Calenduloside E (CE) is a saponin isolated from Aralia elata (Miq) Seem, which has anti-cardiovascular disease effects. This study aims to evaluate the anti-myocardial ischemia-reperfusion injury (MIRI) mechanisms of CE and regulation of BAG3 on calcium overload. We adopted siRNA to interfere with BAG3 expression in H9c2 cardiomyocytes and used adenovirus to interfere with BAG3 expression (Ad-BAG3) in primary neonatal rat cardiomyocytes (PNRCMs) to clarify the role of BAG3 in mitigating MIRI by CE. The results showed that CE reduced calcium overload, and Ad-BAG3 had a significant regulatory effect on L-type Ca²⁺ channels (LTCC) but no effects on other calcium-related proteins. And BAG3 and LTCC were colocalized in myocardial tissue and BAG3 inhibited LTCC expression. Surprisingly, CE had no regulatory effect on LTCC mRNA, but CE promoted LTCC degradation through the autophagy-lysosomal pathway rather than the ubiquitination-protease pathway. Autophagy inhibitor played a negative regulation of cardiomyocyte contraction rhythm and field potential signals. Ad-BAG3 inhibited autophagy by regulating the expression of autophagy-related proteins and autophagy agonist treatment suppressed calcium overload. Therefore, CE promoted autophagy through BAG3, thereby regulating LTCC expression, inhibiting calcium overload, and ultimately reducing MIRI.

Calenduloside E (CE) 是一种从Aralia elata (Miq) Seem 中分离出来的皂苷，具有抗心血管疾病的作用。本研究旨在评估 CE 的抗心肌缺血再灌注损伤 (MIRI) 机制和 BAG3 对钙超载的调节。我们采用 siRNA 干扰 H9c2 心肌细胞中 BAG3 的表达，并使用腺病毒干扰原代新生大鼠心肌细胞 (PNRCMs) 中的 BAG3 表达 (Ad-BAG3)，以阐明 BAG3 在通过 CE 减轻 MIRI 中的作用。结果表明，CE降低钙超载，Ad-BAG3对L型Ca ^{2+有显着调节作用}通道（LTCC），但对其他钙相关蛋白没有影响。BAG3和LTCC共定位于心肌组织中，BAG3抑制LTCC的表达。令人惊讶的是，CE 对 LTCC mRNA 没有调节作用，但 CE 通过自噬-溶酶体途径而不是泛素化-蛋白酶途径促进 LTCC 降解。自噬抑制剂对心肌细胞收缩节律和场电位信号起负调控作用。Ad-BAG3 通过调节自噬相关蛋白的表达来抑制自噬，而自噬激动剂治疗可抑制钙超载。因此，CE通过BAG3促进自噬，从而调节LTCC表达，抑制钙超载，最终降低MIRI。