Role of Anthrax Toxin Receptors in Angiogenesis and Endothelium

描述（由申请人提供）：允许炭疽与宿主相互作用的细胞受体被认为是血管生成受体。了解它们的功能可能对设计干扰炭疽毒素作用的策略至关重要。例如，阻断炭疽-受体相互作用的试剂可能干扰天然配体-受体相互作用，从而影响血管完整性、血管生成和表皮细胞。本研究确定了与炭疽保护抗原（PA）亲和力最高的受体ANTXR2/CMG2的血管生成功能。将研究ANTXR2/CMG2在炭疽暴露的组织部位，特别是皮肤中的功能。我们的初步研究表明，ANTXR2/CMG2对内皮细胞的毛细血管样管形成、增殖和迁移具有重要作用。我们描述了与炭疽暴露相关的ANTXR2/CMG2表达位点，并证明了CMG2细胞外结构域的可溶性形式抑制皮肤中vegf驱动的新生血管形成。我们将重点研究ANTXR2/CMG2在真皮血管生成、角化细胞功能以及与这些细胞结合的炭疽保护抗原（PA）中的功能。我们的总体目标是了解ANTXR2/CMG2在皮肤细胞中的功能，以研究抑制炭疽毒素/受体相互作用对宿主细胞功能的影响。为了实现这一目标，在Aim I中，我们评估了ANTXR2/CMG2在真皮微血管内皮细胞中的功能，使用敲低和受体拮抗剂来干扰功能。我们假设ANTXR2/CMG2促进真皮血管生成的关键步骤。这一假设也将在Aims II和III中进行评估，Aims II和III的重点是在体内评估ANTXR2/CMG2在血管发育、VEGF诱导的皮肤血管生成和伤口修复过程中的功能。在Aim III中，我们将有条件地切除ANTXR2/CMG2的表达。我们的初步结果表明，ANTRX2/CMG2在多种细胞类型中表达，因此我们将有条件地去除内皮细胞或角化细胞中的基因功能，这两个细胞都是炭疽相互作用的潜在位点。最后，在Aim IV中，我们通过评估pa -受体在敲低内皮细胞和内皮特异性受体表达缺失的突变小鼠中的相互作用，验证了ANTXR2/CMG2作为内皮中主要炭疽受体的假设。允许炭疽与宿主相互作用的细胞受体被认为参与新血管的生长，因此了解其功能可能对设计干扰炭疽毒素作用的策略至关重要。例如，阻断炭疽毒素的试剂可能会干扰正常的受体功能，从而影响皮肤、肺和肠道中的血管和其他细胞。这项研究将确定使用旨在阻断炭疽的新药物后的潜在不良影响，从而有助于确保这种策略是安全的。

DESCRIPTION (provided by applicant): The cellular receptors that allow Anthrax interaction with host are proposed to be angiogenic receptors. Understanding their function may be critical in designing strategies to interfere with Anthrax toxin action. For instance, reagents that block anthrax-receptor interaction may interfere with native ligand-receptor interactions thus affecting vessel integrity, angiogenesis and epidermal cells. This proposal defines the angiogenic functions of the receptor with highest affinity for the anthrax protective antigen (PA), that is ANTXR2/CMG2. The function of ANTXR2/CMG2 will be studied in tissues sites of anthrax exposure, specifically skin. Our preliminary studies shows that ANTXR2/CMG2 is important for capillary-like tube formation, proliferation and migration of endothelial cells. We describe sites of ANTXR2/CMG2 expression of relevance to Anthrax exposure and we demonstrate that a soluble form of the extracellular domain of CMG2 inhibits VEGF-driven neovascularization in skin. Our emphasis here will be on ANTXR2/CMG2 function in dermal angiogenesis, in keratinocyte function and on anthrax protective antigen (PA) binding to such cells. Our overall objective is to understand ANTXR2/CMG2 function in cells of the skin, in order to study the consequence of inhibition of anthrax toxin/receptor interaction on host cell function. To achieve this objective, in Aim I we evaluate ANTXR2/CMG2 function in dermal microvascular endothelial cells, using knockdown and receptor antagonists to interfere with function. We hypothesize that ANTXR2/CMG2 promotes key steps in dermal angiogenesis. This hypothesis will also be evaluated in Aims II and III that focus on in vivo assessment of ANTXR2/CMG2 function during vascular development, dermal angiogenesis induced by VEGF and during wound repair. In Aim III we will conditionally ablate ANTXR2/CMG2 expression. Our preliminary results show that ANTRX2/CMG2 is expressed in diverse cell types thus we will conditionally remove gene function in endothelial cells or keratinocytes, both potential sites of anthrax interaction. Finally, in Aim IV we test the hypothesis that ANTXR2/CMG2 serves as the major anthrax receptor in endothelium by evaluating PA-receptor interaction in knockdown endothelial cells and mutant mice with endothelial-specific loss of receptor expression.The cellular receptors that allow Anthrax interaction with host are thought to be involved in the growth of new blood vessels thus understanding their function may be critical in designing strategies to interfere with Anthrax toxin action. For instance, reagents that block anthrax toxin may interfere with the normal receptor function thus affecting blood vessels and other cells in skin, lung, and gut. This study will define the potential adverse effects after use of new agents designed to block anthrax and thus help assure that such strategies are safe.