BioProject

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. More...

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. Overall design: 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. Less...