2015 ACVIM Forum Research Abstract Program

Median length of the small RNA reads was 22 bp (range: 10-46 bp). Principal component analysis showed a significant difference in expression profiles between MR dogs and controls (P < 0.01). Using a paired sample design, the expression profiles of 164 miRNAs were found differentially regulated between MR dogs and controls. Cfa-miR-196b (involved in stem cell differentiation) was the most highly expressed and cfa-miR-208a (associated with cardiac hypertrophy) the most negatively regulated miRNAs on the mitral valve of MR dogs as quantified by RNA sequencing (P < 0.001). Cfa-mir-128 and cfa-mir-218 were upregulated (P < 0.001), and their predicted target gene, phosphodiesterase 3a (PDE3a), was down-regulated via qRT-PCR validation (P = 0.038). Gene ontology analysis revealed that differentially expressed miRNAs regulate a set of genes involved in the signalling pathways of myxomatous mitral valve degeneration including TGF-b and Wnt.