Nuclear translocation of TSC-22 (TGF-beta-stimulated clone-22) concomitantwith apoptosis: TSC-22 as a putative transcriptional regulator

We examined the alteration of the subcellular localization of TSC-22 (TGF-b eta -stimulated clone-22) after induction of apoptosis and the transcriptio n-regulatory activity of TSC-22. In the living cells, TSC-22-green fluoresc ent protein (GFP) fusion protein was clearly localized to the cytoplasm, ho wever, in the apoptotic cells, the TSC-22-GFP fusion protein was translocat ed from the cytoplasm to the nucleus. TSC-22 fused to GAL4-DNA binding doma in (GAL4BD) did not show the transcriptional activity on the reporter genes in yeast and in HSG (salivary gland cancer cells) and Hela. However, in CH O cells, TSC-22-GAL4BD fusion protein strongly activated the reporter gene. The transcriptional activity of the leucine zipper structure of TSC-22 is greater than that of the full-length TSC-22. These findings suggest that af ter receiving the apoptotic stimuli, TSC-22 translocates from the cytoplasm to the nucleus and shows the transcription-regulatory activity. (C) 2000 A cademic Press.