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

血红蛋白是由两条α-珠蛋白链和两条β-珠蛋白链组成的异四聚体。将蛋白质 由两个不同的基因座编码许多人类遗传性疾病都与基因突变有关。 人β-珠蛋白基因座并导致轻度或重度贫血。严重急性胰腺炎的治疗选择 病例有限，并且通常伴有有害的副作用。最常见的突变， 导致血红蛋白病降低成人β-珠蛋白基因的表达。预计知识 关于球蛋白基因在分化和发育过程中是如何调节的， 包括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 在发育过程中仅在红系细胞中顺序表达。的高效表达 这些基因是由一个基因座控制区，一个强大的和复杂的DMA调控元件，位于 基因的上游。基因座控制区是显著的，因为它能够赋予位置- 在转基因测定中独立和高水平表达球蛋白基因 基因治疗实验，其目的是表达生理水平的治疗性珠蛋白基因， 红系细胞最近的证据表明，基因控制区，其中包括几个核心 包含许多转录因子结合位点的区域，募集建立转录因子结合位点所需的活动。 β-珠蛋白基因座中的可接近染色质结构域。此外，最近的几份报告表明， RNA聚合酶II被募集到基因座控制区核心元件。我们假设LCR 代表用于募集转录复合物的初级附着位点，所述转录复合物被递送至细胞。 珠蛋白基因在发育阶段特异性的方式。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，我们将研究螺旋-环-螺旋的作用 蛋白USF和TFII-I在β-珠蛋白基因调控中的作用。我们的数据表明，这些蛋白质拮抗 调节成人β-珠蛋白基因的表达，并可能参与阶段特异性表达的 珠蛋白基因我们将产生转基因小鼠表达显性负突变体的这些蛋白质 并分析这些蛋白的表达对小鼠体内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.