Regulation of skeletal cell differentiation by BMP and its inhibitor, noggin

信号分子之间的协调相互作用是正常骨骼发育的先决条件。最近，noggin被证明与BMP相互作用以抑制它们与受体的结合，并且还被报道在哺乳动物的软骨形态发生中起作用。然而，noggin在软骨形成中的作用以及noggin与骨形成蛋白之间的相互作用尚不清楚。在本研究中，我们研究了noggin在软骨形成中的可能作用，并探讨了noggin和骨形成蛋白在骨骼发生中的功能关系。为此，主要采取了两种办法。一是通过原位杂交技术分析小鼠胚胎发育过程中noggin的表达模式，并与骨形成蛋白进行比较。另一种方法是在体外培养小鼠长骨器官的基础上，将noggin或BMPs蛋白加入培养液中或与载体一起注入肢体原基中，观察其对长骨发育的影响。 ...更多信息 Noggin mRNA在第11.5天开始表达于颅骨、无骨和中轴骨的骨骼冷凝。noggin转录本在软骨中的表达持续到15.5dpc的肥大前期。在11.5 ~ 15.5dpc的肢体骨发育过程中，BMP 7和BMP 4转录子的表达区域与noggin的表达区域相似。将BMP-7蛋白植入11.5dpc胚胎的肢原基可诱导noggin的表达，而在14.5dpc胚胎的肢原基中未观察到这种作用。将14.5dpc的离体股骨或腓骨在noggin重组蛋白存在下培养。与对照组相比，软骨发育受到阻碍。在四肢长骨培养中加入BMP 7蛋白导致软骨过度生长，当同时加入noggin和BMP 7蛋白时，这种作用被抵消。这些结果表明，在软骨形成过程中表达的头蛋白负调控软骨发育，并且头蛋白表达在早期骨骼形成中由BMP 7诱导，并且表明头蛋白在骨骼发育中BMP信号传导的负反馈回路中起负信号作用。少

Coordinated interaction between signaling molecules are prerequisite for normal skeletal development. Recently, noggin was shown to interact with BMPs to inhibit their binding to receptor and has been also reported to function in cartilage morphogenesis in mammals. However, presice roles of noggin in cartilage formation and interaction beweeen noggin and BMPs during skeletogenesis were not yet to be elucidated. In this study, we examined possible roles of noggin in cartilage formation and investigated functional relationship between noggin and BMPs during skeletogenesis. Mainly two approaches were undertaken for these purposes. One is to analyze expression patterns of noggin during mouse embryogenesis and compare those or BMPs by in situ hybridization. The other is that mouse long bone organ culture was performed in vitro and noggin or BMPs protein were added to the medium or impalnted with a carrier into limb primordia to examine the effects of those proteins on long bone development. … More Noggin mRNA started to be expressed at the onset of skeletal condensation on day 11.5 dpc in cranial, appendicular and axial skeleton. The expression of noggin transcrpts persisted in cartilage until prehypertrophic stage on 15.5dpc. Exression domain of BMP7 and BMP4 transcipts are compasatory for that of noggin durig limb bone development from day 11.5dpc to 15.5dpc. Implantation of BMP7 protein inthe limb primordia of 11.5 dpc embryos induced noggin expression and this effects were not observed on 14.5 dpc limb. When isolated femur or fibula of 14.5 dpc were cultured in the presence of noggin recombinant protein. cartilage development were hampered in comparison with control. Addition of BMP7 protein in limb long bone culture resulted in overgrowth of cartilage and this effect was cancelled when noggin and BMP7 proteins were added simultaneously . These results indicate that noggin, expressed during chondrogenesis, negatively regulated cartilage development and noggin expression is induced by BMP7 in the early skeletogenesis, and suggest that noggin function as a negative signal in the negative feed back loop of BMP signaling in skeletal development. Less