Description
BMPs are proteins that act to induce the differentiation of mesenchymal-type cells into chondrocytes and osteoblasts before initiating bone formation. They promote the differentiation of cartilage-forming cells and bone-forming cells near sites of fractures but also at ectopic locations. Some of the proteins induce the synthesis of alkaline phosphatase and collagen in osteoblasts. Some BMPs act directly on osteoblasts and promote their maturation while at the same time suppressing myogenous differentiation. Other BMPs promote the conversion of typical fibroblasts into chondrocytes and are capable also of inducing the expression of an osteoblast phenotype in non-osteogenic cell types. Intracellular signaling following engagement of receptors for some BMP proteins has been shown to involve the action of SMAD proteins. BMP4 and BMP7 have been shown to be involved also in the differentiation of sympathetic neurons. They enhance the formation of adrenergic sympathetic neurons in cultures of neural crest cells