Abstract 059: miR-29 is Required for Normal Endothelium-dependent Vasodilation and Protects Against Hypertension

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MicroRNA miR-29 is down-regulated in Dahl salt-sensitive (SS) rats compared to salt-insensitive SS-13 BN rats. We investigated the role of miR-29 in endothelial function and the development of hypertension. Using TALENs (Transcriptional Activator-Like Effector Nucleases) we deleted 4 nucleotides from Mir29b-1 gene in SS-13 BN rats. The targeted mutation resulted in reduced abundance of miR-29b-3p and the co-transcribed miR-29a-3p in arteriolar endothelial cells. When stimulated with acetylcholine to induce endothelium-dependent vasodilation (EDVD), gluteal arterioles from Mir29b-1 -/- rats were only able to dilate to an average 47% of maximum diameter while wild-type littermates dilated to 77% (N=7 and 9, respectively, p<0.05). The development of hypertension was significantly exacerbated in Mir29b-1 -/- compared to Mir29b-1 +/+ littermates. Mean arterial blood pressure was 129 ± 2 mmHg in Mir29b-1 +/+ rats after 2 weeks of 4% NaCl diet and 140 ± 5 mmHg in Mir29b-1 -/- rats (N=6, 10, respectively, p<0.05). Gluteal arterioles from Mir29b-1 -/- rats exhibited significantly reduced nitric oxide (NO) levels compared to Mir29b-1 +/+ littermates as measured by DAF2-DA intensity (N=6, 11, respectively). Mutation of the Mir29b-1 gene resulted in preferential differential expression of genes in arterioles related to the regulation of NO levels including Lypla1. Lypla1 is a direct target of miR-29 and could abrogate the effect of miR-29 in promoting NO production. Reduction of LYPLA1 by transfection of pre-miR-29b or a Lypla1 siRNA resulted in a significant increase in NO as measured by DAF2-DA in cultured human dermal microvascular endothelial cells. Taken together, we have shown that targeted mutation of Mir29b-1 reduces EDVD and exacerbates the development of hypertension. We have identified a mechanism by which miR-29 affects NO production. These findings indicate miR-29 is required for normal endothelial function in rats and has therapeutic potential for hypertension.