Pathogenesis of age-related macular degeneration (AMD), the leading cause of vision loss in the elderly, remains poorly understood due to the paucity of animal models that fully replicate the human disease. Recently, we showed that senescence-accelerated OXYS rats develop a retinopathy similar to human AMD. To identify alterations in response to normal aging and progression of AMD-like retinopathy, we compared gene expression profiles of retina from 3- and 18-mo-old OXYS and control Wistar rats by means of high-throughput RNA sequencing (RNA-Seq). We identified 160 and 146 age-regulated genes in Wistar and OXYS retinas, respectively. The majority of them are related to the immune system and extracellular matrix turnover. Only 24 age-regulated genes were common for the two strains, suggestive of different rates and mechanisms of aging. Over 600 genes showed significant differences in expression between the two strains. These genes are involved in disease-associated pathways such as immune response, inflammation, apoptosis, Ca ( 2+) homeostasis and oxidative stress. The altered expression for selected genes was confirmed by qRT-PCR analysis. To our knowledge, this study represents the first analysis of retinal transcriptome from young and old rats with biologic replicates generated by RNA-Seq technology. We can conclude that the development of AMD-like retinopathy in OXYS rats is associated with an imbalance in immune and inflammatory responses. Aging alters the expression profile of numerous genes in the retina, and the genetic background of OXYS rats has a profound impact on the development of AMD-like retinopathy.
Background The three epidemiologically important Opisthorchiidae liver flukes Opisthorchis felineus , O. viverrini , and Clonorchis sinensis , are believed to harbour similar potencies to provoke hepatobiliary diseases in their definitive hosts, although their populations have substantially different ecogeographical aspects including habitat, preferred hosts, population structure. Lack of O. felineus genomic data is an obstacle to the development of comparative molecular biological approaches necessary to obtain new knowledge about the biology of Opisthorchiidae trematodes, to identify essential pathways linked to parasite-host interaction, to predict genes that contribute to liver fluke pathogenesis and for the effective prevention and control of the disease. Results Here we present the first draft genome assembly of O. felineus and its gene repertoire accompanied by a comparative analysis with that of O. viverrini and Clonorchis sinensis . We observed both noticeably high heterozygosity of the sequenced individual and substantial genetic diversity in a pooled sample. This indicates that potency of O. felineus population for rapid adaptive response to control and preventive measures of opisthorchiasis is higher than in O. viverrini and C. sinensis . We also have found that all three species are characterized by more intensive involvement of trans-splicing in RNA processing compared to other trematodes. Conclusion All revealed peculiarities of structural organization of genomes are of extreme importance for a proper description of genes and their products in these parasitic species. This should be taken into account both in academic and applied research of epidemiologically important liver flukes. Further comparative genomics studies of liver flukes and non-carcinogenic flatworms allow for generation of well-grounded hypotheses on the mechanisms underlying development of cholangiocarcinoma associated with opisthorchiasis and clonorchiasis as well as species-specific mechanisms of these diseases. Electronic supplementary material The online version of this article (10.1186/s12864-019-5752-8) contains supplementary material, which is available to authorized users.
BackgroundChIP-Seq is widely used to detect genomic segments bound by transcription factors (TF), either directly at DNA binding sites (BSs) or indirectly via other proteins. Currently, there are many software tools implementing different approaches to identify TFBSs within ChIP-Seq peaks. However, their use for the interpretation of ChIP-Seq data is usually complicated by the absence of direct experimental verification, making it difficult both to set a threshold to avoid recognition of too many false-positive BSs, and to compare the actual performance of different models.ResultsUsing ChIP-Seq data for FoxA2 binding loci in mouse adult liver and human HepG2 cells we compared FoxA binding-site predictions for four computational models of two fundamental classes: pattern matching based on existing training set of experimentally confirmed TFBSs (oPWM and SiteGA) and de novo motif discovery (ChIPMunk and diChIPMunk). To properly select prediction thresholds for the models, we experimentally evaluated affinity of 64 predicted FoxA BSs using EMSA that allows safely distinguishing sequences able to bind TF. As a result we identified thousands of reliable FoxA BSs within ChIP-Seq loci from mouse liver and human HepG2 cells. It was found that the performance of conventional position weight matrix (PWM) models was inferior with the highest false positive rate. On the contrary, the best recognition efficiency was achieved by the combination of SiteGA & diChIPMunk/ChIPMunk models, properly identifying FoxA BSs in up to 90% of loci for both mouse and human ChIP-Seq datasets.ConclusionsThe experimental study of TF binding to oligonucleotides corresponding to predicted sites increases the reliability of computational methods for TFBS-recognition in ChIP-Seq data analysis. Regarding ChIP-Seq data interpretation, basic PWMs have inferior TFBS recognition quality compared to the more sophisticated SiteGA and de novo motif discovery methods. A combination of models from different principles allowed identification of proper TFBSs.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-80) contains supplementary material, which is available to authorized users.
