RANK/NF-KappaB signaling in chondrogenesis

描述（由申请人提供）： 大多数骨骼通过高度调节的过程中的软骨内骨化形成，其中骨骼元件首先在胚胎发生期间在软骨框架中放置。这些软骨成分被血管侵入并部分被骨替代，由骨形成成骨细胞放置并由骨骺生长板处的骨破坏破骨细胞重塑，骨骺生长板在生长骨的末端附近形成并控制骨骼生长。在过去的十年中，许多基因已被确定为这一过程的调节因子，它们的突变或缺失可导致各种软骨发育不良，包括侏儒症。RANKL/RANK/NF- B信号传导在小鼠中缺失这些基因后显示出调节破骨细胞生成，这些基因导致破骨细胞形成失败导致骨硬化症。令人惊讶的是，这些敲除小鼠也有短肢，但这种信号通路在软骨内骨化中的作用尚未详细研究。在这项提案中，我们计划获得初步数据，这将提供明确的证据，这一途径在软骨形成中的作用，并开发一种检测方法，将允许在体外形态学评估操纵这一信号通路和其他信号通路。我们的具体目标是：1）确定RANKL/RANK/NF- B信号传导在软骨形成中的作用; 2）确定RANK/NF- B信号传导缺失对软骨细胞基因表达的影响。NF- B转录因子调节参与许多细胞过程的多种基因的表达，包括肢体发育的早期阶段。这些因素在软骨内骨化中的特定作用的描述，应该为迄今为止还没有确定的分子基础的许多形式的软骨发育不良的发病机制开辟一个新的研究领域。

DESCRIPTION (provided by applicant): Most of the skeleton forms by endochondral ossification in a highly regulated process in which skeletal elements are first laid down during embryogenesis in a cartilaginous framework. These cartilage elements are invaded by blood vessels and partly replaced by bone, laid down by bone forming osteoblasts and remodeled by bone destroying osteoclasts at epiphyseal growth plates, which form near the ends of the growing bones and control skeletal growth. Many genes have been identified during the past decade as regulators of this process, and mutation or deletion of them can result in various chondrodysplasias, including dwarfism. RANKL/RANK/NF- B signaling was shown to regulate osteoclastogenesis after deletion of these genes in mice led to osteopetrosis due to failure of osteoclast formation. Surprisingly, these knockout mice also have short limbs, but the role of this signaling pathway in endochondral ossification has not been studied in detail. In this proposal, we plan to obtain preliminary data that will provide definitive evidence of a role for this pathway in chondrogenesis and to develop an assay that will permit in vitro morphologic assessment of manipulation of this and other signaling pathways. Our Specific Aims are: 1) To determine the role of RANKL/RANK/NF- B signaling in chondrogenesis; 2) To determine the effects of absent RANK/NF- B signaling on chondrocyte gene expression. NF- B transcription factors regulate the expression of a variety of genes involved in numerous cell processes, including the early stages of limb development. Delineation of a specific role for these factors in endochondral ossification should open up a new field of investigation into the pathogenesis of the many forms of chondrodysplasia that to date do not yet have an identified molecular basis.