Morphogenetic Proteins in Embryogenesis and Tissue Regen

我们的主要目标是识别和定义可用于修复因创伤、辐射、肿瘤或其他病理性损伤而受损的组织或结构的蛋白质的作用。我们已经鉴定了十几种新的蛋白质。其中两种诱导软骨的形成，一种诱导骨和造血组织的形成，一种在确定胚胎发育的整体模式中起关键作用，另外三种功能未知。其中一种蛋白Frzb是Wnt生长因子致癌基因信号传导的分泌抑制剂，是一个不断增长的相关蛋白家族的原型。揭示了Wnt和骨形态发生蛋白（BMP）家族的分泌生长因子与这些蛋白的分泌拮抗剂之间的关键反馈相互作用。发现BMP 4和7、Wnt-8、BMP拮抗剂chordin和noggin以及Wnt拮抗剂Frzb的局部表达建立了形成脊椎动物肌肉最早前体的形态发生场。这些蛋白的表达模式的关系似乎维持了Wnt-8和bmp - 4和7途径控制组织命运之间的动态平衡。

Our primary goal is to identify and define the actions of proteins that can be used to repair tissues or structures that have been damaged by trauma, radiation, neoplasia, or other pathologic insult. We have identified over a dozen novel proteins. Two of these induce the formation of cartilage, one induces the formation of bone and hematopoietic tissue, one plays a key role in defining the overall pattern of the developing embryo, and three others have unknown functions. One of these proteins, Frzb, is a secreted inhibitor of signaling by the Wnt growth factor oncogenes, and is the prototype of a growing family of related proteins. Key feedback interactions between secreted growth factors belonging to the Wnt and Bone Morphogenetic Protein (BMP) families and secreted antagonists of these proteins were elucidated. Localized expression of BMPs 4 and 7, Wnt-8, the BMP antagonists chordin and noggin, and the Wnt antagonist Frzb were found to establish the morphogenetic field giving rise to the earliest precursors of vertebrate muscle. The relationship of expression pattern of these proteins appears to maintain a dynamic balance between Wnt-8 and BMPs 4 and 7 pathways that controls tissue fate. To examine the interactions of these signals, technologies to enable loss-of-function experiments will be useful if not essential. We are therefore isolating genes encoding the proteins under study from X. tropicalis, a diploid relative of X.laevis that may allow construction of deletions using site-specific DNA repair and more facile application of third-generation antisense technologies. We have also prepared recombinant adenoviruses encoding Frzb and ADMP for both high-level protein expression and evaluation in mammalian models of skeletal repair; the latter experiments are in progress. We have isolated amphibian orthologs of CDMP-1/GDF-5 and a novel calmodulin binding protein and have characterized their biological distributions. Functional studies are in progress. We have also isolated a cDNA encoding a protein of unknown function with sequence similar to that of the murine ky gene, associated with profound kyphosis, and have defined its domain of expression. We are also developing procedures to evaluate the effects of morphogens on signal transduction pathways using novel proteomic techniques. This has required development of a novel technique for introducing epitope tags using Type II restriction endonucleases that will be of general applicability.