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ObjectiveTo study the mechanism of Renshen Baidusan in regulating adenylate-activated protein kinase （AMPK）/Unc-51-like kinase 1 （ULK1） autophagy pathway to inhibit mucosal barrier damage in the mouse model of ulcerative colitis （UC）. MethodSixty SD rats were randomized into normal， model， sulfasalazine enteric-coated tablets （0.312 5 g·kg-1， western medicine）， and high-， medium-， and low-dose （31.2， 15.6， 7.8 g·kg-1， respectively） Renshen Baidusan groups. The UC model was induced by 2，4，6-trinitrobenzenesulfonic acid （TNBS）/50% ethanol. The drugs were administrated by gavage for 2 weeks， and then the histopathological changes of the colon were examined. Real-time quantitative polymerase chain reaction was conducted to measure the mRNA level of AMP-activated protein kinase subunit alpha （AMPKα）. Western blot was employed to determine the protein levels of closure protein （Occludin）， compact linking protein-2 （Claudin-2）， autophagy marker p62， microtubule-associated protein 1 light chain 3B （LC3B）， phosphorylated AMPK （p-AMPK）， and phosphorylated ULK1 （p-ULK1）. ResultCompared with the normal group， the model group showed increased colon injury score （P<0.05）， down-regulated mRNA level of AMPKα （P<0.05） and protein levels of p-AMPK， p-ULK1， and Occludin， decreased LC3Ⅱ/Ⅰ ratio （P<0.05）， and up-regulated protein levels of p62 and Claudin-2 （P<0.05）. Compared with the model group， all the doses of Renshen Baidusan lowered the colon injury score， up-regulated the mRNA level of AMPKα and the protein levels of p-AMPK， p-ULK1， and Occluding， increased LC3Ⅱ/Ⅰ ratio， and down-regulated the protein levels of p62 and Claudin-2. Moreover， the medium-dose group showed a significant intervention effect （P<0.05）. ConclusionRenshen Baidusan can protect the intestinal mucosal barrier from damage， and the medium dose showed the best efficacy. It may activate the AMPK/ULK1 pathway to accelerate the transformation of LC3Ⅰ to LC3Ⅱ and promote the degradation of p62， so as to improve the function of Occludin and Claudin-2 and repair the mechanical damage of the intestinal barrier.
RESUMO
BACKGROUND: Duchenne muscular dystrophy (DMD) is an X-linked lethal genetic disorder for which there is no effective treatment. Previous studies have shown that stem cell transplantation into mdx mice can promote muscle regeneration and improve muscle function, however, the specific molecular mechanisms remain unclear. DMD suffers varying degrees of hypoxic damage during disease progression. This study aimed to investigate whether induced pluripotent stem cells (iPSCs) have protective effects against hypoxia-induced skeletal muscle injury. RESULTS: In this study, we co-cultured iPSCs with C2C12 myoblasts using a Transwell nested system and placed them in a DG250 anaerobic workstation for oxygen deprivation for 24 h. We found that iPSCs reduced the levels of lactate dehydrogenase and reactive oxygen species and downregulated the mRNA and protein levels of BAX/BCL2 and LC3II/ LC3I in hypoxia-induced C2C12 myoblasts. Meanwhile, iPSCs decreased the mRNA and protein levels of atrogin-1 and MuRF-1 and increased myotube width. Furthermore, iPSCs downregulated the phosphorylation of AMPKA and ULK1 in C2C12 myotubes exposed to hypoxic damage. CONCLUSIONS: Our study showed that iPSCs enhanced the resistance of C2C12 myoblasts to hypoxia and inhibited apoptosis and autophagy in the presence of oxidative stress. Further, iPSCs improved hypoxia-induced autophagy and atrophy of C2C12 myotubes through the AMPK/ULK1 pathway. This study may provide a new theoretical basis for the treatment of muscular dystrophy in stem cells.