Department of Anesthesiology, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Tianjin's Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin, China.
Department of Anesthesiology, Tianjin Medical University General Hospital, Tianjin, China.
Shock. 2023 Jan 1;59(1):91-98. doi: 10.1097/SHK.0000000000002031. Epub 2023 Jan 8.
Ischemic postconditioning (I/Post) reduces I/R injury by activating endogenous cardioprotection mechanisms, such as the JAK/signal transducer and activator of transcription 3 (STAT3) and PI3K/Akt pathways, which offer a traditional approach to myocardial protection. According to a previous study, cardioprotection by I/Post may be lost in aged mice, and in our previous research, hypoxic postconditioning (H/Post) lacked a protective effect in senescent cardiomyocytes, which was associated with low expression of long noncoding RNA H19. The N6-methyladenosine (m 6 A) modification is a dynamic and reversible process that has been confirmed to play a role in cardiovascular diseases. However, the mechanisms of m 6 A modification in myocardial I/Post remain to be explored. Neonatal cardiomyocytes were isolated from 2-day-old Sprague-Dawley rats, and senescence was induced by d -galactose, followed by stimulation of hypoxia-reoxygenation and H/Post. Hypoxic injury was evaluated by cell viability and the Bcl-2/Bax protein ratio. Total m 6 A levels were measured using a colorimetric m 6 A RNA Methylation Quantification Kit, and the m 6 A modified and differentially expressed mRNA was determined by MeRIP (methylated RNA immunoprecipitation). We found that H/Post increased m 6 A methylation and decreased RNA mA demethylase alkB homolog 5 (ALKBH5) expression in aged cardiomyocytes. Furthermore, ALKBH5 knockdown exacerbated injury following H/Post in senescent cardiomyocytes. In addition, ALKBH5 regulated STAT3 expression by mediating its m 6 A modification and long noncoding RNA H19/miR-124-3p. ALKBH5 also alleviated the H/Post injury induced by the low expression of STAT3 in senescent cardiomyocytes.
缺血后处理（I/Post）通过激活内源性保护机制，如 JAK/信号转导和转录激活因子 3（STAT3）和 PI3K/Akt 途径，减轻 I/R 损伤，为心肌保护提供了一种传统方法。根据之前的一项研究，I/Post 的心脏保护作用可能会在老年小鼠中丧失，而在我们之前的研究中，低氧后处理（H/Post）在衰老的心肌细胞中缺乏保护作用，这与长链非编码 RNA H19 的低表达有关。N6-甲基腺苷（m6A）修饰是一个动态且可逆的过程，已被证实与心血管疾病有关。然而，心肌 I/Post 中 m6A 修饰的机制仍有待探索。本研究从 2 日龄 Sprague-Dawley 大鼠中分离出新生大鼠心肌细胞，并用 D-半乳糖诱导衰老，然后进行缺氧复氧和 H/Post 刺激。通过细胞活力和 Bcl-2/Bax 蛋白比值评估缺氧损伤。使用比色 m6A RNA 甲基化定量试剂盒测量总 m6A 水平，并用 MeRIP（甲基化 RNA 免疫沉淀）测定 m6A 修饰和差异表达的 mRNA。结果发现，H/Post 增加了衰老心肌细胞中的 m6A 甲基化，并降低了 RNA mA 去甲基酶 alkB 同源物 5（ALKBH5）的表达。此外，在衰老的心肌细胞中，ALKBH5 的敲低加剧了 H/Post 后的损伤。此外，ALKBH5 通过调节其 m6A 修饰和长链非编码 RNA H19/miR-124-3p 来调节 STAT3 的表达。ALKBH5 还缓解了衰老心肌细胞中 STAT3 低表达引起的 H/Post 损伤。
