Biological Activity and Structural Analysis of Secreted Frizzled-Related Protein

在过去的一年里，我们继续将我们的研究重点放在一种分泌的FrizzledRelated Protein(SFRP-1)的研究上，这种蛋白被认为在胚胎发育和肿瘤发生中具有重要作用。我们开发了丰富的重组SFRP-1来源，以证明它可以直接与Wnt蛋白结合，并对Wnt活性起到双相作用。几项与重组SFRP-1的合作研究拓宽了我们对其生物学活性的理解。在大鼠胚胎肾器官培养中，SFRP-1可能通过抑制WNT-4的活性来阻断小管的形成。我们最近与其他重组SFRP家族成员的研究表明，它们的生物学活性和功能存在差异。我们还一直在研究SFRP-1的基因结构和表征其启动子活性，以更好地了解其表达是如何调控的。在HGF/SF的结构-功能分析方面正在进行的合作取得了实质性进展。实验正在进行中，以确认负责肝素结合的氨基酸残基的身份，并确定它们被不会介导肝素相互作用的残基取代的后果。关于角质形成细胞生长因子(KGF或成纤维细胞生长因子-7)活性的合作研究已经获得了新的信息。研究涉及KGF/KGFR信号在胸腺发育和T细胞成熟中的作用，以及KGF缓解骨髓移植相关移植物抗宿主病影响的机制。

During the past year, we have continued to focus our research efforts on the study of a secreted, Frizzled-related protein (sFRP-1) that is thought to have an important role in embryonic development and perhaps neoplasia. We developed an abundant source of recombinant sFRP-1 to demonstrate that it can bind directly to Wnt protein and exert a biphasic effect on Wnt activity. Several collaborative studies with recombinant sFRP-1 are broadening our understanding of its biological activity. In a rat embryonic kidney organ culture, sFRP-1 can block tubulogenesis presumably by inhibiting Wnt-4 activity. Our recent work with other recombinant sFRP family members indicates differences in their biological activities and functions. We also have been investigating sfrp-1 gene structure and characterizing its promoter activity to better understand how its expression is regulated. Substantial progress has been made in an ongoing collaboration concerning the structure-function analysis of HGF/SF. Experiments are in progress to confirm the identity of the amino acid residues responsible for heparin-binding, and to determine the consequences of their replacement with residues that will not mediate heparin interactions. Collaborative studies have yielded new information about the activity of keratinocyte growth factor (KGF or FGF-7). Investigations concern the role of KGF/KGFR signaling in thymus development and T cell maturation, and the mechanisms responsible for KGF's ability to ameliorate the impact of graft versus host disease associated with bone marrow transplantation.