Triad1 regulates myelopoiesis and functions as a leukemia suppressor

Triad1 调节骨髓细胞生成并发挥白血病抑制因子的作用

• 批准号: 9032480
• 负责人: Elizabeth Ann Eklund
• 金额: $ 35.34万
• 依托单位: NORTHWESTERN UNIVERSITY AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-04-01 至 2020-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9032480
• 关键词: 11q23; Acute Myelocytic Leukemia; Affinity; Apoptosis; Bone Marrow; CREBBP gene; Cell Proliferation; Cell Survival; Cells; Chimeric Proteins; Cytokine Receptors; Development; Disease Progression; Drug resistance; EGF gene; Epithelial Cells; Event; FLT3 gene; Feedback; Gene Targeting; Genes; Genetic Transcription; Goals; Granulopoiesis; Growth; Health; Homeobox Genes; Human; Hypersensitivity; In Vitro; Incidence; Individual; Inositol; Integrin alphaV; Integrin alphaVbeta3; Integrin beta3; Integrins; Lesion; MLL gene; Mediating; Modeling; Molecular; Mus; Mutation; Myelogenous; Myeloid Cells; Myelopoiesis; Myeloproliferative disease; Phosphorylation; Phosphotransferases; Production; Proteins; Recycling; Refractory; Repression; Role; Sampling; Signal Transduction; Stem cells; Stream; TP53 gene; Time; Transplantation; Tyrosine Phosphorylation; Ubiquitin; Ubiquitination; autocrine; cytokine; homeodomain; in vivo; leukemia; leukemogenesis; mouse model; mutant; novel; outcome forecast; overexpression; prevent; progenitor; promoter; receptor; response; therapeutic target; transcription factor; ubiquitin-protein ligase

 DESCRIPTION (provided by applicant): Triad1 is an E3 ubiquitin ligase that impairs proliferation of bone marrow progenitor cells and increases in expression during granulopoiesis. We found that Triad1 enhances ubiquitin (Ub) mediated degradation of Fgf- R1, Flt3 and av integrin in myeloid cells. Fgf-R1 and Flt3 activate phospho-inositol-3-kinase; resulting in stabilization of ßcatenin and expression of ßcatenin-target-genes involved in proliferation/survival. Syk is activated by avß3 integrin, resulting in Pak1-dependent proliferatin and PLC-dependent survival. Triad1 also inhibits Ub of p53 by Mdm2. We hypothesize that increasing Triad1 expression during granulopoiesis favors degradation of Fgf-R1, Flt3 and avß3 integrin, but stabilizes p53; decreasing proliferation and enhancing sensitivity to apoptosis. This identifies a possible leukemia suppressor function for Triad1, since impaired activity would sustain Fgf-R1, Flt3 and avß3 signaling and destabilize p53. Consistent with this, Triad1 is specifically decreased in subsets of acute myeloid leukemia (AML) with MLL-translocations (i.e. 11q23-AML) or activating FLT3 mutation. Our studies identified a mechanism for this. 11q23-AML is characterized by increased expression of a set of HOX genes, including HoxA9 and A10. We found that HoxA9 and A10 regulate transcription of ARIH2 (encoding Triad1) in a manner that requires cytokine-induced tyrosine phosphorylation of the Hox proteins. We found that constitutive activation of Shp2-PTP blocks ARIH2 transcription by preventing Hox phosphorylation. Interestingly, FLT3 mutations are frequent in Hox-over- expressing AML and activate Shp2. A myeloproliferative neoplasm (MPN) develops in mice transplanted with bone marrow expressing MLL1 fusion proteins or overexpressing HoxA9 or A10. This MPN evolves to AML over time, suggesting that Hox-overexpression is inadequate for AML in the absence of cooperating mutations. We find constitutive Shp2-activation performs this function. We hypothesize Triad1 is a leukemia suppressor that decreases proliferation/survival of cytokine-stimulated progenitor cells, and that impaired Triad1-activity facilitates disease progression/drug resistance in Hox-overexpressing AML. We will pursue this via 3 aims: Aim 1: Identify Triad1-regulated events that have functional implications for leukemia. The influence of Triad1 on Ub/degradation of Fgf-R1, avß3, Flt3 and p53 will be investigated in vitro and in vivo. Aim 2: Determine if Triad1 is a leukemia suppressor in AML with Hox-overexpression and Shp2 activation. The contributions of Triad1-expression and Shp2-activation to drug resistance/disease progression will be explored in studies with murine AML models and human AML bone marrow samples. Aim 3: Define targetable mechanisms of leukemia suppression by Triad1. Contributions of Fgf-R1, Flt3, av integrin and p53 to leukemogenesis and drug resistance will be explored in vivo in murine models. Hox-overexpressing AML has poor prognosis and is treatment refractory. Clarifying cooperating lesions and down-stream events may suggest therapeutic targets for this subset of individuals.

