Organ-specific Heparan Sulfate Structural Phenotypes

Xiaofeng Shi,Joseph Zaia

doi:10.1074/jbc.m809637200

Abstract

The functions of heparan sulfate (HS) depend on the expression of structural domains that interact with protein partners. Glycosaminoglycans (GAGs) exhibit a high degree of polydispersity in their composition, chain length, sulfation, acetylation, and epimerization patterns. It is essential for the understanding of GAG biochemistry to produce detailed structural information as a function of spatial and temporal factors in biological systems. Toward this end, we developed a set of procedures to extract GAGs from various rat organ tissues and examined and compared HS expression levels using liquid chromatography/mass spectrometry. Here we demonstrate detailed variations in HS GAG chains as a function of organ location. These studies shed new light on the structural variation of GAG chains with respect to average length, disaccharide composition, and expression of low abundance structural epitopes, including unsubstituted amino groups and lyase-resistant oligosaccharides. The data show the presence of a disaccharide with an unsubstituted amino group that is endogenous and widely expressed in mammalian organ tissues.

Highlights

The elucidation of structural details as a function of developmental stage, disease state, mutation, and cellular phenotype has led to an evolving understanding of GAG structure-function relationships (14 –17)
It has been demonstrated that the formation of unsubstituted glucosamine amino groups in heparan sulfate (HS) is related to limiting availability of 3Ј-phosphoadenosine 5Ј-phosphosulfate (PAPS) during enzymatic N-deacetylase/N-sulfotransferase reactions [19]
We applied a new system based on size exclusion chromatography (SEC) with mass spectrometry (MS) detection to the problem of detection of free amino-containing disaccharides and other products of depolymerized HS to show their distributions in different organ tissues

Summary

Introduction

The elucidation of structural details as a function of developmental stage, disease state, mutation, and cellular phenotype has led to an evolving understanding of GAG structure-function relationships (14 –17). We applied a new system based on size exclusion chromatography (SEC) with mass spectrometry (MS) detection to the problem of detection of free amino-containing disaccharides and other products of depolymerized HS to show their distributions in different organ tissues. The results demonstrate the presence of ⌬HexA-GlcNH26S disaccharides that have not been detected previously in studies of HS isolated from mammalian organ tissues or embryos.

Results

Conclusion