The BTB/POZ domain targets the LAZ3/BCL6 oncoprotein to nuclear dots and mediates homomerisation in vivo

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Item Type:	Article
Title:	The BTB/POZ domain targets the LAZ3/BCL6 oncoprotein to nuclear dots and mediates homomerisation in vivo
Creators Name:	Dhordain, P., Albagli, O., Ansieau, S., Koken, M., Deweindt, C., Quief, S., Lantoine, D., Leutz, A., Kerckaert, J.P. and Leprince, D.
Abstract:	The LAZ3/BCL6 gene was identified by its disruption in 3q27 translocations associated with diffuse large cell lymphomas. It is predicted to be a transcription factor as it contains six Krüppel-like Zinc finger motifs and a N-terminal BTB/POZ domain, a protein/protein interaction interface that is widely conserved in Metazoans. Using two antisera raised against non overlapping regions of the predicted ORF, we demonstrate that the LAZ3/BCL6 protein appears as a close ca. 79 kDa doublet in B lymphoid cell lines with either a rearranged or a non rearranged LAZ3/BCL6 locus. By immunofluorescence experiments on transiently transfected COS-1 or NIH3T3 cells, we show that the LAZ3/BCL6 protein displays a punctuated nuclear localisation. This appears to rely on LAZ3/BCL6 proper folding and/or activities as it is impaired in a hormone reversible-fashion through fusion of LAZ3/BCL6 to the ligand-binding domain of the oestrogen receptor. Moreover, deletion of its BTB/POZ domain leads to the disappearance of the nuclear dots although the protein remains nuclear. In addition, by using the yeast two-hybrid system, we show that the LAZ3/BCL6 BTB/POZ domain homomerises in vivo. Thus, the LAZ3/BCL6 BTB/POZ domain has the capability to self-interact and target the protein to discrete nuclear substructures.
Keywords:	LAZ3/BCL6, Lymphoma, BTB/POZ Domain, Krueppel-Like Zinc Finger, Nuclear Dots, Two-Hybrid System, Animals, Mice
Source:	Oncogene
ISSN:	0950-9232
Publisher:	Nature Publishing Group
Volume:	11
Number:	12
Page Range:	2689-2697
Date:	21 December 1995
PubMed:	View item in PubMed

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