PPAR family and its relationship to metabolic syndrome

Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptor superfamily of ligand--activated transcription factors. Three PPAR isoforms , designated PPARalpha, -beta/delta, and -gamma, have been identified and attracted enormous attention due to the key role these receptors play in regulating adipogenesis, lipid metabolism, insulin sensitivity, inflammation and blood pressure. Growing evidence points to a causative relationship between PPAR activity and the metabolic syndrome, including insulin resistance, glucose intolerance or type II diabetes, obesity, dyslipidemia, hypertension, atherosclerosis, and albuminuria. Importantly, both PPARalpha activators such as fibric acid class of hypolipidemic drugs and PPARgamma agonists including antidiabetic thiazolidinediones (TZDs) have been proved to be effective for improving metabolic syndrome. All three PPAR isoforms appear to play important roles in the development of type II diabetes and diabetic nephropathy. Accumulating data has begun to emerge suggesting PPARs may serve as potential therapeutic targets for treating the metabolic syndrome and its related complications. Here we review the literature pertaining to the action, ligand selectivity and physiological role of PPARs. Particular emphasis is placed on their pathogenic roles in the metabolic syndrome and the therapeutic utility of PPAR modulators in the treatment of type II diabetes.