Kim Sol, Lee Hye Jin, Jun Hee Jung, Kim Jungho
Laboratory of Molecular and Cellular Biology, Department of Life Science, Sogang University, Seoul, Korea.
Int J Cancer. 2008 Jun 1;122(11):2446-53. doi: 10.1002/ijc.23379.
Human extraskeletal myxoid chondrosarcoma (EMC) is caused by a chromosomal translocation that involves TEC (translocated in extraskeletal myxoid chondrosarcoma), and either EWS (Ewing's sarcoma) or hTAF(II)68 (human TATA-binding protein-associated factor II 68), which generates EWS-TEC or hTAF(II)68-TEC fusion proteins, respectively. Although there has been a great deal of progress in characterizing EWS-TEC, there is relatively little known about the biological function of hTAF(II)68-TEC. We have examined the functional consequences of the fusion of the amino terminal domain (NTD) of hTAF(II)68 to TEC in EMC. The chimeric gene encodes a nuclear protein that binds DNA with the same sequence specificity as parental TEC. Nuclear localization of hTAF(II)68-TEC was dependent on the DNA binding domain, and we identified a cluster of basic amino acids in the DNA binding domain, KRRR, that specifically mediate the nuclear localization of hTAF(II)68-TEC. The transactivation activity of hTAF(II)68-TEC was higher than TEC towards a known target promoter that contained several TEC binding sites. Finally, deletion analysis of hTAF(II)68-TEC indicated that the hTAF(II)68 NTD, and the AF1 and AF2 domains of hTAF(II)68-TEC are necessary for full transactivation potential. These results suggest that the oncogenic effect of the t(9;17) translocation may be due to the hTAF(II)68-TEC chimeric protein and that fusion of the hTAF(II)68 NTD to the TEC protein produces a gain of function chimeric product.
人类骨外黏液样软骨肉瘤（EMC）由一种涉及TEC（骨外黏液样软骨肉瘤中易位的基因）以及EWS（尤因肉瘤）或hTAF(II)68（人TATA结合蛋白相关因子II 68）的染色体易位引起，分别产生EWS-TEC或hTAF(II)68-TEC融合蛋白。尽管在表征EWS-TEC方面已经取得了很大进展，但关于hTAF(II)68-TEC的生物学功能相对了解较少。我们研究了hTAF(II)68的氨基末端结构域（NTD）与EMC中TEC融合的功能后果。嵌合基因编码一种核蛋白，其与亲本TEC具有相同的序列特异性结合DNA。hTAF(II)68-TEC的核定位依赖于DNA结合结构域，并且我们在DNA结合结构域中鉴定出一簇碱性氨基酸KRRR，其特异性介导hTAF(II)68-TEC的核定位。hTAF(II)68-TEC对含有多个TEC结合位点的已知靶启动子的反式激活活性高于TEC。最后，对hTAF(II)68-TEC的缺失分析表明，hTAF(II)68 NTD以及hTAF(II)68-TEC的AF1和AF2结构域对于完全反式激活潜力是必需的。这些结果表明，t(9;17)易位的致癌作用可能归因于hTAF(II)68-TEC嵌合蛋白，并且hTAF(II)68 NTD与TEC蛋白的融合产生了一种功能获得性嵌合产物。
