| Background |
Adiponectin, also known as Adipocyte complement-related protein of 30 kDa (Acrp30), is an adipocyte-specific protein that plays a role in glucose regulation and fatty acid oxidation. Encoded by the ADIPOQ gene, Adiponectin is a 244 amino acid protein with a collagen-like N-terminal domain and a globular domain at the C-terminus. The globular domain can be further cleaved into the globular Adiponectin (gAdiponectin). Recombinant gAdiponectin is associated with weight reduction as well as free fatty acid oxidation in mouse muscle and liver. Two Adiponectin receptors, AdipoR1 and AdipoR2, have been identified and are widely expressed in a number of tissues and organs including skeletal muscle, spleen, lung, heart, kidney, and liver. It has been reported that levels of Adiponectin are negatively associated with insulin resistance and type II diabetes. Reportedly, Adiponectin in combination with leptin completely reverse insulin resistance in mice. Adiponectin automatically self-associates into larger structures including trimers (low molecular weight), hexamers (middle molecular weight), and higher order oligomeric structures (high molecular weight). High-molecular-weight Adiponectin may be the most biologically active form maintaining glucose homeostasis and is related to a lower risk of diabetes. However, it was showed that coronary artery disease is positively affected by high molecular weight Adiponectin.
Clinically, Adiponectin has been an important biomarker for metabolic syndromes. For instance, it has been observed that patients with type-2 diabetes exhibit decreased circulating Adiponectin and Thiazolidinediones can elevate Adiponectin in insulin-resistant patients. In addition, a negative correlation between obesity and circulating Adiponectin has been reported. |
