gw-1929 and Diabetes-Mellitus

Topics: Animals; Diabetes Mellitus; Drug Design; Humans; Hyperlipidemias; Hypertension; Inflammation; Ligands; Models, Molecular; Neoplasms; Nuclear Proteins; Obesity; Receptors, Cytoplasmic and Nuclear; Transcription Factors

Diabetes is associated with increased formation of advanced glycation end products (AGEs), which have been implicated in micro and macrovascular complications of diabetes. Our earlier reports showed proangiogenic effect of AGE-bovine serum albumin (BSA). In order to understand the mechanism of AGE-mediated angiogenesis, the possibility of involvement of peroxisome prolifeator activated receptor (PPAR) gamma, a ligand activated transcription factor was examined. The angiogenic effect was studied in chick chorio allantoic membrane (CAM) and by analyzing angiogenic markers in human umbilical vein endothelial cells (HUVECs) in culture. The involvement of PPAR y was investigated using synthetic PPAR gamma agonist GW 1929 and antagonist GW 9662 and by RT-PCR. In CAM assay, PPAR gamma antagonist GW 9662 reversed the AGE-induced effect on vascularity. In HUVECs in culture, GW 9662 reversed the effect of AGE-BSA and decreased the expression of CD 31, E-Selectin and VEGF. RT-PCR analysis showed that treatment with AGE-BSA caused upregulation of PPAR gamma mRNA levels. The reversal of the effect of AGE on angiogenesis by treatment with PPAR gamma antagonists and up-regulation of PPAR gamma gene in HUVECs treated with AGE-BSA suggested the possible involvement of PPAR gamma-dependent downstream pathway in mediating the angiogenic effect of AGE.

Topics: Angiogenesis Inducing Agents; Anilides; Animals; Benzophenones; Cells, Cultured; Chick Embryo; Chorioallantoic Membrane; Diabetes Mellitus; E-Selectin; Glycation End Products, Advanced; Human Umbilical Vein Endothelial Cells; Humans; Platelet Endothelial Cell Adhesion Molecule-1; PPAR gamma; RNA; Tyrosine; Vascular Endothelial Growth Factor A

Peroxisome proliferator-activated receptor gamma (PPAR gamma) agonists, including the glitazone class of drugs, are insulin sensitizers that reduce glucose and lipid levels in patients with type 2 diabetes mellitus. To more fully understand the molecular mechanisms underlying their therapeutic actions, we have characterized the effects of the potent, tyrosine-based PPAR gamma ligand GW1929 on serum glucose and lipid parameters and gene expression in Zucker diabetic fatty rats. In time-course studies, GW1929 treatment decreased circulating FFA levels before reducing glucose and triglyceride levels. We used a comprehensive and unbiased messenger RNA profiling technique to identify genes regulated either directly or indirectly by PPAR gamma in epididymal white adipose tissue, interscapular brown adipose tissue, liver, and soleus skeletal muscle. PPAR gamma activation stimulated the expression of a large number of genes involved in lipogenesis and fatty acid metabolism in both white adipose tissue and brown adipose tissue. In muscle, PPAR gamma agonist treatment decreased the expression of pyruvate dehydrogenase kinase 4, which represses oxidative glucose metabolism, and also decreased the expression of genes involved in fatty acid transport and oxidation. These changes suggest a molecular basis for PPAR gamma-mediated increases in glucose utilization in muscle. In liver, PPAR gamma activation coordinately decreased the expression of genes involved in gluconeogenesis. We conclude from these studies that the antidiabetic actions of PPAR gamma agonists are probably the consequence of 1) their effects on FFA levels, and 2), their coordinate effects on gene expression in multiple insulin-sensitive tissues.

Topics: Adipose Tissue; Adipose Tissue, Brown; Animals; Benzophenones; Diabetes Mellitus; Fatty Acids; Gene Expression; Gene Expression Profiling; Glucose; Homeostasis; Insulin; Liver; Muscle, Skeletal; Obesity; Rats; Rats, Zucker; Receptors, Cytoplasmic and Nuclear; Transcription Factors; Tyrosine