Human Vav1 expression in hematopoietic and cancer cell lines is regulated by c-Myb and by CpG methylation.
Human Vav1 expression in hematopoietic and cancer cell lines is regulated by c-Myb and by CpG methylation.
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DOI：
10.1371/journal.pone.0029939
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发表时间：
2012
期刊：
影响因子：
3.7
通讯作者：
Katzav S
中科院分区：
文献类型：
--
作者：
Ilan L;Katzav S
Vav 1是一种信号转导蛋白，在造血系统中作为Rho/Rac GTP酶的鸟嘌呤核苷酸交换因子发挥作用，在造血系统中Vav 1仅表达。最近，Vav 1被证明参与了几种人类恶性肿瘤，包括神经母细胞瘤，肺癌和胰腺导管腺癌（PDA）。虽然一些影响vav 1表达的因素是已知的，但vav 1表达的生理学或病理学调节都不完全清楚。我们在此证明，在vav 1启动子的假定的转录因子结合位点的突变影响其在不同组织学起源的细胞中的转录。在这些位点中有一个c-Myb的共有位点，c-Myb是一种造血特异性转录因子，也存在于表达Vav 1的肺癌细胞系中。使用siRNA耗尽c-Myb导致这些细胞中vav 1表达的显著降低。与此一致，c-Myb的共转染激活了Vav 1启动子-荧光素酶报告基因构建体在缺乏Vav 1表达的肺癌细胞中的转录。总之，这些结果表明c-Myb参与肺癌细胞中vav 1的表达。我们还研究了vav 1启动子的甲基化状态。亚硫酸氢盐测序显示，vav 1启动子在人类淋巴细胞中完全未甲基化，但在正常情况下不表达vav 1的组织中甲基化程度不同。vav 1启动子不包含CpG岛附近的转录起始位点，然而，我们证明了CpG二核苷酸在一个共识Sp1结合位点的vav 1启动子中的甲基化干扰蛋白质结合在体外。我们的数据确定了vav 1表达的两种调控机制：c-Myb的结合和5′调控序列的CpG甲基化。其他假定的转录因子结合位点的突变表明，其他因素调节vav 1的表达。
Vav1 is a signal transducer protein that functions as a guanine nucleotide exchange factor for the Rho/Rac GTPases in the hematopoietic system where it is exclusively expressed. Recently, Vav1 was shown to be involved in several human malignancies including neuroblastoma, lung cancer, and pancreatic ductal adenocarcinoma (PDA). Although some factors that affect vav1 expression are known, neither the physiological nor pathological regulation of vav1 expression is completely understood. We demonstrate herein that mutations in putative transcription factor binding sites at the vav1 promoter affect its transcription in cells of different histological origin. Among these sites is a consensus site for c-Myb, a hematopoietic-specific transcription factor that is also found in Vav1-expressing lung cancer cell lines. Depletion of c-Myb using siRNA led to a dramatic reduction in vav1 expression in these cells. Consistent with this, co-transfection of c-Myb activated transcription of a vav1 promoter-luciferase reporter gene construct in lung cancer cells devoid of Vav1 expression. Together, these results indicate that c-Myb is involved in vav1 expression in lung cancer cells. We also explored the methylation status of the vav1 promoter. Bisulfite sequencing revealed that the vav1 promoter was completely unmethylated in human lymphocytes, but methylated to various degrees in tissues that do not normally express vav1. The vav1 promoter does not contain CpG islands in proximity to the transcription start site; however, we demonstrated that methylation of a CpG dinucleotide at a consensus Sp1 binding site in the vav1 promoter interferes with protein binding in vitro. Our data identify two regulatory mechanisms for vav1 expression: binding of c-Myb and CpG methylation of 5′ regulatory sequences. Mutation of other putative transcription factor binding sites suggests that additional factors regulate vav1 expression as well.
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DOI：
10.1186/1756-9966-29-172
发表时间：
2010-12-30
期刊：
Journal of experimental & clinical cancer research : CR
影响因子：
--
作者：
Chen RX;Xia YH;Xue TC;Ye SL
通讯作者：
Ye SL
DOI：
10.1073/pnas.0502041102
发表时间：
2005-07-12
影响因子：
11.1
作者：
Feng, DX;Kan, YW
通讯作者：
Kan, YW
影响因子：
20.3
作者：
Greig, Kylie T.;de Graaf, Carolyn A.;Nutt, Stephen L.
通讯作者：
Nutt, Stephen L.
影响因子：
4
作者：
Denkinger, DJ;Lambrecht, TQ;Kawahara, RS
通讯作者：
Kawahara, RS
影响因子：
2.6
作者：
Almarza, E;Segovia, JC;Bueren, JA
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Bueren, JA