Myocardial ischemia is a serious disease which threatens human's life. Lentinan (LEN) possesses multiple biological properties: anticancer, antibacterial, antiviral and antioxidant effects. Our study investigated the effects of LEN on hypoxia-stimulated cardiomyocytes and the underlying mechanism. Primary neonatal rat ventricular cardiomyocytes (PNCM) were isolated from neonate rat pups. PNCM and H9c2 cells were stimulated by hypoxia and treated by LEN. Cell viability and apoptosis were detected by cell counting kit-8 and flow cytometry, respectively. Moreover, apoptotic factors were examined by western blot. Phosphatidylinositol 3'-kinase (PI3K)/protein kinase B (AKT) and β-catenin pathways related proteins were analyzed by western blot. Furthermore, the expression of microRNA-22 (miR-22) was detected by qRT-PCR. Altered expression of miR-22 and silenced information regulator 1 (Sirt1) was achieved by transfection. The relationship between miR-22 and Sirt1 was verified by luciferase assay. We found that LEN promoted cell viability and decreased apoptosis which led to the contrary results with what hypoxia induced. Moreover, LEN decreased the ratio of Bax to Bcl-2 and the level of cleaved caspase-3, as well as activated PI3K/AKT and β-catenin. LEN decreased the expression of miR-22 which was upregulated by hypoxia. miR-22 overexpression broken the promoting effects led by LEN. Moreover, Sirt1 was verified to be a target of miR-22. Silence of Sirt1 led to the opposite results with LEN. In conclusion, LEN relieved hypoxia-induced cellular injuries evidenced by increasing viability and decreasing apoptosis via down-regulation of miR-22, which was accompanied by activation of PI3K/AKT and β-catenin pathways. Highlights Lentinan alleviates hypoxia-induced injuries of PNCM and H9c2 cells; microRNA-22 expression is decreased by lentinan; Lentinan reduces hypoxia-induced injury by microRNA-22 downregulation; Lentinan regulates PI3K/AKT and Wnt/β-catenin by regulation of microRNA-22/Sirt1.

中文翻译：

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香菇多糖通过调节 microRNA-22/Sirt1 保护心肌细胞免受缺氧诱导的损伤。

心肌缺血是一种严重威胁人类生命的疾病。香菇多糖 (LEN) 具有多种生物学特性：抗癌、抗菌、抗病毒和抗氧化作用。我们的研究调查了 LEN 对缺氧刺激心肌细胞的影响及其潜在机制。从新生大鼠幼崽中分离出原代新生大鼠心室心肌细胞 (PNCM)。PNCM 和 H9c2 细胞被缺氧刺激并被 LEN 处理。细胞活力和凋亡分别通过细胞计数试剂盒-8 和流式细胞术检测。此外，通过蛋白质印迹检查凋亡因子。通过蛋白质印迹分析磷脂酰肌醇 3'-激酶 (PI3K)/蛋白激酶 B (AKT) 和 β-连环蛋白途径相关蛋白。此外，通过qRT-PCR检测microRNA-22（miR-22）的表达。miR-22 和沉默信息调节因子 1 (Sirt1) 的表达改变是通过转染实现的。miR-22和Sirt1之间的关系通过荧光素酶测定验证。我们发现 LEN 促进细胞活力并减少细胞凋亡，这导致与缺氧诱导的结果相反。此外，LEN 降低了 Bax 与 Bcl-2 的比率和裂解的 caspase-3 的水平，以及激活的 PI3K/AKT 和 β-catenin。LEN降低了缺氧上调的miR-22的表达。miR-22 的过表达破坏了 LEN 导致的促进作用。此外，Sirt1 被证实是 miR-22 的靶标。Sirt1 的沉默导致了与 LEN 相反的结果。总之，LEN 减轻了缺氧诱导的细胞损伤，这可以通过下调 miR-22 增加活力和减少细胞凋亡来证明，伴随着 PI3K/AKT 和 β-catenin 通路的激活。亮点香菇多糖减轻缺氧引起的 PNCM 和 H9c2 细胞损伤；香菇多糖降低 microRNA-22 表达；香菇多糖通过 microRNA-22 下调减少缺氧诱导的损伤；香菇多糖通过调节 microRNA-22/Sirt1 来调节 PI3K/AKT 和 Wnt/β-catenin。