A new functional domain of Bcl6 family that recruits histone deacetylases

The proto-oncogene Bc16 and its family gene. BAZF. encode a sequence-specif ic transcriptional repressor which contains the BTB/POZ domain in NH2-termi nal region and zinc finger motifs in COOH-terminal region. The BTB/POZ doma in and the middle portion of Bc16 and BAZF are known to display transrepres sor activity. Since we have identified the identical 17-amino acid (aa) seq uence in the middle portion of Bc16 and BAZF, the 17aa region may be anothe r repressive domain of the middle portion. The reporter gene assay indicate s that the 27aa sequence including the 17aa region recruits historic deacet ylases to express transrepressor activity. Furthermore, overexpression of B c16 or Bc16(POZ-) (Bc16 deleted with the BTB/POZ domain) induced apoptosis in NIH3T3 cells, and the apoptosis was inhibited by the addition of histori c deacetylase inhibitor in the culture. However. apoptosis was not induced in NIH3T3 cells by overexpression of Bc16(POZ-) deleted with the 17aa regio n. These results indicate that the 17aa region in the middle portion of Bc1 6 is a functional domain of transrepressor activity and is responsible for inducibility of apoptosis in NIH3T3 cells. (C) 2001 Elsevier Science BN. Al l rights reserved.