Zhang Jing, Luo Chang-Jun, Xiong Xiao-Qi, Li Jun, Tang San-Hua, Sun Lin, Su Qiang
Department of Cardiovascular Medicine, Liuzhou Municipal Liutie Central Hospital, Liuzhou, China.
Department of Clinical Laboratory, Liuzhou Municipal Liutie Central Hospital, Liuzhou, China.
J Geriatr Cardiol. 2021 Dec 28;18(12):1029-1043. doi: 10.11909/j.issn.1671-5411.2021.12.004.
For patients with coronary heart disease, reperfusion treatment strategies are often complicated by ischemia/reperfusion (I/R) injury (IRI), leading to serious organ damage and malfunction. The miR-21/programmed cell death protein 4 (PDCD4) pathway is involved in the IRI of cardiomyocytes; however, the aberrant miR-21 expression remains unexplained. Therefore, this study aimed to explore whether circRNA_0031672 downregulates miR-21-5p expression during I/R and to determine whether miR-21-5p-expressing bone marrow mesenchymal stem cells (BMSCs) reduce myocardial IRI.
CircRNA_0031672, miR-21-5p, and PDCD4 expressions were evaluated in the I/R rat model and hypoxia/re-oxygenation (H/R)-treated H9C2 cells. Their interactions were subsequently investigated using luciferase reporter and RNA pulldown assays. Methyltransferase-like 3, a methyltransferase catalyzing N6-methyladenosine (m6A), was overexpressed in H9C2 cells to determine whether m6A modification influences miR-21-5p targeting PDCD4. BMSCs stably expressing miR-21 were co-cultured with H9C2 cells to investigate the protective effect of BMSCs on H9C2 cells upon H/R.
I/R downregulated miR-21-5p expression and upregulated circRNA_0031672 and PDCD4 expressions. CircRNA_0031672 knockdown increased miR-21-5p expression, but repressed PDCD4 expression, indicating that circRNA_0031672 competitively bound to miR-21-5p and prevented it from targeting PDCD4 mRNA. The m6A modification regulated PDCD4 expression, but had no effect on miR-21-5p targeting PDCD4. The circRNA_0031672/miR-21-5p/PDCD4 axis regulated myocardial cells viability and apoptosis after H/R treatment; co-culture with miR-21-5p-expressing BMSCs restored miR-21-5p abundance in H9C2 cells and further reduced H9C2 cells apoptosis induced by H/R.
We identified a novel circRNA_0031672/miR-21-5p/PDCD4 signaling pathway that mediates the apoptosis of cardiomyocytes and successfully alleviates IRI in myocardial cells by co-culture with miR-21-5p-expressing BMSCs, offering novel insights into the IRI pathogenesis in cardiovascular diseases.
对于冠心病患者，再灌注治疗策略常因缺血/再灌注（I/R）损伤（IRI）而变得复杂，导致严重的器官损伤和功能障碍。miR-21/程序性细胞死亡蛋白4（PDCD4）通路参与心肌细胞的IRI；然而，miR-21表达异常的原因尚不清楚。因此，本研究旨在探讨circRNA_0031672在I/R过程中是否下调miR-21-5p的表达，并确定表达miR-21-5p的骨髓间充质干细胞（BMSC）是否能减轻心肌IRI。
在I/R大鼠模型和缺氧/复氧（H/R）处理的H9C2细胞中评估circRNA_0031672、miR-21-5p和PDCD4的表达。随后使用荧光素酶报告基因和RNA下拉实验研究它们之间的相互作用。在H9C2细胞中过表达催化N6-甲基腺苷（m6A）的甲基转移酶样3，以确定m6A修饰是否影响miR-21-5p靶向PDCD4。将稳定表达miR-21的BMSC与H9C2细胞共培养，以研究BMSC对H/R处理的H9C2细胞的保护作用。
I/R下调miR-21-5p的表达，上调circRNA_0031672和PDCD4的表达。敲低circRNA_0031672可增加miR-21-5p的表达，但抑制PDCD4的表达，表明circRNA_0031672与miR-21-5p竞争性结合，阻止其靶向PDCD4 mRNA。m6A修饰调节PDCD4的表达，但对miR-21-5p靶向PDCD4没有影响。circRNA_0031672/miR-21-5p/PDCD4轴调节H/R处理后心肌细胞的活力和凋亡；与表达miR-21-5p的BMSC共培养可恢复H9C2细胞中miR-21-5p的丰度，并进一步减少H/R诱导的H9C2细胞凋亡。
我们鉴定了一条新的circRNA_0031672/miR-21-5p/PDCD4信号通路，该通路介导心肌细胞凋亡，并通过与表达miR-21-5p的BMSC共培养成功减轻心肌细胞的IRI，为心血管疾病中IRI的发病机制提供了新的见解。
