Data from: Dysregulation of valvular interstitial cell let-7c, miR-17, miR-20a, and miR-30d in naturally occurring canine myxomatous mitral valve disease

Canine myxomatous mitral valve disease (MMVD) resembles the early stages of myxomatous pathology seen in human non-syndromic mitral valve prolapse, a common valvular heart disease in the adult human population. Canine MMVD is seen in older subjects, suggesting age-related epigenetic dysregulation leading to derangements in valvular cell populations and matrix synthesis or degradation. We hypothesized that valvular interstitial cells (VICs) undergo disease-relevant changes in miRNA expression. In primary VIC lines from diseased and control valves, miRNA expression was profiled using RT-qPCR and next generation sequencing. VICs from diseased valves showed phenotypic changes consistent with myofibroblastic differentiation (vimentinlow+, a-SMAhigh+), increases in senescence markers (p21, SA-b-gal), and decreased cell viability and proliferation potential. RT-qPCR and miRNA sequencing analyses both showed significant (p<0.05) downregulation of let-7c, miR-17, miR-20a, and miR-30d in VICs from diseased valves compared to controls. Decreased let-7c, miR-17, and miR-20a may contribute to myofibroblastic differentiation in addition to cell senescence, and decreased miR-30d may disinhibit cell apoptosis. These data support the hypothesis that epigenetic dysregulation plays an important role in age-related canine MMVD.

犬黏液瘤性二尖瓣疾病（myxomatous mitral valve disease, MMVD）与人类非综合征性二尖瓣脱垂的黏液瘤病理早期阶段高度相似，后者是成人人群中常见的瓣膜性心脏病。犬MMVD多见于老年个体，提示年龄相关的表观遗传失调可引发瓣膜细胞群紊乱以及细胞外基质合成与降解失衡。本研究提出假说：瓣膜间质细胞（valvular interstitial cells, VICs）的微小RNA（microRNA, miRNA）表达会发生与疾病相关的特异性改变。研究对来自病变瓣膜与对照瓣膜的原代VIC系开展实验，采用实时荧光定量聚合酶链反应（real-time quantitative polymerase chain reaction, RT-qPCR）与下一代测序（next generation sequencing, NGS）对其miRNA表达谱进行分析。结果显示，病变瓣膜来源的VICs呈现出与肌成纤维细胞分化相符的表型特征：波形蛋白（vimentin）低表达阳性、α-平滑肌肌动蛋白（alpha-smooth muscle actin, α-SMA）高表达阳性，衰老标志物（p21、衰老相关β-半乳糖苷酶（senescence-associated beta-galactosidase, SA-β-gal））表达上调，同时细胞活力与增殖潜能显著下降。RT-qPCR与miRNA测序分析均证实，与对照组相比，病变瓣膜来源的VICs中let-7c、miR-17、miR-20a以及miR-30d的表达量显著下调（p<0.05）。进一步分析表明，let-7c、miR-17与miR-20a的表达下调不仅可促进细胞衰老，还可能推动肌成纤维细胞分化；而miR-30d的表达下调则可能解除对细胞凋亡的抑制作用。上述实验数据支持了“表观遗传失调在年龄相关性犬MMVD中发挥关键调控作用”这一研究假说。