Human glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a coactivator of the oncogenic transcription factor hTAF_II68-TEC.

A128

Tumor-specific chromosomal rearrangements are known to creat chimeric products with the ability to generate many human cancers. hTAF_II68-TEC is such a fusion product, resulting from a t(9;17) chromosomal translocation found in extraskeletal myxoid chondrosarcomas, where the hTAF_II68 N-terminal domain (NTD) is fused to TEC protein. To identify proteins that control hTAF_II68-TEC function, we used affinity chromatography on immobilized hTAF_II68 (NTD) and MALDI-TOF mass spectrometry and isolated a novel hTAF_II68-TEC-interacting protein, glyceraldehyde-3-phosphate dehydrogenase (GAPDH). GAPDH is a glycolytic enzyme that is mutifunctional protein. hTAF_II68-TEC and GAPDH were co-immunoprecipitated from cell extracts, and GST pull-down assays revealed that the C-terminus of hTAF_II68 (NTD) was required for interaction with GAPDH. In addition, three independent regions of GAPDH (amino acids 1-66, 67-160, and 160-248) were involved in binding to hTAF_II68 (NTD). hTAF_II68-TEC-dependent transcription was enhanced by GAPDH but not by a GAPDH mutant defective in hTAF_II68-TEC binding. Moreover, a fusion of GAPDH with the GAL4 DNA-binding domain increased the promoter activity. Our results suggest that GAPDH stimulates the transactivation potential of the hTAF_II68-TEC.