BMP7

Bone morphogenetic protein 7 or BMP7 (also known as osteogenic protein-1 or OP-1) is a protein that in humans is encoded by the BMP7 gene.

The protein encoded by this gene is a member of the TGF-β superfamily. Like other members of the bone morphogenetic protein family of proteins, it plays a key role in the transformation of mesenchymal cells into bone and cartilage. It is inhibited by noggin and a similar protein, chordin, which are expressed in the Spemann-Mangold Organizer. BMP7 may be involved in bone homeostasis. It is expressed in the brain, kidneys and bladder.

BMP7 induces the phosphorylation of SMAD1 and SMAD5, which in turn induce transcription of numerous osteogenic genes. It has been demonstrated that BMP7 treatment is sufficient to induce all of the genetic markers of osteoblast differentiation in many cell types.

The role of BMP7 in mammalian kidney development is through induction of MET of the metanephrogenic blastema. The epithelial tissue emerging from this MET process eventually forms the tubules and glomeruli of the nephron. BMP-7 is also important in homeostasis of the adult kidney by inhibiting ephithelial-mesenchymal transition (EMT). BMP-7 expression is attenuated when the nephron is placed under inflammatory or ischemic stress, leading to EMT, which can result in fibrosis of the kidney. This type of fibrosis often leads to renal failure, and is predictive of end stage renal disease.

BMP7 has been discovered to be crucial in the determination of ventral-dorsal organization in zebrafish. BMP7 causes the expression of ventral phenotypes while its complete inhibition creates a dorsal phenotype. Moreover, BMP7 is eventually partially "turned off" in embryonic development in order to create the dorsal parts of the organism.

In many early developmental experiments using zebrafish, scientists used caBMPR (constitutively active) and tBMP (truncated receptor) to determine the effect of BMP7 in embryogensis. They found that the constitutively active, which causes BMP to be expressed everywhere creates a ventralized phenotype, whereas truncated, dorsalized.

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