Understanding vessel regression

描述（由申请人提供）：本提案的长期目标是确定信号中继通路如何协调构成血管生成程序的各种细胞反应。本建议的目的是确定PLC伽马诱导血管回归的机制。我们目前对血管退化/不稳定的理解表明了PLCg工作的两种情况。在第一个实验中，PLCg诱导细胞因子如血管生成素2 （Ang2）的表达，从而诱导血管不稳定/退化。在第二种方法中，PLCg拮抗促生存通路，如PI3K/Akt通路，从而增加细胞凋亡和血管退化。该建议的中心假设是，PLCg通过增加回归因子的水平和/或拮抗促生存信号通路来增加血管不稳定和退化。我的实验室对我们理解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。1. 确定PLCg是否促进了诱导血管退化因子的分泌。这一目标的工作假设是，PLCg增加了可溶性因子（如Ang2）的表达和分泌，导致现有血管的不稳定和退化。我们将确定回归因子是否被分泌，Ang2对该活动的相对贡献，以及回归因子的数量是否由PLCg调节。这些实验将直接评估PLCg通过Ang2等回归因子驱动血管不稳定/回归的可能性。2. 确定PLCg是否通过拮抗PI3K诱导血管退化。这一目标的工作假设是，PLCg与PI3K竞争底物磷酸肌肽4,5 P2，从而抑制对血管稳定性至关重要的PI3K/Akt通路。我们将使用表征良好的信号突变体面板来比较PLCg激活或未激活条件下PI3K/Akt通路的输出。此外，我们将测试Akt （PI3K的下游）是否能防止血管退化。这些实验将确定PLCg是否通过拮抗“阳性”PI3K/Akt通路促进血管退化。拟议的研究具有高度创新性，原因有二。首先，通过研究信号酶来理解细胞反应的协调是一种新的策略。其次，PLCg负责促进血管退化的想法是一个新颖且未被探索的概念。这一建议具有“高影响力”，因为由此产生的信息可能会大大推进我们对血管生成如何被调节的基本理解，并为几种主要的致盲疾病提供新的治疗靶点。

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.