Project description:Background: DNA methylation (DNAm) profiling has emerged as a powerful tool for characterizing the placental methylome. However, previous studies have focused primarily on whole placental tissue, which is a mixture of epigenetically distinct cell populations. Here, we present the first methylome-wide analysis of first trimester (n=9) and term (n=19) human placental samples of four cell populations: trophoblasts, Hofbauer cells, endothelial cells, and stromal cells, using the Illumina EPIC methylation array, which quantifies DNAm at >850,000 CpGs. Results: The most distinct DNAm profiles were those of placental trophoblasts, which are central to many pregnancy-essential functions, and Hofbauer cells, which are a rare fetal-derived macrophage population. Cell-specific DNAm occurs at functionally-relevant genes, including genes associated with placental development and preeclampsia. Known placental-specific methylation marks, such as those associated with genomic imprinting, repetitive element hypomethylation, and placental partially methylated domains, were found to be more pronounced in trophoblasts and often absent in Hofbauer cells. Lastly, we characterize the cell composition and cell-specific DNAm dynamics across gestation. Conclusions: Our results provide a comprehensive analysis of DNAm in human placental cell types from first trimester and term pregnancies. This data will serve as a useful DNAm reference for future placental studies, and we provide access to this data via download from dbGAP (phs002013.v1.p1), through interactive exploration from the web browser (https://robinsonlab.shinyapps.io/Placental_Methylome_Browser/), and through the R package planet, which allows estimation of cell composition directly from placental DNAm data.
Project description:Horse-specific genes are not readily identified from available equine EST/cDNA resources due to relatively limited coverage. In addition, equine gene sets predicted in silico by Ensembl and NCBI will not identify horse specific genes since they rely on homology-based projection of gene structure annotation from other species. In this study, RNA-seq of 8 equine RNA samples representing 6 distinct tissues was performed and used to improve and refine equine gene structure annotation. The samples and RNA were collected as part of the related study E-GEOD-21925 and are described in Coleman et al 2010. Anim Genet 41 Suppl 2: 121-30 (PMID: 21070285). The RNA from these samples was re-sequenced in this experiment. The tissues were i). the articular cartilage and synovial membrane samples from a 3-year-old male pony. The left carpal joints received four LPS injections (0.5 ng) over 8 days, while the right carpal joints received control injections of PBS. ii) A cerebellum sample was collected from a 2-year-old female thoroughbred. iii) A testis sample from a 4-year-old thoroughbred. iv) A placental villous sample collected immediately post-partum from a full-term female thoroughbred foal. v) A whole embryo sample was obtained from a 34-day-old male thoroughbred conceptus. The embryo, cerebellum, testis and placental samples were of apparent normal gross morphology.
Project description:DNA methylation is a repressive epigenetic modification that is essential for development, exemplified by the embryonic and perinatal lethality observed in mice lacking de novo DNA methyltransferases (DNMTs). Here we characterise the role for DNMT3A, 3B and 3L in gene regulation and development of the mouse placenta. We demonstrate that each of the DNMTs is required to establish the placental methylome and is distinctly targeted to genome based on underlying chromatin features. Loss of Dnmt3b results in de-repression of germline genes in trophoblast lineages and impaired development of the placental maternal-foetal interface. Critically, loss of DNA methylation in the placenta did not lead to abnormalities in lineage specification or cell identity, but to defective formation and vascularisation of the placental labyrinth. Using Sox2-Cre to delete Dnmt3b in the embryo, leaving expression intact in placental trophoblast cells, we were able to rescue the placental phenotype and, consequently, the embryonic lethality, as Dnmt3b null embryos could now survive to birth. We conclude that the principal function of DNA methylation during embryogenesis is to regulate placental function, which in turn is critical for embryo survival.
Project description:A tissue survey of gene expression was conducted using microarray-based transcriptional profiling to compare equine articular cartilage to 10 other normal adult horse tissues. The ten comparative tissues were bladder, cerebellum, kidney, liver, lung, lymph node, muscle, placental villous, spleen, and testis.
Project description:The placental epigenome plays a vital role in regulating mammalian growth and development. Aberrations in placental DNA methylation are linked to several disease states, including intrauterine growth restriction and preeclampsia. Studying the evolution and development of the placental epigenome is critical to understanding the origin and progression of such diseases. Although high resolution studies have found substantial variation between placental methylomes of different species, the nature of methylome variation has yet to be characterized within any individual species. We conducted a study of placental DNA methylation at high resolution in multiple strains and closely related species of house mice (Mus musculus musculus, Mus m. domesticus, and M. spretus), across developmental timepoints (embryonic days 15 to 18), and between the labyrinthine transport and junctional endocrine layers. We observed substantial genome-wide methylation heterogeneity in mouse placenta compared to other differentiated tissues. Species-specific methylation profiles were concentrated in retrotransposon subfamilies, specifically RLTR10 and RLTR20 subfamilies. Regulatory regions such as gene promoters and CpG islands displayed cross-species conservation, but showed strong differences between layers and developmental timepoints. Partially methylated domains exist in the mouse placenta and widen during development. Taken together, our results characterize the mouse placental methylome as a highly heterogeneous and deregulated landscape globally, intermixed with actively regulated promoter and retrotransposon sequences.
Project description:DNA methylation is a key mechanism in transcription regulation, and aberrant methylation is a common and important mechanism in tumor initiation, maintenance, and progression. To find genes that are aberrantly regulated by altered methylation in horse sarcoids, we used reduced representation bisulfite sequencing (RRBS) accompanied by RNA sequencing (RNA-Seq) for methylome (whole genome DNA methylation sequencing) and transcriptome profiling, respectively. We found that the DNA methylation level was generally lower in lesion samples than in controls. In the analyzed samples, a total of 14,692 differentially methylated sites (DMSs) in the context of CpG (where cytosine and guanine are separated by a phosphate), and 11,712 differentially expressed genes (DEGs) were identified. The integration of the methylome and transcriptome data suggests that aberrant DNA methylation may be involved in the deregulation of expression of the 493 genes in equine sarcoid. Furthermore, enrichment analysis of the genes demonstrated the activation of multiple molecular pathways related to extracellular matrix (ECM), oxidative phosphorylation (OXPHOS), immune response, and disease processes that can be related to tumor progression. The results provide further insight into the epigenetic alterations in equine sarcoids and provide a valuable resource for follow-up studies to identify biomarkers for predicting susceptibility to this common condition in horses.
Project description:Tissue specific DNA methylation is present across many genomic elements, including large genomic regions. Most human tissues posses highly methylated genomes (>70%), but recent data has suggested the presence of partially methylated domains (PMDs) in some cell-lines. Placenta is a unique human tissue which has very different molecular properties than most tissues. It is the aim of this study to identify the presence/absence of PMDs in placental tissue and further define the DNA methylation landscape of the placenta. In particular this experiment is designed to look at the placental methylome across gestational ages in chromosome 21 to detect methylomic differences throughout development.