MULTIPLE DOMAINS PARTICIPATE IN DISTANCE-INDEPENDENT LAZ3 BCL6-MEDIATED TRANSCRIPTIONAL REPRESSION/

The LAZ3/BCL6 gene implicated in diffuse large cell lymphomas encodes a transcriptional repressor containing Kruppel-like zinc fingers. It h arbours at its N-terminus a conserved protein/protein interaction moti f, the BTB/POZ domain, which is also an autonomous transcriptional rep ression domain. We demonstrate here using several GAL4-LAZ3/BCL6 chime ras that the BTB/POZ domain plays an important but not exclusive role as its deletion gives rise to a GAL4 chimera that mediates significant , albeit reduced, transcriptional repression. Moreover, the repressive effect mediated either by LAZ3/BCL6 or by the isolated domains occurs with unaltered efficiency even at long distance (1.6 Kbp), ruling out steric hindrance mechanisms. Finally, though the absence of a TATA bo x appears to weaken this activity, it is largely promoter independent. Taken together, our results demonstrate that multiple domains partici pate in the promoter and distance-independent LAZ3/BCL6-mediated trans criptional repression. (C) 1996 Academic Press, Inc.