Sialylation of Human Natural Killer (NK) Cells is Regulated by IL-2.

Philip Rosenstock,Chiara Massa,Philipp Selke,Barbara Seliger,Rüdiger Horstkorte,Kaya Bork

doi:10.3390/jcm9061816

Philip Rosenstock, Chiara Massa + Show 4 more

Open Access

https://doi.org/10.3390/jcm9061816

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Abstract

Sialic acids are terminal sugars on the cell surface that are found on all cell types including immune cells like natural killer (NK) cells. The attachment of sialic acids to different glycan structures is catalyzed by sialyltransferases in the Golgi. However, the expression pattern of sialyltransferases in NK cells and their expression after activation has not yet been analyzed. Therefore, the present study determines which sialyltransferases are expressed in human NK cells and if activation with IL-2 changes the sialylation of NK cells. The expression of sialyltransferases was analyzed in the three human NK cell lines NK-92, NKL, KHYG-1 and primary NK cells. NK-92 cells were cultured in the absence or presence of IL-2, and changes in the sialyltransferase expression were measured by qPCR. Furthermore, specific sialylation was investigated by flow cytometry. In addition, polySia and NCAM were measured by Western blot analyses. IL-2 leads to a reduced expression of ST8SIA1, ST6GAL1 and ST3GAL1. α-2,3-Sialylation remained unchanged, while α-2,6-sialylation was increased after IL-2 stimulation. Moreover, an increase in the amount of NCAM and polySia was observed in IL-2-activated NK cells, whereas GD3 ganglioside was decreased. In this study, all sialyltransferases that were expressed in NK cells could be identified. IL-2 regulates the expression of some sialyltransferases and leads to changes in the sialylation of NK cells.

Highlights

All cells of the human body, including immune cells, are glycosylated and glycan structures are crucial for different immune functions [1,2]
Our experiments further show that the expression of sialyltransferases as well as the sialylation of natural killer (NK) cells is influenced by their activation with IL-2
RNA was isolated from the human NK cell lines NK-92, NKL and KHYG-1, and cDNA was synthesized

Summary

Introduction

All cells of the human body, including immune cells, are glycosylated and glycan structures are crucial for different immune functions [1,2]. Sialic acids are located at the outside of cells as terminal sugars of N- and O-glycans and glycosphingolipids. They are comprised of a 9-carbon backbone and are derivatives of neuraminic acid. The almost only sialic acid that is synthesized in humans is N-acetylneuraminic acid (Neu5Ac) [3,4]. CMP-Neu5Ac is transported to the Golgi, where different sialyltransferases catalyze the attachment to other sugar molecules [6]. Α-2,8-sialyltransferases (ST8Sia; EC 2.4.99.8) catalyze the attachment of Neu5Ac to other sialic acids via α-2,8-linkage. MMed.o2r0e20o, v9,exrF,OtRhePEβER-gRaEVlaIEcWtoside α-2,6- and β-galactoside α-2,3-sialyltransferases (oSf T126Gal, EC 2.4.99.1; ST3Gal, EC 2.4.99.4) catalyze the attachment of Neu5Ac to galactose (Gal) via α-2,6 or α-2,3-tloingkaalgaceto[7se]. Our experiments further show that the expression of sialyltransferases as well as the sialylation of NK cells is influenced by their activation with IL-2

Cells and Cell Culture

PCR and Quantitative Real-Time PCR Analysis

Flow Cytometry Analysis

Western Blot Analysis

Expression of Sialyltransferases in Human NK Cells

Discussion