Regulation of bone morphogenetic protein-4 activity by sequence elements within the prodomain.
Bone morphogenetic protein-4 (BMP-4) is synthesized as a large precursor protein, which undergoes proprotein convertase-mediated proteolytic maturation along the secretory pathway to release the active ligand. Pro-BMP-4 is initially cleaved at a consensus furin motif adjacent to the mature ligand domain (the S1 site), and this allows for subsequent cleavage at an upstream motif (the S2 site). This sequential cleavage liberates a small, evolutionarily conserved, prodomain fragment (the linker peptide) of unknown fate and function. Here we show that the linker domain is essential for proper folding, exit from the endoplasmic reticulum, and thus cleavage of the BMP-4 precursor when overexpressed in Xenopus oocytes and embryos but not in cultured mammalian cells. Mature BMP-4 synthesized from a precursor in which the S1 site is non-cleavable, such that the linker domain remains covalently attached to the ligand, has little or no activity in vivo. Finally, analysis of folding, cleavage, and bioactivity of chimeric precursors containing the BMP-7 prodomain and BMP-4 mature domain, or vice versa, with or without the BMP-4 linker domain revealed that the linker domain is only functional in the context of the BMP-4 prodomain, and that differential cleavage around this domain can regulate the activity of a heterologous ligand.
Sopory
Shailaja
S
Department of Cell and Developmental Biology, Oregon Health and Science University, Portland, Oregon 97239, USA.
Nelsen
Sylvia M
SM
Degnin
Catherine
C
Wong
Crispin
C
Christian
Jan L
JL
D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D055415:Bone Morphogenetic Protein 4; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins / Q000235:genetics / Q000378:metabolism*; D018076:DNA, Complementary / Q000378:metabolism; D005260:Female; D045683:Furin / Q000737:chemistry; D008024:Ligands; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism; D045702:Proprotein Convertase 5 / Q000378:metabolism; D011485:Protein Binding; D017510:Protein Folding; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D017386:Sequence Homology, Amino Acid; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism; D029867:Xenopus Proteins; D014982:Xenopus laevis / Q000378:metabolism
D055415:Bone Morphogenetic Protein 4; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins; D018076:DNA, Complementary; D008024:Ligands; D016212:Transforming Growth Factor beta; D029867:Xenopus Proteins; C525812:bmp4 protein, Xenopus; C525822:bmp7.1 protein, Xenopus; D045702:Proprotein Convertase 5; D045683:Furin