Endocrine Abstracts

Fractures are associated with suffering and increased mortality in patients and great costs for society. It is well established that sex steroids are important regulators of skeletal growth and bone metabolism and estrogen is known to protect against bone loss and prevent fractures. Estrogen not only protects the female skeleton, but is also associated with bone mass and fracture risk in the male skeleton. However, the use of this hormone as a therapeutic drug against bone loss is restricted due to severe side-effects, such as increased risk of breast cancer and stroke. It is therefore important to increase our knowledge regarding the mechanisms underlying the protective effects of estrogen on the skeleton in order to provide the possibility to develop new bone-specific treatment options which can separate the positive, bone-protective, effects from adverse estrogenic effects. Estrogen exerts its effects via estrogen receptors and ERα is an important mediator of the protective estrogenic effects on bone, both in the female and the male skeleton. In experimental studies, using different genetically modified animal models, our research group is working on determining i) the importance of estrogen signaling in different specific celltypes and ii) the role of different signaling pathways in cells, including the importance of different posttranslational modification sites in the ERα. The aim is to provide a summary of what is known regarding sex steroids and their impact on bone metabolism with focus on target cells for estrogen and estrogen receptor signalling pathways.