Sprouty Genes in Vertebrate Development and Disease

描述(申请人提供)：脊椎动物胚胎发育的几乎所有方面都依赖于邻近组织中细胞之间的信号传递。这种信号很大程度上是由受体酪氨酸激酶(RTK)介导的。在成年人中，RTK信号的中断可能会产生深远的影响，导致包括肿瘤形成在内的各种形式的疾病。由于RTK在胚胎和成体中的重要作用，人们一直致力于了解RTK信号的调控机制。在果蝇和哺乳动物细胞培养中的研究表明，Sprouty基因家族的成员是RTK信号转导的抑制因子，而对脊椎动物胚胎的研究表明，Sprouty家族的三个成员在不同的发育阶段都有表达。这里提出的研究使用了一种遗传方法来确定Sprouty(Spry)基因在小鼠中的功能。在当前的授权期内，已经产生了携带SPRY2和SPRY4功能等位基因无效和有条件丢失的小鼠，以及携带有条件SPRY2功能等位基因获得的小鼠品系，这些小鼠可以通过Cre介导的重组在特定组织中激活。对这些小鼠的分析表明，SPRY2功能的丧失会导致严重的听力障碍和乳腺发育异常，并且SPRY4基因缺失的小鼠有异常的前肢。本实验旨在阐明SPRY2在内耳和乳腺中的功能，以及SPRY4在肢体发育中的作用。其他研究的目的是评估小鼠Sprouty基因的功能等价性，方法是培育缺乏Sprouty零等位基因不同组合的小鼠，并产生一组小鼠系，每个小鼠系携带不同的Sprouty基因条件功能等位基因插入到小鼠基因组中完全相同的位置。当被激活时，这些小鼠品系中的Sprouty基因将得到相同的表达，从而可能对不同Sprouty基因的活性进行有意义的比较。最后，描述了旨在确定Sprouty基因是否作为体外肿瘤细胞转化和乳腺肿瘤发生的抑制因子的实验。这些研究结果将有助于深入了解Sprouty基因的功能，这将对预防人类先天性缺陷和治疗疾病具有重要意义。

DESCRIPTION (provided by applicant): Virtually all aspects of vertebrate embryonic development are dependent on signaling between cells in neighboring tissues. Much of this signaling is mediated by Receptor Tyrosine Kinases (RTKs). In the adult, disruptions in RTK signaling can have profound effects, resulting in various forms of disease including tumor formation. Because of its central importance in both the embryo and adult, considerable attention has been devoted to understanding the mechanisms that regulate RTK signaling. Studies in Drosophila and in mammalian cell culture have demonstrated that members of the Sprouty gene family are inhibitors of RTK signaling, and studies in vertebrate embryos have indicated that three members of the Sprouty family are expressed at various stages of development. The studies proposed here employ a genetic approach to determine the functions of the Sprouty (Spry) genes in the mouse. In the course of the current grant period, mice carrying null and conditional loss of function alleles of both Spry2 and Spry4, as well as a line of mice carrying a conditional Spry2 gain of function allele that can be activated in specific tissues by Cre-mediated recombination have been produced. Analyses of these mice have revealed that loss of Spry2 function causes a severe hearing deficit and abnormal mammary gland development, and that Spry4 null mice have abnormal forelimbs. The experiments proposed here are aimed at elucidating the functions of Spry2 in the inner ear and mammary gland, and of Spry4 in the developing limb. Additional studies are aimed at assessing the functional equivalence of the mouse Sprouty genes by generating mice that lack different combinations of Sprouty null alleles, and by producing a set of mouse lines, each carrying a different Sprouty gene conditional gain of function allele inserted into precisely the same site in the mouse genome. When activated, the Sprouty genes in these mouse lines will be identically expressed, making possible a meaningful comparison of the activities of the different Sprouty genes. Finally, experiments are described aimed at determining whether Sprouty genes function as suppressors of neoplastic cell transformation in vitro and tumorigenesis in the mammary gland. The results of the proposed studies will lead to a deep understanding of the function of the Sprouty genes, which should have important implications for preventing human congenital defects and treating disease.