylationâ??, â??respiratory chain complex Iâ??, â??respiratory chain complex IVâ??, and â??respiratory chain complex Vâ??, were statistically associated with AHL-correlated genes in the cochlea of 36-week-old DBA mice, and that 25 genes encoding components of the mitochondrial respiratory chain (respiratory chain complex I, IV, and V) were significantly down-regulated in the cochlea. These observations provide evidence that AHL is associated with down-regulation of genes involved in the mitochondrial respiratory chain in the cochlea of DBA mice, and suggest that mitochondrial respiratory chain dysfunction may be a key feature of AHL in mammalian cochlea. Experiment Overall Design: To determine the effects of age-related hearing loss, each 7-week-old sample (n = 3) was compared to each 36-week-old sample (n = 3), generating a total of nine pairwise comparisons. Using DAVIS and EASE, the identified genes were assign to â??GO: Biological Processâ?? categories of Gene Ontology Consortium. Furthermore, we used EASE to determine the total number of genes that were assigned to each biological process category, and to perform Fisher exact test. Quality control measures were not used. No replicates were done. Dye swap was not used.
Project description:Age-related hearing loss (AHL) is the progressive loss of auditory function with aging. The DBA/2J (DBA) mice have been used as a model of AHL and undergoes progressive, age-related hearing loss by 12 weeks of age. Here we analyzed cochlear gene expression of 7-week-old and 36-week-old DBA mice using microarrays. Auditory brainstem response (ABR) analysis confrimed that severe age-related hearing loss occured in 36-week-old mice, whereas moderate hearing loss occured in 7-week-old mice. Comprehensive gene expression analysis identified genes correlated with AHL and revealeed that 15 mitochondrial process categories, including “mitochondrial electron transport chain”, “oxidative phosphorylation”, “respiratory chain complex I”, “respiratory chain complex IV”, and “respiratory chain complex V”, were statistically associated with AHL-correlated genes in the cochlea of 36-week-old DBA mice, and that 25 genes encoding components of the mitochondrial respiratory chain (respiratory chain complex I, IV, and V) were significantly down-regulated in the cochlea. These observations provide evidence that AHL is associated with down-regulation of genes involved in the mitochondrial respiratory chain in the cochlea of DBA mice, and suggest that mitochondrial respiratory chain dysfunction may be a key feature of AHL in mammalian cochlea. Keywords: Disease state analysis, Time course analysis
Project description: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. Experiment Overall Design: To examine the effects of aging, a comparison of cochlea tissues from YC (3 samples) and MC (3 samples) mice was conducted. To examine the effects of calorie restriction (CR), a comparison of cochleae from MC (3 samples) and CR (3 samples) mice was conducted. We examined age-related changes in gene expression in the cochlea and calorie restriction-induced changes in gene expression in the cochlea. We pooled four cochleae from two mice for one sample and used three samples per group (n = 3). Quality control measures were not used. No replicates were done. Dye swap was not used.
Project description:Aging is associated with major nuclear changes affecting genomic integrity and gene expression. Here we compare the gene expression profiles in the neocortex of young (5 months old) and old (30 months old) B6xC3 F1 mice. In a related study, we compare genes that change expression with age to SIRT1 associated genes identified by ChIP on chip (NimbleGen) and find a significant overlap, indicating that SIRT1 target genes are preferentially deregulated with age. Keywords: gene expression comparison, age-comparison