The function of I(3)mbt in hematopoietic cancers

描述(申请人提供)：我们最近通过外显子捕捉法分离了人L(3)MBT基因，该基因位于20号染色体(20Q)的长臂上，位于血液系统恶性肿瘤中经常缺失的区域内。人L(3)MBT蛋白与果蝇致死性恶性脑瘤[L(3)MBT]蛋白同源，均属于多梳组(PcG)转录调控蛋白家族，PcG蛋白在维持同源异型盒和细胞周期调控基因等关键基因的抑制中起重要作用。PcG基因表达或功能的异常已被证明在淋巴瘤和其他癌症的发生或发展中发挥关键作用。为了更全面地确定人类L(3)MBT基因在血液病中的作用，我们建议定义L(3)MBT的生物学活性和作用机制。为了研究L(3)MBT的生物学效应，我们在造血细胞和RAS转化的NIH3T3细胞中表达了野生型和突变型L(3)MBT。我们还将通过建立L(3)MBT条件性基因敲除小鼠并分析它们的表型来评估缺乏MBT对造血的影响。我们将通过鉴定L(3)MBT相互作用蛋白和含有L(3)MBT蛋白的多蛋白复合体，以及利用微阵列技术鉴定髓系细胞中真的1(3)MBT靶基因来确定其作用机制。我们还将对L(3)MBT蛋白的不同结构域进行仔细的结构-功能分析，以评估它们在其转录调控特性、相关的生化活性和生物学效应中的作用。PcG蛋白家族正越来越多地与肿瘤发生有关，这些研究将为L(3)MBT在血液系统恶性肿瘤中所扮演的角色提供洞察力。

DESCRIPTION (provided by applicant): We recently isolated the human l(3)mbt gene by exon trapping based on its location on the long arm of chromosome 20 (20q), within a region frequently deleted in hematologic malignancies. The human l(3)mbt protein is homologous to the Drosophila lethal malignant brain tumor [l(3)mbt] protein, and both belong to the polycomb group (PcG) family of transcriptional regulatory proteins; PcG proteins play vital roles in the maintenance of repression of key genes such as homeobox-containing and cell cycle regulatory genes. Abnormalities in the expression or function of PcG genes have been shown to play a key role in the development or progression of lymphomas and other cancers. To more completely define the role of the human l(3)mbt gene in hematologic cancers, we propose to define the biologic activities and mechanism of action of l(3)mbt. To characterize the biological effects of l(3)mbt we will express wild type and mutant forms of l(3)mbt in hematopoietic cells, and in Ras transformed NIH 3T3 cells. We will also assess how the lack of l(3)mbt affects hematopoiesis by generating l(3)mbt conditional knock-out mice and analyzing their phenotype. We will define its mechanism of action by identifying l(3)mbt interacting proteins and the multi-protein complex that contains the l(3)mbt protein, and by identifying true 1(3) mbt target genes in myeloid cells, using microarray technology. We will also conduct a careful structure-function analysis of the distinct domains in the l(3)mbt protein to assess their role in its transcriptional regulatory properties, its associated biochemical activities and its biological effects. The PcG family of proteins is being increasingly implicated in carcinogenesis, and these studies will provide insights into the role that l(3)mbt plays in hematologic malignancies.