Genetic Analysis of Bone Morphogenic Proteins

描述（由申请人提供）：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，骨形成蛋白是脊椎动物在胚胎发育过程中诱导软骨和骨形成，以及刺激成人骨折修复的内源性信号。最近的研究表明，一些BMP家族成员也在关节形成中发挥重要作用，并且可能需要BMP信号传导来维持出生后的关节软骨。当植入异位部位时，这些蛋白质诱导新骨骼组织形成的显著能力提高了它们可能形成骨折修复、脊柱融合、增加骨强度和维持关节软骨的重要新临床治疗的基础的可能性。尽管骨形成蛋白在骨骼生物学中的重要性，但对控制它们在何时何地正常表达的分子机制知之甚少。对这一领域的进一步了解可能会提出在特定部位和发育阶段操纵BMP表达的新方法，或在异位骨形成疾病中抑制BMP表达。我们正在进行详细的遗传学，基因组学和功能的调控序列，控制3种不同的BMP基因在正常发育过程中的表达研究。这些研究已经表明，控制BMP表达的调节序列分布在编码序列周围的巨大距离上。BMP表达的总体模式由许多模块化元件建立，每个模块化元件负责控制整个骨骼的小解剖子集中的表达。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的组合来识别负责BMP表达的最小控制元件，所述BMP表达在围绕生长的骨骼元件的关键增殖层中，以及在标记关节形成的位点的区间中。通过这些元件起作用的转录因子将通过表达筛选和与野生型和突变体控制元件的生物化学相互作用的组合来鉴定。分离的控制元件也将用于测试BMP信号传导在控制肋骨的大小、形状和曲率中的功能作用。最后，关节特异性控制元件将用于开发一个通用系统，用于研究关节中其他基因的作用。

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.