Transcriptional control of growth plate chondrocytes

项目摘要 生长板是高度专业化的软骨结构，确保骨骼生长和软骨内分泌 在胎儿和出生后的发育过程中骨化。它们由软骨细胞形成和维持，如 这些细胞遵循在空间和时间上严格控制的多步分化程序。本 该项目的重点是转录因子，这些转录因子在影响该计划中起着关键作用，但其转录模式 行动仍然不完全破译。它将检验范式转换假说，即SOX 9及其辅因子 SOX 5和SOX 6以及RUNX 2和RUNX 3以协作的方式实现它们的许多主要功能。这 假设是基于一个坚实的科学前提，包括共同表达的因素，在生长板 软骨细胞，在许多软骨细胞特异性增强子中存在与SOX 9结合的RUN结构域基序， 以及SOX和RUNX蛋白在增强子激活中具有协同活性的初步证据。 具体目标1是确定SOX 5/6、SOX 9和RUNX 2/3在生长板期间是否发生遗传相互作用 在小鼠胎儿中的形成和在幼年小鼠中的活跃生长板的维持中。具体目标二是 分析生长板软骨细胞中SOX 5/6、SOX 9和RUNX 2/3的整个遗传靶组， 评估并验证它们的重叠。具体目标3是确定SOX 5/6、SOX 9和 RUNX 2/3协同性。这些蛋白质将被测试在诱导染色质可及性和三个方面的作用- 三维连接性，以及DNA结合和功能伴侣募集中的协同性。新 研究结果应该对目前对管理这些疾病的基本机制的理解产生重大影响。 生长板和其他软骨类型的形成和维持。因此，他们应该帮助揭示 许多类型的病理学的分子基础，包括软骨发育不良、肿瘤和关节退行性变 疾病，并提出新的，创新的和有效的治疗这些仍然不能令人满意的治疗 疾病

PROJECT SUMMARY Growth plates are highly specialized cartilage structures that ensure skeletal growth and endochondral ossification during fetal and postnatal development. They are formed and maintained by chondrocytes, as these cells follow a spatially and temporally tightly controlled multi-step differentiation program. The present project focuses on transcription factors that have pivotal roles in effecting this program, but whose modes of actions remain incompletely deciphered. It will test the paradigm-shifting hypothesis that SOX9, its cofactors SOX5 and SOX6, and RUNX2 and RUNX3 fulfill many of their main functions in a cooperative manner. This hypothesis is based on a solid scientific premise that includes co-expression of the factors in growth plate chondrocytes, the presence of RUNT-domain motifs in many chondrocyte-specific enhancers bound by SOX9, and preliminary evidence that the SOX and RUNX proteins have synergistic activities in enhancer activation. Specific Aim 1 is to determine whether SOX5/6, SOX9 and RUNX2/3 genetically interact during growth plate formation in mouse fetuses and in the maintenance of active growth plates in juvenile mice. Specific Aim 2 is to profile the whole genetic targetomes of SOX5/6, SOX9 and RUNX2/3 in growth plate chondrocytes, and to assess and validate their overlap. Specific Aim 3 is to identify mechanisms underlying SOX5/6, SOX9 and RUNX2/3 cooperativity. The proteins will be tested for roles in inducing chromatin accessibility and three- dimensional connectivity, and for cooperativity in DNA binding and recruitment of functional partners. New findings should have a significant impact on current understanding of fundamental mechanisms governing the formation and maintenance of growth plates and other cartilage types. They should thereby help uncover the molecular basis of many types of pathologies, including chondrodysplasias, tumors and joint degenerative diseases, and also suggest novel, innovative and efficient treatments for these still unsatisfactorily treatable diseases.