Dataset Information

Transcription profiling of Ts65Dn vs control mice in nine different mouse tissues

ABSTRACT: To understand the molecular basis of Down syndrome pathogenesis, we performed a transcriptome analysis of nine different tissues in Ts65Dn, an established mouse model of human trisomy 21. Ts65Dn mice have segmental trisomy of mouse chromosome 16 with ca. 128 genes at dosage imbalance (Reeves et al. 1995). The Ts65Dn mouse is widely used as a model for studies of DS because it is at dosage imbalance for the orthologs of about half the 284 Chr21 genes. Ts65Dn mice have several features that directly parallel developmental anomalies of DS. We compare here the expression of 136 mouse orthologs of Chr21 genes, 77 of which are triplicated in Ts65Dn, in trisomic and euploid mice.

We designed a mouse cDNA expression array interrogating 136 mmu21 genes. RNA pools from four adult male Ts65Dn mice and four male euploid littermates were prepared from cortex and dissected from three to four month-old mice. Directly labeled first strand cDNA probes from nine different tissues were hybridized to the arrays in replicated hybridizations. A total of 446 genes that are not triplicated in Ts65Dn mice served as controls. These included 62 mmu21 genes from MMU10, MMU17, and non-triplicated portions of MMU16, plus 384 randomly distributed mouse cDNAs from the Unigene collection.

ORGANISM(S): Mus musculus

SUBMITTER: Marie-Laure Yaspo

PROVIDER: E-MEXP-102 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Transcript level alterations reflect gene dosage effects across multiple tissues in a mouse model of down syndrome.

Kahlem Pascal P Sultan Marc M Herwig Ralf R Steinfath Matthias M Balzereit Daniela D Eppens Barbara B Saran Nidhi G NG Pletcher Mathew T MT South Sarah T ST Stetten Gail G Lehrach Hans H Reeves Roger H RH Yaspo Marie-Laure ML

Genome research 20040701 7

Human trisomy 21, which results in Down syndrome (DS), is one of the most complicated congenital genetic anomalies compatible with life, yet little is known about the molecular basis of DS. It is generally accepted that chromosome 21 (Chr21) transcripts are overexpressed by about 50% in cells with an extra copy of this chromosome. However, this assumption is difficult to test in humans due to limited access to tissues, and direct support for this idea is available for only a few Chr21 genes or i ...[more]

PMID: 15231742

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Project description:A major challenge in Down syndrome (DS) is to understand how the extra-dose of functional chromosome 21 (HSA21) genetic elements can impact on the tissue-specific transcriptome to contribute to phenotypic alterations. MiRNAs are post-transcriptional modulators with genome-wide regulatory effects. Five microRNAs have been identified in HSA21 that are present in triple copy in DS individuals. Interestingly, in the Ts65Dn mouse model of DS two of these miRNAs, miR-155 and miR-802, are also triplicated resulting in its overexpression. In the current work, we have developed a lentiviral miRNA-sponge genetic strategy for miR-155 and miR-802 (Lv-miR155-802T) to identify novel mRNA targets involved in hippocampal function. Hippocampal injection of the lentiviral sponge in Ts65Dn mice reduced miR-155 and miR-802 overexpression. Noticeable lentiviral sponge rescued the expression of the miRNA predicted targets showing the potential of the strategy to identify miRNA dosage-sensitive genes with potential involvement in DS-hippocampal phenotypes. Euploid and trisomic adult mice were bilaterally injected at the level of the ventral hippocampus at selected coordinates (AP=-3.3mm, L=+/- 3mm, DV=-3.3mm and -2.3mm relative to bregma). Up to 108 transducing units (3µl of viral suspensions of Lv-Contol or Lv-miR155-802T) were injected into each hemisphere at a rate of 0.2 µl/min, under the precise control of an infusion pump (Ultramicropump, World Precision Instruments). Mice were euthanized for hippocampus collection at day 23 after administration. Transcriptome of hippocampus of euploid and trisomic mice treated with Lv-Control or Lv-miR155-802T was analysed using an Agilent SurePrint G3 Mouse gene expression 8x60K Microarray (ID 028005). A total RNA 100 ng, obtained using miRNeasy Mini Ki (QIAGEN), were labeled using LowInputQuick Amp Labeling kit (Agilent 5190-2305) following manufacturer instructions. Briefly, mRNA was reverse transcribed in the presence of T7-oligo-dT primer to produce cDNA. cDNA was then in vitro transcribed with T7 RNA polymerase in the presence of Cy3-CTP to produce labeled cRNA. The labeled cRNA was hybridized to the Agilent SurePrint G3 Mouse gene expression 8x60K Microarray (ID 028005) according to the manufacturer's protocol. The arrays were washed, and scanned on an Agilent G2565CA microarray scanner at 100% PMT and 3µm resolution. Intensity data was extracted using the Feature Extraction software (Agilent). Replicates from each genotypes and treatment group were distributed as follows: EU+Lv-Contol n=4, EU+Lv-miR155-802T n=4, TS+Lv-Contol n=5, TS+Lv-miR155-802T n=3.

