Cardiovascular Department, Shanghai Xuhui Central Hospital, Fudan University, Shanghai, 200031, China; National Clinical Research Center for Interventional Medicine, Shanghai, 200032, China.
National Clinical Research Center for Interventional Medicine, Shanghai, 200032, China; Department of General Surgery, Shanghai Xuhui Central Hospital, Fudan University, Shanghai, 200031, China.
Redox Biol. 2024 Apr;70:103081. doi: 10.1016/j.redox.2024.103081. Epub 2024 Feb 9.
Heart failure with preserved ejection fraction (HFpEF) is a devastating health issue although limited knowledge is available for its pathogenesis and therapeutics. Given the perceived involvement of mitochondrial dysfunction in HFpEF, this study was designed to examine the role of mitochondrial dynamics in the etiology of HFpEF.
Adult mice were placed on a high fat diet plus l-NAME in drinking water ('two-hit' challenge to mimic obesity and hypertension) for 15 consecutive weeks. Mass spectrometry revealed pronounced changes in mitochondrial fission protein Drp1 and E3 ligase FBXL4 in 'two-hit' mouse hearts. Transfection of FBXL4 rescued against HFpEF-compromised diastolic function, cardiac geometry, and mitochondrial integrity without affecting systolic performance, in conjunction with altered mitochondrial dynamics and integrity (hyperactivation of Drp1 and unchecked fission). Mass spectrometry and co-IP analyses unveiled an interaction between FBXL4 and Drp1 to foster ubiquitination and degradation of Drp1. Truncated mutants of FBXL4 (Delta-Fbox) disengaged interaction between FBXL4 and Drp1. Metabolomic and proteomics findings identified deranged fatty acid and glucose metabolism in HFpEF patients and mice. A cellular model was established with concurrent exposure of high glucose and palmitic acid as a 'double-damage' insult to mimic diastolic anomalies in HFpEF. Transfection of FBXL4 mitigated 'double-damage'-induced cardiomyocyte diastolic dysfunction and mitochondrial injury, the effects were abolished and mimicked by Drp1 knock-in and knock-out, respectively. HFpEF downregulated sarco(endo)plasmic reticulum (SR) Ca uptake protein SERCA2a while upregulating phospholamban, RYR1, IP3R1, IP3R3 and Na-Ca exchanger with unaltered SR Ca load. FBXL4 ablated 'two-hit' or 'double-damage'-induced changes in SERCA2a, phospholamban and mitochondrial injury.
FBXL4 rescued against HFpEF-induced cardiac remodeling, diastolic dysfunction, and mitochondrial injury through reverting hyperactivation of Drp1-mediated mitochondrial fission, underscoring the therapeutic promises of FBXL4 in HFpEF.
射血分数保留的心力衰竭（HFpEF）是一种严重的健康问题，尽管其发病机制和治疗方法的知识有限。鉴于线粒体功能障碍在 HFpEF 中的作用，本研究旨在研究线粒体动力学在 HFpEF 发病机制中的作用。
成年小鼠连续 15 周接受高脂肪饮食加 l-NAME 饮用水（“双重打击”以模拟肥胖和高血压）。质谱分析显示，“双重打击”小鼠心脏中线粒体分裂蛋白 Drp1 和 E3 连接酶 FBXL4 发生明显变化。FBXL4 转染可挽救 HFpEF 引起的舒张功能障碍、心脏几何形状和线粒体完整性，而不影响收缩功能，同时改变线粒体动力学和完整性（Drp1 过度激活和不受控制的分裂）。质谱分析和共免疫沉淀分析揭示了 FBXL4 与 Drp1 之间的相互作用，以促进 Drp1 的泛素化和降解。FBXL4 的截断突变体（Delta-Fbox）使 FBXL4 与 Drp1 之间的相互作用脱钩。代谢组学和蛋白质组学发现 HFpEF 患者和小鼠存在脂肪酸和葡萄糖代谢紊乱。建立了一个细胞模型，同时暴露于高葡萄糖和棕榈酸，以模拟 HFpEF 的舒张异常。FBXL4 转染可减轻“双重打击”诱导的心肌细胞舒张功能障碍和线粒体损伤，这些作用分别被 Drp1 敲入和敲除所消除和模拟。HFpEF 下调肌浆网（SR）Ca 摄取蛋白 SERCA2a，而上调肌球蛋白轻链磷酸酶、肌质网 RyR1、IP3R1、IP3R3 和 Na-Ca 交换体，而 SR Ca 负荷不变。FBXL4 消除了“双重打击”或“双重打击”诱导的 SERCA2a、肌球蛋白轻链磷酸酶和线粒体损伤的变化。
FBXL4 通过逆转 Drp1 介导的线粒体分裂的过度激活，挽救 HFpEF 引起的心脏重构、舒张功能障碍和线粒体损伤，凸显了 FBXL4 在 HFpEF 中的治疗潜力。
