LMO2 Oncoprotein Stability in T-Cell Leukemia Requires Direct LDB1 Binding.
LMO2 Oncoprotein Stability in T-Cell Leukemia Requires Direct LDB1 Binding.
复制标题
T 细胞白血病中 LMO2 癌蛋白的稳定性需要直接结合 LDB1。
DOI：
10.1128/mcb.00901-15
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发表时间：
2016
影响因子：
5.3
通讯作者：
Davé,UtpalP
中科院分区：
文献类型：
--
作者：
Layer,JustinH;Alford,CatherineE;McDonald,WHayes;Davé,UtpalP
LMO 2是多亚基DNA结合转录因子复合物的一个组成部分，在造血干细胞和祖细胞发育中调节基因表达。LMO 2的强化表达通过诱导T细胞祖细胞中的造血干细胞样特征而引起白血病，但LMO 2功能的生化机制尚未完全阐明。在这项研究中，我们系统地解剖了LMO 2/LDB 1结合界面，以研究这种相互作用在T细胞白血病中的作用。LDB 1的LIM相互作用结构域的丙氨酸扫描诱变揭示了LMO 2结合所需的离散基序R320 LITR。最引人注目的是，全长，野生型LDB 1的共表达增加LMO 2稳态丰度，而LMO 2结合缺陷的突变蛋白的共表达损害LMO 2的稳定性。这些突变的LDB 1蛋白质也在不同的白血病细胞系中对生长和转录产生显性负效应。白血病细胞系中LDB 1结合伴侣的质谱分析支持LMO 2/LDB 1在白血病中的功能发生在多亚基复合物的背景下，这也保护LMO 2癌蛋白免于降解。总的来说，这些数据表明，通过直接LDB 1相互作用将LMO 2组装成复合物是一种潜在的分子靶点，可用于对现有化疗方案具有抗性的LMO 2驱动的白血病。
LMO2 is a component of multisubunit DNA-binding transcription factor complexes that regulate gene expression in hematopoietic stem and progenitor cell development. Enforced expression of LMO2 causes leukemia by inducing hematopoietic stem cell-like features in T-cell progenitor cells, but the biochemical mechanisms of LMO2 function have not been fully elucidated. In this study, we systematically dissected the LMO2/LDB1-binding interface to investigate the role of this interaction in T-cell leukemia. Alanine scanning mutagenesis of the LIM interaction domain of LDB1 revealed a discrete motif, R320LITR, required for LMO2 binding. Most strikingly, coexpression of full-length, wild-type LDB1 increased LMO2 steady-state abundance, whereas coexpression of mutant proteins deficient in LMO2 binding compromised LMO2 stability. These mutant LDB1 proteins also exerted dominant negative effects on growth and transcription in diverse leukemic cell lines. Mass spectrometric analysis of LDB1 binding partners in leukemic lines supports the notion that LMO2/LDB1 function in leukemia occurs in the context of multisubunit complexes, which also protect the LMO2 oncoprotein from degradation. Collectively, these data suggest that the assembly of LMO2 into complexes, via direct LDB1 interaction, is a potential molecular target that could be exploited in LMO2-driven leukemias resistant to existing chemotherapy regimens.