Novel mannosidase inhibitors probe glycoprotein degradation pathways in cells.

Journal article

Multiple isoforms of mammalian alpha-mannosidases are active in the pathways of N-linked glycoprotein synthesis and catabolism. They differ in specificity, function and location within the cell and can be selectively inhibited by imino sugar monosaccharide mimics. Previously, a series of structurally related novel 7-membered iminocyclitols were synthesised and found to be inhibitors of alpha-mannosidase using in vitro assays. The present study aimed to delineate alpha-mannosidases hydrolytic pathways in azepane inhibitor treated cells by the analysis of free oligosaccharides (FOS) as markers of endoplasmic reticulum (ER), Golgi, lysosomal and cytosolic alpha-mannosidase activities. Two compounds were identified as potent and selective cytosolic alpha-mannosidase inhibitors. Two related compounds were shown to be potent inhibitors of lysosomal alpha-mannosidase with different potencies towards alpha1,6 mannosidase. The specificities of these novel 7-membered imino sugars are related to differences in their structure and D: -mannose-like stereochemistry. Specific ER-mannosidase inhibition by kifunensine also reveals significant non-proteasomal degradation following FOS analysis and appears to be cell line dependent. The availability of more selective inhibitors allows the pathways of N-linked oligosaccharide metabolism to be dissected.

Authors: Butters, T; Alonzi, D; Kukushkin, N; Ren, Y; Blériot, Y

• Publication status: Published
• Journal: Glycoconjugate journal
• Volume: 26
• Issue: 9
• Pages: 1109-1116
• Publication date: 2009-12-01
• DOI: 10.1007/s10719-009-9231-3
• EISSN: 1573-4986
• ISSN: 0282-0080
• Language: English
• Keywords: Metabolic Networks and Pathways; Chromatography, High Pressure Liquid; Oligosaccharides; Humans; Mannosidases; Enzyme Inhibitors; Glycoproteins; Molecular Sequence Data; Alkaloids; HL-60 Cells; Carbohydrate Sequence; Rats; Structure-Activity Relationship; Cells; Animals