In vivo functions of possible tumor suppressor Dab2

可能的肿瘤抑制因子 Dab2 的体内功能

• 批准号: 6752904
• 负责人: Jonathan A Cooper
• 金额: $ 47.56万
• 依托单位: FRED HUTCHINSON CANCER RESEARCH CENTER
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-06-01 至 2007-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6752904
• 关键词: SDS polyacrylamide gel electrophoresis; biological signal transduction; embryogenesis; endocytosis; endoderm; gene targeting; genetically modified animals; immunocytochemistry; kidney cell; laboratory mouse; mitogen activated protein kinase; myosins; phosphorylation; polymerase chain reaction; protein structure function; protein transport; renal tubule; southern blotting; tissue /cell culture; tumor suppressor genes; western blottings

DESCRIPTION (provided by applicant): The Disabled-2 (Dab2) gene inhibits tumor growth through unknown mechanisms. There are 2 Dab2 protein forms, p96 and p67 that appear to be adaptor proteins. Some adaptor proteins regulate endocytosis and others function in signal transduction. One exciting idea that we'll test for Dab2 is that some proteins do both. Our overall goal is to define the molecular mechanisms underlying the in vivo functions of Dab2. We've found that p96 but not p67 binds to endocytic proteins and localizes to clathrin-coated pits. In addition, both p96 and p67 contain a PTB/PID domain that associates with the endocytosis signals of lipoprotein receptors, and a separate domain that binds to a non-muscle myosin, myosin VI, that has been implicated in endocytosis. Indeed, we've shown that lack of Dab2 in the kidney causes protein transport defects similar to those of mice lacking the lipoprotein receptor, megalin. Thus we hypothesize that Dab2 normally regulates megalin traffic. In addition, we've found that Dab2 has another important function prior to gastrulating, when p67 is the predominant form. Dab2 mutant embryos have a defect in an extraembryonic epithelium, the visceral endoderm, and this defect prevents induction of the anterior posterior axis. The phenotype appears to result from impaired signaling by Nodal, a TGFbeta family member. We hypothesize that p67 is involved in signaling in the visceral endoderm. Since p67 lacks signals for coated pit localization, it is possible it is directly involved in signal transduction. We will identify the defective signaling pathways in Dab2-mutant visceral endoderm, and identify the step requiring Dab2. We will test whether p96 is specialized to regulate kidney transport and p67 is specialized for signal transduction, or whether each form is multifunctional. Coupled with studies on subcellular localization of Dab2 proteins in kidney and visceral endoderm, this approach will provide evidence whether the embryonic requirement for Dab2 is an indirect consequence of a role in receptor trafficking, or whether p67 has a signaling function. We will investigate the mechanism by which Dab2 regulates megalin traffic in the kidney, especially the importance of binding to components of clathrin-coated pits and myosin VI. We've also found that Dab2 is phosphorylated in mitogen-stimulated cells by MAP kinase, and will investigate the significance of Dab2 phosphorylation in regulating biological responses.

描述（由申请人提供）：残疾2（DAB2）基因通过未知机制抑制肿瘤的生长。有2种DAB2蛋白形式，P96和P67似乎是衔接蛋白。一些衔接蛋白调节内吞作用，而另一些则在信号转导中起作用。我们将测试DAB2的一个令人兴奋的想法是，有些蛋白质两者兼而有之。我们的总体目标是定义DAB2体内函数的分子机制。我们发现P96而不是P67与内吞蛋白结合，并定位于网格蛋白涂层的凹坑。此外，p96和p67都包含一个与脂蛋白受体的内吞作用信号相关联的PTB/PID结构域，以及与非肌肉肌球蛋白VI结合的单独结构域，该结构已与内吞作用有关。确实，我们已经表明，肾脏缺乏DAB2会导致蛋白质转运缺陷，类似于缺乏脂蛋白受体Megalin的小鼠。因此，我们假设DAB2通常会调节Megalin流量。此外，我们发现，当p67是主要形式时，dab2在胃结构之前具有另一个重要功能。 DAB2突变胚胎在胚外上皮，内脏内胚层中具有缺陷，并且该缺陷阻止了前轴前轴的诱导。表型似乎是由于TGFBETA家族成员Nodal的信号传导受损而引起的。我们假设p67参与内脏内胚层中的信号传导。由于p67缺少涂层坑定位的信号，因此它可能直接参与信号转导。我们将确定DAB2突变内脏内胚层中有缺陷的信号通路，并确定需要DAB2的步骤。我们将测试P96是否专门用于调节肾脏运输，P67专门用于信号转导，或者每种形式是否具有多功能。再加上DAB2蛋白在肾脏和内脏内胚层中DAB2蛋白亚细胞定位的研究，该方法将提供证据，证据是否是DAB2的胚胎需求是在受体运输中作用的间接结果，还是p67是否具有信号功能。我们将研究DAB2调节肾脏中的巨林流量的机制，尤其是将粘合蛋白涂层凹坑和肌球蛋白VI组成部分结合的重要性。我们还发现，DAB2通过MAP激酶在有丝分裂原刺激的细胞中磷酸化，并将研究DAB2磷酸化在调节生物学反应中的重要性。