Endocrine role for skeleton

The skeleton functions as a part of the endocrine system and plays a role in regulating energy metabolism in the body, according to a study published this week in Cell. "It's a sparkling observation," said Jake Kushner of the University of Pennsylvania in Philadelphia, who was not affiliated with the study. "The findings show that bone is an endocrine organ, and that it affects glucose homeostasis. This concept is totally novel." The researchers showed that osteocalcin, a protein secreted by bone cells, regulates insulin production and insulin sensitivity in the body, answering a long-standing question about the protein's function. "Osteocalcin has been the flagship molecule of the bone field for decades," said Gerard Karsenty of the Columbia University Medical Center, the study's lead author. "It's the only molecule uniquely secreted by osteoblasts, but no one has been able to show what role it plays in the body."...