Understanding vessel regression

描述(由申请人提供)：本提案的长期目标是确定信号传递通路如何协调构成血管生成计划的不同细胞反应。这项建议的目的是确定PLC伽马诱导血管退变的机制。我们目前对血管退变/失稳的理解提出了两种情况，即PLCg的运作方式。在第一种途径中，PLCg诱导血管生成素2(Ang2)等细胞因子的表达，从而导致血管不稳定/退化。在第二个途径中，PLCg拮抗PI3K/Akt等促生存通路，从而增加细胞凋亡和血管退行性变。这一建议的中心假设是，PLCg通过增加回归因子水平和/或拮抗有利于生存的信号通路来增加血管不稳定和退化。我的实验室为我们理解PI3K和PLCg如何驱动细胞反应做出了重要贡献，在这个过程中，我们获得了所有拟议实验所需的专业知识和工具。目标如下所示。1.确定PLCg是否促进诱导血管退缩的因子的分泌。这一目的的工作假设是PLCg增加了诸如Ang2等导致现有血管不稳定和退化的可溶性因子的表达和分泌。我们将确定是否分泌回归因子，Ang2对这一活性的相对贡献，以及回归因子的数量是否受PLCg调节。这些实验将直接评估PLCg通过回归因子(如Ang2)驱动血管失稳/回归的可能性。2.确定PLCg是否通过拮抗PI3K而诱导血管退缩。这一目的的工作假设是PLCg与PI3K竞争其底物磷脂酰肌醇4，5-P2，从而抑制对血管稳定性至关重要的PI3K/Akt通路。我们将使用我们特征良好的信号突变小组来比较PLCg激活或未激活的条件下PI3K/Akt通路的输出。此外，我们将测试使用Akt(位于PI3K下游)是否可以防止血管退化。这些实验将确定PLCg是否通过拮抗“积极的”PI3K/Akt途径来促进血管退化。拟议的研究具有很高的创新性，原因有两个。首先，研究信号酶以了解细胞反应协调的方法是一种新的策略。第二，认为PLCg负责促进血管回归的想法是一个新的、未被探索的概念。这项提议的影响很大，因为由此产生的信息可能会极大地促进我们对血管生成如何调控的基本理解，并为几种主要的致盲疾病提供新的治疗目标。

DESCRIPTION (provided by applicant): The long-term objective of this proposal is to determine how signal relay pathways orchestrate the diverse cellular response that constitutes the angiogenic program. The objective of this proposal is to determine the mechanism by which PLC gamma induces vessel regression. Our current understanding of vessel regression/destabilization suggests 2 scenarios by which PLCg operates. In the first one, PLCg induces expression of cellular factors such as angiopoetin 2 (Ang2) that induce vessel destabilization/regression. In the second one, PLCg antagonizes pro-survival pathways such as the PI3K/Akt pathway and thereby increases apoptosis and vessel regression. The central hypothesis of this proposal is that PLCg increases vessel destabilization and regression by either increasing the levels of regression factors and/or antagonizing pro-survival signaling pathways. My laboratory has made important contributions to our understanding of how PI3K and PLCg drive cellular responses, and in the process we have gained the necessary expertise and tools for all of the proposed experiments. The aims are listed below. 1. To determine if PLCg promotes the secretion of factors that induce vessel regression. The working hypothesis for this aim is that PLCg increases the expression and secretion of soluble factors such as Ang2 that lead to destabilization and regression of existing vessels. We will determine if a regression factor is secreted, the relative contribution of Ang2 to this activity, and if the quantity of the regression factor is regulated by PLCg. These experiments will directly assess the possibility that PLCg acts through a regression factor such as Ang2 to drive the destabilization/regression of vessels. 2. To determine if PLCg induces vessel regression by antagonizing PI3K. The working hypothesis for this aim is that PLCg competes with PI3K for its substrate phosphoinositide 4,5 P2, and thereby suppress the PI3K/Akt pathway that is essential for vessel stability. We will use our well-characterized panel of signaling mutants to compare the output of the PI3K/Akt pathway under conditions when PLCg is or is not activated. In addition, we will test if engaging the Akt (which is downstream of PI3K) prevents vessel regression. These experiments will determine if PLCg is promoting vessel regression by antagonizing the "positive" PI3K/Akt pathway. The proposed studies are highly innovative for two reasons. First, the approach of studying signaling enzymes to understand the coordination of cellular responses is a fresh strategy. Second, the idea that PLCg is responsible for promoting vessel regression is a novel and unexplored concept. This proposal is "high impact" because the resulting information is likely to substantially advance both our basic understanding of how angiogenesis is regulated, and to provide new therapeutic targets for several major, blinding diseases.