GENETIC ANALYSIS OF CHONDROGENESIS

描述（由申请人提供）：本项目的目标是确定Sox 5和Sox 6在软骨形成和维护中的作用，从妊娠晚期到成年。这些基因编码类似的Sry相关转录因子，并且先前被证明在小鼠胚胎的软骨形成中具有重要的冗余作用。它们通过在多个步骤中控制软骨细胞分化来促进软骨内骨的软骨模板的形成和生长板的建立。由于产生的常规突变体在出生前或出生后不久死亡，Sox 5/Sox 6在妊娠晚期的一些作用是未知的，出生后的作用仍然完全未知。虽然在胚胎中获得的数据以及胚胎和出生后软骨之间的强烈相似性表明了生命后期的重要功能，但需要新的实验来验证这一假设。该项目将专门确定Sox 5/Sox 6是否需要关节和关节软骨形成，这发生在妊娠后期和新生儿期，以及整个成年期的生长板和关节软骨维护。在后一种情况下，假设关节软骨细胞中Sox 5/Sox 6表达失败导致骨关节炎。基于Sox 5/Sox 6在决定软骨细胞命运中的作用，本项目还将测试Sox 5/Sox 6是否控制除了先前鉴定的细胞外基质基因之外的调节基因的表达。为了避免早期致死，目标1是使用Cre-loxP系统来产生具有Sox 5/Sox 6条件等位基因的小鼠系。目的2是将这些小鼠与已建立的Cre转基因小鼠结合使用，以在软骨细胞或软骨形成部位的子集中特异性地表达Sox 5/Sox 6，以研究从胚胎发育到成年的功能。目的3是使用已建立的Cre小鼠或产生新的以时间调节的方式表达Sox 5/Sox 6，从而研究独立于胚胎功能的出生后功能。组织学和分子生物学分析提出了突变小鼠的特点。目的4是使用基因表达阵列和定量体内分析，以获得软骨细胞中Sox 5/Sox 6相关基因表达的详细资料。这项研究应显着扩展我们的知识的重要软骨形成转录因子的作用，并应提供新的见解的分子机制，控制关节形成，软骨生长板，关节软骨形成，关节骨关节炎性关节退行性变的维护。

DESCRIPTION (provided by applicant): The goal of this project is to identify the roles of Sox5 and Sox6 in cartilage formation and maintenance from late gestation onto adulthood. The genes encode similar Sry-related transcription factors and were previously demonstrated to have essential, redundant roles in chondrogenesis in the mouse embryo. They promote formation of the cartilage templates of endochondral bones and establishment of growth plates by controlling chondrocyte differentiation at multiple steps. Since the conventional mutants generated to determine these functions die before or soon after birth, some of the roles of Sox5/Sox6 in late gestation are unknown and postnatal roles remain totally unknown. While the data obtained in embryos and strong similarities between embryonic and postnatal cartilages suggest important functions later in life, new experiments are needed to test this hypothesis. This project will specifically determine whether Sox5/Sox6 are needed for joint and articular cartilage formation, which occur in late gestation and the neonatal period, and for growth plate and articular cartilage maintenance throughout adulthood. In the latter case, failure to express Sox5/Sox6 in articular chondrocytes is hypothesized to lead to osteoarthritis. Based on the roles of Sox5/Sox6 in determining chondrocyte fate, this project will also test whether Sox5/Sox6 control expression of regulatory genes besides the extracellular matrix genes previously identified. To bypass early lethality, Aim 1 is to use the Cre-loxP system to generate mouse lines harboring Sox5/Sox6 conditional alleles. Aim 2 is to use these mice in conjunction with established Cre transgenic mice to inactivate Sox5/Sox6 specifically in chondrocytes or in subsets of chondrogenic sites to study functions from embryogenesis through adulthood. Aim 3 is to use established Cre mice or generate new ones to inactivate Sox5/Sox6 in a temporally regulated manner and thereby study postnatal functions independently of embryonic functions. Histological and molecular analyses are proposed to characterize mutant mice. Aim 4 is to use gene expression arrays and quantitative in vivo assays to obtain a detailed profile of Sox5/Sox6-related gene expression in chondrocytes. This study should significantly extend our knowledge of the roles of important chondrogenic transcription factors and should provide novel insights into the molecular mechanisms that control joint formation, maintenance of cartilage growth plate, articular cartilage formation, and osteoarthritic degeneration of articular joints.