Genomic and functional profiling of human Down syndrome neural progenitors implicates S100B and aquaporin 4 in cell injury

Department of Human Physiology and Pharmacology, Vittorio Erspamer Faculty of Pharmacy, University of Rome La Sapienza, Rome, Italy.
Human Molecular Genetics (Impact Factor: 6.39). 03/2008; 17(3):440-57. DOI: 10.1093/hmg/ddm322
Source: PubMed


Down syndrome (DS) is caused by trisomy of chromosome 21 and is characterized by mental retardation, seizures and premature Alzheimer's disease. To examine neuropathological mechanisms giving rise to this disorder, we generated multiple human DS neural progenitor cell (NPC) lines from the 19-21 week frontal cortex and characterized their genomic and functional properties. Microarray profiling of DS progenitors indicated that increased levels of gene expression were not limited to chromosome 21, suggesting that increased expression of genes on chromosome 21 altered transcriptional regulation of a subset of genes throughout the entire genome. Moreover, many transcriptionally dysregulated genes were involved in cell death and oxidative stress. Network analyses suggested that upregulated expression of chromosome 21 genes such as S100B and amyloid precursor protein activated the stress response kinase pathways, and furthermore, could be linked to upregulation of the water channel aquaporin 4 (AQP4). We further demonstrate in DS NPCs that S100B is constitutively overexpressed, that overexpression leads to increased reactive oxygen species (ROS) formation and activation of stress response kinases, and that activation of this pathway results in compensatory AQP4 expression. In addition, AQP4 expression could be induced by direct exposure to ROS, and siRNA inhibition of AQP4 resulted in elevated levels of ROS following S100B exposure. Finally, elevated levels of S100B-induced ROS and loss of AQP4 expression led to increased programmed cell death. These findings suggest that dysregulation of chromosome 21 genes in DS neural progenitors leads to increased ROS and thereby alters transcriptional regulation of cytoprotective, non-chromosome 21 genes in response to ongoing cellular insults.

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Available from: Volney L Sheen, Dec 16, 2013
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    • "Only two studies have investigated gene expression changes in fetal brains, but these were performed on post-mortem tissue [Mao et al., 2003; Mao et al., 2005]. To circumvent the limited access to human samples, other studies have investigated transcriptome differences in cultured neural progenitor cells derived from affected post-mortem human fetal brains or amniotic fluid cell-free RNA [Esposito et al., 2008; Slonim et al., 2009; Weick et al., 2013]. Multiple processes affecting brain development and function were shown to be dysregulated in these samples, including neurogenesis, GABAR activity, ion transport, G-protein signaling, oxidative stress, and apoptosis. "
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    ABSTRACT: Human fetuses with Down syndrome demonstrate abnormal brain growth and reduced neurogenesis. Despite the prenatal onset of the phenotype, most therapeutic trials have been conducted in adults. Here, we present evidence for fetal brain molecular and neonatal behavioral alterations in the Ts1Cje mouse model of Down syndrome. Embryonic day 15.5 brain hemisphere RNA from Ts1Cje embryos (n = 5) and wild type littermates (n = 5) was processed and hybridized to mouse gene 1.0 ST arrays. Bioinformatic analyses were implemented to identify differential gene and pathway regulation during Ts1Cje fetal brain development. In separate experiments, the Fox scale, ultrasonic vocalization and homing tests were used to investigate behavioral deficits in Ts1Cje pups (n = 29) versus WT littermates (n = 64) at postnatal days 3-21. Ts1Cje fetal brains displayed more differentially regulated genes (n = 71) than adult (n = 31) when compared to their age-matched euploid brains. Ts1Cje embryonic brains showed up-regulation of cell cycle markers and down-regulation of the solute-carrier amino acid transporters. Several cellular processes were dysregulated at both stages, including apoptosis, inflammation, Jak/Stat signaling, G-protein signaling, and oxidoreductase activity. In addition, early behavioral deficits in surface righting, cliff aversion, negative geotaxis, forelimb grasp, ultrasonic vocalization, and the homing tests were observed. The Ts1Cje mouse model exhibits abnormal gene expression during fetal brain development, and significant neonatal behavioral deficits in the pre-weaning period. In combination with human studies, this suggests that the Down syndrome phenotype manifests prenatally and provides a rationale for prenatal therapy to improve perinatal brain development and postnatal neurocognition. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.
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    • "Several studies have looked at altered gene expression levels in DS subjects, for example, (Esposito et al., 2008; Costa et al., 2011; Letourneau et al., 2014). (Letourneau et al., 2014) showed that the nuclear compartments of trisomic cells undergo modifications of the chromatin environment influencing the overall transcriptome. "
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    • "How AQP4 levels are altered by ethanol binges requires study, but several stimuli known to potentiate brain or astroglial AQP4 levels/activity are reported by others to be increased by ethanol in various exposure protocols. For example, ROS [62], lactic acid [[63], proinflammatory cytokines [64], and glutamate [65] have been shown to increase the water channel. Depending on the model, ethanol and/or ethanol withdrawal can promote or potentiate brain levels of all of these factors [9], [66], [67]. "
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