Constitutional Trisomy 8 Mosaicism as a Model for Epigenetic Studies of Aneuploidy (microRNA)
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ABSTRACT: To increase our understanding of epigenetic patterns associated with aneuploidy we used constitutional trisomy 8 mosaicism as a model, enabling analyses of single cell clones, harboring either trisomy or disomy 8, from the same patient. We profiled gene and miRNA expression as well as genome-wide and promoter specific DNA methylation and hydroxymethylation patterns in trisomic and disomic fibroblasts, using microarrays and methylated DNA immunoprecipitation. comparison of trisomy 8 cells with disomic as well as reference fibroblasts
Project description:To increase our understanding of epigenetic patterns associated with aneuploidy we used constitutional trisomy 8 mosaicism as a model, enabling analyses of single cell clones, harboring either trisomy or disomy 8, from the same patient. We profiled gene and miRNA expression as well as genome-wide and promoter specific DNA methylation and hydroxymethylation patterns in trisomic and disomic fibroblasts, using microarrays and methylated DNA immunoprecipitation. comparison of trisomy 8 cells with disomic as well as reference fibroblasts
Project description:To increase our understanding of epigenetic patterns associated with aneuploidy we used constitutional trisomy 8 mosaicism as a model, enabling analyses of single cell clones, harboring either trisomy or disomy 8, from the same patient. We profiled gene and miRNA expression as well as genome-wide and promoter specific DNA methylation and hydroxymethylation patterns in trisomic and disomic fibroblasts, using microarrays and methylated DNA immunoprecipitation. comparison of trisomy 8 cells with disomic as well as reference fibroblasts
Project description:To increase our understanding of epigenetic patterns associated with aneuploidy we used constitutional trisomy 8 mosaicism as a model, enabling analyses of single cell clones, harboring either trisomy or disomy 8, from the same patient. We profiled gene and miRNA expression as well as genome-wide and promoter specific DNA methylation and hydroxymethylation patterns in trisomic and disomic fibroblasts, using microarrays and methylated DNA immunoprecipitation.
Project description:To increase our understanding of epigenetic patterns associated with aneuploidy we used constitutional trisomy 8 mosaicism as a model, enabling analyses of single cell clones, harboring either trisomy or disomy 8, from the same patient. We profiled gene and miRNA expression as well as genome-wide and promoter specific DNA methylation and hydroxymethylation patterns in trisomic and disomic fibroblasts, using microarrays and methylated DNA immunoprecipitation.
Project description:To increase our understanding of epigenetic patterns associated with aneuploidy we used constitutional trisomy 8 mosaicism as a model, enabling analyses of single cell clones, harboring either trisomy or disomy 8, from the same patient. We profiled gene and miRNA expression as well as genome-wide and promoter specific DNA methylation and hydroxymethylation patterns in trisomic and disomic fibroblasts, using microarrays and methylated DNA immunoprecipitation.
Project description:BACKGROUND: To investigate epigenetic patterns associated with aneuploidy we used constitutional trisomy 8 mosaicism (CT8M) as a model, enabling analyses of single cell clones, harboring either trisomy or disomy 8, from the same patient; this circumvents any bias introduced by using cells from unrelated, healthy individuals as controls. We profiled gene and miRNA expression as well as genome-wide and promoter specific DNA methylation and hydroxymethylation patterns in trisomic and disomic fibroblasts, using microarrays and methylated DNA immunoprecipitation. RESULTS: Trisomy 8-positive fibroblasts displayed a characteristic expression and methylation phenotype distinct from disomic fibroblasts, with the majority (65%) of chromosome 8 genes in the trisomic cells being overexpressed. However, 69% of all deregulated genes and non-coding RNAs were not located on this chromosome. Pathway analysis of the deregulated genes revealed that cancer, genetic disorder, and hematopoiesis were top ranked. The trisomy 8-positive cells displayed depletion of 5-hydroxymethylcytosine and global hypomethylation of gene-poor regions on chromosome 8, thus partly mimicking the inactivated X chromosome in females. CONCLUSIONS: Trisomy 8 affects genes situated also on other chromosomes which, in cooperation with the observed chromosome 8 gene dosage effect, has an impact on the clinical features of CT8M, as demonstrated by the pathway analysis revealing key features that might explain the increased incidence of hematologic malignancies in CT8M patients. Furthermore, we hypothesize that the general depletion of hydroxymethylation and global hypomethylation of chromosome 8 may be unrelated to gene expression regulation, instead being associated with a general mechanism of chromatin processing and compartmentalization of additional chromosomes.
