Aims: Activation of an osteogenic transcriptional program contributes to the initiation of aortic calcification in atherosclerosis. The role of microRNAs in regulating aortic calcification is under-studied. We tested the hypothesis that miR-30e regulates an osteogenic program in bone marrow derived mesenchymal stem cells (MSCs), aortic smooth muscle cells (SMCs), and ApoE-/- mice.  

Method and Results: In aortas of wild type mice, we found that miR-30e is highly expressed in medial SMCs. In aortas of old ApoE-/- mice, we found that miR-30e transcripts are downregulated in an inverse relation to the osteogenic markers Runx2, Opn, and Igf2. In vitro, miR-30e over-expression reduced the proliferation of MSCs and SMCs while increasing adipogenic differentiation of MSCs and smooth muscle differentiation of SMCs. In MSCs and SMCs over-expressing miR-30e, microarrays and qPCR showed repression of an osteogenic gene panel including Igf2. Inhibiting miR-30e in MSCs increased Igf2 transcripts. In SMCs, IGF2 recombinant protein rescued miR-30e-repressed osteogenic differentiation. Luciferase and mutagenesis assays showed binding of miR-30e to a novel and essential site at the 3’UTR of Igf2. In ApoE-/- mice, injections of antimiR-30e oligos increased Igf2 expression in the aortas and livers and significantly enhanced OPN protein expression and calcium deposition in aortic valves. 

Conclusion: MiR-30e represses the osteogenic program in MSCs and SMCs by targeting IGF2, and drives their differentiation into adipogenic or smooth muscle lineage, respectively. Our data suggest that downregulation of miR-30e in aortas with age and atherosclerosis triggers vascular calcification. The miR-30e pathway plays an important regulatory role in vascular diseases.

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