Smad4 controls bone homeostasis through regulation of osteoblast/osteocyte viability

A protein called Smad4 plays a significant role in regulating viability of and balance between cells that build and maintain healthy bones. Making bones requires regulated cooperation among different cells. Osteoblast cells in the bone marrow produce proteins that form the intercellular ‘matrix’ that holds bone cells together. Osteoclast cells break down bone tissue when necessary for maintenance, remodeling and repair. Smad4 was known to control the activity of several proteins and signaling pathways involved in bone formation. Eui-Sic Cho and co-workers at Chonbuk National University in South Korea have now further clarified the role of Smad4 in osteoblasts and osteoclasts. Investigating the effects of controlled disruption of Smad4 activity in mice confirmed that the protein participates in maintaining viable and suitably balanced populations of these specific types of cell.