Mensah A, Mulligan C, Linehan J, Ruf S, O'Doherty A, Grygalewicz B et al.. An additional human chromosome 21 causes suppression of neural fate of pluripotent mouse embryonic stem cells in a teratoma model. BMC Dev Biol 7: 131

Centre for Haematology, Institute of Cell and Molecular Science, Barts & The London, Queen Mary's School of Medicine, University of London, 4 Newark Street, London E1 2AT, UK.
BMC Developmental Biology (Impact Factor: 2.67). 02/2007; 7(1):131. DOI: 10.1186/1471-213X-7-131
Source: PubMed


Down syndrome (DS), caused by trisomy of human chromosome 21 (HSA21), is the most common genetic cause of mental retardation in humans. Among complex phenotypes, it displays a number of neural pathologies including smaller brain size, reduced numbers of neurons, reduced dendritic spine density and plasticity, and early Alzheimer-like neurodegeneration. Mouse models for DS show behavioural and cognitive defects, synaptic plasticity defects, and reduced hippocampal and cerebellar neuron numbers. Early postnatal development of both human and mouse-model DS shows the reduced capability of neuronal precursor cells to generate neurons. The exact molecular cause of this reduction, and the role played by increased dosage of individual HSA21 genes, remain unknown.
We have subcutaneously injected mouse pluripotent ES cells containing a single freely segregating supernumerary human chromosome 21 (HSA21) into syngeneic mice, to generate transchromosomic teratomas. Transchromosomic cells and parental control cells were injected into opposite flanks of thirty mice in three independent experiments. Tumours were grown for 30 days, a time-span equivalent to combined intra-uterine, and early post-natal mouse development. When paired teratomas from the same animals were compared, transchromosomic tumours showed a three-fold lower percentage of neuroectodermal tissue, as well as significantly reduced mRNA levels for neuron specific (Tubb3) and glia specific (Gfap) genes, relative to euploid controls. Two thirds of transchromosomic tumours also showed a lack of PCR amplification with multiple primers specific for HSA21, which were present in the ES cells at the point of injection, thus restricting a commonly retained trisomy to less than a third of HSA21 genes.
We demonstrate that a supernumerary chromosome 21 causes Inhibition of Neuroectodermal DIfferentiation (INDI) of pluripotent ES cells. The data suggest that trisomy of less than a third of HSA21 genes, in two chromosomal regions, might be sufficient to cause this effect.

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    • "Alternatively, other reports suggest that HSA21 associated DYRK1A causes a skewed ratio of primitive endoderm at the expense of neuroectodermal progenitors, leading to a reduction in neurogenesis (Canzonetta et al., 2008). Mensah also reported an inhibition of neuroectodermal differentiation in a teratoma model transplanted with mouse ES cells injected with HSA21 (Mensah et al., 2007). Our prior studies of DS HNPs had demonstrated a constitutive increase in the glial and HSA21 associated S100B protein, which in turn, enhanced expression of another glial-associated protein, the water channel AQP4. "

