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: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: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:Hui2014 - Age-related changes in articular
cartilage
This model is described in the article:
Oxidative changes and
signalling pathways are pivotal in initiating age-related
changes in articular cartilage
Wang Hui1, David A Young1, Andrew D
Rowan1, Xin Xu2, Tim E Cawston1, Carole J Proctor1,3
Annals of the Rheumatic Diseases
Abstract:
Objective: To use a computational approach to investigate
the cellular and extracellular matrix changes that occur with
age in the knee joints of mice. Methods: Knee joints from an
inbred C57/BL1/6 (ICRFa) mouse colony were harvested at
3–30?months of age. Sections were stained with H&E,
Safranin-O, Picro-sirius red and antibodies to matrix
metalloproteinase-13 (MMP-13), nitrotyrosine, LC-3B, Bcl-2, and
cleaved type II collagen used for immunohistochemistry. Based
on this and other data from the literature, a computer
simulation model was built using the Systems Biology Markup
Language using an iterative approach of data analysis and
modelling. Individual parameters were subsequently altered to
assess their effect on the model. Results: A progressive loss
of cartilage matrix occurred with age. Nitrotyrosine, MMP-13
and anaplastic lymphoma kinase (ALK1) staining in cartilage
increased with age with a concomitant decrease in LC-3B and
Bcl-2. Stochastic simulations from the computational model
showed a good agreement with these data, once transforming
growth factor-? signalling via ALK1/ALK5 receptors was
included. Oxidative stress and the interleukin 1 pathway were
identified as key factors in driving the cartilage breakdown
associated with ageing. Conclusions: A progressive loss of
cartilage matrix and cellularity occurs with age. This is
accompanied with increased levels of oxidative stress,
apoptosis and MMP-13 and a decrease in chondrocyte autophagy.
These changes explain the marked predisposition of joints to
develop osteoarthritis with age. Computational modelling
provides useful insights into the underlying mechanisms
involved in age-related changes in musculoskeletal tissues.
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