Selective Regulation of Pro-inflammatory Genes in Macrophages

描述(由申请人提供)：炎症有助于对微生物病原体的正常免疫反应。然而，长期的炎症会在感染过程中促进组织损伤，并与多种疾病密切相关，包括癌症、动脉粥样硬化和几种炎症性自身免疫性疾病。虽然有许多抗炎药物可用，但由于各种原因，包括靶向性不足和效力有限，没有一种被认为是理想的。因此，需要新的策略来开发促炎基因和蛋白的抑制剂。寻找抑制特定促炎基因转录的药物的一个主要限制是，我们对负责选择性基因调控的分子机制的了解仍处于初级阶段。转录因子如核因子？B和AP-1参与了许多促炎基因的激活。然而，由于它们的广泛功能，这些因子可能不是抑制特定诱导基因亚群的合适靶点。在过去的几年里，许多由Toll样受体和其他跨膜受体激活的信号转导通路已经被阐明，从而在识别导致选择性基因调控的通路方面取得了长足的进步。然而，如果不了解与促炎基因相关的控制区和DNA序列元件的逻辑组织，就很难完全理解促炎基因的差异调控机制。我们的实验室发现，脂多糖(LPS)诱导的小鼠巨噬细胞中的基因可以根据几个标准分为六大类，包括：(1)新的蛋白质合成需要；(2)ATP依赖的核小体重塑复合体SWI/SNF家族的需要；(3)转录因子IRF3的需要；(4)CpG岛启动子的存在。本申请中提出的实验集中在四类主要反应基因上，这些基因被定义为在没有新的蛋白质合成的情况下由内毒素信号通路直接激活的基因。拟议的实验将检验各种假说，包括初级反应基因的关键属性是刺激特异的假说，以及CpG岛经常与SWI/SNF非依赖性初级反应基因相关的假说，因为高CpG含量与稳定的核小体的组装不相容。我们还将研究IRF3在依赖SWI/SNF的特定类别的初级反应基因激活中的作用。最后，我们将利用细菌人工染色体，其中包含每个基因类别的代表性成员，以启动更详细的不同激活机制的分析。总而言之，这些研究应该会极大地扩展我们对先天免疫系统细胞中促炎症基因的选择性调控的知识。 公共卫生相关性：特定致炎基因的异常表达在许多常见疾病中起主要作用，包括癌症、动脉粥样硬化和一些炎症性自身免疫性疾病。值得注意的是，最近的研究表明，一些炎症基因的增强表达有助于预防疾病，而其他基因则促进疾病的进展。这项研究的目的是为了更好地了解免疫系统细胞中炎症基因差异表达的分子机制。这项研究的长期目标是开发药物策略，选择性地调节促炎基因，从而增强保护性基因的表达，减少有害基因的表达。

DESCRIPTION (provided by applicant): Inflammation can be beneficial for a normal immune response to microbial pathogens. However, prolonged inflammation can promote tissue damage during infection and has been closely linked to a diverse range of diseases, including cancer, atherosclerosis, and several inflammatory autoimmune diseases. Although a number of anti-inflammatory drugs are available, none of them are considered to be ideal for a variety of reasons, including insufficient target specificity and limited potency. Therefore, new strategies are needed for the development of inhibitors of pro-inflammatory genes and proteins. One major limitation in pursuing pharmaceuticals that inhibit the transcription of specific pro-inflammatory genes is that our understanding of the molecular mechanisms responsible for selective gene regulation remains rudimentary. Transcription factors such as NF-?B and AP-1 contribute to the activation of many pro-inflammatory genes. However, because of their broad functions, these factors may not be appropriate targets for the inhibition of specific subsets of inducible genes. During the past few years, a number of signal transduction pathways activated by Toll-like receptors (TLRs) and other transmembrane receptors have been elucidated, resulting in great strides toward the identification of pathways that lead to selective gene regulation. However, it will be difficult to fully appreciate the mechanisms responsible for the differential regulation of pro-inflammatory genes without an understanding of the logical organization of the control regions and DNA sequence elements associated with these genes. Our laboratory has found that genes induced by lipopolysaccharide (LPS) in murine macrophages can be divided into six broad classes on the basis of several criteria, including their (1) requirement for new protein synthesis, (2) requirement for nucleosome remodeling by the SWI/SNF family of ATP-dependent nucleosome remodeling complexes, (3) requirement for the transcription factor IRF3, and (4) the presence of a CpG island promoter. The experiments proposed in this application focus on the four classes of primary response genes, which are defined as genes directly activated by LPS signaling pathways in the absence of new protein synthesis. The proposed experiments will examine a variety of hypotheses, including the hypothesis that the critical properties of primary response genes are stimulus-specific and the hypothesis that CpG islands are frequently associated with SWI/SNF-independent primary response genes because the high CpG-content is incompatible with the assembly of stable nucleosomes. We will also examine the role of IRF3 in the activation of a specific class of SWI/SNF-dependent primary response genes. Finally, we will make use of bacterial artificial chromosomes containing representative members of each gene class to initiate more detailed analyses of the diverse activation mechanisms. Together, these studies should greatly expand our knowledge of the selective regulation of pro-inflammatory genes in cells of the innate immune system. PUBLIC HEALTH RELEVANCE: The aberrant expression of specific pro-inflammatory genes plays a major role in a number of common diseases, including cancer, atherosclerosis, and a number of inflammatory autoimmune disorders. Significantly, recent studies have shown that enhanced expression of some inflammatory genes helps protect against disease, whereas other genes enhance disease progression. The objective of the proposed research is to better understand the molecular mechanisms regulating the differential expression of inflammatory genes in cells of the immune system. The long-term goal of this research is to develop pharmacologic strategies for the selective modulation of pro-inflammatory genes, leading to the enhanced expression of protective genes and reduced expression of detrimental genes.