Role of Trps1 in endochondral bone formation

描述（由申请人提供）： 人类TRPS 1基因突变导致显性遗传性骨骼发育不良-鼻-趾骨综合征（TRPS）。虽然该基因在几年前就被发现，但TRPS的分子和细胞机制在很大程度上是未知的。Trps 1是一种GATA型转录因子，作为转录抑制因子。最近，我们已经证明，在小鼠中的Trps 1基因的破坏导致生长板的显着延长和延迟的软骨骨替代。这些异常伴随着增加的印度刺猬（Ihh）表达和升高的Ihh和BMP信号。虽然BMP和Ihh通路平行作用以调节软骨内骨形成的各个方面，但尚不清楚它们如何在转录水平整合和控制。该建议的假设是Trps 1抑制Ihh-BMP正反馈回路，以确保软骨细胞成熟的及时进展和软骨细胞发育与软骨膜矿化的同步。我们提出的研究旨在阐明Trps 1分子网络及其在调节分化软骨细胞和软骨膜之间的串扰的作用。具体来说，我们将专注于了解延迟软骨去除和软骨内骨化的Trps 1突变小鼠的机制。为了解决这些问题，我们提出了以下具体目标：1。了解Trps 1基因破坏引起生长板延长的分子和细胞机制。2.确定Trps 1如何调节BMP和hedgehog信号。第一个目标将通过TRPS小鼠模型生长板异常的组织学和分子学分析来实现。为了实现第二个目标，我们将采用电泳迁移率变动分析（EMSA），报告基因表达分析和分析的Trps 1缺陷和过度表达对BMP和hedgehog信号在软骨形成的细胞模型的影响的组合。此外，我们将使用Trps 1;Ihh双突变小鼠测试Trps 1和Ihh的遗传拮抗作用。这些研究结果将明确鼻-指-趾综合征骨骼发育不良的分子机制。重要的是，这些研究的结果将直接影响我们对BMP和hedgehog信号传导的转录控制的理解，这些信号传导广泛参与多器官系统的发育。 公共卫生相关性： 本项目的重点是阐明鼻-指-趾综合征（TRPS）骨骼异常的分子机制。这项研究的结果将直接影响我们对骨骼发育的分子调控的理解。

DESCRIPTION (provided by applicant): ABSTRACT Mutations of the human TRPS1 gene cause a dominantly inherited skeletal dysplasia tricho-rhino-phalangeal syndrome (TRPS). Although the gene was identified several years ago, the molecular and cellular mechanisms underlying TRPS are largely unknown. Trps1 is a GATA-type transcription factor that acts as a transcriptional repressor. Recently, we have demonstrated that disruption of the Trps1 gene in mice results in dramatic elongation of growth plates and delayed replacement of cartilage by bone. These abnormalities are accompanied by increased Indian hedgehog (Ihh) expression and elevated Ihh and BMP signaling. Although BMP and Ihh pathways act in parallel to regulate various aspects of endochondral bone formation, it is unclear how they are integrated and controlled at the transcriptional level. The hypothesis of this proposal is that Trps1 constrains the Ihh-BMP positive feedback loop to assure timely progression of chondrocyte maturation and synchronization of chondrocyte development with perichondrial mineralization. We propose studies aimed at elucidating the Trps1 molecular network and its role in regulation of the cross-talk between differentiating chondrocytes and perichondrium. Specifically, we will focus on understanding the mechanisms of delayed cartilage removal and endochondral ossification in Trps1 mutant mice. To address these questions we propose the following specific aims: 1. To understand the molecular and cellular mechanisms of the growth plate elongation caused by disruption of the Trps1 gene. 2. To determine how Trps1 regulates BMP and hedgehog signaling. The first aim will be accomplished by histological and molecular analyses of abnormalities in the growth plate of the mouse model of TRPS. To achieve the second aim we will employ a combination of electrophoretic mobility shift assay (EMSA), reporter expression assays and analyses of the effect of the Trps1 deficiency and over-expression on BMP and hedgehog signaling in a cellular model of chondrogenesis. Additionally, we will test the Trps1 and Ihh genetic antagonism using Trps1;Ihh double mutant mice. Results of the proposed studies will define molecular mechanisms underlying skeletal dysplasia in tricho-rhino-phalangeal syndrome. Importantly, the results of these studies will directly impact our understanding of the transcriptional control of BMP and hedgehog signaling, that are widely involved in the development of multiple organ systems. PUBLIC HEALTH RELEVANCE: Project Narrative This project is focused on elucidating the molecular mechanisms of skeletal abnormalities in tricho-rhino-phalangeal syndrome (TRPS). The results of this study will directly impact our understanding of molecular regulation of skeletal development.