Structure and Function of the Human Beta-Globin Locus Control Region

血红蛋白是一种由两个α和两个β-珠蛋白链组成的杂四聚体。这些蛋白质是 由两个不同的基因座编码。许多人类遗传病与基因突变有关 人类β-珠蛋白基因座并导致轻度或严重形式的贫血。重症患者的治疗选择 病例有限，而且常常伴随着有害的副作用。最常见的突变是 导致血红蛋白疾病降低成人β-珠蛋白基因的表达。可以预料到，知识 关于珠蛋白基因在分化和发育过程中是如何调节的将导致新形式的 涉及基因和干细胞疗法的治疗。人类β-珠蛋白基因座由五个基因组成。 在发育过程中只在红系细胞中顺序表达。的高水平表达 这些基因是由一个位点控制区介导的，它是一个强大而复杂的DNA调节元件，位于 在基因的上游很远。轨迹控制区的显著之处在于它能够赋予位置- 在转基因检测中对珠蛋白基因的独立和高水平表达该活性在 基因治疗实验，旨在表达治疗性珠蛋白基因的生理水平 红系细胞。最近的证据表明，由几个核心组成的轨迹控制区 含有许多转录因子结合位点的区域，招募建立 β-珠蛋白基因座中可访问的染色质结构域。此外，最近的几份报告表明， RNA聚合酶II被招募为基因座控制区的核心元件。我们假设LCR 表示用于招募转录复合体的主要附着位置，这些转录复合体被传递到 珠蛋白基因以发育阶段特有的方式。我们将使用生物化学，分子细胞生物学， 和基因实验来测试这个模型。此外，我们还将研究螺旋-环-螺旋的作用 β-珠蛋白基因调控中的USF和TFII-I蛋白。我们的数据表明，这些蛋白质具有拮抗性 调节成体β-珠蛋白基因的表达并可能参与成体β-珠蛋白基因的阶段特异性表达 珠蛋白基因。我们将产生表达这些蛋白质的显性负突变的转基因小鼠。 并分析这些蛋白的表达对小鼠珠蛋白基因调控的影响 发展。

Hemoglobin is a heterotetramer composed of two alpha and two beta-globin chains. The proteins are encoded by two different gene loci. Many human genetic diseases are associated with mutations in the human beta-globin gene locus and lead to mild or severe forms of anemia. Treatment options for severe cases are limited and often accompanied by deleterious side effects. The most common mutations that cause hemoglobinopathies reduce expression of the adult beta-globin gene. It is anticipated that knowledge about how the globin genes are regulated during differentiation and development will lead to new forms of treatement involving gene and stem cell therapies. The human beta-globin gene locus consists of five genes that are sequentially expressed during development exclusively in erythroid cells. High-level expression of these genes is mediated by a locus control region, a powerful and complex DMAregulatory element located far upstream of the genes. The locus control region is remarkable in that it is able to confer position- independent and high-level expression to globin genes in transgenic assays This activity is important in gene therapy experiments, which are aimed at expressing physiological levels of a therapeutic globin gene in erythroid cells. Recent evidence suggests that the locus control region, which consists of several core regions harboring many transcription factor binding sites, recruits activities that are required for establishing accessible chromatin domains in the beta-globin locus. Moreover, several recent reports demonstrate that RNA polymerase II is recruited to locus control region core elements. We hypothesize that the LCR represents the primary attachment site for recruitment of transcription complexes, which are delivered to the globin genes in a developmental stage specific manner. We will use biochemical, molecular cell biological, and genetic experiments to test this model. In addition, we will investigate the role of helix-loop-helix proteins USF and TFII-I in beta-globin gene regulation. Our data suggest that these proteins antagonistically regulate expression of the adult beta-globin gene and may participate in the stage-specific expression of the globin genes. We will generate transgenic mice expressing dominant negative mutants of these proteins and analyze the consequence of expression of these proteins on globin gene regulation during mouse development.