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Project description:Histones are pivotal carriers of epigenetic information through post-translational modifications (PTMs), crucial for regulating gene expression, proper cellular function and maintaining cell identity. Perturbations in histone levels within the aging genome can profoundly impact chromatin structure and gene expression profiles. In this study, we examined the effects of age-related changes on histone levels and histone acetylation in the retinal pigment epithelium (RPE) and retina of mice. Our findings revealed a global reduction in histones H1, H2A, H2B, H3, and H4 within the aged RPE/choroid, while the neural retina remained unaffected. Transcriptome analysis unveiled a significant downregulation of histone genes in the aged RPE/choroid, including key components of the histone locus body (HLB) complex involved in histone pre-mRNA processing. Knockdown of HINFP, a critical HLB component, in human RPE cells resulted in histone loss, induction of senescence, and upregulation of senescence-associated secretory phenotype (SASP) markers. Replicative aging of human RPE cells exhibited progressive histone loss and acquisition of the SASP phenotype. Immunostaining of human retina sections demonstrated a gradual decline in histones within the aging RPE. Additionally, aging in mice RPE/choroid led to diminished global histone acetylation levels, particularly H3K14ac, H3K56ac, and H4K16ac marks. These alterations in histone acetylation were metabolically driven and correlated with changes in acetyl-CoA abundance. Collectively, our findings highlight the characteristic loss of histones as a hallmark of aging in the RPE/choroid, shedding light on potential mechanisms linking histone dynamics, cellular senescence, and age-related functional changes in RPE cells.
2023-07-15 | GSE236220 | GEO
Project description:Histones are pivotal carriers of epigenetic information through post-translational modifications (PTMs), crucial for regulating gene expression, proper cellular function and maintaining cell identity. Perturbations in histone levels within the aging genome can profoundly impact chromatin structure and gene expression profiles. In this study, we examined the effects of age-related changes on histone levels and histone acetylation in the retinal pigment epithelium (RPE) and retina of mice. Our findings revealed a global reduction in histones H1, H2A, H2B, H3, and H4 within the aged RPE/choroid, while the neural retina remained unaffected. Transcriptome analysis unveiled a significant downregulation of histone genes in the aged RPE/choroid, including key components of the histone locus body (HLB) complex involved in histone pre-mRNA processing. Knockdown of HINFP, a critical HLB component, in human RPE cells resulted in histone loss, induction of senescence, and upregulation of senescence-associated secretory phenotype (SASP) markers. Replicative aging of human RPE cells exhibited progressive histone loss and acquisition of the SASP phenotype. Immunostaining of human retina sections demonstrated a gradual decline in histones within the aging RPE. Additionally, aging in mice RPE/choroid led to diminished global histone acetylation levels, particularly H3K14ac, H3K56ac, and H4K16ac marks. These alterations in histone acetylation were metabolically driven and correlated with changes in acetyl-CoA abundance. Collectively, our findings highlight the characteristic loss of histones as a hallmark of aging in the RPE/choroid, shedding light on potential mechanisms linking histone dynamics, cellular senescence, and age-related functional changes in RPE cells.
2023-07-15 | GSE236219 | GEO
Project description:Age-related histone loss and altered histone acetylation in mouse retinal pigment epithelium.
| PRJNA989276 | ENA
Project description:Age-related histone loss and altered histone acetylation in mouse retinal pigment epithelium. [Total RNA]
| PRJNA989279 | ENA
Project description:Age-related histone loss and altered histone acetylation in mouse retinal pigment epithelium. [polyA RNA]
| PRJNA989278 | ENA
Project description:BackgroundAge-related changes in the retina are often accompanied by visual impairment but their mechanistic details remain poorly understood.MethodologyProteomic studies were pursued toward a better molecular understanding of retinal pigment epithelium (RPE) aging mechanisms. RPE cells were isolated from young adults (3-4 month-old) and old (24-25 month-old) F344BN rats, and separated into subcellular fractions containing apical microvilli (MV) and RPE cell bodies (CB) lacking their apical microvilli. Proteins were extracted in detergent, separated by SDS-PAGE, digested in situ with trypsin and analyzed by LC MS/MS. Select proteins detected in young and old rat RPE were further studied using immunofluorescence and Western blot analysis.Principal findingsA total of 356 proteins were identified in RPE MV from young and 378 in RPE MV from old rats, 48% of which were common to each age group. A total of 897 proteins were identified in RPE CB from young rats and 675 in old CB, 56% of which were common to each age group. Several of the identified proteins, including proteins involved in response to oxidative stress, displayed both quantitative and qualitative changes in overall abundance during RPE aging. Numerous proteins were identified for the first time in the RPE. One such protein, collectrin, was localized to the apical membrane of apical brush border of proximal tubules where it likely regulates several amino acid transporters. Elsewhere, collectrin is involved in pancreatic β cell proliferation and insulin secretion. In the RPE, collectrin expression was significantly modulated during RPE aging. Another age-regulated, newly described protein was DJ-1, a protein extensively studied in brain where oxidative stress-related functions have been described.Conclusions/significanceThe data presented here reveals specific changes in the RPE during aging, providing the first protein database of RPE aging, which will facilitate future studies of age-related retinal diseases.
| S-EPMC3372495 | biostudies-literature
Project description:Aging of the retinal pigment epithelium (RPE) leads to a gradual decline in RPE homeostasis over time, significantly impacting retinal health. Understanding the mechanisms underlying RPE aging is crucial for elucidating the background in which many age-related retinal pathologies develop. In this study, we compared the transcriptomes of young and aged mouse RPE and found a marked upregulation of immunogenic and proinflammatory genes in aging RPE. Additionally, aging RPE exhibited dysregulation of pathways associated with visual perception and extracellular matrix production. Research on aging in post-natal quiescent RPE is hindered by the absence of relevant in vitro models. We evaluated an in vitro model of chronologically aged primary human RPE to address this gap, which displayed gene expression patterns comparable to native-aged RPE. Profiling this in vitro aging model highlighted its potential utility in investigating cellular and molecular mechanisms of RPE aging and in preliminary testing of therapeutic compounds. Overall, our findings suggest chronological aging of RPE leads to the acquisition of a proinflammatory phenotype, impacting RPE function and serving as a significant factor in the development of age-related retinal pathologies.