Alzheimer’s disease (AD) is the most common type of dementia, with increasing prevalence and no disease-modifying treatment available yet. There is increasing evidence—from interventions targeting mitochondria—that may shed some light on new strategies for the treatment of AD. Previously, using senescence-accelerated OXYS rats that simulate key characteristics of sporadic AD, we have shown that treatment with mitochondria-targeted antioxidant SkQ1 (plastoquinonyl-decyltriphenylphosphonium) from age 12 to 18 months (that is, during active progression of AD-like pathology)—via improvement of mitochondrial function—prevented the neuronal loss and synaptic damage, enhanced neurotrophic supply, and decreased amyloid-β1–42 protein levels and tau hyperphosphorylation in the hippocampus. In the present study, we continued to explore the mechanisms of the anti-AD effects of SkQ1 in an OXYS rat model through deep RNA sequencing (RNA-seq) and focused upon the cell-specific gene expression alterations in the hippocampus. According to RNA-seq results, OXYS rats had 1,159 differentially expressed genes (DEGs) relative to Wistar rats (control), and 6-month treatment with SkQ1 decreased their number twofold. We found that 10.5% of all DEGs in untreated (control) OXYS rats were associated with mitochondrial function, whereas SkQ1 eliminated differences in the expression of 76% of DEGs (93 from 122 genes). Using transcriptome approaches, we found that the anti-AD effects of SkQ1 are associated with an improvement of the activity of many signaling pathways and intracellular processes. SkQ1 changed the expression of genes in neuronal, glial, and endothelial cells, and these genes are related to mitochondrial function, neurotrophic and synaptic activity, calcium processes, immune and cerebrovascular systems, catabolism, degradation, and apoptosis. Thus, RNA-seq analysis yields a detailed picture of transcriptional changes during the development of AD-like pathology and can point to the molecular and genetic mechanisms of action of the agents (including SkQ1) holding promise for the prevention and treatment of AD.
The free-living flatworm Macrostomum lignano is a hidden tetraploid. Its genome was formed by a recent whole genome duplication followed by chromosome fusions. Its karyotype (2n = 8) consists of a pair of large chromosomes (MLI1), which contain regions of all other chromosomes, and three pairs of small metacentric chromosomes. Comparison of MLI1 with metacentrics was performed by painting with microdissected DNA probes and fluorescent in situ hybridization of unique DNA fragments. Regions of MLI1 homologous to small metacentrics appeared to be contiguous. Besides the loss of DNA repeat clusters (pericentromeric and telomeric repeats and the 5S rDNA cluster) from MLI1, the difference between small metacentrics MLI2 and MLI4 and regions homologous to them in MLI1 were revealed. Abnormal karyotypes found in the inbred DV1/10 subline were analyzed, and structurally rearranged chromosomes were described with the painting technique, suggesting the mechanism of their origin. The revealed chromosomal rearrangements generate additional diversity, opening the way toward massive loss of duplicated genes from a duplicated genome. Our findings suggest that the karyotype of M. lignano is in the early stage of genome diploidization after whole genome duplication, and further studies on M. lignano and closely related species can address many questions about karyotype evolution in animals.
Preeclampsia is one of the most severe gestational complications which is one of the leading causes of maternal and perinatal morbidity and mortality. A growth in the incidence of severe and combined forms of the pathology has been observed in recent years. According to modern concepts, inadequate cytotrophoblast invasion into the spiral arteries of the uterus and development of the ischemia-reperfusion syndrome in the placental tissue play the leading role in the development of preeclampsia, which is characterized by multipleorgan failure. In this regard, our work was aimed at studying the patterns of placental tissue transcriptome that are specific to females with PE and with physiological pregnancy, as well as identifying the potential promising biomarkers and molecular mechanisms of this pathology. We have identified 63 genes whose expression proved to differ significantly in the placental tissue of females with PE and with physiological pregnancy. A cluster of differentially expressed genes (DEG) whose expression level is increased in patients with preeclampsia includes not only the known candidate genes that have been identified in many other genome-wide studies (e.g., LEP, BHLHB2, SIGLEC6, RDH13, BCL6), but also new genes (ANKRD37, SYDE1, CYBA, ITGB2, etc.), which can be considered as new biological markers of preeclampsia and are of further interest. The results of a functional annotation of DEG show that the development of preeclampsia may be related to a stress response, immune processes, the regulation of cell-cell interactions, intracellular signaling cascades, etc. In addition, the features of the differential gene expression depending on preeclampsia severity were revealed. We have found evidence of the important role of the molecular mechanisms responsible for the failure of immunological tolerance and initiation of the pro-inflammatory cascade in the development of severe preeclampsia. The results obtained elaborate the concept of the pathophysiology of preeclampsia and contain the information necessary to work out measures for targeted therapy of this disease. ;
Age-related macular degeneration (AMD) is a major cause of blindness in developed countries, and the molecular pathogenesis of early events in AMD is poorly understood. Senescence-accelerated OXYS rats develop AMD-like retinopathy. The aim of this study was to explore the differences in retinal gene expression between OXYS and Wistar (control) rats at age 20 d and to identify the pathways of retinal cell death involved in the OXYS retinopathy initiation and progression. Retinal mRNA profiles of 20-day-old OXYS and Wistar rats were generated at the sequencing read depth 40 mln, in triplicate, using Illumina GAIIx. A terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling (TUNEL) assay was performed to measure the apoptosis level. GeneMANIA was used to construct interaction networks for differentially expressed (DE) apoptosis-related genes at ages 20 d and 3 and 18 months. Functional analysis was suggestive of a developmental process, signal transduction, and cell differentiation as the most enriched biological processes among 245 DE genes at age 20 d An increased level of apoptosis was observed in OXYS rats at age 20 d but not at advanced stages. We identified functional clusters in the constructed interaction networks and possible hub genes (Rasa1, cFLAR, Birc3, Cdk1, Hspa1b, Erbb3, and Ntf3). We also demonstrated the significance of the extrinsic apoptotic pathway at preclinical, early, and advanced stages of retinopathy development. Besides the cell death signaling pathways, immune system-related processes and lipid-metabolic processes showed overrepresentation in the clusters of all networks. These characteristics of the expression profile of the genes functionally associated with apoptosis may contribute to the pathogenesis of AMD-like retinopathy in senescence-accelerated OXYS rats.
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