The Role of RNase L in Cardiovascular Diseases

描述（由申请人提供）：动脉粥样硬化定义为大动脉的慢性炎症性疾病，是心脏病和中风的主要原因。炎症是动脉粥样硬化各个阶段的中心过程。早期动脉粥样硬化病变的形成涉及免疫细胞，特别是巨噬细胞的募集和活化。巨噬细胞的功能在动脉粥样硬化的发展中起着关键作用。虽然研究已经获得了很多关于巨噬细胞在动脉粥样硬化中的作用的信息，但巨噬细胞功能的分子基础，例如促炎基因的调节表达，氧化低密度脂蛋白（oxLDL）的摄取以形成泡沫细胞和凋亡，仍有待于完全理解。2-5A依赖性RNase L（RNase L）是干扰素（IFN）抗病毒和细胞增殖的关键酶之一。此外，RNase L在基因表达和细胞凋亡的调节中的作用在过去十年中已经得到很好的确立。在这项研究中，我们假设RNase L调节不同致动脉粥样硬化刺激诱导的促炎基因的巨噬细胞表达，并调节巨噬细胞功能，从而促进动脉粥样硬化发展过程中的炎症反应和病变形成。这一假设是基于我们的初步研究，即RNase L作为小鼠胚胎成纤维细胞（MEF）中环氧合酶-2（考克斯-2）和过氧化物酶体增殖物激活受体γ（PPAR-y）表达的调节剂发挥作用。这两个基因都参与了动脉粥样硬化发展过程中的炎症过程。RNase L还介导M-CSF撤除后骨髓源性巨噬细胞凋亡。为了验证我们的假设，我们提出了以下目的：（1）为了研究RNase L对促炎基因表达的影响，我们将检测RNase L +/+和-/-骨髓源性巨噬细胞在脂多糖（LPS）、多聚肌苷酸-多聚胞苷酸（Polyinosinic-polycytidylic acid，PICS）和脂多糖（LPS）刺激下考克斯-2、PPAR-y和诱导型一氧化氮合酶（inducible nitric oxide synthase，iNOS）的表达。（Poly I：C）和oxLDL;（2）为了确定RNase L在介导动脉粥样硬化病变发展中的作用，我们将首先确定RNase L在泡沫细胞形成和巨噬细胞凋亡中的作用。我们还将确定RNase L null和野生型小鼠在动脉粥样硬化发展中的脆弱性。本研究将为动脉粥样硬化发展的分子机制提供新的见解。

DESCRIPTION (provided by applicant): Atherosclerosis defined as a chronic inflammatory disease of large arteries is the primary cause of heart diseases and stroke. Inflammation is a central process in all stages of atherosclerosis. The formation of early atherosclerotic lesions involves the recruitment and activation of immune cells, particularly macrophages. The functions of macrophages play a critical role in the development of atherosclerosis. Although studies have yielded much information about the role of macrophages in atherosclerosis, the molecular basis of macrophage functions, such as the regulatory expression of proinflammatory genes, uptake of oxidized low-density lipoprotein (oxLDL) to form foam cells and apoptosis, remains to be fully understood. 2-5A dependent RNase L (RNase L) is one of the key enzymes involved in the interferon (IFN) functions against viral infection and cell proliferation. Furthermore, the role of RNase L in the regulation of gene expression and cell apoptosis has been well established in the last decade. In this proposed study, we hypothesize that RNase L regulates the macrophage expression of proinflammatory genes induced by different atherogenic stimuli, and modulates macrophage functions, resulting in the promotion of inflammatory response and lesion formation in the process of atherosclerotic development. This hypothesis is based on our preliminary studies that RNase L functions as a regulator for the expression of cyclooxygenase-2 (Cox-2) and peroxisome proliferators-activated receptorgamma (PPAR-y,) in mouse embryonic fibroblasts (MEF). Both genes are involved in the inflammatory process during the development of atherosclerosis. RNase L also mediates bone marrow-derived macrophage apoptosis after withdrawal of M-CSF. To test our hypothesis, the following aims are proposed: (1) To investigate the effect of RNase L on the expression of proinflammatory genes, we will examine the expression of Cox-2, PPAR-y and inducible nitric oxide synthase (iNOS) in RNase L +/+ and -/- bone marrow-derived macrophages stimulated by lipopolysaccharide (LPS), polyinosinic-polycytidylic (Poly I:C) and oxLDL; (2) To determine the role of RNase L in mediating the development of atherosclerotic lesions, we will first determine the role of RNase L in the formation of foam cells and macrophage apoptosis. We will also determine the vulnerability of RNase L null and wild type mice in the development of atherosclerosis. This study will provide new insights into the molecular mechanism of atherosclerotic development.