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Gene and miRNA arrays

  • MicroRNAs (miRNAs) are a class of small, non-coding RNAs (~22 nt) encoded in human, animal and plant genomes that are post-translational gene regulators. miRNAs, which implement their biological functions through suppression of protein expression by binding to 3’UTR of mRNA, are critical regulators of gene expression during embryonic development.
  • Understanding the role of uniquely and commonly dysregulated miRNAs in the different classes of BPH/5 placentas and in cardiovascular regulatory circuits in the CNS may provide clues to the molecular basis of pre-eclampsia and neurogenic hypertension, respectively. We hypothesize that there is an altered miRNA expression profile:
    1. amongst Class I, II and III BPH/5 feto-placental units as well as compared to C57Bl/6 control.
    2. in cardiovascular regulatory control nuclei (e.g., SFO, PVN, RVLM) during "slow-pressor" Ang-II hypertension and myocardial infarction (MI)-induced heart failure.
  • Pre-eclampsia studies: Venn diagram analysis of differentially expressed miRNAs (>1.5 fold, p<0.05) in Class I, II and III BPH/5 mouse placentas identified 94 differentially expressed miRNAs, 21 of which were dysregulated in all three classes. Specifically, miR-136 and miR-467b were significantly decreased in all three classes, which was confirmed by real-time RT-PCR. Subsequent target gene analysis of miR-136 and miR-467b (done using PicTar) identified thrombospondin-2 (Thbs2), an inhibitor of angiogenesis, as a putative target. Taken together, these findings suggest that Thbs2 may play an important pathophysiological role in feto-placental defects in BPH/5 mice and that miRNA-136 and miRNA-467b, which are regulators of Thbs2, may be novel therapeutic targets for treating preeclampsia.
  • Cardiovascular studies: Hierarchical clustering analysis has also shown that there is differential miRNA expression in the SFO, PVN and RVLM of mouse brain. For example, miR-34c and miR-375 are upregulated in the SFO; miR-7b expression is highest in the PVN; and miR-10b and miR-9b are predominantly expressed in the RVLM. Some of these chip data have also been confirmed by real-time RT-PCR. Further studies are underway to examine the spatial expression of highly expressed miRNAs in these cardiovascular regulatory nuclei to understand their role in regulating gene expression in these nuclei under normal and pathophysiological conditions.

miRNA profiling using microarray in different classes of BPH/5 mouse feto-placental units.

Venn diagram showing differentially expressed miRNAs in BPH/5 placentas.

Hierarchical clustering analysis shows differential miRNA expression in several cardiovascular regulatory nuclei of moues brain.

Representative microarray chip showing dysreguated miRNA expression in BPH/5 mouse placenta.

Unsupervised hierarchical clustering analysis of differentially regulated miRNAs across BPH/5 mouse placenta Class I, II and III compare red to control C57 placenta.