title: Gliclazide increases insulin receptor tyrosine phosphorylation but not p38 phosphorylation in insulin-resistant skeletal muscle cells.
abstract: Sulfonylurea drugs are used in the treatment of type 2 diabetes. The mechanism of action of sulfonylureas is to release insulin from pancreatic cells and they have been proposed to act on insulin-sensitive tissues to enhance glucose uptake. The goal of the present study was to test the hypothesis that gliclazide, a second-generation sulfonylurea, could enhance insulin signaling in insulin-resistant skeletal muscle cells. We demonstrated that gliclazide enhanced insulin-stimulated insulin receptor tyrosine phosphorylation in insulin-resistant skeletal muscle cells. Although insulin receptor substrate-1 tyrosine phosphorylation was unaffected by gliclazide treatment, phosphatidylinositol 3-kinase activity was partially restored by treatment with gliclazide. No increase in 2-deoxyglucose uptake in insulin-resistant cells by treatment with gliclazide was observed. Further investigations into the mitogen-activated protein kinase (MAPK) pathway revealed that insulin-stimulated p38 phosphorylation was impaired, as compared with extracellular-signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK), which were phosphorylated normally in insulin-resistant cells. Treatment with gliclazide could not restore p38 phosphorylation in insulin-resistant cells. We propose that gliclazide can regulate part of the insulin signaling in insulin-resistant skeletal muscle, and p38 could be a potential therapeutic target for glucose uptake to treat insulin resistance.
authors.affiliation: Department of Biotechnology, National Institute of Pharmaceutical Education and Research, Punjab, India.
authors.forename: Naresh
authors.initials: N
authors.lastname: Kumar
authors.forename: Chinmoy S
authors.initials: CS
authors.lastname: Dey
mesh_terms: D000818:Animals; D002460:Cell Line; D003847:Deoxyglucose / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005907:Gliclazide / Q000494:pharmacology*; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology; D007333:Insulin Resistance; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D051379:Mice; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D011725:Pyridines / Q000494:pharmacology; D011972:Receptor, Insulin / Q000737:chemistry*; D015398:Signal Transduction; D014443:Tyrosine / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D004791:Enzyme Inhibitors; D007004:Hypoglycemic Agents; D007093:Imidazoles; D007328:Insulin; D011725:Pyridines; D014443:Tyrosine; D003847:Deoxyglucose; D019869:Phosphatidylinositol 3-Kinases; D011972:Receptor, Insulin; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases; D005907:Gliclazide; C093642:SB 203580