Quercetin reverses β1-adrenoceptor autoantibody-induced heart 1 failure by promoting MDM2-mediated ubiquitination and 2 degradation of p53 in cardiomyocytes

Mingxia MaXintai JiangWeiqian LiuJin XueYuan YuanXiaoyan ZhiJiayan FengYaolin LongYang LiZhijun ZhangXiaohui WangLi Wang^*

• Shanxi Medical University, Taiyuan, China

Introduction: Cardiomyocyte autophagy is essential for preserving cardiac 24 homeostasis. Previous studies revealed that β1-adrenergic receptor autoantibody 25 (β1-AA) suppressed cardiomyocyte autophagy, triggering cell death and heart failure 26 (HF). Qiliqiangxin capsule enhances autophagy and mitigates HF through multiple 27 pathways, but its complex composition complicates mechanistic clarity. Network 28 pharmacology identified quercetin as a pivotal autophagy-inducing component in 29 Qiliqiangxin, yet its role in counteracting β1-AA-induced autophagy impairment 30 remains unvalidated. In this study quercetin's therapeutic potential and mechanisms in 31 restoring autophagy in β1-AA-associated HF. 32 Methods: Bioinformatics methods, including a STRING database analysis, PPI 33 network construction, and Cytoscape-based pathway mapping, were used to delineate 34 quercetin's autophagy-related targets. The in vivo efficacy was assessed in 35 β1-AA-positive mice treated with quercetin (100 mg/[kg·d], intraperitoneal). The in 36 vitro validation used H9c2 cardiomyocytes pretreated with quercetin (100 μM) prior 37 to β1-AA exposure. Autophagy markers, p53 signaling, and ubiquitination pathways 38 were analyzed by immunoblotting and functional enrichment analysis using the 39 GOrilla database. A p53 knockdown and overexpressing cardiomyocyte model 40 confirmed pathway specificity. 41 Results: Quercetin administration significantly restored myocardial autophagy levels 42 in β1-AA-positive mice, which improved cardiac function and survival rates. In H9c2 43 cells, quercetin pretreatment reversed β1-AA-induced autophagy suppression. 44 Bioinformatics linked quercetin to p53 pathway modulation, with experimental 45 validation showing quercetin downregulated p53 expression via MDM2-mediated 46 ubiquitination. p53 knockdown enhanced autophagy, while its overexpression blocked 47 quercetin's effect, indicating quercetin restores autophagy in a p53-dependent manner. 48 GO enrichment highlighted the association between quercetin and 49 ubiquitin-dependent protein degradation, which was corroborated by elevated MDM2 50 levels and accelerated p53 degradation in quercetin-treated cells. 51 字体: (默认)Times New Roman Italic, 倾斜 设置格式[Mingxia Ma]: 3 Discussion: Quercetin rescues β1-AA-impaired cardiomyocyte autophagy by 52 activating MDM2-dependent p53 ubiquitination and degradation, thereby attenuating 53 HF progression. These findings establish quercetin as a mechanistic basis of the 54 cardioprotective effects of Qiliqiangxin and provide preclinical evidence for targeting 55 autophagy by regulating p53 in β1-AA-induced cardiac dysfunction.