Project description:Down syndrome (trisomy 21) is the most common genetic cause of intellectual disability, but the precise molecular mechanisms underlying impaired cognition remain unclear. Elucidation of these mechanisms has been hindered by the lack of a model system that contains full trisomy of chromosome 21 (Ts21) in a human genome that enables normal gene regulation. To overcome this limitation,we created Ts21-induced pluripotent stem cells (iPSCs) from two sets of Ts21 human fibroblasts. One of the fibroblast lines had low level mosaicism for Ts21 and yielded Ts21 iPSCs and an isogenic control that is disomic for human chromosome 21 (HSA21). Differentiation of all Ts21 iPSCs yielded similar numbers of neurons expressingmarkers characteristic of dorsal forebrain neurons that were functionally similar to controls. Expression profiling of Ts21 iPSCs and their neuronal derivatives revealed changes in HSA21 genes consistent with the presence of 50% more genetic material as well as changes in non- HSA21 genes that suggested compensatory responses to oxidative stress. Ts21 neurons displayed reduced synaptic activity, affecting excitatory and inhibitory synapses equally. Thus, Ts21 iPSCs and neurons display unique developmental defects that are consistent with cognitive deficits in individuals with Down syndrome and may enable discovery of the underlying causes of and treatments for this disorder. Three independent RNA samples were collected from Down syndrome (DS) and control iPSCs between passages 24 and 48. Three independent RNA samples were collected from 30 day old neurons differentiated from Down syndrome (DS) and control iPSCs.
Project description:Background: Down syndrome is the most common genetic cause of mental retardation in humans, occurring in ~1 in 800 newborns. It is caused by chromosome 21 trisomy. Disruption of the phenotype is thought to be the result of gene dosage imbalance. The aim of the study was to classify chromosome 21 genes according to their level of expression in Down syndrome. Results: Variations in chromosome 21 gene expression were analyzed in lymphoblastoid cell lines derived from 10 Down syndrome patients and 11 control individuals. Of the 359 genes and predictions displayed on a specifically designed high content chromosome 21 oligoarray, 132 genes were expressed in lymphoblastoid cell lines. By using a powerful statistical analysis, 58 genes were found overexpressed and 42 unchanged in cell lines from Down syndrome patients. Microarray data were validated by quantitative PCR on 10 genes. Conclusions: The 132 chromosome 21 genes expressed by derived lymphoblastoid cell lines were classified into four categories: Class I: 24 genes controlled by the gene dosage effect with an increase in expression in Down syndrome between 1.4 and 1.6; Class II: 14 amplified genes with expression ratio above 1.6; Class III: 32 compensated genes with expression ratio between 0.82 to 1.4 and Class IV: 30 genes with high variability between individuals. Class I and II genes are likely to be involved in the Down syndrome phenotype, in contrast to the compensated Class III genes; Class IV genes could account for the variable phenotypes observed in patients. Keywords: HSA21 gene expression in Down syndrome
Project description:Gene expression profiling of immortalized human mesenchymal stem cells with hTERT/E6/E7 transfected MSCs. hTERT may change gene expression in MSCs. Goal was to determine the gene expressions of immortalized MSCs.
Project description:We have sequenced miRNA libraries from human embryonic, neural and foetal mesenchymal stem cells. We report that the majority of miRNA genes encode mature isomers that vary in size by one or more bases at the 3’ and/or 5’ end of the miRNA. Northern blotting for individual miRNAs showed that the proportions of isomiRs expressed by a single miRNA gene often differ between cell and tissue types. IsomiRs were readily co-immunoprecipitated with Argonaute proteins in vivo and were active in luciferase assays, indicating that they are functional. Bioinformatics analysis predicts substantial differences in targeting between miRNAs with minor 5’ differences and in support of this we report that a 5’ isomiR-9-1 gained the ability to inhibit the expression of DNMT3B and NCAM2 but lost the ability to inhibit CDH1 in vitro. This result was confirmed by the use of isomiR-specific sponges. Our analysis of the miRGator database indicates that a small percentage of human miRNA genes express isomiRs as the dominant transcript in certain cell types and analysis of miRBase shows that 5’ isomiRs have replaced canonical miRNAs many times during evolution. This strongly indicates that isomiRs are of functional importance and have contributed to the evolution of miRNA genes
Project description:Down syndrome (trisomy 21) is the most common genetic cause of intellectual disability, but the precise molecular mechanisms underlying impaired cognition remain unclear. Elucidation of these mechanisms has been hindered by the lack of a model system that contains full trisomy of chromosome 21 (Ts21) in a human genome that enables normal gene regulation. To overcome this limitation,we created Ts21-induced pluripotent stem cells (iPSCs) from two sets of Ts21 human fibroblasts. One of the fibroblast lines had low level mosaicism for Ts21 and yielded Ts21 iPSCs and an isogenic control that is disomic for human chromosome 21 (HSA21). Differentiation of all Ts21 iPSCs yielded similar numbers of neurons expressingmarkers characteristic of dorsal forebrain neurons that were functionally similar to controls. Expression profiling of Ts21 iPSCs and their neuronal derivatives revealed changes in HSA21 genes consistent with the presence of 50% more genetic material as well as changes in non- HSA21 genes that suggested compensatory responses to oxidative stress. Ts21 neurons displayed reduced synaptic activity, affecting excitatory and inhibitory synapses equally. Thus, Ts21 iPSCs and neurons display unique developmental defects that are consistent with cognitive deficits in individuals with Down syndrome and may enable discovery of the underlying causes of and treatments for this disorder.