ABSTRACT
To investigate the mechanism by which Schisandra Chinensis mediates the phenotypic transformation of microglia via microRNA-124 (miR-124)-based regulation of the Toll-like receptor 4 (TLR4) pathway, a model was established using lipopolysaccharide (LPS) stimulation of BV2 cells. Cells were treated with different doses of Schisandra Chinensis extract (SCE). MiR-124 inhibitors and negative control sequences (NC inhibitor) were transfected into LPS-induced BV2 cells and treated with SCE. The MTT assay was used for cell activity detection; an NO kit was used to measure NO release; ELISA kits were used to measure the levels of interleukin-10 (IL-10) and tumor necrosis factor-α (TNF-α). Microglia markers, including ionized calcium binding adapter molecule-1 (IBA-1) and arginase-1 (Arg-1), and the nuclear translocation of nuclear factor-kappa B (NF-κB) were evaluated by immunofluorescent staining. NF-κB p65, IBA-1, Arg-1, TLR4, myeloid differentiation primary factor 88 (MyD88), inhibitor of nuclear factor-kappa B kinases-α (IKK-α), IL-10, TNF-α were detected by immunoblot. SCE at concentrations ranging from 31.25 to 250 μg·mL-1 had no significant effect on cell activity. SCE treatment significantly inhibited NO release induced by LPS (P < 0.001, P < 0.01), increased the level of IL-10 (P < 0.05), and decreased the level of TNF-α (P < 0.001). In addition, SCE significantly reduced the expression of TNF-α, IBA-1, TLR4, and MyD88 (P < 0.01, P < 0.001) and elevated the expression of IL-10, Arg-1, NF-κB P65 and IKK-α (P < 0.001, P < 0.01, P < 0.05). SCE treatment could also promote the expression of miR-124 (P < 0.01). However, transfection with the miR-124 inhibitor increased TNF-α (P < 0.001), decreased the level of IL-10 (P < 0.05), increased the mRNA level and the protein expression of TNF-α and IBA-1 (P < 0.05, P < 0.01, P < 0.001), and decreased the mRNA level and protein expression of IL-10 and Arg-1 (P < 0.001, P < 0.01). In addition, the inhibition of TLR4 and MyD88 was attenuated. In conclusion, SCE appears to inhibit the activation of TLR4 signaling pathway by upregulating miR-124 so as to inhibit microglia M1 polarization and promote microglia M2 polarization.
ABSTRACT
The 2-oxoglutarate-dependent dioxygenase (2-ODD) gene is regarded as the key enzyme gene involved with aryl naphthalene lignan-podophyllotoxin synthesis. To study the expression pattern and function of the Sc2-ODD gene, a full-length cDNA of the gene was cloned. Bioinformatic analysis, the expression pattern, and prokaryotic expression and purification were implemented. The open reading frame of Sc2-ODD gene was 1 077 bp and encoded 358 amino acids with a molecular weight of 40.16 kD. The Sc2-ODD protein contained the conserved 2OG-FeII-oxy sequence of the 2-ODD protein. The results of phylogenetic analysis revealed that Sc2-ODD is most closely related to Corchorus olitorius 2-ODD. qRT-PCR results showed that Sc2-ODD expression displayed obvious up-regulation at the fruit-swelling stage, then down-regulation in the fruit-coloring period. The Sc2-ODD gene was cloned into the bacterial expression vector pGS21T, the recombinant Sc2-ODD protein was expressed in Escherichia coli Rosetta (DE3) cells and the fusion protein was obtained and purified by GST fusion protein purification technology. This study will lay a foundation for further research on the function and expressional regulation of the Sc2-ODD gene in the aryl naphthalene lignans biosynthesis pathway, and also provides a scientific basis for improving the lignan content and the medicinal quality of Schisandra chinensis using plant genetic engineering.