Repression of the PDCD2 gene by BCL6 and the implications for the pathogenesis of human B and T cell lymphomas.
The human BCL6 gene on chromosome 3 band q27, which encodes a transcriptional repressor, is implicated in the pathogenesis of human lymphomas, especially the diffuse large B-cell type. We previously identified the human PDCD2 (programmed cell death-2) gene as a target of BCL6 repression. PDCD2 encodes a protein that is expressed in many human tissues, including lymphocytes, and is known to interact with corepressor complexes. We now show that BCL6 can bind directly to the PDCD2 promoter, repressing its transcription. Knockdown of endogenous BCL6 in a human B cell lymphoma line by introduction of small interfering RNA duplexes increases PDCD2 protein expression. Furthermore, there is an inverse relationship between the expression levels of the BCL6 and PDCD2 proteins in the lymphoid tissues of mice overexpressing human BCL6 (high BCL6 levels, minimal PDCD2) and controls (minimal BCL6, high PDCD2) as well as in tissues examined from some human B and T cell lymphomas. These data confirm PDCD2 as a target of BCL6 and support the concept that repression of PDCD2 by BCL6 is likely important in the pathogenesis of certain human lymphomas.
Baron
Beverly W
BW
Department of Pathology, University of Chicago, Chicago, IL 60637, USA. beverly.baron@uchospitals.edu
Zeleznik-Le
Nancy
N
Baron
Miriam J
MJ
Theisler
Catherine
C
Huo
Dezheng
D
Krasowski
Matthew D
MD
Thirman
Michael J
MJ
Baron
Rebecca M
RM
Baron
Joseph M
JM
D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000235:genetics* / Q000378:metabolism; D002460:Cell Line; D002522:Chlorocebus aethiops; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics*; D006801:Humans; D016393:Lymphoma, B-Cell / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D016399:Lymphoma, T-Cell / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D051379:Mice; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D051560:Proto-Oncogene Proteins c-bcl-6 / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D014158:Transcription, Genetic / Q000235:genetics
D051017:Apoptosis Regulatory Proteins; C094601:PDCD2 protein, human; D051560:Proto-Oncogene Proteins c-bcl-6; D034741:RNA, Small Interfering