Genetic and Biochemical Analyses of Mixed Lineage Leukemia Cleavage

混合谱系白血病裂解的遗传和生化分析

• 批准号: 7279780
• 负责人: JAMES J HSIEH
• 金额: $ 14.38万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-08-01 至 2008-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7279780
• 关键词: 11q23; Amino Acids; Biochemical Genetics; C-terminal; Characteristics; Chimeric Proteins; Chromosomal translocation; Cleaved cell; Complex; Data; Development; Diffuse; Disruption; Doctor of Medicine; Doctor of Philosophy; Drosophila genus; Endopeptidases; Gene Expression; Gene Expression Regulation; Gene Targeting; Genes; Hematopoiesis; Human; Knock-in Mouse; Leukemic Cell; Localized; MLL gene; Malignant Neoplasms; Mammals; Modeling; Molecular Profiling; Mus; Mutation; N-terminal; Nuclear; Nuclear Protein; Nuclear Proteins; Pattern; Peptide Hydrolases; Principal Investigator; Process; Proteins; Proteolysis; Research; Role; Role playing therapy; Site; Specificity; Structural Protein; base; fly; leukemia; leukemogenesis; mouse model; programs

DESCRIPTION (provided by applicant): The mixed-lineage leukemia gene (MLL, ALL1, HRX) encodes a 3,969 amino acid nuclear protein homologous to Drosophila trithorax and is required to maintain proper Hox gene expression. Deregulation of Hox and perhaps other gene expression causes transformation of segmental identities and contributes to human malignancy. Chromosome translocations in human leukemia disrupt MLL (11q23), generating chimeric proteins between the N-terminus of MLL and multiple translocation partners. More than 20 MLL translocation partners have been identified. They vary widely from nuclear factors to cytoplasmic structural proteins and there are no common characteristics identified among them. However, mouse models demonstrated an indispensable role played by the various fusion partners in MLL leukemias. Gene expression profiles of human leukemia bearing an MLL translocation identified a pattern of upregulated genes. Among these genes were some of the well-recognized targets of wild type MLL. This argues that the common MLL N-terminus is sufficient to confer at least some target gene specificity to MLL-fusion proteins. However, the mechanism by which MLL regulates downstream gene expression is still unclear. In preliminary studies, I demonstrate that MLL is normally cleaved at two conserved sites (D/GADD and D/GVDD) and that mutation of these sites abolishes the proteolysis. The cleavage site sequences are highly conserved from flies to mammals. MLL cleavage generates N-terminal p320 (N320) and C-terminal p180 (C180) fragments, which then interact to form a stable complex that localizes to a subnuclear compartment. Disruption of the interaction between N320 and C180 leads to a marked decrease in the level of N320 and a redistribution of C180 to a diffuse nuclear pattern. Based on these data, I propose a model in which a dynamic post-cleavage association confers stability to N320 and directs correct nuclear sublocalization of the complex, thereby controlling the availability of N320 for target gene regulation. This model predicts that MLL-fusion proteins of leukemia lose the ability to complex with C180 and instead have their stability conferred by the fusion partners, thus providing one mechanism for the altered target gene expression observed in MLL leukemic cells. Further characterization of MLL cleavage will help elucidate how MLL regulates target genes, which is crucial for both development and leukemogenesis. In this regard, I propose the following specific aims: (1) Characterize the MLL cleavage and determine its role in protein stability and nuclear sublocalization; (2) Generate knock-in mice with a noncleavable MLL; (3) Identify and characterize the protease responsible for MLL cleavage.

描述（由申请人提供）：混合细胞性白血病基因（MLL，All1，HRX）编码与果蝇Trithorax同源的3,969个氨基酸核蛋白，并需要保持适当的HOX基因表达。 HOX和其他基因表达的放松管制会导致节段性的转化，并导致人类恶性肿瘤。 人白血病中的染色体易位破坏了MLL（11q23），在MLL的N末端和多个易位伴侣之间产生嵌合蛋白。 已经确定了20多个MLL转运伙伴。 它们从核因子到细胞质结构蛋白的差异很大，它们之间没有共同的特征。 但是，小鼠模型表现出各种融合伙伴在MLL白血病中起着必不可少的作用。 具有MLL易位的人白血病的基因表达谱鉴定了上调基因的模式。 这些基因是野生型MLL的一些良好认可的靶标。 这认为常见的MLL N末端足以赋予至少某些靶基因特异性对MLL融合蛋白。 但是，MLL调节下游基因表达的机制仍不清楚。 在初步研究中，我证明了MLL通​​常在两个保守的位点（D/GADD和D/GVDD）上切割，并且这些位点的突变消除了蛋白水解。 裂解位点序列是从蝇到哺乳动物的高度保守。 MLL裂解会生成N末端P320（N320）和C末端P180（C180）片段，然后相互作用以形成稳定的复合物，该复合物位于核下腔室。 N320和C180之间相互作用的破坏导致N320水平明显降低，并且C180的重新分布到弥漫性核模式。 基于这些数据，我提出了一个模型，其中动态的裂解后关联赋予了N320的稳定性，并指导了复合物的正确核综合化，从而控制了N320对靶基因调节的可用性。 该模型预测，白血病的MLL融合蛋白失去了与C180复合物的能力，而是由融合伙伴赋予其稳定性，从而为MLL白血病细胞中观察到的改变的靶基因表达提供了一种机制。 MLL裂解的进一步表征将有助于阐明MLL如何调节靶基因，这对于发育和白血病生成至关重要。 在这方面，我提出了以下特定目的：（1）表征MLL裂解并确定其在蛋白质稳定性和核综合化中的作用； （2）用不可揭开的MLL产生敲入小鼠； （3）识别并表征负责MLL裂解的蛋白酶。

项目成果

Therapeutic Guide for mTOuRing through the Braided Kidney Cancer Genomic River.

• DOI: 10.1158/1078-0432.ccr-16-0035
• 发表时间: 2016-05-15
• 期刊: Clinical cancer research : an official journal of the American Association for Cancer Research
• 作者: Voss MH;Hsieh JJ
• 通讯作者: Hsieh JJ

Taspase1 functions as a non-oncogene addiction protease that coordinates cancer cell proliferation and apoptosis.

• DOI: 10.1158/0008-5472.can-10-0027
• 发表时间: 2010-07-01
• 期刊: Cancer research
• 影响因子: 11.2
• 作者: Chen DY;Liu H;Takeda S;Tu HC;Sasagawa S;Van Tine BA;Lu D;Cheng EH;Hsieh JJ
• 通讯作者: Hsieh JJ