Interleukin-2 Carbohydrate Recognition Modulates CTLL-2 Cell Proliferation

Abstract

Interleukin-2 (IL-2) specifically recognizes high-mannose type glycans with five or six mannosyl residues. To determine whether the carbohydrate recognition activity of IL-2 contributes to its physiological activity, the inhibitory effects of high-mannose type glycans on IL-2-dependent CTLL-2 cell proliferation were investigated. Man 5 GlcNAc 2 Asn added to CTLL-2 cell cultures inhibited not only phosphorylation of tyrosine kinases but also IL-2-dependent cell proliferation. We found that a complex of IL-2, IL-2 receptor ␣, ␤, ␥ subunits, and tyrosine kinases was formed in rhIL-2-stimulated CTLL-2 cells. Among the components of this complex, only the IL-2 receptor ␣ subunit was stained with Galanthus nivalis agglutinin which specifically recognizes high-mannose type glycans. This staining was diminished after digestion of the glycans with endo-␤-N-acetylglucosaminidase H or D, suggesting that at least a N-glycan containing Man 5 GlcNAc 2 is linked to the extracellular portion of the IL-2 receptor ␣ subunit. Our findings indicate that IL-2 binds the IL-2 receptor ␣ subunit through Man 5 GlcNAc 2 and a specific peptide sequence on the surface of CTLL-2 cells. When IL-2 binds to the IL-2R␣ subunit, this may trigger formation of the high affinity complex of IL-2-IL-2R␣, -␤, and -␥ subunits, leading to cellular signaling.

Carbohydrate Recognition Site of Interleukin-2 in Relation to Cell Proliferation

“…We reported in a previous paper that the carbohydrate recognition of IL-2 is essential for expression of its physiological function (12). In this study, we prepared several mutant forms of IL-2 based on the homology with three mannose-binding proteins (13), and we compared the proliferation activities and carbohydrate recognition activities among them.…”

“…We showed in a previous paper (12) that the formation of IL-2⅐IL-2R␣ complex triggers the formation of a high affinity complex that consists of IL-2, IL-2R␣, -␤, -␥, and other tyrosine kinases. The cell proliferation activity and carbohydrate recognition activity of IL-2 could be seen mostly in the dimeric form, which was separated on Superose 12 column chromatography.…”

“…When IL-2R␣, -␤, or -␥ was independently expressed, IL-2R␣ bound IL-2 with low affinity (K d ϳ10 nM); IL-2R␤ bound IL-2 with very low affinity (K d ϳ100 nM), and IL-2R␥ had no measurable affinity for IL-2, whereas co-expressed IL-2R␣, -␤, and -␥ bound IL-2 with a very high affinity constant (K d ϳpM) (9 -11). We reported previously that IL-2 binds IL-2R␣ through Man 5 GlcNAc 2 and a specific peptide sequence in IL-2R␣ on the surface of CTLL-2 cells and that this dual recognition triggers formation of the high affinity complex of IL-2⅐IL-2R␣, -␤, -␥, leading to downstream signaling (12).…”

Sodium Polyprenyl Phosphate (Phosprenyl) Exerts an Il-2-Dependent Restorative Effect Upon in Vivo DTH Inhibition

“…Фоспренил сохраняет способ-ность к взаимодействию с гликопротеинами, которые подобно CD25 и γ-глобулину содержат в своей простетической части стереохимически идентичные N-гликаны, распознаваемые также интерлейкином 2 (IL-2) [4,6].…”

The immunomodulating roles of glycoproteins in epithelial ovarian cancer

“…However, it has been proposed that in addition to their peptide binding epitopes, cytokines also possess novel carbohydrate recognition domains that allow them to recognize a variety of oligosaccharide ligands (201,202). IL-1alpha IL-1beta, IL-2, IL-3, IL-4, IL-6, IL-7, and other cytokines have been shown to possess carbohydrate recognition domains that allow them to bind to specific oligosaccharides (201,(203)(204)(205)(206)(207)(208)(209)(210). Cytokines bind to specific glycan sequences expressed on glycoproteins such as ribonuclease B, Tamm Horsfall glycoprotein and uromodulin (211)(212)(213)(214)(215).…”