GLOBIN GENE REGULATION BY GATA-1 AND CHROMATIN

珠蛋白基因仅在红系细胞中表达， 不同的发展阶段。 珠蛋白基因 因为更详细的知识， 这一过程可能有助于治疗严重的 血红蛋白病，如地中海贫血和镰状细胞病，和 因为球蛋白基因是复杂多基因的经典模型 调控 我们的长期目标是了解球蛋白基因是如何 仅在红细胞中表达，以及单个基因是如何 通过发展控制。 在红细胞分化过程中， 是细胞核中染色质的进行性浓缩， 完全停止转录;珠蛋白基因继续 直到这个过程的后期才被转录。 我们研究一种核因子，加塔- 1，这似乎在球蛋白的表达中起着重要作用， 其他典型的红系基因在红系终末期 在各个发展阶段的差异。 我们开发了一个模型 其中加塔-1用于将球蛋白和其它红细胞基因保持在一个 活跃状态，而基因不是必要的红细胞程序， 压抑为了验证这一假设，我们开发了一种检测方法， beta-geo报告基因区分基因水平的影响 对表观遗传稳定性的影响;基因表达的先前研究 监管没有将这两个参数分开。 我们建议 研究红细胞转录控制元件的相互作用 与染色质，使用β-geo测定结合位点- 特异性重组以控制位置效应。 我们将解剖 γ-珠蛋白启动子，询问其内哪些元件调节 基因表达水平，并抵消抑制。 我们将 继续我们对5'HS2珠蛋白增强子的研究，我们已经证明 它的行动主要是为了减轻镇压，并把重点放在 其组成部分对其功能的贡献。 我们还将 分析染色质因子HMG-1在发育中的作用， γ-珠蛋白基因的调节，以及抑制性的 染色质蛋白在终末阶段。 最终，我们希望这些 研究将有助于更好地了解 珠蛋白基因和血红蛋白病的改良疗法。

Globin genes are expressed exclusively in the erythroid lineage, and at distinct stages of development. The mechanisms by which the globin genes are regulated are of interest because a more detailed knowledge of the process is likely to contribute to therapies for severe hemoglobinopathies such as thalassemia and sickle cell disease, and because the globin genes are classic models of complex multigene regulation. Our long-term goal is to understand how the globin genes are expressed only in red blood cells, and how the individual genes are controlled through development. During erythroid differentiation, there is a progressive condensation of chromatin in the nucleus culminating in complete cessation of transcription; the globin genes continue to be transcribed until late in this process. We study a nuclear factor, GATA- 1, that appears to have a central role in the expression of globins and other typically erythroid genes in the terminal phase of erythroid differentiation at all stages of development. We have developed a model in which GATA-1 serves to keep globins and other erythroid genes in an active state while genes not essential for the erythroid program are repressed. To test this hypothesis we have developed an assay that uses the beta-geo reporter to distinguish effects on the level of gene expression from effects on epigenetic stability; previous studies of gene regulation have not separated these two parameters. We propose to investigate the interaction of erythroid transcriptional control elements with chromatin, using the beta-geo assay in conjunction with site- specific recombination to control for position effects. We will dissect the gamma-globin promoter, asking which elements within it regulate the level of gene expression and which counteract repression. We will continue our study of the 5'HS2 globin enhancer, in which we have shown that it acts primarily to relieve repression, and focus on the contribution of its component elements to its function. We will also analyze the role of the chromatin factor HMG-l in developmental regulation of the gamma-globin gene, and the expression of repressive chromatin proteins in the terminal phase. Ultimately we hope that these studies will lead to better understanding of developmental regulation of the globin genes and improved therapies for the hemoglobinopathies..