Abstract
To probe increased O-GlcNAc levels as an independent mechanism governing insulin resistance in 3T3-L1 adipocytes, a new class of O-GlcNAcase (OGA) inhibitor was studied. 6-Acetamido-6-deoxy-castanospermine (6-Ac-Cas) is a potent inhibitor of OGA. The structure of 6-Ac-Cas bound in the active site of an OGA homolog reveals structural features contributing to its potency. Treatment of 3T3-L1 adipocytes with 6-Ac-Cas increases O-GlcNAc levels in a dose-dependent manner. These increases in O-GlcNAc levels do not induce insulin resistance functionally, measured using a 2-deoxyglucose (2-DOG) uptake assay, or at the molecular level, determined by evaluating levels of phosphorylated IRS-1 and Akt. These results, and others described, provide a structural blueprint for improved inhibitors and collectively suggest that increased O-GlcNAc levels, brought about by inhibition of OGA, does not by itself cause insulin resistance in 3T3-L1 adipocytes.
Copyright © 2010 Elsevier Ltd. All rights reserved.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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3T3-L1 Cells
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Acetylglucosamine / analogs & derivatives
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Acetylglucosamine / pharmacology
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Adipocytes / drug effects*
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Adipocytes / enzymology
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Adipocytes / metabolism
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Animals
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Binding Sites
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Catalytic Domain
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Crystallography, X-Ray
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Deoxyglucose / metabolism
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Enzyme Inhibitors / chemistry*
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Enzyme Inhibitors / pharmacology
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Humans
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Indolizines / chemistry*
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Indolizines / pharmacology
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Insulin / pharmacology*
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Insulin Receptor Substrate Proteins / metabolism
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Insulin Resistance
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Mice
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Oximes / pharmacology
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Phenylcarbamates / pharmacology
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Phosphorylation
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Proto-Oncogene Proteins c-akt / metabolism
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beta-N-Acetylhexosaminidases / antagonists & inhibitors*
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beta-N-Acetylhexosaminidases / metabolism
Substances
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6-acetamido-6-deoxycastanospermine
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Enzyme Inhibitors
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Indolizines
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Insulin
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Insulin Receptor Substrate Proteins
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Irs1 protein, mouse
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Oximes
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Phenylcarbamates
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N-acetylglucosaminono-1,5-lactone O-(phenylcarbamoyl)oxime
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Deoxyglucose
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Proto-Oncogene Proteins c-akt
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hexosaminidase C
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beta-N-Acetylhexosaminidases
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Acetylglucosamine