Laboratory of Medical Genetics, Harbin Medical University, Harbin, China; Division of Cardiovascular Surgery, Toronto General Research Institute and Peter Munk Cardiac Centre, University Health Network, Toronto, Ontario, Canada; Department of Surgery, Division of Cardiac Surgery, University of Toronto, Toronto, Ontario, Canada.
Division of Cardiovascular Surgery, Toronto General Research Institute and Peter Munk Cardiac Centre, University Health Network, Toronto, Ontario, Canada; Department of Surgery, Division of Cardiac Surgery, University of Toronto, Toronto, Ontario, Canada; Department of Anatomy, Shanxi Medical University, Taiyuan, China.
J Am Coll Cardiol. 2016 Jun 28;67(25):2965-77. doi: 10.1016/j.jacc.2016.04.027.
Patients with a bicuspid aortic valve (BAV) are at increased risk for progressive aortic dilation associated with extracellular matrix (ECM) degradation by matrix metalloproteinases (MMP). However, the mechanisms responsible for initiating this process are unknown. In the heart, MMP activity is regulated by micro-ribonucleic acid-17 (miR-17)-related downregulation of tissue inhibitors of metalloproteinases (TIMP); a similar process may exist in the aorta.
This study sought to ascertain whether aortic matrix degradation in BAV patients progresses by miR-17-related miRNA regulation of TIMP-MMP.
To eliminate confounding patient-related factors, severely dilated and less dilated aortic tissue samples were collected from 12 BAV patients. Gene and protein expression levels were evaluated in paired tissue samples from the same patient and were compared to aortic samples from 16 patients with aortas that appeared to be normal.
Gene expression analyses confirmed increased expression of miR-17-related miRNAs in less dilated compared with severely dilated tissue from the same patient or normal aortic sample. TIMP-1, -2, and -3 were significantly decreased, and MMP2 activity was significantly increased in less dilated samples, suggesting that this normal-looking tissue was in the early stages of ECM degradation. Smooth muscle cells isolated from normal or BAV aortas transfected with an miR-17 mimic had decreased TIMP-1 and -2 expression and increased MMP2 activity, whereas the opposite effects were seen with an miR-17 inhibitor, suggesting that miR-17 may control the TIMP-MMP balance in these tissues. Luciferase reporter assays demonstrated that miR-17 regulated TIMP-1 and -2 expression.
Our in vitro and in vivo studies taken together confirm that miR-17 directly regulates TIMP-1 and -2. Less dilated aortic BAV tissue may be in the initial stages of dilation under the control of miR-17-related miRNAs. New therapies that inhibit these miRNAs may prevent aortic dilation.
二叶式主动脉瓣（BAV）患者的主动脉扩张风险增加，这与细胞外基质（ECM）降解有关，降解由基质金属蛋白酶（MMP）引起。然而，负责启动这一过程的机制尚不清楚。在心脏中，MMP 活性受 micro-ribonucleic acid-17（miR-17）下调组织金属蛋白酶抑制剂（TIMP）调节；在主动脉中可能存在类似的过程。
本研究旨在确定 BAV 患者的主动脉基质降解是否通过 miR-17 相关 miRNA 对 TIMP-MMP 的调控而进展。
为了消除与患者相关的混杂因素，从 12 名 BAV 患者中收集了严重扩张和扩张程度较轻的主动脉组织样本。对同一患者的配对组织样本进行基因和蛋白表达水平评估，并与 16 名主动脉外观正常的患者的主动脉样本进行比较。
基因表达分析证实，与同一患者严重扩张组织或正常主动脉样本相比，轻度扩张组织中 miR-17 相关 miRNA 的表达增加。TIMP-1、-2 和-3 显著减少，轻度扩张样本中 MMP2 活性显著增加，表明这种外观正常的组织处于 ECM 降解的早期阶段。用 miR-17 模拟物转染的正常或 BAV 主动脉平滑肌细胞 TIMP-1 和-2 表达减少，MMP2 活性增加，而用 miR-17 抑制剂则相反，这表明 miR-17 可能控制这些组织中的 TIMP-MMP 平衡。荧光素酶报告基因检测表明，miR-17 调节 TIMP-1 和-2 的表达。
我们的体内外研究共同证实，miR-17 直接调节 TIMP-1 和-2。BAV 轻度扩张的主动脉组织可能在 miR-17 相关 miRNA 的控制下处于扩张的初始阶段。抑制这些 miRNA 的新疗法可能预防主动脉扩张。
