Regulation and Function of the TAL 1/SCL Gene

描述(申请人提供)：TAL1/SCL基因的错误表达是 在T细胞急性淋巴母细胞中发现最常见的功能获得突变 白血病。基因敲除和过度表达研究已经证明了这一点 基本螺旋-环-螺旋转录因子是确定 胚胎发生、发育过程中血细胞的形成和血管重塑 在成人所有造血细胞类型中，和终末分化 红系和巨核系。我们实验室的研究表明 证明TAL1可以与辅阻遏子以一种相互作用的方式相互作用 共激活复合体在分化小鼠红白血病细胞中的作用 该翻译后修饰可以修改TAL1与 核辅阻遏子mSin3A，蛋白4.2基因是一种生理学基因 靶标受含TAL1的序列抑制和激活 MEL细胞分化中的复合体。此续订申请将 研究TAL1具有实验上可分离功能的假设 由其与特定辅助调节复合体的相互作用确定，并将测试 TAL1介导的红系细胞TAL1作用模型 转录抑制抑制分化和/或刺激 增殖和TAL1介导的反式激活促进末端 差异化。第一个目标是确定 选择TAL1-协同调节器相互作用。TAL1相互作用的关键残基 利用仅LIM蛋白LMO2和辅阻遏子mSin3A将被确定 通过突变，TAL1的特异性相互作用缺陷等位基因将被 已确认身份。第二个目标是确定特定TAL1的重要性 -TAL1靶基因表达中的协同调节相互作用。TAL1‘S 与辅阻遏子和辅活化子复合体的相互作用将是 活体细胞中蛋白4.2启动子的研究 反式显性TAL1和辅助调节突变体将在蛋白质4.2上确定 基因表达。第三个目标是确定 红系分化过程中TAL1-辅助调节因子的相互作用。的影响 黄曲霉显性负性突变体TAL1的互作缺陷突变体 含TAL1的络合物(L.dbl)中存在的辅助调节子，以及实验 TAL1和有效的激活和抑制结构域的嵌合体将在 两种实验模型中红系的增殖和分化 原代小鼠造血细胞。这些研究的结果将会取得进展 对造血分化的基本了解，并提供对 白血病发生的机制。

DESCRIPTION (provided by applicant): Misexpression of the TAL1/SCL gene is the most frequent gain-of-function mutation observed in T-cell acute lymphoblastic leukemia. Gene knockout and overexpression studies have demonstrated that this basic helix-loop-helix transcription factor is essential for specification of blood cell formation and vascular remodeling during embryogenesis, generation of all hematopoietic cell types in the adult, and terminal differentiation of the erythroid and megakaryocytic lineages. Studies from our laboratory have demonstrated that TAL1 can interact in a reciprocal manner with corepressor and coactivator complexes in differentiating murine erythroleukemia (MEL) cells, that posttranslational modification can modify TAL1 interaction with the nuclear corepressor mSin3A, and that the Protein 4.2 gene is a physiologic target subject to sequential repression and activation by TAL1-containing complexes in differentiating MEL cells. This renewal application will investigate the hypothesis that TAL1 has experimentally separable functions determined by its interaction with specific coregulator complexes and will test a model of TAL1 action in erythroid cells that has TAL1-mediated transcriptional repression inhibiting differentiation and/or stimulating proliferation and TAL1-directed transactivation promoting terminal differentiation. The first aim is to determine the structural requirements for select TAL1-coregulator interactions. Residues critical for TAL1 interaction with the LIM-only protein LMO2 and corepressor mSin3A will be determined through mutagenesis, and specific interaction-defective alleles of TAL1 will be identified. The second aim is to determine the importance of specific TAL1 -coregulator interactions in the expression of a TAL1 target gene. TAL1's interaction with components of corepressor and coactivator complexes will be investigated on the Protein 4.2 promoter in living cells, and the effects of trans-dominant TAL1 and coregulator mutants will be determined on Protein 4.2 gene expression. The third aim is to determine the importance of TAL1-coregulator interactions in erythroid differentiation. The effects of interaction-defective mutants of TAL1, a dominant negative mutant of a coregulator present in TAL1-containing complexes (L.dbl), and experimental chimeras of TAL1 and potent activation and repression domains will be tested on erythroid proliferation and differentiation in two experimental models and in primary murine hematopoietic cells. The results of these studies will advance basic understanding of hematopoietic differentiation and provide insights into mechanisms of leukemogenesis.