Regulation of Gene Expression in the Th2 Cytokine Locus

描述（由申请人提供）：在发育为Th 2 T细胞效应子期间，IL-4基因座的染色质结构发生显著变化，促进基因座内基因的协调表达。这些变化包括但不限于DNA酶1敏感性、组蛋白乙酰化和DNA甲基化的变化。在许多已鉴定的基因座中，这些变化是协调的，并且可能由顺式作用元件调节，如基因座控制区（LCR）和绝缘子或边界元件。 到目前为止，在IL-4基因座中还没有鉴定出这样的元件。我们已经确定了一个以前未被识别的区域的RAD 50基因，这成为DNA酶1超敏（HS），特别是在Th 2细胞，并包含一个基因座控制区的属性。我们假设这个区域包含基因座控制区的元素，可能还有绝缘体。本项目的主要目标是描绘和功能特性的元素在这个区域内拥有LCR和/或绝缘体活动。第一个具体目标是表征区域内HS元件的潜在增强子活性，因为LCR具有强的谱系特异性增强子活性。我们将使用转基因小鼠系统来实现这一目标。第二个具体目标是评估整个基因座的染色质特征，重点是乙酰化和DNasel敏感性模式的转变。这些实验旨在识别轨迹内的潜在边界元素。将进行后续实验以表征这些元件阻断增强子功能和/或防止浓缩染色质侵入的能力。 不适当的Th 2分化与许多病理状态有关，最显著的是过敏性疾病。从这些研究中收集的信息将有助于我们理解Th 2分化的过程，并有望实现最终目标，即干预这一过程，并提高我们避免或纠正这些病理表现的能力。

DESCRIPTION (provided by applicant): During development into Th2 T cell effectors, the IL-4 locus undergoes significant changes in chromatin structure that facilitate coordinated expression of the genes within the locus. These changes include, but are not limited to, changes in DNase l sensitivity, histone acetylation, and DNA methylation. In a number of identified loci, these changes are coordinated, and possibly regulated by cis-acting elements, such as Locus Control Regions (LCR) and insulators or boundary elements. No such elements in the IL-4 locus have been identified to date. We have identified a previously unrecognized region of the RAD50 gene, which becomes DNase l hypersensitive (HS) specifically in Th2 cells and contains the properties of a Locus Control Region. We hypothesize that this region comprises elements of a Locus Control Region and possibly an insulator. The principal goal of this project is to delineate and functionally characterize elements within this region that possess LCR and/or insulator activity. The first specific aim is to characterize potential enhancer activity of HS elements within the region, as LCRs possess strong lineage-specific enhancer activity. We will use a transgenic mouse system to fulfill the goals of this aim. The second specific aim is to assess the chromatin character across the entire locus, focusing on transitions in acetylation and DNasel sensitivity patterns. These experiments are designed to identify potential boundary elements within the locus. Subsequent experiments will be performed to characterize these elements in terms of their ability to block enhancer function and/or prevent the encroachment of condensed chromatin. Inappropriate Th2 differentiation has been implicated in a number of pathological states, most notably allergic diseases. The information gleaned from these studies will contribute to our understanding of the process of Th2 differentiation, and will hopefully enable the ultimate goal, which is to intervene in this process, and enhance our ability to avoid or correct these pathological manifestations.