Expression of BMP family proteins in mammalian cells and production of monoclonal antibodies

点击翻译按钮获取中文摘要

We have screened a genomic DNA library of Xenopus laevis with rat activin betaA gene as a probe. We have isolated 5 independent genes and one of the genes was found to be encoding a protein closely related to mammalian activin. Interestingly, the rest of the gene contained an amphibian counterpart of mammalian bone morphogenetic proteins, which was purified based on their ability to induce ectopic bone formation in vivo. Eventually, we isolated cDNAs of Xenopus BMP-2,-4 and -7. In order to obtain pure BMP proteins and supply them for experimental and clinical studies, we tried to express BMP proteins in mamalian cells. We have found that expression rate is relatively high(20 ug/L) when BMP-4 cDNA is introduced into CHO cells with pSD(X) expression vector. On the other hand, we successfully raised polyclonal antibodies against BMP-2 peptide and beta-galactosidase/BMP-4 fusion protein. The former antibody (Ab383) was found to react with BMP-4 as well as BMP-2 and the latter (Ab97) was specific to BMP-4. We partially purified the BMP-4 expressed in CHO cells based on its immunoreactivity. The final preparation of the recombinant Xenopus BMP-Xenopus BMP-2 has been shown be indistinguishable from mammalian BMP-2 biochemically ann biologically. Therefore, Xenopus BMPs are thought to be a promising molecule to develop drugs for bone fracture and osteoporosis. In addition, our antibodies are demonstrated to be useful to screen BMPs in the extract of bovine bone.