Gene silencing of β-galactosamide α-2,6-sialyltransferase 1 inhibits human influenza virus infection of airway epithelial cells

Dong Wu,Wenda Guan,Nanshan Zhong,Runfeng Li,Zifeng Yang,Wenbo Huang,Yutao Wang

doi:10.1186/1471-2180-14-78

Abstract

BackgroundHuman influenza virus hemagglutinin prefers to use sialic acid (SA) receptors via α-2,6 linkages. The β-galactoside α-2,6-sialyltransferase I (ST6Gal I) protein is encoded by the ST6GAL1 gene and is responsible for the addition of α-2,6 linked SA to the Galβ1-4GlcNAc disaccharide of glycans and glycoproteins found on the cellular surface. Therefore, ST6GAL1 could be a potential target for anti-influenza therapeutics. We used specific small interfering RNAs (siRNAs) to block expression of ST6GAL1 and limit distribution of SA receptors on the surface of airway epithelial cells.ResultsThe siRNA duplexes we used inhibited ST6GAL1 mRNA expression and subsequent expression of the encoding protein. As a result, synthesis of α-2,6 SA galactose was inhibited. Adsorption of influenza virus particles to the surface of cells transfected with appropriate specific siRNAs was significantly reduced. Intracellular viral genome copy number and virus titer within the supernatant of cells transfected with siRNAs was significantly reduced in a dose-dependent manner compared with those for untransfected cells and cells transfected with non-specific siRNAs.ConclusionsWe used siRNAs targeting ST6GAL1 to inhibit the expression of certain cell surface receptors, thereby preventing virus adsorption. This resulted in the inhibition of human influenza virus infection. Our findings are a significant development in the identification of potential new anti-influenza drug targets.

Highlights

Human influenza virus hemagglutinin prefers to use sialic acid (SA) receptors via α-2,6 linkages
Weinstein et al concluded that one enzyme, βgalactoside α2,6sialyltransferase I (ST6Gal I), encoded by ST6GAL1, was responsible for the addition of α-2,6 SAs to the Galβ14GlcNAc disaccharide found on the glycans of N-linked and some O-linked glycoproteins [12]
ST6Gal Ι expression in small interfering RNAs (siRNAs)-transfected A549, human bronchial epithelium (HBE), and HEp-2 respiratory epithelial cells Using qPCR assays, we determined there was an 80–90% reduction in ST6GAL1 mRNA expression levels up to 48 h post-transfection (Figure 1A,B)

Summary

Introduction

Human influenza virus hemagglutinin prefers to use sialic acid (SA) receptors via α-2,6 linkages. The β-galactoside α-2,6-sialyltransferase I (ST6Gal I) protein is encoded by the ST6GAL1 gene and is responsible for the addition of α-2,6 linked SA to the Galβ1-4GlcNAc disaccharide of glycans and glycoproteins found on the cellular surface. Sialic acid (SA) molecules, found at the non-reducing terminal position of glycoproteins or glycolipids on the surface of cells, are binding targets for influenza A virus (IAV) hemagglutinin (HAs) [8]. The binding of HA to its appropriate receptor is crucial for the initiation of infection and serves as a potential therapeutic target. Weinstein et al concluded that one enzyme, βgalactoside α2,6sialyltransferase I (ST6Gal I), encoded by ST6GAL1, was responsible for the addition of α-2,6 SAs to the Galβ14GlcNAc disaccharide found on the glycans of N-linked and some O-linked glycoproteins [12]. Lin et al found that antisense-oligodeoxynucleotides targeting ST6GAL1 mRNAs could inhibit the enzymatic activity of ST6Gal I, and reduced 2,6-sialylation at the cell surface [13,14]

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Conclusion