Abstract
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. © 2008 Wiley‐Liss, Inc.