Developing human lung and kidney are major sites for synthesis of bone morphogenetic protein-3 (osteogenin).

Bone morphogenetic protein-3 (BMP-3; osteogenin) is a member of the transforming growth factor-beta superfamily. We used human BMP-3 cDNA probes and a specific BMP-3 polyclonal peptide antibody to analyze BMP-3 expression and synthesis in human fetal and adult tissues. Northern blot hybridization revealed two mRNA species of 7 and 3 KB. High levels of BMP-3 mRNA were found in fetal lungs. By in situ hybridization, the BMP-3 transcripts were found in lung bronchial epithelium, straight collecting kidney tubules, intestinal mucosa, perichondrium, periosteum, and osteoblasts of human embryos of 6-14 weeks' gestation. Cellular BMP-3 immunostaining co-localized with the distribution of RNA. In addition, bone matrix showed intensive BMP-3 staining. These data suggest that although BMP-3 has been isolated from bone matrix, it may have additional regulatory roles in the morphogenesis and/or function of human lung, kidney, and intestine.