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载脂蛋白A5对心肌脂质沉积的调控及机制

杨晓洁^1,2, 李江¹, 陈静远¹, 朱腾腾¹, 陈雨思¹, 仇海花¹, 陈文杰¹, 罗小琴¹, 罗俊^1,*

¹中南大学湘雅二医院心血管内科，长沙 410011；²郑州大学附属郑州市中心医院心血管内科，郑州 450007

摘要

本研究旨在明确载脂蛋白A5 (apolipoprotein A5, ApoA5)和乳脂球表皮生长因子8 (milk fat globule-epidermal growthfactor 8, Mfge8)在调控心肌脂质沉积中的作用并探究二者之间的关系。对比不同人群血清中ApoA5 与Mfge8 含量，建立高脂饮食(high-fat diet, HFD)诱导肥胖小鼠模型，另从乳鼠提取和鉴定原代心肌细胞，加入0.8 mmol/L 棕榈酸钠建立脂质沉积心肌细胞模型。转染腺病毒以过表达ApoA5 并观察其对HFD诱导肥胖小鼠心脏功能和脂质影响，以及相关基因或蛋白表达变化；免疫共沉淀验证相关蛋白间的相互作用，免疫荧光染色观察相关蛋白在细胞中的定位。向心肌细胞中添加重组rMfge8以探究ApoA5 对Mfge8 的调控机制。结果显示：单纯肥胖组人群与健康对照组相比，血清ApoA5 水平显著降低(P < 0.05)，Mfge8 水平显著升高(P < 0.05)。ApoA5 显著减轻HFD肥胖小鼠体重(P < 0.05)、使左心室等容舒张时间(isovolumic relaxationtime, IVRT)缩短，左心室射血分数(left ventricular ejection fraction, LVEF)增加，血浆中甘油三酯(triglycerides, TG)和胆固醇含量(P < 0.05)均显著降低。ApoA5 显著减少心肌组织和细胞中TG的沉积(P < 0.05)、脂肪酸转位酶(fatty acid translocase, FAT/CD36)、脂肪酸结合蛋白(fatty acid-binding protein, FABP)、脂肪酸转运蛋白(fatty acid transport protein, FATP)的转录(P <0.05)，以及Mfge8 的蛋白表达(P < 0.05)，但对Mfge8 的转录没有显著改变(P > 0.05)。在体外以ApoA5 为诱饵蛋白捕获到了Mfge8 蛋白，说明二者之间存在直接相互作用。过表达ApoA5 会导致Mfge8 与ApoA5 或溶酶体膜相关蛋白2 (lysosomeassociatedmembrane protein 2, LAMP2)在脂质沉积状态下心肌细胞中的共定位增加，在此基础上外源添加重组rMfge8 会抵消ApoA5 对心肌细胞脂质沉积的改善作用。以上结果表明，ApoA5 可通过调控Mfge8 蛋白的含量和细胞定位，下调FAT/CD36等脂肪酸转运蛋白的表达，减少脂质沉积状态下心肌细胞对脂肪酸的摄取，从而显著减轻心肌脂质沉积并改善心脏舒张和收缩功能。

关键词： 载脂蛋白A5; 心肌细胞脂质沉积; 乳脂球表皮生长因子8

The regulation and mechanism of apolipoprotein A5 on myocardial lipid deposition

YANG Xiao-Jie^1,2, LI Jiang¹, CHEN Jing-Yuan¹, ZHU Teng-Teng¹, CHEN Yu-Si¹, QIU Hai-Hua¹, CHEN Wen-Jie¹, LUO Xiao-Qin¹, LUO Jun^1,*

¹Department of Cardiovascular Medicine, The Second Xiangya Hospital of Central South University, Changsha 410011, China；²Department of Cardiovascular Medicine, Zhengzhou Central Hospital Affiliated to Zhengzhou University, Zhengzhou 450007, China

Abstract

The current study aimed to clarify the roles of apolipoprotein A5 (ApoA5) and milk fat globule-epidermal growth factor 8 (Mfge8) in regulating myocardial lipid deposition and the regulatory relationship between them. The serum levels of ApoA5 and Mfge8 in obese and healthy people were compared, and the obesity mouse model induced by the high-fat diet (HFD) was established. In addition, primary cardiomyocytes were purified and identified from the hearts of suckling mice. The 0.8 mmol/L sodium palmitate treatment was used to establish the lipid deposition cardiomyocyte model in vitro. ApoA5-overexpressing adenovirus was used to observe its effects on cardiac function and lipids. The expressions of the fatty acid uptake-related molecules and Mfge8 on transcription or translation levels were detected. Co-immunoprecipitation was used to verify the interaction between ApoA5 and Mfge8 proteins. Immunofluorescence was used to observe the co-localization of Mfge8 protein with ApoA5 or lysosome-associated membrane protein 2 (LAMP2). Recombinant rMfge8 was added to cardiomyocytes to investigate the regulatory mechanism of ApoA5 on Mfge8. The results showed that participants in the simple obesity group had a significant decrease in serum ApoA5 levels (P < 0.05) and a significant increase in Mfge8 levels (P < 0.05) in comparison with the healthy control group. The adenovirus treatment successfully overexpressed ApoA5 in HFD-fed obese mice and palmitic acid-induced lipid deposition cardiomyocytes, respectively. ApoA5 reduced the weight of HFD-fed obese mice (P < 0.05), shortened left ventricular isovolumic relaxation time (IVRT), increased left ventricular ejection fraction (LVEF), and significantly reduced plasma levels of triglycerides (TG) and cholesterol (CHOL) (P < 0.05). In myocardial tissue and cardiomyocytes, the overexpression of ApoA5 significantly reduced the deposition of TG (P < 0.05), transcription of fatty acid translocase (FAT/CD36) (P < 0.05), fatty acid-binding protein (FABP) (P < 0.05), and fatty acid transport protein (FATP) (P < 0.05), and protein expression of Mfge8 (P < 0.05), while the transcription levels of Mfge8 were not significantly altered (P > 0.05). In vitro, the Mfge8 protein was captured using ApoA5 as bait protein, indicating a direct interaction between them. Overexpression of ApoA5 led to an increase in co-localization of Mfge8 with ApoA5 or LAMP2 in cardiomyocytes under lipid deposition status. On this basis, exogenous added recombinant rMfge8 counteracted the improvement of lipid deposition in cardiomyocytes by ApoA5. The above results indicate that the overexpression of ApoA5 can reduce fatty acid uptake in myocardial cells under lipid deposition status by regulating the content and cellular localization of Mfge8 protein, thereby significantly reducing myocardial lipid deposition and improving cardiac diastolic and systolic function.

Key words: apolipoprotein A5; cardiomyocyte lipid deposition; milk fat globule-epidermal growth factor 8

收稿日期：　　录用日期：

通讯作者：罗俊　　E-mail:

DOI: 10.13294/j.aps.2025.0009

引用本文：

杨晓洁, 李江, 陈静远, 朱腾腾, 陈雨思, 仇海花, 陈文杰, 罗小琴, 罗俊. 载脂蛋白A5对心肌脂质沉积的调控及机制[J]. 生理学报 2025; 77 (1): 35-46.

YANG Xiao-Jie, LI Jiang, CHEN Jing-Yuan, ZHU Teng-Teng, CHEN Yu-Si, QIU Hai-Hua, CHEN Wen-Jie, LUO Xiao-Qin, LUO Jun. The regulation and mechanism of apolipoprotein A5 on myocardial lipid deposition. Acta Physiol Sin 2025; 77 (1): 35-46 (in Chinese with English abstract).