O-GlcNAc modification on IRS-1 and Akt2 by PUGNAc inhibits their phosphorylation and induces insulin resistance in rat primary adipocytes.
- Author:
Seung Yoon PARK
1
;
Jiwon RYU
;
Wan LEE
Author Information
1. Department of Biochemistry College of Medicine, Dongguk University Gyeongju 780-714, Korea. wanlee@dongguk.ac.kr
- Publication Type:Original Article ; Research Support, Non-U.S. Gov't
- Keywords:
Akt2;
GLUT4;
insulin resistance;
IRS-1;
O-GlcNAc;
PUGNAc
- MeSH:
Acetylglucosamine/*analogs & derivatives/metabolism/pharmacology;
Adipocytes/*metabolism;
Animals;
Deoxyglucose/pharmacokinetics;
Glycosylation;
Immunoprecipitation;
*Insulin Resistance;
Male;
Monosaccharide Transport Proteins/metabolism;
Oximes/*pharmacology;
Phenylcarbamates/*pharmacology;
Phosphoproteins/*metabolism;
Phosphorylation;
Protein-Serine-Threonine Kinases/*metabolism;
Proto-Oncogene Proteins/*metabolism;
Rats;
Rats, Sprague-Dawley;
Research Support, Non-U.S. Gov't;
Subcellular Fractions/metabolism;
beta-N-Acetylhexosaminidase/antagonists & inhibitors
- From:Experimental & Molecular Medicine
2005;37(3):220-229
- CountryRepublic of Korea
- Language:English
-
Abstract:
It has been known that O-linked beta-N-acetylglucosamine (O-GlcNAc) modification of proteins plays an important role in transcription, translation, nuclear transport and signal transduction. The increased flux of glucose through the hexosamine biosynthetic pathway (HBP) and increased O-GlcNAc modification of protein have been suggested as one of the causes in the development of insulin resistance. However, it is not clear at the molecular level, how O-GlcNAc protein modification results in substantial impairment of insulin signaling. To clarify the association of O-GlcNAc protein modification and insulin resistance in rat primary adipocytes, we treated the adipocytes with O-(2-acetamido-2deoxy-D-glucopyranosylidene)amino-N-phenylcarbamate (PUGNAc), a potent inhibitor of O-GlcNAcase that catalyzes removal of O-GlcNAc from proteins. Prolonged treatment of PUGNAc (100 micrometer for 12 h) increased O-GlcNAc modification on proteins in adipocytes. PUGNAc also drastically decreased insulin-stimulated 2-deoxyglucose (2DG) uptake and GLUT4 translocation in adipocytes, indicating that PUGNAc developed impaired glucose utilization and insulin resistance in adipocytes. Interestingly, the O-GlcNAc modification of IRS-1 and Akt2 was increased by PUGNAc, accompanied by a partial reduction of insulin-stimulated phosphorylations of IRS-1 and Akt2. The PUGNAc treatment has no effect on the expression level of GLUT4, whereas O-GlcNAc modification of GLUT4 was increased. These results suggest that the increase of O-GlcNAc modification on insulin signal pathway intermediates, such as IRS-1 and Akt2, reduces the insulin-stimulated phosphorylation of IRS-1 and Akt2, subsequently leading to insulin resistance in rat primary adipocytes.
