Identification of a BMP7 homolog in zebrafish expressed in developing organ systems

The Bone morphogenetic proteins (BMPs) act in many key regulatory processes during development, including dorsoventral axis specification and organ development and are part of a conserved signal pathway. Specifically, BMP7 is a vital signaling molecule for normal development in the mammalian system. The zebrafish mutant snailhouse (snh) was originally isolated as being strongly dorsalized and the mutation was determined to lie within the bmp7 gene. We report here the cloning and expression of a second bmp7 homolog, which we term bmp7b. Sequence alignments show that bmp7b is more closely related to human, mouse and non-mammalian BMP7 than is snh. We further show that bmp7b is strongly expressed in developing organ systems such as the eyes, the ears, the pronephric kidney and the gastrointestinal system.