Biological Activity and Structural Analysis of Secreted Frizzled-Related Protein

在过去的一年中，我们继续把我们的研究工作集中在一种分泌的卷曲相关蛋白（sFRP-1）的研究上，这种蛋白被认为在胚胎发育和肿瘤形成中起重要作用。我们开发了丰富的重组sFRP-1的来源，以证明它可以直接结合Wnt蛋白，并对Wnt活性产生双相作用。 一些与重组sFRP-1的合作研究正在扩大我们对其生物活性的理解。在大鼠胚胎肾器官培养中，sFRP-1可能通过抑制Wnt-4活性来阻断肾小管形成。 我们最近与其他重组sFRP家族成员的工作表明，他们的生物活性和功能的差异。 我们也一直在研究sfrp-1基因的结构和表征其启动子活性，以更好地了解其表达是如何调节的。目前正在进行的关于HGF/SF结构-功能分析的合作已取得实质性进展。 正在进行实验，以确认负责肝素结合的氨基酸残基的身份，并确定将其替换为不会介导肝素相互作用的残基的后果。 合作研究已经产生了关于角质细胞生长因子（KGF或FGF-7）活性的新信息。 研究关注KGF/KGFR信号传导在胸腺发育和T细胞成熟中的作用，以及负责KGF改善与骨髓移植相关的移植物抗宿主病影响的能力的机制。

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.