Role of Trps1 in endochondral bone formation

描述(由申请人提供)： 摘要人类TRPS1基因突变导致一种显性遗传性骨骼发育不良-鼻毛-指骨综合征(TRPS)。尽管该基因早在几年前就被发现，但TRPS背后的分子和细胞机制在很大程度上尚不清楚。Trps1是一种GATA型转录因子，起转录抑制因子的作用。最近，我们在小鼠中证明了Trps1基因的破坏导致生长板显著延长和软骨被骨替代的延迟。这些异常伴随着印度刺猬(IHH)表达的增加和IHH和BMP信号的升高。尽管BMP和IHH途径同时作用于调控软骨内骨形成的各个方面，但尚不清楚它们是如何在转录水平上整合和控制的。该方案的假设是Trps1抑制IHH-BMP正反馈环，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Trps1分子网络及其在调节分化的软骨细胞和软骨膜之间的串扰中的作用。具体地说，我们将重点了解Trps1突变小鼠延迟去除软骨和软骨内成骨的机制。为了解决这些问题，我们提出了以下具体目标：1.了解Trps1基因中断导致生长板延长的分子和细胞机制。2.确定Trps1是如何调节BMP和Hedgehog信号的。第一个目标将通过对TRPS小鼠模型生长板异常的组织学和分子分析来实现。为了实现第二个目标，我们将在软骨形成的细胞模型中结合使用电泳迁移率改变分析(EMSA)、报告表达分析以及Trps1缺乏和过度表达对BMP和Hedgehog信号的影响的分析。此外，我们将使用Trps1；IHH双突变小鼠来测试Trps1和IHH的遗传拮抗作用。拟议的研究结果将确定毛鼻指骨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信号转录控制的理解，这两种信号广泛参与多器官系统的发育。 公共卫生相关性： 项目简介本项目致力于阐明毛鼻指骨综合征(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.