Control of Erythroid Differentiation by Transcription Elongation

项目总结（见说明）： 红系分化在转录水平上受细胞特异性DNA结合蛋白SCL控制 GATA 1。利用斑马鱼遗传学，我们在红系细胞中发现了一个新的分化检查点， 确保成功成熟。我们在脊椎动物中进行了第一次隐性抑制筛选， 一种新的突变体，可以在贫血斑马鱼突变体月光的背景下恢复红细胞生成。 Moonshine编码转录中间因子1 γ（TIFly）的斑马鱼直系同源物，并且 月光的第一抑制基因编码cdc 73，cdc 73是一种参与转录延长的染色质因子。 月光突变体暂停血液特异性RNA转录，cdc 73缺陷允许延长， 发生并挽救红细胞基因表达。TIFly结合SCL转录因子复合物和PTEFb， 磷酸化pol II并调节RNA转录物延伸的激酶。我们有 检查了TIFly的条件性敲除小鼠的造血表型。骨髓 红细胞生成有缺陷，骨髓生成增加，B细胞严重缺乏。我们计划 评估该小鼠突变体的红系和髓系祖细胞中的转录延长。移植 实验计划评估一个假定的干细胞功能缺陷和自主性的红细胞 缺损我们将确定在诸如低色素性疾病中是否存在差异检查点， 贫血或膜组件缺陷。HEXIM 1最初被鉴定为在MEL期间诱导的基因， 它与其他蛋白质和7SK RNA复合以调节P-TEFb活性。我们 推测HEXIM复合物可作为红系分化的传感器。我们计划定义 HEXIM在红系细胞中的结合伴侣，并评估HEXIM复合物亚基的功能 在鱼和老鼠的红细胞生成过程中。HEXIM的7SK RNA组分的功能将是 投资。一项新的测序技术将确定其他小RNA是否与HEXIM结合。 复杂.转录延长在红系细胞分化检查点的调控将是 与地中海贫血、镰状细胞性贫血、缺铁和膜缺陷等疾病相关。

PROJECT SUMMARY (See instructions): Erythroid differenfiafion is controlled at the transcripfional level by the cell-specific DNA-binding proteins SCL and GATA1. Using zebrafish genefics, we found a new differentiation checkpoint in erythroid cells that likely ensures successful maturafion. We undertook the flrst recessive suppressor screen in vertebrates to find a novel mutant that can recover erythropoiesis in the background ofthe anemic zebrafish mutant moonshine. Moonshine encodes the zebrafish ortholog of transcripfional intermediary factor 1 gamma (TIFly), and the first suppressor of moonshine encoded cdc73, a chromatin factor involved in transcripfion elongafion. Moonshine mutants have paused blood-specific RNA transcripts, and cdc73 deficiency allows elongafion to occur and rescues erythroid gene expression. TIFly binds to the SCL transcription factor complex and PTEFb, the kinase that phosphorylates pol II and regulates the elongation of RNA transcripts. We have examined the hematopoiefic phenotype of a condifional mouse knockout for TIFly. Bone marrow erythropoiesis is defective, myelopoiesis is increased, and there is a severe deficiency of B cells. We plan to evaluate transcripfion elongation in erythroid and myeloid progenitors of this mouse mutant. Transplantafion experiments are planned to evaluate a putative stem cell funcfional defect and the autonomy ofthe red cell defect. We will establish if the differenfiafion checkpoint is acfivated in diseases such as hypochromic anemias or membrane assembly defects. HEXIM 1 was originally identified as a gene induced during MEL differenfiation, and it complexes with other proteins and 7SK RNA to regulate P-TEFb activity. We hypothesize that HEXIM complexes could serve as a sensor of erythroid differenfiafion. We plan to define the binding partners of HEXIM in erythroid cells, and to evaluate the funcfion ofthe HEXIM complex subunits during erythropoiesis in fish and mice. The function ofthe 7SK RNA component of HEXIM will be invesfigated. A new sequencing technology will determine if other small RNAs are bound to the HEXIM complex. The regulation of transcription elongation in the differentiation checkpoint of erythroid cells wili be relevant to diseases such as thalassemia, sickle cell anemia, iron deflciency, and membrane defects.