Bone Morphogenetic Protein-5 (BMP-5) is a TGF-beta superfamily homodimeric cytokine. Cellular responses to BMP-5 are mediated by the formation of hetero-oligomeric complexes of type I and type II serine/threonine kinase receptors. BMP-5 is expressed by chondrocytes in proliferating and hypertrophic zones of bone growth plates. It contributes to limb development by promoting proliferation and differentiation of chondrocytes as well as apoptosis of undifferentiated mesoderm. Genetic defects in BMP-5 which cause C-terminal truncation or loss of the proteolytic cleavage site result in multiple skeletal abnormalities, including the short ear phenotype in mice. BMP-5 is also expressed by ovarian granulosa cells where it functions as an autocrine factor to promote GC proliferation and inhibit their production of progesteron. In the nervous system, BMP-5 promotes dendrite outgrowth and dopaminergic neuronal differentiation. It is upregulated in oral squamous carcinoma cells and induces the apoptosis of some myeloma cell lines.
