Regulation of Bone Morphogenetic Protein 9 by Redox-Dependent Proteolysis
Journal of Biological Chemistry
American Society for Biochemistry and Molecular Biology
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Wei, Z., Salmon, R., Upton, P., Morrell, N., & Li, W. (2014). Regulation of Bone Morphogenetic Protein 9 by Redox-Dependent Proteolysis. Journal of Biological Chemistry, 289 31150-31159. https://doi.org/10.1074/jbc.M114.579771
BMP9, a member of the TGFβ superfamily, is a homodimer that forms a signaling complex with two type I and two type II receptors. Signaling through high-affinity activin receptor-like kinase 1 (ALK1) in endothelial cells, circulating BMP9 acts as a vascular quiescence factor, maintaining endothelial homeostasis. BMP9 is also the most potent BMP for inducing osteogenic signaling in mesenchymal stem cells in vitro and promoting bone formation in vivo. This activity requires ALK1, the lower-affinity type I receptor ALK2, and higher concentrations of BMP9. In adults, BMP9 is constitutively expressed in hepatocytes and secreted into the circulation. Optimum concentrations of BMP9 are essential to maintain the highly specific endothelialprotective function. Factors regulating BMP9 stability and activity remain unknown. Here, we showed by chromatography and a 1.9 Å crystal structure that stable BMP9 dimers could form either with (D-form) or without (Mform) an intermolecular disulfide bond. Although both forms of BMP9 were capable of binding to the prodomain and ALK1, the Mform demonstrated less sustained induction of Smad1/5/8 phosphorylation. The two forms could be converted into each other by changing the redox potential and this redox switch caused a major alteration in BMP9 stability. The M-form displayed greater susceptibility to redox-dependent cleavage by proteases present in serum. This study provides a mechanism for the regulation of circulating BMP9 concentrations, and may provide new rationales for approaches to modify BMP9 levels for therapeutic purposes.
Funding was provided by the British Heart Foundation. Infrastructure support was provided by the Cambridge NIHR Biomedical Research Centre.
British Heart Foundation (PG/12/54/29734)
British Heart Foundation (CH/09/001/25945)
British Heart Foundation (RG/13/4/30107)
British Heart Foundation (PG/11/10/28724)
External DOI: https://doi.org/10.1074/jbc.M114.579771
This record's URL: https://www.repository.cam.ac.uk/handle/1810/245994
Attribution 2.0 UK: England & Wales
Licence URL: http://creativecommons.org/licenses/by/2.0/uk/