Astrocyte-specific expression of serpin genes

描述(申请人提供)：α-L-抗糜蛋白酶(ACT)是一种丝氨酸蛋白酶抑制物(丝氨酸蛋白酶抑制剂)，与阿尔茨海默病患者大脑中的β-淀粉样蛋白沉积特异性地共定位。ACT还促进了阿尔茨海默病双转基因小鼠模型中β-淀粉样蛋白沉积的形成。星形胶质细胞是脑内ACT的主要来源，这种蛇毒蛋白在脑部炎症过程中表达增强。本研究的目的是阐明ACT在人脑星形胶质细胞中的组织特异性表达机制以及IL-1和肿瘤坏死因子(TNF)对这些细胞中ACT表达的上调作用。编码ACT的基因位于染色体14q32.1上的远端serp亚群中。位于这个亚簇中的所有基因都在肝细胞中表达，但只有ACT基因在星形胶质细胞中转录。此外，肝细胞特异性转录因子在星形胶质细胞中不表达。根据我们的初步研究，我们假设这个远端亚群的“星形胶质细胞特有的”染色质结构决定了大脑中丝氨酸基因的表达模式。然而，决定这种星形胶质细胞特异性结构的组织特异性转录因子尚不清楚，它们的鉴定对于全面了解ACT基因的组织特异性表达至关重要。因此，我们提出以下具体目标： 1)比较星形胶质细胞、肝细胞和组织特异性微细胞杂交瘤细胞远端丝氨酸亚群的染色质结构。 2)确定星形胶质细胞特异性表达ACT基因的调控元件和转录因子。 3)探讨IL-1和肿瘤坏死因子对ACT基因的组织特异性激活机制。

DESCRIPTION (provided by applicant): alpha-l-antichymotrypsin (ACT) is a serine proteinase inhibitor (serpin) that specifically co-localizes with beta-amyloid deposits in the brains of Alzheimer's patients. ACT also enhances the formation of beta-amyloid deposits in a double transgenic mouse model of Alzheimer's disease. Astrocytes are the major source of ACT found in the brain and expression of this serpin is enhanced during brain inflammatory processes. The goals of this research proposal have been designed to elucidate mechanisms of tissue-specific expression of ACT in human brain astrocytes and its up-regulation by IL-1 and tumor necrosis factor (TNF) in these cells. The gene encoding ACT is located in a distal serpin subcluster on chromosome 14q32.1. All genes located in this subcluster are expressed in hepatocytes but only the ACT gene is transcribed in astrocytes. In addition, hepatocyte-specific transcription factors are not expressed in astrocytes. Based on our preliminary studies we hypothesized that "astrocyte specific" chromatin structure of this distal subcluster determines the expression pattern of serpin genes in the brain. However, tissue-specific transcription factors that determine this "astrocyte specific" structure are not known and their identification is critical for a full understanding of the tissue-specific expression of the ACT gene. Therefore, we propose the following specific aims: 1) To compare the chromatin structure of the distal serpin subcluster in astrocytes to that in hepatocytes and tissue-specific microcell hybrids. 2) To identify the specific regulatory elements and transcription factors that are responsible for astrocyte-specific expression of the ACT gene. 3) To identify the mechanism of tissue-specific activation of the ACT gene by IL-1 and TNF.