Compelling data from many laboratories have documented an essential role for glucosamine metabolism in the induction of insulin-resistance, the underlying cause of type II diabetes. Signaling via the insulin receptor is mediated by a complex, but fairly well studied signal transduction cascade. We and others have described the dynamic O-GlcNAc modification of a myriad of nucleocytoplasmic proteins and its interplay with phosphate on a number of signaling and regulatory proteins. Hyperglycemia induced insulin-resistance is accompanied by a dramatic increase in O-GlcNAc on many proteins. Strikingly, a specific inhibitor of O-GlcNAcase, the enzyme that removes O-GlcNAc from proteins, causes insulin-resistance in the absence of hyperglycemia, providing direct evidence that hyper-O-GlcNAcylation itself is sufficient to disrupt insulin signaling. Given the wealth of knowledge of the insulin signaling pathway, our aims are straight-forward.
Aim 1 will systematically determine the site(s) in the insulin signaling pathway which are blocked by hyper-O-GlcNAcylation. Points of involvement of O-GlcNAc in insulin signaling will be mapped by functional analysis at each known step in the pathway, and by a non-biased proteomic analysis of insulin-responsive O-GlcNAc modified proteins.
Aim 2 will biochemically characterize the structure/function, site occupancy, and relationship to 0-phosphate of key insulin-signaling proteins that are already known to be O-GlcNAc modified, including GSK3 beta, IRS-1 & 2, Akt/PKB, and PPAR-gamma-RXR.
Aim 3 will systematically study the role of insulin-signaling and hyperglycemia in the regulation of the adipocyte enzymes controlling O-GlcNAc cycling, O-GlcNAc Transferase and O-GlcNAcase. The 3T3-L1 adipocyte insulin-signaling system not only provides a great model to elucidate the functions of O-GlcNAc in insulin signaling, but also these studies will likely provide a new understanding of the molecular mechanisms causing diabetes, and may lead to unexpected avenues for its treatment.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK061671-02
Application #
6623109
Study Section
Physiological Chemistry Study Section (PC)
Program Officer
Blondel, Olivier
Project Start
2002-05-01
Project End
2005-04-30
Budget Start
2003-05-01
Budget End
2004-04-30
Support Year
2
Fiscal Year
2003
Total Cost
$276,827
Indirect Cost
Name
Johns Hopkins University
Department
Biochemistry
Type
Schools of Medicine
DUNS #
001910777
City
Baltimore
State
MD
Country
United States
Zip Code
21218
Liu, Wei; Han, Guanghui; Yin, Yalin et al. (2018) AANL (Agrocybe aegerita lectin 2) is a new facile tool to probe for O-GlcNAcylation. Glycobiology 28:363-373
Ma, Junfeng; Hart, Gerald W (2017) Analysis of Protein O-GlcNAcylation by Mass Spectrometry. Curr Protoc Protein Sci 87:24.10.1-24.10.16
Ma, Junfeng; Banerjee, Partha; Whelan, Stephen A et al. (2016) Comparative Proteomics Reveals Dysregulated Mitochondrial O-GlcNAcylation in Diabetic Hearts. J Proteome Res 15:2254-64
Ma, Junfeng; Hart, Gerald W (2016) Mass Spectrometry-Based Quantitative O-GlcNAcomic Analysis. Methods Mol Biol 1410:91-103
Banerjee, Partha S; Lagerlöf, Olof; Hart, Gerald W (2016) Roles of O-GlcNAc in chronic diseases of aging. Mol Aspects Med 51:1-15
Hardivillé, Stéphan; Hart, Gerald W (2016) Nutrient regulation of gene expression by O-GlcNAcylation of chromatin. Curr Opin Chem Biol 33:88-94
Lagerlöf, Olof; Slocomb, Julia E; Hong, Ingie et al. (2016) The nutrient sensor OGT in PVN neurons regulates feeding. Science 351:1293-6
Ramirez-Correa, Genaro A; Ma, Junfeng; Slawson, Chad et al. (2015) Removal of Abnormal Myofilament O-GlcNAcylation Restores Ca2+ Sensitivity in Diabetic Cardiac Muscle. Diabetes 64:3573-87
Ma, Junfeng; Liu, Ting; Wei, An-Chi et al. (2015) O-GlcNAcomic Profiling Identifies Widespread O-Linked ?-N-Acetylglucosamine Modification (O-GlcNAcylation) in Oxidative Phosphorylation System Regulating Cardiac Mitochondrial Function. J Biol Chem 290:29141-53
Banerjee, Partha S; Ma, Junfeng; Hart, Gerald W (2015) Diabetes-associated dysregulation of O-GlcNAcylation in rat cardiac mitochondria. Proc Natl Acad Sci U S A 112:6050-5

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