Microfluidic Chip-LC/MS-based Glycomic Analysis Revealed Distinct N-glycan Profile of Rat Serum.

Wei-Na Gao,Zhi-Hong Jiang,Liang Liu,Min Jiang,Lee-Fong Yau,Ju Liu,Jing-Rong Wang,Xing Zeng,Da-Can Chen

doi:10.1038/srep12844

Abstract

The rat is an important alternative for studying human pathology owing to certain similarities to humans. Glycomic studies on rat serum have revealed that variations in the N-glycans of glycoproteins correlated with disease progression, which is consistent with the findings in human serum. Therefore, we comprehensively characterized the rat serum N-glycome using microfluidic chip-LC-ESI-QTOF MS and MS/MS techniques. In total, 282 N-glycans, including isomers, were identified. This study is the first to present comprehensive profiling of N-glycans containing O-acetylated sialic acid, among which 27 N-glycans are novel. In addition, the co-existence of N-acetylneuraminic acid (NeuAc) and N-glycolylneuraminic acid (NeuGc) in a single N-glycan (‘mixed’ N-glycan) was detected and represents a new type of N-glycan in rat serum. The existence of O-acetylated sialic acid is the characteristic feature of rat serum that distinguishes it from mouse and human sera. Comparisons between the rat, mouse, and human serum glycomes revealed that the rat glycome is more similar to that of human sera than to that of mouse sera. Our findings highlight the similarities between the glycomic profile of rat and human sera and provided important selection criteria for choosing an appropriate animal model for pathological and pharmacological studies.

Highlights

In the post-genomic era, glycosylation has been brought to public attention as a frontier[4]
Glycomic studies of liver cancer in rats revealed that variations in fucosylation of N-glycans in serum glycoproteins was closely related to the progression of hepatocellular carcinomas
Direct measurements of free N-glycans may seem to be limited in that the information associated with the structure of the glycoprotein is lost owing to the deglycosylation step, such measurements are still significative because: (1) N-glycans are often the crucial functional elements in cellular and biomolecular interactions; (2) glycomic techniques are methodologically easier than the glycoproteomic approaches 5.To carry out a comprehensive glycomic study, the primary analytical challenge is the detection and identification of rat-specific N-glycans, especially those in low abundance and unknown N-glycans

Summary

Introduction

In the post-genomic era, glycosylation has been brought to public attention as a frontier[4]. Glycomic studies of liver cancer in rats revealed that variations in fucosylation of N-glycans in serum glycoproteins was closely related to the progression of hepatocellular carcinomas. This was consistent with observations for human liver cancer[9,10,11]. We developed a microfluidic porous graphitized carbon (PGC) chip-LC/MS-based approach for the profiling of rat serum N-glycans. The PGC-based stationary phase enables isomer-specific separation of N-glycans, and facilitates maximum resolution of the overlapping ions[15] Employment of this microfluidic PGC chip-LC/MS technique in glycomic studies would provide high sensitivity and high resolution. This report describes the comprehensive glycome profiling of rat serum using this newly developed technique and reports glycomic comparisons of rat, mouse, and human sera

Objectives

Methods

Results

Conclusion