Project description:Human trisomies can alter cellular phenotypes and produce congenital abnormalities such as Down Syndrome (DS). Here we have generated induced pluripotent stem cells (iPSCs) from DS fibroblasts, and introduced a TKNEO transgene into one copy of chromosome 21 by gene targeting. When selecting against TKNEO, spontaneous chromosome loss was the most common cause for survival, with a frequency of ~10-4, while point mutations, epigenetic silencing, and TKNEO deletions occurred at lower frequencies in this unbiased comparison of inactivating mutations. Mitotic recombination events resulting in extended loss of heterozygosity were not observed in DS iPSCs. The disomic cells that we derived proliferated faster and produced more endothelia in vivo than their otherwise isogenic trisomic counterparts, but hematopoietic differentiation, pluripotency and survival were statistically unchanged. Our study describes the first targeted removal of a human trisomy, which could prove useful in both clinical and research applications. RNA samples were from two trisomic iPSC clone (C2-4, C3-5) and four derived disomic subclones (C2-4-3, C2-4-4 and C3-5-11, C3-5-13). Duplicate RNA samples from human embyonic stem cells (H1) were included as control.
Project description:Individuals with Trisomy 21 (T21) exhibit numerous hematological abnormalities, including reductions in numbers of circulating B and T lymphocytes. To elucidate molecular mechanisms underlying these phenotypes, we differentiated human isogenic disomic and trisomic pluripotent cells, and observed that trisomic cells showed defects in B cell, but not T, cell differentiation. Global gene expression of differentiated, trisomic B cells revealed reduced expression of genes encoding endothelin signaling components, namely the Endothelin Receptor B (Ednrb), and its ligand Endothelin1 (Edn1).. Depletion of Ednrb mRNA in cord blood CD34+ cells led to defective B cell differentiation, supporting an hypothesis that low expression of Ednrb in T21 contributes to intrinsic lymphoid defects. Further evidence for the role of the Ednrb pathway in B cell differentiation was obtained through CRISPR/Cas9 gene targeting in disomic and trisomic iPS cells. Knockout of Ednrb in both cell backgrounds reduced the capacity for B cell differentiation. Collectively, this work identifies downregulation of Ednrb as a causative factor for impaired B lymphocyte generation in trisomic cells, which may contribute to defects in immune function associated with T21. Furthermore, a novel role for endothelin signaling in regulation of B cell development has been identified.
Project description:This study examines cortical organoids generated from a panel of isogenic trisomic and disomic iPSC lines (subclones) as a model of early fetal brain development in Down syndrome. An initial experiment comparing organoids from one trisomic and one disomic line showed many genome-wide transcriptomic differences and modest differences in cell-type proportions, suggesting there may be a neurodevelopmental phenotype that is due to trisomy of chr 21. To better control for multiple sources of variation, we undertook a highly robust study of ∼1,200 organoids using an expanded panel of six all-isogenic lines, three disomic, and three trisomic. The power of this experimental design was indicated by strong detection of the ∼1.5- fold difference in chr21 genes. However, the numerous expression differences in non-chr21 genes seen in the smaller experiment fell away, and the differences in cell-type representation between lines did not correlate with trisomy 21. Results suggest that the initial smaller experiment picked up differences between small organoid samples and individual isogenic lines, which “averaged out” in the larger panel of isogenic lines. Our results indicate that even when organoid and batch variability are better controlled for, variation between isogenic cell lines (even subclones) may obscure, or be conflated with, subtle neurodevelopmental phenotypes that may be present in ∼2nd trimester DS brain development. Interestingly, despite this variability between organoid batches and lines, and the “fetal stage” of these organoids, an increase in secreted Aβ40 peptide levels—an Alzheimer-related cellular phenotype—was more strongly associated with trisomy 21 status than were neurodevelopmental shifts in cell-type composition.