MFG-E8 Mediates MAPK Signaling Pathway And Its Effect On Aging Rat Muscle Regeneration

Milk fat globule-epidermal growth factor 8?MFG-E8?is a kind of peripheral membrane glycoprotein separated from milk fat globule membrane?MFGM?which has much biological function.It is expressed in mammary gland,spleen,kidney,lymph node,brain and other tissues,and plays an important regulatory role in the clearance of apoptotic cells,angiogenesis and adaptive immunity.However,there are few studies on the improvement of physiological activity and mechanism of MFG-E8 in muscle atrophy.This study investigated whether bovine-derived MFG-E8 has a positive effect on prevention and treatment of sarcopenia via MAPK/ERK signal pathway in vitro C₂C₁₂2 myoblasts.The effect of MFG-E8 on C₂C₁₂2 myogenic cell vitality was assessed by MTT assay.The effect of MFG-E8 on C₂C₁₂2 myogenic cell proliferation,structure and cell cycle was assessed by fluorescence microscopy,transmission electron microscopy and flow cytometry.The effect of MFG-E8 on MAPK signaling pathway key regulatory factors was assessed by using qRT-PCR and Western Blot.Results showed that In vitro cell experiments MFG-E8 regulates C₂C₁₂2 cell proliferation mainly by regulating cell cycle and mediating MAPK/ERK signaling pathway,rather than JNK and p38 signaling pathways.To further study the effect of MFG-E8 on muscle atrophy in aging rats.aging model was established by injection of D-gal in SD rats,the therapeutic effect of MFG-E8 on muscle atrophy was investigated in aging rat model.Results showed that the body weight and organ coefficient of the model rats significantly decreased,soleus muscle mass decreased by 24.14%,SOD content in serum decreased by28.10%,MDA content increased by 38.54%.The physiological indexes of rats in MFG-E8 group showed that the quality of gastrocnemius muscle and soleus muscle increased by 65.47%,35.61%,respectively.the contents of TG,MDA and NEFA decreased by 44.83%,38.76%,51.50%,respectively.And the content of SOD increased by 32.31%.These results demonstrated that MFG-E8 can promoting muscle regeneration in aging rats by mediating MAPK/ERK signaling pathway?MAPK/p38 may have synergistic effect?and cell cycle at molecular level in vivo rat model.