Identification and antioxidative mechanism of novel mitochondria-targeted MFG-E8 polypeptides in virtual screening and in vitro study

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 re-dox equilibrium. However, the composition of MFG-E8 polypeptides and their mechanisms on mitigating sar-copenia 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, hav-ing been determined to exceed 1%. Molecular docking assay found that IDLG, KDPG, YYR, and YYK exhib-ited high binding affinity with keap1. MTT, dichlorodi-hydrofluorescein 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, vacuola-tion, 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-1 alpha. Therefore, MFG-E8-derived IDLG and KDPG could be potential polypeptides coun-tering oxidative stress in the treatment of sarcopenia, via the linked disorder Sartori tion, tion, accompanied lular mitochondrial oxidant/antioxidant drial Nrf2 mon muscle the adverse (Matsumaru chondrial cellular Rapid further ATP and muscle further been fat

Automated summary

Milk fat globule-EGF factor VIII (MFG-E8) is a potential source of bioactive peptides that can counteract oxidative stress in the treatment of sarcopenia. This study identified 95 peptides in MFG-E8 and found that IDLG and KDPG exhibited high binding affinity with keap1. In cell experiments, IDLG and KDPG alleviated oxidative stress-induced L6 cell injury and improved mitochondrial homeostasis. These effects were attributed to the downregulation of keap1 expression and upregulation of Nrf2, HO-1, and PGC-1 alpha expression.