Selective Regulation of Pro-inflammatory Genes in Macrophages

描述（由申请人提供）：炎症可能有利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期间促进组织损伤，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，包括目标特异性不足和效力有限，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。在寻找抑制特定促炎基因转录的药物时，一个主要的限制是我们对选择性基因调控的分子机制的理解仍然是初级的。转录因子如NF-？B和AP-1参与许多促炎基因的激活。然而，由于其广泛的功能，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toll样受体（TLRs）和其他跨膜受体激活的信号转导通路已经被阐明，导致选择性基因调控的途径的鉴定取得了很大的进展。然而，如果不了解与这些基因相关的控制区和DNA序列元件的逻辑组织，就很难充分了解促炎基因差异调控的机制。我们的实验室发现，在小鼠巨噬细胞中，脂多糖（LPS）诱导的基因可以根据几个标准分为六大类，包括：(1)新蛋白合成的需要，(2)atp依赖性核小体重塑复合物的SWI/SNF家族的需要，(3)转录因子IRF3的需要，以及(4)CpG岛启动子的存在。本申请中提出的实验主要关注四类主要应答基因，这些基因被定义为在没有新蛋白合成的情况下直接被LPS信号通路激活的基因。这些实验将检验各种假设，包括初级反应基因的关键特性是刺激特异性的假设，以及CpG岛经常与SWI/ snf无关的初级反应基因相关的假设，因为高CpG含量与稳定核小体的组装不相容。我们还将研究IRF3在激活一类特定SWI/ snf依赖的初级反应基因中的作用。最后，我们将利用含有每个基因类代表成员的细菌人工染色体，对不同的激活机制进行更详细的分析。总之，这些研究将极大地扩展我们对先天免疫系统细胞中促炎基因的选择性调节的认识。

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.