 描述（由申请方提供）：Triad 1是一种E3泛素连接酶，可损害骨髓祖细胞的增殖，并在粒细胞生成过程中增加表达。我们发现Triad 1增强了骨髓细胞中泛素（Ub）介导的Fgf-R1、Flt 3和α v整联蛋白的降解。Fgf-R1和Flt 3激活磷酸肌醇-3-激酶;导致β连环蛋白的稳定和参与增殖/存活的β连环蛋白靶基因的表达。Syk被α v β 3整联蛋白激活，导致Pak 1依赖性增殖和PLC β 1依赖性存活。Triad 1还通过Mdm 2抑制p53的Ub。我们假设在粒细胞生成过程中增加Triad 1表达有利于Fgf-R1、Flt 3和av β 3整联蛋白的降解，但稳定p53，降低增殖并增强对凋亡的敏感性。这 鉴定了Triad 1的可能的白血病抑制功能，因为受损的活性将维持Fgf-R1、Flt 3和av β 3信号传导并使p53不稳定。与此一致，Triad 1在具有ML易位（即11 q23-AML）或激活FLT 3突变的急性髓性白血病（AML）亚组中特异性降低。我们的研究确定了一种机制。11 q23-AML的特征是一组HOX基因的表达增加，包括HoxA 9和A10。我们发现，HoxA 9和A10调节ARIH 2（编码Triad 1）的转录，需要甘氨酸诱导的Hox蛋白酪氨酸磷酸化的方式。我们发现Shp 2-PTP的组成性激活通过阻止Hox磷酸化来阻断ARIH 2的转录。有趣的是，FLT 3突变在Hox过度表达的AML中频繁发生，并激活Shp 2。骨髓增生性肿瘤（MPN）在移植有表达MLL 1融合蛋白或过表达HoxA 9或A10的骨髓的小鼠中发展。随着时间的推移，这种MPN演变为AML，这表明在缺乏协同突变的情况下，Hox过表达不足以治疗AML。我们发现组成型Shp 2激活执行此功能。我们假设Triad 1是一种白血病抑制因子，可降低受苦参碱刺激的祖细胞的增殖/存活，并且受损的Triad 1活性可促进疾病进展/药物治疗。 Hox过表达AML的耐药性。我们将通过3个目标来实现这一目标：目标1：识别对白血病有功能影响的Triad 1调节事件。将在体外和体内研究Triad 1对Fgf-R1、av β 3、Flt 3和p53的Ub/降解的影响。 目的2：确定Triad 1是否是Hox过表达和Shp 2激活的AML中的白血病抑制因子。Triad 1表达和Shp 2激活对耐药性/疾病进展的贡献将在鼠AML模型和人AML骨髓样本的研究中进行探索。 目的3：确定Triad 1抑制白血病的靶向机制。Fgf-R1、Flt 3、α v整联蛋白和p53对白血病发生和耐药性的贡献将在鼠模型中体内探索。 过表达Hox的AML预后差，治疗难治。澄清合作病变和下游事件可能会建议为这个子集的个人的治疗目标。