N-glycoproteomic analysis of Ginsenoside Rb1 on a hyperlipidemia rat model

Abstract

Abstract Background: Ginsenoside Rb1, known as Renshen in traditional Chinese medicine, is one of the major bioactive saponins isolated from Panax ginseng C.A.Mey. N-glycosylation is the most common type of post-translational modification in cells. The widespread localization of N-glycosylated proteins (N-glycoproteins) between extracellular spaces and on the cell surfaces give them unique advantages as disease biomarkers and drug targets. Previous study found that Ginsenoside Rb1 could potentially play a preventive role in hyperlipidemia. This study aims to reveal the hypolipidemic effect at the protein modification level. Methods: 24 male SD rats were randomly devided into 3 groups: control group (CON), high fat diet group (HFD) and Ginsenoside Rb1 group (Rb1). Both HFD and Rb1 groups were fed with high-fat diet for 12 weeks. The Rb1 group started intragastric administering Ginsenoside Rb1 200 mg·kg -1 ·d -1 at 5th week for 8 weeks, while the CON and HFD group the same amount of normal saline for the same amount of time. Lipid levels and liver histology were assayed to evaluate the effects of Ginsenoside Rb1 intake on hyperlipidemia rats. Furthermore, the workflow by combination of isotope TMT labeling, HILIC enrichment, and high-resolution LC-MS/MS analysis were employed to exploring the mechanisms of regulation role in hyperlipidemia rats.Results: The histopathologic characteristics and biochemical data shows that Ginsenoside Rb1 exhibited regulative effects on hyperlipidemia rats. After being analyzed by N-glycoproteomic, 98 differential N-glycosylation sites on 53 glycoproteins between 2 comparison groups (HFD: CON, Rb1: HFD) were identified. Analyses of N-glycosylation sites distribution found that albumin (Alb) and Serpinc1 were most heavily modified with 6 N-glycosylation sites changed in this work. GO enrichment analysis showed that differential modified glycoproteins were involved in inflammatory response, cellular iron ion homeostasis and positive regulation of cholesterol efflux etc. biosynthetic process. Complement and coagulation cascades was the most significant enriched in the KEGG pathway enrichment analysis. Conclusions: This study presents a comprehensive analysis of a new set of N-glycoproteins which are altered by Ginsenoside Rb1 and offers some valuable clues for novel mechanistic insights into the ragulative mechanism of Ginsenoside Rb1. Results from N-glycoproteomic suggest that to suppress hyperlipidemia, Rb1 may regulates N-glycosylation of Alb, Serpinc1, PON1, Lrp1, Cp and THBS1, as well as differentially modified glycoproteins in complement and coagulation cascades, which in turn improve the imbalance of lipid homeostasis.