Role of multimeric forms of adiponectin in metabolic disorders

Adiponectin, also called Acrp30, is a 30-kDa protein that circulates in the blood at high levels (2-10 µg/ml in human) and constitutes 0.01% of the total plasma protein. In contrast to other adipokines such as leptin, adiponectin is believed to be an anti-inflammatory and insulin-sensitizing hormone whose levels are reduced in obesity. Adiponectin can exist in the blood as a trimer, with the potential to associate into hexamers and finally into multimers of high molecular weight (HMW) species. Adiponectin primarily mediates its insulin-sensitizing effects through various signaling proteins including the activation of adenosine monophosphate (AMP)-activated protein kinase (AMPK). Recent reports suggest the anti-inflammatory and cytoprotective effects of adiponectin are mediated by direct activation of PI3K-Akt pathway. Interestingly adiponectin is also reported to decrease body weight by centrally mediated stimulation of energy expenditure