title: Myostatin signals through a transforming growth factor beta-like signaling pathway to block adipogenesis.
abstract: Myostatin, a transforming growth factor beta (TGF-beta) family member, is a potent negative regulator of skeletal muscle growth. In this study we characterized the myostatin signal transduction pathway and examined its effect on bone morphogenetic protein (BMP)-induced adipogenesis. While both BMP7 and BMP2 activated transcription from the BMP-responsive I-BRE-Lux reporter and induced adipogenic differentiation, myostatin inhibited BMP7- but not BMP2-mediated responses. To dissect the molecular mechanism of this antagonism, we characterized the myostatin signal transduction pathway. We showed that myostatin binds the type II Ser/Thr kinase receptor. ActRIIB, and then partners with a type I receptor, either activin receptor-like kinase 4 (ALK4 or ActRIB) or ALK5 (TbetaRI), to induce phosphorylation of Smad2/Smad3 and activate a TGF-beta-like signaling pathway. We demonstrated that myostatin prevents BMP7 but not BMP2 binding to its receptors and that BMP7-induced heteromeric receptor complex formation is blocked by competition for the common type II receptor, ActRIIB. Thus, our results reveal a strikingly specific antagonism of BMP7-mediated processes by myostatin and suggest that myostatin is an important regulator of adipogenesis.
mesh_terms: D017667:Adipocytes / Q000378:metabolism*; D000818:Animals; D055396:Bone Morphogenetic Protein 2; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins / Q000378:metabolism; D019556:COS Cells; D002454:Cell Differentiation; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism; D017930:Genes, Reporter; D006706:Homeostasis; D006801:Humans; D051379:Mice; D008809:Mice, Inbred C3H; D008954:Models, Biological; D055435:Myostatin; D041681:NIH 3T3 Cells; D010766:Phosphorylation; D016133:Polymerase Chain Reaction; D011485:Protein Binding; D012313:RNA / Q000378:metabolism; D034622:RNA Interference; D015398:Signal Transduction; D051899:Smad2 Protein; D013997:Time Factors; D015534:Trans-Activators / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000378:metabolism*
chemical_list: C525718:BMP2 protein, human; C525819:BMP7 protein, human; C525719:Bmp2 protein, mouse; D055396:Bone Morphogenetic Protein 2; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins; D004268:DNA-Binding Proteins; C525911:MSTN protein, human; C525912:Mstn protein, mouse; D055435:Myostatin; C497782:SMAD2 protein, human; D051899:Smad2 Protein; C497783:Smad2 protein, mouse; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D012313:RNA