Guan Kaifang, Li He, Liu DanDan, Liu Min, He Canxia
Jiangsu Engineering Research Center of Cardiovascular Drugs Targeting Endothelial Cells, College of Health Sciences, School of Life Sciences, Jiangsu Normal University, Xuzhou 221116, Jiangsu, PR China; School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150090, Heilongjiang, PR China.
Jiangsu Engineering Research Center of Cardiovascular Drugs Targeting Endothelial Cells, College of Health Sciences, School of Life Sciences, Jiangsu Normal University, Xuzhou 221116, Jiangsu, PR China.
J Dairy Sci. 2023 Mar;106(3):1562-1575. doi: 10.3168/jds.2022-22745. Epub 2023 Jan 27.
Milk fat globule-EGF factor VIII (MFG-E8) has been identified as an important source of bioactive peptides, which may exert a pivotal role in regulating biologic redox equilibrium. However, the composition of MFG-E8 polypeptides and their mechanisms on mitigating sarcopenia remain unknown. The aim of this study was to identify the composition of MFG-E8 polypeptides and its effects against oxidative stress in dexamethasone-induced L6 cell injury. Simulated digestion in vitro and liquid chromatography-tandem mass spectrometry were used in this investigation. A total of 95 peptides were identified during complete simulated digestion; among them, the contents of 21 peptides were analyzed, having been determined to exceed 1%. Molecular docking assay found that IDLG, KDPG, YYR, and YYK exhibited high binding affinity with keap1. MTT, dichlorodihydrofluorescein diacetate, mito- and lyso-tracker, and transmission electron microscope assay demonstrated that IDLG and KDPG can alleviate oxidative stress-injured L6 cell vitality, mitochondria activity, vacuolation, and function decrease, and increased autophagy, thereby improving mitochondrial homeostasis. From a molecular perspective, IDLG and KDPG can decrease the expression of keap1 and increase the expression of Nrf2, HO-1, and PGC-1α. Therefore, MFG-E8-derived IDLG and KDPG could be potential polypeptides countering oxidative stress in the treatment of sarcopenia, via the keap1/Nrf2/HO-1 signaling pathway.
乳脂肪球表皮生长因子 VIII（MFG-E8）已被确定为生物活性肽的重要来源，其可能在调节生物氧化还原平衡中发挥关键作用。然而，MFG-E8 多肽的组成及其缓解肌肉减少症的机制仍不清楚。本研究的目的是确定 MFG-E8 多肽的组成及其对 dexamethasone 诱导的 L6 细胞损伤中氧化应激的影响。本研究采用体外模拟消化和液相色谱-串联质谱法。在完全模拟消化过程中总共鉴定出 95 种肽；其中，分析了 21 种肽的含量，已确定其含量超过 1%。分子对接分析发现，IDLG、KDPG、YYR 和 YYK 与 keap1 表现出高结合亲和力。MTT、二氯二氢荧光素二乙酸酯、线粒体和溶酶体追踪器以及透射电子显微镜分析表明，IDLG 和 KDPG 可以减轻氧化应激损伤的 L6 细胞活力、线粒体活性、空泡化和功能下降，并增加自噬，从而改善线粒体稳态。从分子角度来看，IDLG 和 KDPG 可以降低 keap1 的表达并增加 Nrf2、HO-1 和 PGC-1α 的表达。因此，源自 MFG-E8 的 IDLG 和 KDPG 可能是通过 keap1/Nrf2/HO-1 信号通路在治疗肌肉减少症中对抗氧化应激的潜在多肽。
