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。这种信号大部分是由受体酪氨酸激酶（RTKs）介导的。在成人中，RTK信号的中断可以产生深远的影响，导致各种形式的疾病，包括肿瘤的形成。由于RTK信号在胚胎和成体中都具有重要意义，因此人们对其调控机制的研究一直非常关注。对果蝇和哺乳动物细胞培养的研究表明，Sprouty基因家族的成员是RTK信号的抑制剂，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表达。本文提出的研究采用遗传方法来确定小鼠的Spry基因的功能。在目前的资助期间，已经产生了携带Spry2和Spry4功能等位基因无效和条件缺失的小鼠，以及携带Spry2功能等位基因条件获得的小鼠，该等位基因可以通过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缺陷和乳腺发育异常，而Spry4缺失的小鼠前肢异常。本实验旨在阐明Spry2在内耳和乳腺中的功能，以及Spry4在发育肢体中的功能。进一步的研究旨在通过产生缺乏不同组合的Sprouty零等位基因的小鼠，以及通过产生一组小鼠品系，每个品系携带不同的Sprouty基因条件增益功能等位基因插入小鼠基因组的精确相同位置，来评估小鼠Sprouty基因的功能等效性。当被激活时，这些小鼠系中的Sprouty基因将被相同地表达，从而有可能对不同Sprouty基因的活性进行有意义的比较。最后，实验描述了旨在确定在体外肿瘤细胞转化和乳腺肿瘤发生中，芽生基因是否起抑制作用。这些研究的结果将导致对史普罗蒂基因功能的深入了解，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.