2024-05-10 | GSE263427 | GEO
Project description:PurposeLipofuscin and melanolipofuscin organelles in retinal pigment epithelium (RPE) cells are signal sources for clinical fundus autofluorescence (AF). To elucidate the subcellular basis of AF imaging, we identified, characterized, and quantified the frequency of RPE morphology and AF phenotypes in donor eyes with age-related macular degeneration (AMD).MethodsIn 25 RPE-Bruch's membrane flat mounts from 25 eyes, we analyzed 0.4-?m z-stack epifluorescence images of RPE stained with phalloidin for actin cytoskeleton. Using a custom ImageJ plugin, we classified cells selected in a systematic unbiased fashion in six phenotypes representing increasing degrees of pathology. For each cell, area, AF intensity, and number of Voronoi neighbors were compared with phenotype 1 (uniform AF, polygonal morphology) via generalized estimating equations. We also analyzed each cell's neighborhood.ResultsIn 29,323 cells, compared with phenotype 1, all other phenotypes, in order of increasing pathology, had significantly larger area, reduced AF, and more variable number of neighbors. Neighborhood area and AF showed similar, but subtler, trends. Cells with highly autofluorescent granule aggregates are no more autofluorescent than others and are in fact lower overall in AF. Pre-aggregates were found in phenotype 1. Phenotype 2, which exhibited degranulation despite normal cytoskeleton, was the most numerous nonhealthy phenotype (16.23%).ConclusionsDespite aggregation of granules that created hyperAF aggregates within cells, overall AF on a per cell basis decreased with increasing severity of dysmorphia (abnormal shape). Data motivate further development of subcellular resolution in clinical fundus AF imaging and inform an ongoing reexamination of the role of lipofuscin in AMD.
| S-EPMC6557619 | biostudies-literature
Project description:The retinal pigment epithelium (RPE) is a pigmented monolayer of cells lying between the photoreceptors and a layer of fenestrated capillaries, the choriocapillaris. Choroideremia (CHM) is an X-linked progressive degeneration of these three layers caused by the loss of function of Rab Escort protein-1 (REP1). REP1 is involved in the prenylation of Rab proteins, key regulators of membrane trafficking. To study the pathological consequences of chronic disruption of membrane traffic in the RPE we used a cell type-specific knock-out mouse model of the disease, where the Chm/Rep1 gene is deleted only in pigmented cells (Chm(Flox), Tyr-Cre+). Transmission electron microscopy (TEM) was used to quantitate the melanosome distribution in the RPE and immunofluorescent staining of rhodopsin was used to quantitate phagocytosed rod outer segments in retinal sections. The ultrastructure of the RPE and Bruch's membrane at different ages was characterised by TEM to analyse age-related changes occurring as a result of defects in membrane traffic pathways. Chm/Rep1 gene knockout in RPE cells resulted in reduced numbers of melanosomes in the apical processes and delayed phagosome degradation. In addition, the RPE accumulated pathological changes at 5-6 months of age similar to those observed in 2-year old controls. These included the intracellular accumulation of lipofuscin-containing deposits, disorganised basal infoldings and the extracellular accumulation of basal laminar and basal linear deposits. The phenotype of the Chm(Flox), Tyr-Cre+ mice suggests that loss of the Chm/Rep1 gene causes premature accumulation of features of aging in the RPE. Furthermore, the striking similarities between the present observations and some of the phenotypes reported in age-related macular degeneration (AMD) suggest that membrane traffic defects may contribute to the pathogenesis of AMD.
| S-EPMC3584022 | biostudies-literature
Project description:Inflammation and oxidative stress are involved in age-related macular degeneration (AMD) and possibly associated with an activation of neuronal apoptosis inhibitor protein/class II transcription activator of the Major Histocompatibility Complex (MHC)/heterokaryon incompatibility/telomerase-associated protein 1, leucine-rich repeat or nucleotide-binding domain, leucine-rich repeat-containing family, and pyrin domain-containing 3 (NLRP3) inflammasome. In the present study, we used a translational approach to address this hypothesis. In patients with AMD, we observed increased mRNA levels of NLRP3, pro-interleukin-1 beta (IL-1β) and pro-IL-18 in AMD lesions of the retinal pigment epithelium (RPE) and photoreceptor. In vitro, a similar increase was evoked by oxidative stress or lipopolysaccharide (LPS) stimulation in the adult retinal pigment epithelium (ARPE-19) cell line, and the increase was reduced in siRNA transfected cells to knockdown NLRP3. Ultrastructural studies of ARPE-19 cells showed a swelling of the cytoplasm, mitochondrial damage, and occurrence of autophagosome-like structures. NLRP3 positive dots were detected within autophagosome-like structures or in the extracellular space. Next, we used a mouse model of AMD, Ccl2/Cx3cr1 double knockout on rd8 background (DKO rd8) to ascertain the in vivo relevance. Ultrastructural studies of the RPE of these mice showed damaged mitochondria, autophagosome-like structures, and cytoplasmic vacuoles, which are reminiscent of the pathology seen in stressed ARPE-19 cells. The data suggest that the NLRP3 inflammasome may contribute in AMD pathogenesis.
| S-EPMC4730317 | biostudies-literature