Sprouty Genes in Vertebrate Development and Disease

描述（由申请人提供）： 几乎脊椎动物胚胎发育的所有方面都依赖于邻近组织中细胞之间的信号传导。这种信号传导的大部分由受体酪氨酸激酶（RTK）介导。在成人中，RTK信号传导的中断可能产生深远的影响，导致各种形式的疾病，包括肿瘤形成。由于其在胚胎和成人中的核心重要性，人们一直致力于了解调节RTK信号的机制。在果蝇和哺乳动物细胞培养物中的研究已经证明Sprouty基因家族的成员是RTK信号传导的抑制剂，并且在脊椎动物胚胎中的研究已经表明Sprouty家族的三个成员在发育的不同阶段表达。本文提出的研究采用遗传学方法来确定Sprouty（Spry）基因在小鼠中的功能。在目前的授权期内，已经产生了携带Spry2和Spry4的无效和条件性功能丧失等位基因的小鼠，以及携带可以通过Cre介导的重组在特定组织中激活的条件性Spry2功能获得等位基因的小鼠系。对这些小鼠的分析表明，Spry2功能的丧失会导致严重的听力缺陷和乳腺发育异常，并且Spry4缺失小鼠具有异常的前肢。本文提出的实验旨在阐明Spry2在内耳和乳腺中的功能，以及Spry4在发育肢体中的功能。另外的研究旨在通过产生缺乏Sprouty无效等位基因的不同组合的小鼠，以及通过产生一组小鼠品系来评估小鼠Sprouty基因的功能等效性，所述小鼠品系各自携带插入小鼠基因组中精确相同位点的不同Sprouty基因功能等位基因的条件性获得。当被激活时，这些小鼠品系中的Sprouty基因将被相同地表达，使得不同Sprouty基因的活性的有意义的比较成为可能。最后，实验旨在确定是否Sprouty基因的功能作为肿瘤细胞在体外转化和乳腺肿瘤发生的抑制剂。拟议研究的结果将导致对Sprouty基因功能的深入了解，这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.