    Full-text · Chapter · Aug 2011
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    • "This is why we focussed on the early mesodermal colony formation in vitro, using the transchromosomic system (mouse ESCs) bearing an extra human chromosome 21 (HSA21) (Hernandez et al., 1999)). Though mouse ESCs differ from human ESCs in some components of molecular circuitry, the effects of the supernumerary human chromosome 21 in transchromosomic mouse ESCs recapitulate many molecular and cellular phenotypes observed in human cells from T21 foeti: (i) transchromosomic ESCs show a reduction in the levels of the RE-1 silencing transcription factor (NRSF/REST) (Canzonetta et al., 2008), and reduced neurogenesis with abnormally branching neurites (Mensah et al., 2007; Canzonetta et al., 2008) as do neural stem cells from human T21 foeti (Bahn et al., 2002); (ii) the control of NRSF/REST levels can be attributed to the HSA21 gene DYRK1A in transhromosomic ESCs, mouse neural progenitor cells and human lymphocytes (Canzonetta et al., 2008; Lepagnol-Bestel et al., 2009) and (iii) quantitative proteome changes observed in transchromosomic ESCs recapitulate those in human foetal tissues with T21 (Wang et al., 2009). In addition, the transchromosomic ESCs provide a novel genetic dissection system (something that cannot be achieved even in human T21 iPS that has been recently established (Park et al., 2008)), in allowing modelling of selective reduction-to-disomy of individual supernumerary HSA21 genes. "
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    ABSTRACT: Children with Down's syndrome (DS) have 20-50-fold higher incidence of all leukaemias (lymphoid and myeloid), for reasons not understood. As incidence of many solid tumours is much lower in DS, we speculated that disturbed early haematopoietic differentiation could be the cause of increased leukaemia risk. If a common mechanism is behind the risk of both major leukaemia types, it would have to arise before the bifurcation to myeloid and lymphoid lineages. Using the transchromosomic system (mouse embryonic stem cells (ESCs)) bearing an extra human chromosome 21 (HSA21)) we analyzed the early stages of haematopoietic commitment (mesodermal colony formation) in vitro. We observed that trisomy 21 (T21) causes increased production of haemogenic endothelial cells, haematopoietic stem cell precursors and increased colony forming potential, with significantly increased immature progenitors. Transchromosomic colonies showed increased expression of Gata-2, c-Kit and Tie-2. A panel of partial T21 ESCs allowed us to assign these effects to HSA21 sub-regions, mapped by 3.5 kbp-resolution tiling arrays. The Gata-2 increase on one side, and c-Kit and Tie-2 increases on the other, could be attributed to two different, non-overlapping HSA21 regions. Using human-specific small interfering RNA silencing, we could demonstrate that an extra copy of RUNX1, but not ETS-2 or ERG, causes an increase in Tie-2/c-Kit levels. Finally, we detected significantly increased levels of RUNX1, C-KIT and PU.1 in human foetal livers with T21. We conclude that overdose of more than one HSA21 gene contributes to the disturbance of early haematopoiesis in DS, and that one of the contributors is RUNX1. As the observed T21-driven hyperproduction of multipotential immature precursors precedes the bifurcation to lymphoid and myeloid lineages, we speculate that this could create conditions of increased chance for acquisition of pre-leukaemogenic rearrangements/mutations in both lymphoid and myeloid lineages during foetal haematopoiesis, contributing to the increased risk of both leukaemia types in DS.
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    • "Many phenotypic features of DS are determined very early in development, when the tissue specification is not completely established [3]. Early postnatal development of both human patients and DS mouse models showed the reduced capability of neuronal precursor cells to correctly generate fully differentiated neurons [16], contributing to the specific cognitive and developmental deficits seen in individuals with DS [17]. Canzonetta et al. [18] showed that DYRK1A-REST perturbation has the potential to significantly contribute to the development of defects in neuron number and altered morphology in DS. "
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    ABSTRACT: Dosage imbalance is responsible for several genetic diseases, among which Down syndrome is caused by the trisomy of human chromosome 21. To elucidate the extent to which the dosage imbalance of specific human chromosome 21 genes perturb distinct molecular pathways, we developed the first mouse embryonic stem (ES) cell bank of human chromosome 21 genes. The human chromosome 21-mouse ES cell bank includes, in triplicate clones, 32 human chromosome 21 genes, which can be overexpressed in an inducible manner. Each clone was transcriptionally profiled in inducing versus non-inducing conditions. Analysis of the transcriptional response yielded results that were consistent with the perturbed gene's known function. Comparison between mouse ES cells containing the whole human chromosome 21 (trisomic mouse ES cells) and mouse ES cells overexpressing single human chromosome 21 genes allowed us to evaluate the contribution of single genes to the trisomic mouse ES cell transcriptome. In addition, for the clones overexpressing the Runx1 gene, we compared the transcriptome changes with the corresponding protein changes by mass spectroscopy analysis. We determined that only a subset of genes produces a strong transcriptional response when overexpressed in mouse ES cells and that this effect can be predicted taking into account the basal gene expression level and the protein secondary structure. We showed that the human chromosome 21-mouse ES cell bank is an important resource, which may be instrumental towards a better understanding of Down syndrome and other human aneuploidy disorders.
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