WNT Signaling in osteoarthritis and osteoporosis: what is the biological significance for the clinician?

Osteoporosis and osteoarthritis are common musculoskeletal disorders in which cause and outcome are determined by genetic and environmental factors. The WNT signaling pathway plays an important role in skeletal development and growth. Polymorphisms in a number of genes that belong to this pathway are associated with osteoarthritis and/or osteoporosis. This suggests a role for this molecular signaling pathway in postnatal joint and bone homeostasis and pathology. Increased activity of WNT signaling strengthens the bone but may have adverse effects on the articular cartilage. Frizzled related protein (FRZB) plays a role in both bone and cartilage. Better understanding of the WNT pathway and its modulators may lead to specific therapeutics for both osteoarthritis and osteoporosis. This review focuses on recent studies in human genetics and animal models and highlights the potential clinical relevance of this rapidly evolving field of research.