Genetic Analysis of Bone Morphogenic Proteins

描述(申请人提供)：骨形态发生蛋白(BMP)是控制发育中许多不同步骤的关键信号分子。大量研究表明，BMPs是脊椎动物在胚胎发育过程中用来诱导软骨和骨形成的内源性信号，并刺激成年骨折的修复。最近的研究表明，一些BMP家族成员在关节形成中也发挥了重要作用，BMP信号可能是出生后维持关节软骨所必需的。这些蛋白质在异位植入时能够诱导新的骨组织的形成，这增加了它们可能成为骨折修复、脊柱融合、增加骨强度和维持关节软骨的重要临床治疗的基础的可能性。尽管BMP在骨骼生物学中很重要，但人们对控制它们在何时何地正常表达的分子机制知之甚少。对这一区域的进一步了解可能会提出新的方法来控制特定发育部位和阶段的BMP表达，或者抑制异位骨形成疾病中BMP的表达。我们正在对在正常发育过程中控制3个不同BMP基因表达的调控序列进行详细的遗传、基因组和功能研究。这些研究已经表明，控制BMP表达的调控序列分布在编码序列周围的巨大距离上。BMP表达的整体模式是由许多模块元件组成的，每个模块元件负责控制整个骨骼的一个小解剖子集的表达。我们将在转基因小鼠中使用比较测序、克隆扫描和功能测试相结合的方法来确定在生长骨骼元素周围的关键增殖层和标记关节形成位置的区域中负责BMP表达的最小控制元素。通过这些元件发挥作用的转录因子将通过表达筛选和与野生型和突变控制元件的生化相互作用相结合来识别。分离的控制元件还将用于测试BMP信号在控制肋骨的大小、形状和曲率方面的功能作用。最后，关节特异性控制元件将被用来开发一个通用系统，用于研究其他基因在关节中的作用。

DESCRIPTION (provided by applicant): Bone morphogenetic proteins (BMPs) are key signalling molecules that control many different steps in development. A large number of studies suggest that BMPs are the endogenous signals used by vertebrates to induce formation of cartilage and bone during embryonic development, and to stimulate repair of bone fractures in adults. More recent studies suggest that some BMP family members also play an important role in joint formation, and that BMP signalling may be required to maintain articular cartilage after birth. The remarkable ability of these proteins to induce the formation of new skeletal tissues when implanted at ectopic sites raises the possibility that they may form the basis of important new clinical treatments for fracture repair, spinal fusion, increased bone strength, and maintenance of articular cartilage. Despite the importance of BMPs in skeletal biology, very little is known about the molecular mechanisms that control where and when they are normally expressed. Increased understanding of this area may suggest new ways of manipulating BMP expression at particular sites and stages of development, or to inhibit BMP expression in diseases of ectopic bone formation. We are carrying out a detailed genetic, genomic, and functional study of the regulatory sequences that control expression of 3 different BMP genes during normal development. These studies have already shown that the regulatory sequences that control BMP expression are distributed over enormous distances around the coding sequences. The overall patterns of BMP expression are built up from a number of modular elements, each responsible for controlling expression in a small anatomical subset of the overall skeleton. We will use a combination of comparative sequencing, clone scanning, and functional tests in transgenic mice to identify minimal control elements responsible for BMP expression in the key proliferative layer that surrounds growing skeletal elements, and in interzones that mark the sites of joint formation. Transcription factors that act through these elements will be identified by a combination of expression screening and biochemical interaction with wild-type and mutant control elements. The isolated control elements will also be used to test the functional role of BMP signalling in controlling the size, shape, and curvature of ribs. Finally, joint specific control elements will be used to develop a general system for studying the role of other genes in joints.