Eph Kinase Signaling In Renal Epithelial Cells

描述（由申请人提供）：Eph激酶的14个成员构成哺乳动物系统中最大的受体酪氨酸激酶亚家族，并结合称为肝配蛋白的膜锚定配体。Eph/ephrin相互作用在调节神经和心血管系统发育中的关键作用得到充分证实。然而，它们是否也上皮发育仍然在很大程度上未被探索。申请人的公开和初步结果表明，Eph激酶是上皮分支形态发生的新调节剂。在MDCK肾上皮细胞中，内源性EphA 2的配体激活有效地抑制了HGF/SF诱导的3-D胶原凝胶中的分支形态发生。在体内胚胎肾脏中，EphA 2选择性表达于输尿管芽（UB），而ephrin-A1优先表达于周围的后肾间充质（MM）。我们假设局部Eph/ephrin相互作用UB/MM边界允许肾分支形态发生的接触依赖性指导。支持这一假设，来自EphA 2敲除小鼠的肾脏显示出异常的分支形态发生。该提案的目标是利用我们建立的独特模型系统来确定肾脏发育的Eph激酶调节的细胞和分子基础。在目的1中，我们将建立时空表达谱的所有主要EphA激酶和ephrin-As在后肾发育。在目标2中，我们将专注于EphA/肝配蛋白-A相互作用的扰动如何通过创建EphA 1/EphA 2化合物敲除来影响体内肾形态发生。具体目标3，我们将在体外使用肾上皮细胞来获得EphA激酶如何调节E-钙粘蛋白介导的细胞-细胞粘附和信号转导的见解。完成这一建议将填补空白，我们的理解Eph-ephrin相互作用的发展后肾肾的作用。了解UB分支形态发生的机制不仅具有发育意义，而且具有医学意义。异常的分支形态发生可导致肾发育不全和输尿管错位或重复，这些都是常见的出生缺陷。UB生长和分支的更微妙的缺陷可能导致肾单位数量减少，这可能使个体在以后的生活中容易患肾脏疾病，包括高血压。这项研究可能会为肾脏疾病的治疗提供一种新的调节肾脏细胞行为的方法，这项研究的完成将填补我们对Eph-ephrin相互作用在肾脏发育中的作用的理解上的空白。了解UB分支形态发生的机制不仅具有发育意义，而且具有医学意义。异常的分支形态发生可导致肾发育不全和输尿管错位或重复，这些都是常见的出生缺陷。UB生长和分支的更细微缺陷可能导致肾单位数量减少，这可能使个体在以后的生活中易患肾脏疾病，包括高血压和终末期肾脏疾病。拟议的研究可能会导致一种新的方式来调节肾脏细胞的行为，用于治疗肾脏疾病。公共卫生相关性：该提案的完成将填补我们对Eph-ephrin相互作用在肾脏发育中的作用的理解中的空白。了解UB分支形态发生的机制不仅具有发育意义，而且具有医学意义。异常的分支形态发生可导致肾发育不全和输尿管错位或重复，这些都是常见的出生缺陷。UB生长和分支的更细微缺陷可能导致肾单位数量减少，这可能使个体在以后的生活中易患肾脏疾病，包括高血压和终末期肾脏疾病。拟议的研究可能会导致一种新的方式来调节肾脏细胞的行为，用于治疗肾脏疾病。

DESCRIPTION (provided by applicant): The 14 members of Eph kinases constitute the largest subfamily of receptor tyrosine kinases in mammalian system and bind membrane-anchored ligands called ephrins. The pivotal role of Eph/ephrin interactions in regulating development of nervous and cardiovascular systems is well substantiated. However, whether they also epithelial development remains largely unexplored. The published and preliminary results by the applicant show that Eph kinases are novel regulators of epithelial branching morphogenesis. In MDCK renal epithelial cells, ligand activation of endogenous EphA2 potently inhibited HGF/SF-induced branching morphogenesis in 3-D collagen gels. In embryonic kidneys in vivo, EphA2 was selectively expressed in ureteric bud (UB), while ephrin-A1 was preferentially expressed in surrounding metanephric mesenchyme (MM). We hypothesize that the localized Eph/ephrin interactions UB/MM boundary allows contact-dependent guidance of renal branching morphogenesis. Supporting this hypothesis, kidneys from EphA2 knockout mice showed abnormal branching morphogenesis. The goal of this proposal is to take advantage of the unique model systems that we have established to determine the cellular and molecular bases underlying Eph kinase regulation of kidney development. In Aim 1, we will establish spatiotemporal expression profiles of all major EphA kinases and ephrin-As during metanephric kidney development. In Aim 2, we will focus on how perturbations of EphA/ephrin-A interactions will affect renal morphogenesis in vivo, by creating EphA1/EphA2 compound knockout. Specific Aim 3, we will use renal epithelial cell in vitro to gain insights on how EphA kinases regulate E-cadherin-mediated cell-cell adhesion and signaling. Completion of this proposal will fill a gap in our understanding on the role of Eph-ephrin interactions in the development metanephric kidney. Understanding mechanisms of UB branching morphogenesis has not only developmental significance, but also medical importance. Abnormal branching morphogenesis can lead to renal agenesis and malpositioning or duplication of the ureter, which are common birth defects. More subtle defects in UB growth and branching may result in reduced nephron number, which may predispose individuals to renal diseases later in life, including hypertension. The proposed studies can potentially lead to a new way to modulate kidney cell behaviors for the treatment of kidney diseases.Completion of this proposal will fill a gap in our understanding on the role of Eph-ephrin interactions in the development of the kidney. Understanding mechanisms of UB branching morphogenesis has not only developmental significance, but also medical importance. Abnormal branching morphogenesis can lead to renal agenesis and malpositioning or duplication of the ureter, which are common birth defects. More subtle defects in UB growth and branching may result in reduced nephron number, which may predispose individuals to renal diseases later in life, including hypertension and end stage renal disease. The proposed studies can potentially lead to a new way to modulate kidney cell behaviors for the treatment of kidney diseases. PUBLIC HEALTH RELEVANCE: Completion of this proposal will fill a gap in our understanding on the role of Eph-ephrin interactions in the development of the kidney. Understanding mechanisms of UB branching morphogenesis has not only developmental significance, but also medical importance. Abnormal branching morphogenesis can lead to renal agenesis and malpositioning or duplication of the ureter, which are common birth defects. More subtle defects in UB growth and branching may result in reduced nephron number, which may predispose individuals to renal diseases later in life, including hypertension and end stage renal disease. The proposed studies can potentially lead to a new way to modulate kidney cell behaviors for the treatment of kidney diseases.