Project description:Aging-associated functional decline and disease susceptibility are believed to be mediated, at least in part, through alterations in the epigenome. To explore epigenetic changes that might influence visual function with advanced age, we performed whole genome bisulfite sequencing of purified mouse rod photoreceptors at four different ages and identified 2054 genomic regions that gain or lose DNA methylation. Differentially methylated regions (DMRs) clustered at chromosomal hotspots, especially on Chromosome 10 that included a longevity interactome. DMRs were preferentially detected at an early stage of aging in long neuronal genes and in rod-specific regulatory regions containing open chromatin domains and H3K27 acetylation. Integration of methylome to age-related transcriptome changes, chromatin signatures and first order protein-protein interactions uncovered an enrichment of DMRs in pathways associated with aging, longevity, synaptic function, and energy homeostasis. In concordance, we detected reduced mitochondrial maximum reserve capacity with retinal age in ex vivo assays. Our study reveals age-dependent genomic and chromatin features susceptible to DNA methylation changes in rod photoreceptors and identifies associations with established and cell type-specific pathways altered in aging.
Project description:Aging-associated functional decline and disease susceptibility are believed to be mediated, at least in part, through alterations in the epigenome. To explore epigenetic changes that might influence visual function with advanced age, we performed whole genome bisulfite sequencing of purified mouse rod photoreceptors at four different ages and identified 2054 genomic regions that gain or lose DNA methylation. Differentially methylated regions (DMRs) clustered at chromosomal hotspots, especially on Chromosome 10 that included a longevity interactome. DMRs were preferentially detected at an early stage of aging in long neuronal genes and in rod-specific regulatory regions containing open chromatin domains and H3K27 acetylation. Integration of methylome to age-related transcriptome changes, chromatin signatures and first order protein-protein interactions uncovered an enrichment of DMRs in pathways associated with aging, longevity, synaptic function, and energy homeostasis. In concordance, we detected reduced mitochondrial maximum reserve capacity with retinal age in ex vivo assays. Our study reveals age-dependent genomic and chromatin features susceptible to DNA methylation changes in rod photoreceptors and identifies associations with established and cell type-specific pathways altered in aging.
Project description:Aging-associated functional decline and disease susceptibility are believed to be mediated, at least in part, through alterations in the epigenome. To explore epigenetic changes that might influence visual function with advanced age, we performed whole genome bisulfite sequencing of purified mouse rod photoreceptors at four different ages and identified 2054 genomic regions that gain or lose DNA methylation. Differentially methylated regions (DMRs) clustered at chromosomal hotspots, especially on Chromosome 10 that included a longevity interactome. DMRs were preferentially detected at an early stage of aging in long neuronal genes and in rod-specific regulatory regions containing open chromatin domains and H3K27 acetylation. Integration of methylome to age-related transcriptome changes, chromatin signatures and first order protein-protein interactions uncovered an enrichment of DMRs in pathways associated with aging, longevity, synaptic function, and energy homeostasis. In concordance, we detected reduced mitochondrial maximum reserve capacity with retinal age in ex vivo assays. Our study reveals age-dependent genomic and chromatin features susceptible to DNA methylation changes in rod photoreceptors and identifies associations with established and cell type-specific pathways altered in aging.
Project description:To better understand the mechanistic basis of aging and its relationship with retinal degeneration, we examined gene expression changes in aging rod photoreceptors. Rod photoreceptor cell death is a feature of normal retinal aging and is accelerated in many retinal degenerative diseases, including AMD, the leading cause of untreatable adult blindness in the United States and other western countries. To our knowledge, the examination of age-related gene expression changes in a specific neuronal cell-type is novel, and it has allowed us to identify significant age-related changes with better resolution than is possible with whole retina samples. We used flow cytometry and a transgenic mouse with GFP-tagged rod photoreceptors to purify this specific cell population, and gene expression changes were evaluated at three time points using microarrays and quantitative RT-PCR. Our results suggest that aging is progressive, beginning even in young adult mice. Although rod photoreceptors are highly specialized neurons, our analyses revealed changes in consensus pathways of aging, including oxidative phosphorylation and stress responses affecting transcription and inflammation. In addition, we identified stress response processes that may be especially relevant for the aging retina and retinal diseases, such as angiogenesis and nuclear receptor signaling pathways that affect retinoid and lipid metabolism. We used flow cytometry and a transgenic mouse with GFP-tagged rod photoreceptors to purify this specific cell population, and gene expression changes were evaluated at three time points using microarrays and quantitative RT-PCR.
Project description:To better understand the mechanistic basis of aging and its relationship with retinal degeneration, we examined gene expression changes in aging rod photoreceptors. Rod photoreceptor cell death is a feature of normal retinal aging and is accelerated in many retinal degenerative diseases, including AMD, the leading cause of untreatable adult blindness in the United States and other western countries. To our knowledge, the examination of age-related gene expression changes in a specific neuronal cell-type is novel, and it has allowed us to identify significant age-related changes with better resolution than is possible with whole retina samples. We used flow cytometry and a transgenic mouse with GFP-tagged rod photoreceptors to purify this specific cell population, and gene expression changes were evaluated at three time points using microarrays and quantitative RT-PCR. Our results suggest that aging is progressive, beginning even in young adult mice. Although rod photoreceptors are highly specialized neurons, our analyses revealed changes in consensus pathways of aging, including oxidative phosphorylation and stress responses affecting transcription and inflammation. In addition, we identified stress response processes that may be especially relevant for the aging retina and retinal diseases, such as angiogenesis and nuclear receptor signaling pathways that affect retinoid and lipid metabolism.
Project description:Gene regulatory networks (GRNs) guiding differentiation of cell types and cell assemblies in the nervous system are poorly understood because of inherent complexities and interdependence of signaling pathways. Here, we report transcriptome dynamics of differentiating rod photoreceptors in the mammalian retina. Given that the transcription factor NRL determines rod cell fate, we performed expression profiling of developing NRL-positive (rods) and NRL-negative (S-cone-like) mouse photoreceptors. We identified a large-scale, sharp transition in the transcriptome landscape between postnatal days 6 and 10 concordant with rod morphogenesis. Rod-specific temporal DNA methylation corroborated gene expression patterns. De novo assembly and alternative splicing analyses revealed previously unannotated rod-enriched transcripts and the role of NRL in transcript maturation. Furthermore, we defined the relationship of NRL with other transcriptional regulators and downstream cognate effectors. Our studies provide the framework for comprehensive system-level analysis of the GRN underlying the development of a single sensory neuron, the rod photoreceptor.
Project description:Ep300 and/or CrebBP were conditionally knocked out in differentiating mouse rod photoreceptors using opsin-driven Cre recombinase to elucidate the role of these transcription coactivators in photoreceptor gene expression regulation.