Project description:Down syndrome (DS), a genetic condition leading to intellectual disability, is characterized by triplication of human chromosome 21. Neuropathological hallmarks of DS include abnormal central nervous system development that manifests during gestation and extends throughout life. As a result, newborns and adults with DS exhibit cognitive and motor deficits and fail to meet typical developmental and lack independent life skills. A critical outstanding question is how DS-specific prenatal and postnatal phenotypes are recapitulated in different mouse models. To begin answering this question, we developed a life span approach to directly compare differences in embryonic brain development, cellularity, gene expression, neonatal and adult behavior behavior in three cytogenetically distinct mouse models of DS—Ts1Cje, Ts65Dn and Dp16/1Yey (Dp16). In the last two decades multiple therapeutic trials have been attempted to improve cognition in humans with DS but the results of these interventions lacked efficacy despide their succes in the Ts65Dn mouse model of DS. To better understand how phenotypic changes in humans in DS are recapitulated in different mouse models, we copared embryonic brain development and gene expression, perinatal behavior and brain excitatoty/inhibitory cell distribution, and adult behavior and gene expression in the Dp16, Ts65Dn and Ts1Cje mouse models of DS. The objectives of this study were to determine the best model(s) for prenatal and postnatal therapeutic trials and to identify treatment endpoints that can be used to evaluate the fficacy of these therapies prior to human clinical trials. Our data showed that, at embryonic day 15.5, Ts65Dn mice are the most profoundly and consistently affected with respect to somatic growth, brain morphogenesis, and neurogenesis compared to Ts1Cje and Dp16 embryos. However, gene expression results show that both Ts65Dn and Ts1Cje embryonic forebrains have a relatively high number of differentially expressed genes compared to Dp16, with little overlap in gene identities and genomic distribution observed among these models. Additionally, postnatal histological analyses show varying degrees of cell population and brain histogenesis abnormalities among the three strains. Behavioral testing also highlights differences among the models in their ability to meet various developmental milestones. At adulthood, Ts65Dn and Ts1Cje showed hyperactive behavior in the open field test but not Dp16 mice. In the fear conditioning test, all three strains showed lower freezing versus eupploid mice; Dp16 were the most severely affected. In the Morris water maze, Ts65Dn showed significant delays in the hidden platform, probe and reversal trials. Dp16 mice showed milder deficits in the hidden platform trial but severe deficits in reversal. Ts1Cje mice had no spatial memory deficits. In the rotarod test, Dp16 performed poorly in fixed and accelerating speed trials, while Ts1Cje was only abnormal at high speeds. Ts65Dn rotarod performance was unaffected. Compared to euploid, Ts65Dn had a higher number of differentially expressed (DEX) genes in cortex and cerebellum, while Ts1Cje had more DEX genes in hippocampus and cerebellum. Dp16 had the lowest number of DEX genes in all regions analyzed. Pathway analyses highlighted commonly dysregulated pathways, including G-protein signaling, oxidative stress, interferon signaling, glycosylation and disulfide bonds.

Dataset Information

Transcription profiling of Ts65Dn vs control mice in nine different mouse tissues

Publications

Transcript level alterations reflect gene dosage effects across multiple tissues in a mouse model of down syndrome.

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