CAK-RARa Signaling in HSC and Leukemic Cell Commitment to Differentiation

HSC 和白血病细胞分化中的 CAK-RARa 信号转导

• 批准号: 7539949
• 负责人: LINGTAO WU
• 金额: $ 32.68万
• 依托单位: CHILDREN'S HOSPITAL OF LOS ANGELES
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-01-01 至 2012-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7539949
• 关键词: Binding; Biological Assay; Cell Cycle; Cell Differentiation process; Cell division; Cell model; Cells; Chromatin; Commit; Couples; Data; Development; Differentiation Therapy; Dissociation; Environment; Equilibrium; Gene Expression; Gene Targeting; Goals; Granulopoiesis; Hematopoietic; Hematopoietic stem cells; Human; In Vitro; Leukemic Cell; Ligands; Mediating; Molecular; Myelogenous; Myeloid Cells; Myeloid Leukemia; NOD/SCID mouse; Phosphorylation; Plant Roots; Post-Translational Regulation; Process; Proteolysis; Publishing; Regulation; Reporter Genes; Research; Role; Signal Transduction; Staging; Structure-Activity Relationship; Testing; Time; Transactivation; Transcriptional Regulation; Tretinoin; Ubiquitination; aldehyde dehydrogenases; base; cellular transduction; chromatin immunoprecipitation; cyclin-dependent kinase-activating kinase; design; granulocyte; insight; leukemogenesis; monocyte; mutant; novel; prevent; progenitor; research study; retinoic acid receptor alpha; self-renewal; small hairpin RNA; spatiotemporal; transcription factor

DESCRIPTION (provided by applicant): Aberrant differentiation is a hallmark of myeloid leukemia, reflecting a disruption of the intrinsic balance between proliferation and differentiation. Our published and preliminary data indicate that subverted RAR?-CAK signaling is a pivotal feature of myeloid leukemogenesis and challenges the current paradigm that RA induces cell differentiation solely by transactivating target genes. We propose to determine how RAR?-CAK signaling couples CAK-dependent G1 exit to transcriptional control of granulocytic differentiation in normal and leukemic myeloid cells. The long-term goal of our research is to provide fundamental basis for development of differentiation therapy that can force the terminal differentiation of myeloid leukemia cells. Normal cellular differentiation requires timely exit from the cell cycle. CAK, whose activity is determined by its targeting subunit MAT1, regulates cell cycle G1 exit when cells commonly commit to proliferation or to differentiation. The mechanisms by which transcription factor RAR? mediates the effect of RA to coordinate the granulocytic proliferation/differentiation (P/D) transition during granulopoiesis are unknown. We discovered that, in myeloid leukemic cells, the lack of RA-induced ubiquitination-proteolysis of MAT1 inhibits CAK-dependent G1 exit and sustains CAK hyperphosphorylation of RAR1 to prevent granulocytic differentiation. This contrasts with the P/D transition in normal hematopoietic cells, where intrinsic MAT1 degradation proceeds together with progressive granulocytic differentiation, and the loss of RAR? phosphorylation by CAK induces RA-target gene expression and granulocytic differentiation. Using in vitro cellular models and NOD/SCID mice, the proposed experiments seek to: a) evaluate the role and mechanism of MAT1 expression and degradation in normal granulopoiesis; b) evaluate the mechanisms of RA-induced ubiquitination-proteolysis of MAT1, c) determine the role and mechanism of RAR? hypophosphorylation in transcriptional control of granulocytic differentiation; and d) define the role of ALDH1A1 and 1B1 in initiating RAR?-CAK signaling during granulopoiesis. The proposed specific aims will examine, for the first time, the novel mechanisms by which CAK-RAR? signaling coordinates CAK-dependent post-translational regulation of G1 exit to RAR?-dependent transcriptional control of granulocytic differentiation. This project has the potential to generate valuable insights into the molecular regulation of granulopoiesis and therefore has clear relevance to the design of effective differentiation therapies against myeloid leukemia.

描述(申请人提供)：异常分化是髓系白血病的一个特征，反映了增殖和分化之间内在平衡的破坏。我们已发表的和初步的数据表明，RAR？-CAK信号被颠覆是髓系白血病发生的关键特征，并挑战了目前RA仅通过反式激活靶基因诱导细胞分化的范式。我们建议确定在正常和白血病髓系细胞中，RAR？-CAK信号如何将依赖于CAK的G1退出转录调控粒细胞分化。本研究的长期目标是为发展促进髓系白血病细胞终末分化的分化治疗提供基础。正常的细胞分化需要及时退出细胞周期。CAK的活性由其靶向亚基MAT1决定，当细胞共同致力于增殖或分化时，它调节细胞周期G1的退出。转录因子RAR？在粒细胞生成过程中，RA在协调粒细胞增殖/分化(P/D)过程中的作用尚不清楚。我们发现，在髓系白血病细胞中，缺乏RA诱导的MAT1泛素化-蛋白分解抑制了CAK依赖的G1退出，并维持了RAR1的CAK过度磷酸化，以防止粒细胞分化。这与正常造血细胞的P/D转变形成对比，在正常造血细胞中，内在的MAT1降解伴随着粒细胞的进行性分化而进行，RAR？CAK的磷酸化可诱导RA靶基因表达和粒细胞分化。利用体外细胞模型和NOD/SCID小鼠，本实验试图：a)评估MAT1的表达和降解在正常粒系生成中的作用和机制；b)评估RA诱导的MAT1泛素化-蛋白分解的机制；c)确定RAR？低磷酸化在粒细胞分化的转录调控中的作用；以及d)确定ALDH1A1和1b1在粒细胞生成过程中启动RAR？-CAK信号转导中的作用。提出的具体目标将首次检验CAK-RAR？信号协调依赖于CAK的G1退出的翻译后调节到依赖于RAR？的粒细胞分化的转录控制。这个项目有可能对粒细胞生成的分子调控产生有价值的见解，因此对设计有效的髓系白血病分化治疗方法具有明显的相关性。