Structure identification of selenium-biofortified soybean peptides and its effect on TGF-β mediated liver fibrosis pathway

Abstract

Selenium-biofortified soybean peptides (SeSPs) has been verified to relieve CCl4-induced liver fibrosis in vivo previously. In the present study, the structures of SeSPs were characterized by HPLC-ESI-MS/MS and thirty-eight selenium-containing peptides sequences were identified. KLPISeM was screened out as the most promising peptide to inhibit TGF-β/Smads pathway with stable binding site to TGF-β in molecular docking. Besides, homo sapiens liver cell line (L-O2) and hepatic stellate cells from rat (HSC-T6) were treated with KLPISeM/KLPIM and TGF-β1 to explore the regression fibrosis mechanisms of peptides. Results showed that the apoptosis trend of L-O2 was inhibited while HSC-T6 apoptosis was promoted by KLPISeM. Smad2/3/4 gene levels were reduced by 60.36%, 59.08% and 71.82%, respectively and Smad7 gene expression was upregulated significantly (p < 0.05) after incubation with KLPISeM. More importantly, KLPISeM exhibited strong up-regulation effect on matrix metallo-proteinase (MMPs) and suppressive effect on tissue inhibitor of metalloproteinase gene/protein expressions in HSC-T6. These results suggested that KLPISeM could relieve liver fibrosis by blocking TGF-β/Smads and regulating MMPs/TIMPs pathway.