SKELETAL AUGMENTATION BY MESENCHYMAL/OSTEOBLAST TRANSDIFFERENTIATION

通过间充质/成骨细胞转分化来增强骨骼

• 批准号: 6662813
• 负责人: RIK M DERYNCK
• 金额: $ 11.9万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-08-01 至 2003-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6662813
• 关键词: 3T3 cells; biological signal transduction; bone development; bone morphogenetic proteins; cell differentiation; genetic promoter element; growth factor receptors; mesenchyme; osteoblasts; tissue /cell culture; transcription factor; transforming growth factors

Skeletal development requires a highly complex pattern of bone formation whereby mesenchymal cells differentiate into osteoblasts, which deposit bone, and other mesenchymal cells differentiate into myocytes, which give rise to muscle, and adipocytes, which gives rise to fat. TGF-beta- related factors regulate the differentiation pathways into muscle, fat and bone, but the exact role of these factors in mesenchymal differentiation and the underlying mechanisms remain to be characterized. In this application, we propose to characterize the role of Smads, i.e. the recently identified signaling effectors of the receptors for TGF-beta-related factors, in myogenic, adipocytic and osteoblastic differentiation, using C2C12 and 3T3-F442A cells as model system. The regulation of myoblast and osteoblast differentiation by TGF-beta and BMP-2/4, and the modulation of endogenous ligand and receptor expression during these types of differentiation invite the hypothesis that alterations in Smad signaling regulate normal myogenic, adipocytic and osteoblastic differentiation, using C2C12 and 3T3-F442A cells as model system. The regulation of myoblast and osteoblast differentiation by TGF-beta and BMP-2/4, and the modulation system. The regulation of myoblast and osteoblast differentiation by TGF-beta and BMP-2/4, and the modulation of endogenous ligand and receptor expression during these types of differentiation invite the hypothesis that alterations in Smad signaling regulate normal myogenic adipocytic and osteoblastic differentiation. Our research plan to characterize the role Smad signaling in these differentiation processes is divided in three Aims. Am extensive characterization of the differential events of C2C12 and 3T3-F442A cells in culture will be pursued together with a characterization of the effects of TGF-beta and BMP-2/4 and their receptor signaling systems (Aim 1). We will then manipulate Smad signaling by increasing or decreasing signaling by individual Smads or Smad combinations, and evaluate the effects of these alterations on cell differentiation (Aim 2). Since Smads act as transcription factors, we will then study the mechanisms through which Smads regulate the expression and activities of the "master" transcription factors of these three types of differentiation, i.e. MyoD/myogenin in myogenic differentiation, PPAR-gamma in adipocytic differentiation, and CBFA1 in osteoblastic differentiation (Aim 3). Our understanding of how Smads regulate these three types of mesenchymal differentiation makes it likely that we will be able to regulate these three types of differentiation and to induce transdifferentiation between these three lineages. Our studies will form the basis of further studies on how to recruit myogenic and adipogenic cells to transdifferentiate into osteoblasts, which deposit bone matrix, in vivo. Such an ability would clearly have important therapeutic implications, since the recruitment of mesenchymal cells to differentiate along the osteoblastic lineage and to deposit bone matrix may allow increased bone formation to counteract bone loss, associated with metabolic bone diseases and age-related osteoporosis.

骨骼发育需要高度复杂的骨形成模式，从而使间充质细胞分化为成骨细胞，这些细胞沉积骨，其他间充质细胞分化为肌细胞，从而产生肌肉，并引起脂肪细胞，从而引起脂肪。 TGF-β-相关因素调节分化途径为肌肉，脂肪和骨骼，但是这些因素在间充质分化和潜在机制中的确切作用仍有待表征。在此应用中，我们建议使用C2C12和3T3-F442A细胞作为模型系统来表征SMAD的作用，即与TGF-beta相关因素的最近确定的与TGF-beta相关因子的信号传导效应子，用于肌原性，脂肪细胞和成骨细胞分化。 The regulation of myoblast and osteoblast differentiation by TGF-beta and BMP-2/4, and the modulation of endogenous ligand and receptor expression during these types of differentiation invite the hypothesis that alterations in Smad signaling regulate normal myogenic, adipocytic and osteoblastic differentiation, using C2C12 and 3T3-F442A cells as model system. TGF-BETA和BMP-2/4以及调制系统对成肌细胞和成骨细胞分化的调节。 TGF-beta和BMP-2/4对成肌细胞和成骨细胞分化的调节，以及在这些类型的分化过程中内源性配体和受体表达的调节诱导了以下假说：SMAD信号传导的改变调节正常的肌源性肌元和骨细胞分化。我们的研究计划表征了SMAD信号在这些分化过程中的作用，分为三个目标。将在培养中对C2C12和3T3-F442A细胞的差异事件的广泛表征，以及TGF-beta和BMP-2/4及其受体信号系统的影响的表征（AIM 1）。然后，我们将通过增加或减少单个SMAD或SMAD组合的信号传导来操纵SMAD信号传导，并评估这些改变对细胞分化的影响（AIM 2）。自从SMAD充当转录因子以来，我们将研究SMADS调节这三种分化类型的“主”转录因子的表达和活性的机制，即肌生成分化中的myod/肌蛋白，脂肪细胞分化中的PPAR-pPAR-pPAR-pPAR-pARMA在脂肪细胞分化中，以及cbfa1中的cbfa1和cbfa1中的cbfa1中的cbfa1中的cbfa1 in steplastic分化（目标分化）（目标3）。我们对SMAD如何调节这三种类型的间充质分化的理解使我们可能能够调节这三种类型的分化并诱导这三个谱系之间的转变。我们的研究将构成有关如何募集肌源性和成脂细胞以将骨基质分化为骨基质的成骨细胞的进一步研究的基础。这种能力显然会具有重要的治疗意义，因为募集间充质细胞沿成骨细胞谱系区分并沉积骨基质可以使骨形成增加以抵消骨骼损失，与代谢骨疾病和年龄相关的骨质骨质造成骨骼损失。