Molecular Mechanisms in Joint Development

联合发育的分子机制

• 批准号: 8293424
• 负责人: Anna Spagnoli
• 金额: $ 31.97万
• 依托单位: UNIV OF NORTH CAROLINA CHAPEL HILL
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-07-15 至 2015-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8293424
• 关键词: Affect; American; Angiogenic Factor; Apoptosis; Biochemistry; Cartilage; Cell Count; Cell Differentiation process; Cell Maintenance; Cell Survival; Cell membrane; Cells; Chondrocytes; Controlled Environment; Data; Degenerative polyarthritis; Developed Countries; Development; Digit structure; Disease; Down-Regulation; Economic Burden; Embryo; Epiphysial cartilage; Equilibrium; Event; Failure; Foundations; Functional disorder; Galactosidase; Gene Expression Profile; Genes; Goals; Growth; Implant; Investigation; Joints; Knowledge; Laboratories; Lasers; Lead; Ligands; Limb Development; Limb structure; Maintenance; Mediating; Medical; Mesenchyme; Microscopy; Molecular; Mus; Pathway interactions; Pattern; Phenotype; Population; Process; Proteins; RNA; Reporter; Reporter Genes; Research; Role; Shapes; Signal Transduction; Site; Stream; Symptoms; System; Techniques; Up-Regulation; Vascular Endothelial Growth Factors; base; blastema; clinically significant; cytokine; digital; disability; glycol-chitosan; insight; jagged1 protein; joint function; laser capture microdissection; mouse model; nanoparticle; notch protein; novel; palliative; public health relevance; receptor; socioeconomics

DESCRIPTION (provided by applicant): Osteoarthritis (OA) affects over 46 million Americans imposing a major socio-economic burden. Currently, there are no effective medical treatments for OA. Despite its clinical significance, our knowledge of the joint development process remains limited. Synovial joint development is initiated by the formation of an interzone layer wherein joint-forming cells emerge within the segmenting chondrogenic blastema. The overall goal of this proposal is to determine the mechanisms that lead to joint interzone development, with the concept that a greater understanding of joint formation will provide the foundations to comprehend how cartilage degenerates and to develop novel therapies to treat OA. Investigations from our laboratory have revealed that TGF-2 type II receptor (T2RII) signaling is essential for the emergence of joint interzone cells. Lack of T2RII signaling in developing limbs, resulted in a lack of interphalangeal joints and an aberrant persistence of differentiated chondrocytes, as well as the absence of Noggin and Jagged-1, a Notch ligand. In mice lacking limb T2RII signaling, digital implants that gradually released Jagged-1 led to chondrocyte segmentation and emergence of interzone cells expressing joint markers, including Noggin. Noggin implants led to chondrocyte segmentation, but did not restore joint marker expression. Combining RNA laser-capture microscopy with gene-profiling analysis we have found that interzone cells express specific cell membrane-associated markers and develop in a controlled environment of cytokines, such as CCL-12, and angiogenic factors like VEGF-A, that is clearly distinct from the adjacent growth plate chondrocyte milieu. Based on the unique expression pattern of T2RII in the interzone cells and its functional role in the interzone development, we have isolated an interzone cell population from embryonic autopod mesenchyme that expresses joint specific genes, lack chondrocytic differentiation and is morphologically distinct from the cell population that lacks such markers and differentiates into chondrocytes. Based on our exciting Preliminary Data we propose the following Specific Aims: 1) to define whether activation of the Notch pathway is a mechanism by which T2RII signaling determines joint interzone formation; 2) to determine the interplay between TGF-2-induced Notch activation and Noggin in repressing joint chondrocyte differentiation; 3) to define the ontogeny of joint interzone cells throughout joint development; 4) to characterize the functional roles for CCL-12 and VEGF-A in interzone formation and the requirement for T2RII signaling in controlling their expression. To achieve these Aims, we will combine the use of mouse models, biochemistry and novel nanoparticle delivery system techniques. At the completion of the proposed studies, we will have a better understanding of how T2RII signaling initiates joint interzone formation by operating up-stream of key joint morphogenic genes and, therefore, regulating joint interzone cell survival and chondrocyte segmentation. PUBLIC HEALTH RELEVANCE: Osteoarthritis (OA) is the most common cause of disability in industrialized countries and affects more than 46 million Americans. All present therapies for OA are targeted at symptoms, and none exists that can alter the degenerative course of the disease. The overall goal of this proposal is to understand the mechanisms and molecules that are critical for joint development. The information derived from our studies has major medical relevance and implications. Our studies will provide critical insights into the chain of events that lead to OA and will point the research's direction to novel therapies to restore joint function in OA.

描述（由申请人提供）：骨关节炎（OA）影响了超过4600万美国人，造成了重大的社会经济负担。目前，没有有效的治疗OA的药物。尽管具有临床意义，但我们对关节发育过程的了解仍然有限。滑膜关节的发育是由带间层的形成开始的，其中关节形成细胞出现在分节的软骨原胚中。本提案的总体目标是确定导致关节区间发育的机制，其概念是对关节形成的更深入了解将为理解软骨退行性变和开发治疗OA的新疗法提供基础。我们实验室的研究表明，TGF-2 II型受体（T2RII）信号传导对于联合区间细胞的出现至关重要。发育中的肢体缺乏T2RII信号会导致指间关节的缺失和软骨细胞分化的异常持续，以及Noggin和Notch配体Jagged-1的缺失。在缺乏肢体T2RII信号的小鼠中，逐渐释放Jagged-1的数字植入物导致软骨细胞分裂和表达关节标志物（包括Noggin）的带间细胞的出现。Noggin植入物导致软骨细胞分割，但不能恢复关节标志物的表达。结合RNA激光捕获显微镜和基因谱分析，我们发现区间细胞表达特定的细胞膜相关标记，并在细胞因子（如CCL-12）和血管生成因子（如VEGF-A）的受控环境中发育，这与相邻生长板软骨细胞环境明显不同。基于T2RII在带间细胞中的独特表达模式及其在带间发育中的功能作用，我们从胚胎自胚间充质中分离出一个带间细胞群，该细胞群表达联合特异性基因，缺乏软骨细胞分化，并且在形态上与缺乏这些标记并分化为软骨细胞的细胞群不同。基于我们激动人心的初步数据，我们提出以下具体目标：1)确定Notch通路的激活是否是T2RII信号决定关节区间形成的机制；2)确定tgf -2诱导的Notch激活与Noggin在抑制关节软骨细胞分化中的相互作用；3)确定关节发育过程中关节带间细胞的个体发生；4)研究CCL-12和VEGF-A在区间形成中的功能作用，以及T2RII信号在控制其表达中的作用。为了实现这些目标，我们将结合使用小鼠模型、生物化学和新型纳米颗粒输送系统技术。在完成本研究后，我们将更好地了解T2RII信号如何通过操纵上游关键关节形态发生基因来启动关节带间形成，从而调节关节带间细胞存活和软骨细胞分割。