Characterization of the interaction between hydroxypropyl guar galactomannan and galectin-3

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• 作者：Ashley M. Woodward ; Michelle Senchyna ; Ravaughn Williams ; Pablo Arg¨¹eso
• 关键词：CRD ; carbohydrate recognition domain ; DMEM/F12 ; Dulbecco&rsquo ; s modified Eagle&rsquo ; s medium/F12 ; FLA ; fluoresceinamine ; HPGG ; hydroxypropyl guar galactomannan ; PBS ; phosphate-buffered saline ; PNA ; peanut agglutinin ; rGal ; recombinant galectin ; SDS-PAGE
• 刊名：Biochemical and Biophysical Research Communications
• 出版年：2012
• 出版时间：20 July, 2012
• 年：2012
• 卷：424
• 期：1
• 页码：12-17
• 全文大小：726 K

文摘

Multivalent galactose ligands have been proposed for selective targeting of carbohydrate-binding proteins on epithelial cell surfaces, both in normal and pathological conditions. One cellular partner is galectin-3, a ¦Â-galactoside-binding protein present on many epithelial linings, such as those of the ocular surface. In this study, we investigated the ability of hydroxypropyl guar galactomannan (HPGG) to bind recombinant galectin-3 and to target the apical surface of differentiated human corneal keratinocytes. Pull-down and slot-blot assays demonstrated that fluorescence-labeled HPGG bound recombinant galectin-3 through a galactose-dependent mechanism. In contrast, no binding of HPGG could be detected towards recombinant galectin-8 or -9. In a cell culture system, HPGG bound weakly to biotinylated cell surface corneal isolates containing endogenous galectin-3, and incubation of HPGG with corneal keratinocytes in culture resulted in discrete, galactose-independent, binding to the cell surface. Moreover, HPGG failed to elute the biological counter-receptor MUC16 from galectin-3 affinity columns. We conclude that HPGG binds galectin-3 through the conventional carbohydrate-recognition domain in vitro, but not in a biological system, suggesting that endogenous carbohydrate ligands on epithelial cell surface glycocalyces impair HPGG biorecognition.