Direct transactivation of the anti-apoptotic gene apolipoprotein J (clusterin) by B-MYB.
B-MYB is a ubiquitously expressed transcription factor involved in the regulation of cell survival, proliferation, and differentiation. In an attempt to isolate B-MYB-regulated genes that may explain the role of B-MYB in cellular processes, representational difference analysis was performed in neuroblastoma cell lines with different levels of B-MYB expression. One of the genes, the mRNA levels of which were enhanced in B-MYB expressing cells, was ApoJ/Clusterin(SGP-2/TRMP-2) (ApoJ/Clusterin), previously implicated in regulation of apoptosis and tumor progression. Here we show that the human ApoJ/Clusterin gene contains a Myb binding site in its 5' flanking region, which interacts with bacterially synthesized B-MYB protein and mediates B-MYB-dependent transactivation of the ApoJ/Clusterin promoter in transient transfection assays. Endogenous ApoJ/Clusterin expression is induced in mammalian cell lines following transient transfection of a B-MYB cDNA. Blockage of secreted clusterin by a monoclonal antibody results in increased apoptosis of neuroblastoma cells exposed to the chemotherapeutic drug doxorubicin. Thus, activation of ApoJ/Clusterin by B-MYB may be an important step in the regulation of apoptosis in normal and diseased cells.
Cervellera
M
M
Laboratory of Molecular Pharmacology and Pathology, Consorzio Mario Negri Sud, 66030 S. Maria Imbaro, Italy.
Raschella
G
G
Santilli
G
G
Tanno
B
B
Ventura
A
A
Mancini
C
C
Sevignani
C
C
Calabretta
B
B
Sala
A
A
D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D018797:Cell Cycle Proteins; D051152:Clusterin; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006023:Glycoproteins / Q000096:biosynthesis / Q000235:genetics*; D006801:Humans; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000235:genetics; D009447:Neuroblastoma; D015513:Oncogene Proteins / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D011994:Recombinant Proteins / Q000096:biosynthesis; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D015534:Trans-Activators / Q000378:metabolism*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection; D014407:Tumor Cells, Cultured
C495242:CLU protein, human; D018797:Cell Cycle Proteins; D051152:Clusterin; D004268:DNA-Binding Proteins; D006023:Glycoproteins; C064352:MYBL2 protein, human; D018832:Molecular Chaperones; D009363:Neoplasm Proteins; D015513:Oncogene Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; D015534:Trans-Activators