Regulation of insulator function and globin gene expression by USF and associated

描述（由申请人提供）：红细胞携带和交换氧气的主要功能取决于血红蛋白，血红蛋白是一种由两条α-珠蛋白链和两条<$-珠蛋白链组成的异四聚体，以及相关的铁结合血红素基团。珠蛋白基因突变是最常见的遗传性疾病之一，可导致人类轻度或重度贫血。目前严重贫血的治疗在很大程度上是不令人满意的，它是预期的珠蛋白基因是如何调节的知识将有助于开发新的疗法。红细胞特异性珠蛋白基因的表达需要位于基因近端或远端区域的顺式调控DNA元件。该类珠蛋白基因受基因座控制区（LCR）的调控，LCR由多个DNA酶I超敏位点组成，位于基因上游。HS 2可能是LCR中最强大的调节元件。它由造血和遍在表达的转录因子的几个结合位点组成。这些位点之一是与螺旋-环-螺旋蛋白USF相互作用的E盒。USF还与<$-珠蛋白基因启动子中的E-box元件相互作用，并且先前的工作已经表明，USF是RNA聚合酶II（Pol II）有效募集到LCR元件HS 2和<$-珠蛋白基因启动子所需的。此外，我们已经表明，USF介导的边界活动的鸡2-珠蛋白绝缘子HS 4，它保持了一个访问的染色质构象在红细胞中的珠蛋白基因。我们的初步数据表明，USF 1与含有两个组蛋白甲基转移酶PRMT 1和hSET 1的大的共激活剂复合物相互作用。我们假设USF招募组蛋白修饰酶，以建立和/或维持一个开放的染色质结构，在边界元件和调节元件的？-珠蛋白基因座，这反过来又控制红细胞特异性和发育阶段特异性珠蛋白的表达。我们将测试USF和相关的组蛋白修饰酶在建立和维持染色质屏障功能和组织特异性转录调控的<$-珠蛋白基因座的功能。最后，我们将研究在红系细胞分化过程中USF的稳定性是如何调节的。我们的表观遗传学改变的<$-珠蛋白基因位点的研究，预计提供新的见解珠蛋白基因的转录控制，并可能导致贫血的分子治疗的新策略。此外，解决USF的作用，在？-珠蛋白基因调控可能揭示参与增强子启动子相互作用的机制。

DESCRIPTION (provided by applicant): The main function of red blood cells, which carry and exchange oxygen, depends on hemoglobin, a heterotetramer composed of two a and two ¿-globin chains and associated iron-binding heme groups. Mutations of globin genes are among the most common inherited diseases and cause mild or severe anemia in the human population. Current treatments of severe anemia are largely unsatisfactory and it is anticipated that knowledge of how the globin genes are regulated will aide in the development of novel therapies. Erythroid-specific expression of the globin genes requires cis-regulatory DNA elements located in gene proximal or distal regions. The ¿-like globin genes are regulated by a locus control region (LCR), which is composed of several DNase I hypersensitive (HS) sites and located far upstream of the genes. HS2 is perhaps the most powerful regulatory element in the LCR. It consists of several binding sites for hematopoietic and ubiquitously expressed transcription factors. One of these sites is an E-box that interacts with the helix-loop-helix protein USF. USF also interacts with E-box elements in the ¿-globin gene promoter and previous work has shown that USF is required for efficient recruitment of RNA polymerase II (Pol II) to LCR element HS2 and to the ¿-globin gene promoter. In addition, we have shown that USF mediates the boundary activity of the chicken 2-globin insulator HS4, which maintains an accessible chromatin conformation over the globin genes in erythroid cells. Our preliminary data demonstrate that USF1 interacts with large co-activator complexes containing two histone methyltransferases PRMT1 and hSET1. We hypothesize that USF recruits histone modifying enzymes to establish and/or maintain an open chromatin structure at boundary elements and at regulatory elements in the ¿-globin locus, which in turn controls erythroid-specific and developmental stage-specific globin expression. We will test the function of USF and associated histone modifying enzymes in establishing and maintaining chromatin barrier function and tissue specific transcriptional regulation of the ¿-globin locus. Finally, we will investigate how the stability of USF is regulated during differentiation of erythroid cells. Our studies on epigenetic alterations in the ¿-globin gene locus are anticipated to provide new insight into the transcriptional control of globin genes and may lead to novel strategies for the molecular therapy of anemia. Furthermore, addressing the role of USF in ¿-globin gene regulation may shed light on the mechanisms involved in enhancer promoter interactions.