Sclerostin

Sclerostin, the product of the SOST gene, was originally believed to be a non-classical Bone morphogenetic protein (BMP) antagonist. More recently Sclerostin has been identified as binding to LRP5/6 receptors and activating the Wnt signalling pathway. Wnt activation under these circumstances is antagonistic to bone formation. More recently, it has been revealed that the antagonism of BMP-induced bone formation by sclerostin is mediated by Wnt signalling, but not BMP signalling pathways.

Mutations of Sclerostin is associated with the syndrome Sclerosteosis in which there is an abnormal increase in the growth of bones due to lack of normal Sclerostin expression by osteocytes. This acts upon osteoblasts in the bone in paracrine manner of unknown mechanism.

Currently an anti-Sclerostin antibody is under development for the treatment of osteoporosis by Amgen.