Localization of adiponectin at the plasma membrane in caveolae of human adipocytes
(English)Manuscript (preprint) (Other academic)
The hormone adiponectin is exclusively secreted by adipocytes and it regulates whole body energy homeostasis primarily by affecting liver and muscles. The circulating level of adiponectin inversely correlates with insulin resistance and type 2 diabetes. Little is known about the secretion of adiponectin by the adipocyte, but in caveolin-1 knockout mice the amount of secreted adiponectin is severely reduced. Here we show that in human adipocytes adiponectin was associated with the plasma membrane and to a specific class of high-density-caveolae. Substantial amounts of adiponectin were also found in the microsomal and cytosolic fractions of adipocytes, while very little was associated with mitochondria, nuclei, or the fat. Adiponectin in isolated caveolae was readily degraded by added trypsin, demonstrating that adiponectin was largely bound to the cytosolic face of the caveolae membrane. The findings indicate that caveolae may have a critical role in the secretion of adiponectin by human adipocytes.
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:liu:diva-84835OAI: oai:DiVA.org:liu-84835DiVA: diva2:562342