Jacalin Bound Plasma O-Glycoproteome and Reduced Sialylation of Alpha 2-HS Glycoprotein (A2HSG) in Rheumatoid Arthritis Patients

Ashish Saroha,Bishnu P Chatterjee,Saravanan Kumar,Hasi R Das,Anand S Mehta

doi:10.1371/journal.pone.0046374

Abstract

Glycosylation studies of plasma proteins can reveal information about the onset and progression of diseases, where in the glycan biosynthetic pathways are disturbed as in rheumatoid arthritis (RA). The present study was focused on analysis of O-linked glycoproteins of plasma in RA patients. Two dimensional gel electrophoresis of jacalin bound plasma of RA patients revealed a number of differentially expressed protein spots as compared to healthy controls. Eighteen protein spots were found to have statistically significant (p<0.05) difference in their expression level from four sets of gels and were identified by MALDI-TOF MS. Most of the identified proteins were predicted to be O-glycosylated proteins by Net–O-Gly 3.1 algorithm. Among these the alpha 2HS glycoprotein (A2HSG) was found to be down regulated whereas inter alpha trypsin inhibitor H4 (ITIH4) was up regulated and this was validated by Western blotting. The glycosylation studies showed the reduced N-linked sialylation of A2HSG in RA patients. Altered glycoprotein expression and functional as well as structural studies of glycans might help in the diagnosis of RA and understanding the disease pathogenesis.

Highlights

Glycoproteins play important roles in cellular functions like cell to cell adhesion, cell migration, cell signaling, immunity, and various other intracellular processes through their glycans [1,2,3]
The changes of protein expression in rheumatoid arthritis (RA) patients were calculated with respect to control from four sets of gels
The difference in Macckia ammurensis agglutinin (MAA) binding between control and patients’ plasma reduced significantly after enzyme treatment. These results indicated the 0.3 fold sialylation (Neu5Ac a2, 3) difference in Nlinked glycans of alpha 2HS glycoprotein (A2HSG) in RA patients (Figure 4B)

Summary

Introduction

Glycoproteins play important roles in cellular functions like cell to cell adhesion, cell migration, cell signaling, immunity, and various other intracellular processes through their glycans [1,2,3]. Cellular factors play a pivotal role in the regulation of the glycosylation reactions in cells. Many subtle changes in functions of glycoproteins were found to be attributable to changes in composition or structure of the glycan moieties. Interest in glycoproteomic analysis has gained momentum to identify the glycan based disease markers. As plasma is an important reservoir of glycoproteins and reflects the patho-physiological condition of the body, the plasma glycoproteins hold a great potential to recognize disease specific glycan based molecular fingerprints [7,8]. Disease related biomarker discovery has grown dramatically to replace sub optimal in-vitro diagnostic assays

Methods

Results

Discussion

Conclusion