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Target genes downregulated by the BCL-6/LAZ3 oncoprotein in mouse Ba/F3 cells
1Division of Molecular Medicine, Aichi Cancer Center Research Institute, 1-1 Kanakoden, Nagoya, Chikusa-ku, 464-8681, Japan. yhosokaw@aichi-cc.pref.aichi.jp
Abstract:
The BCL-6/LAZ3 gene encodes a zinc-finger transcriptional repressor and is located at the breakpoint of the 3q27-associated translocations that occur most frequently in non-Hodgkin's lymphomas (NHLs). A number of chromosomal translocations involving BCL-6 have been analyzed, but the biological functions of this protein remain obscure. To examine cell responses and target genes related to the BCL-6 signaling pathway, we established Ba/F3 pro-B cells carrying a human BCL-6 transgene that is inducible under control of the lactose operon. Using a cDNA array hybridization technique, we found that the induced BCL-6 protein can downregulate the expressions of the genes, cyclin A2, chemokine receptor CXCR4, and insulin-like growth factor binding protein-4 (IGFBP-4) in the Ba/F3 cells. Northern blot analysis established that the expressions of these genes were indeed downregulated by the induced BCL-6 protein but in a somewhat different manner. The induced BCL-6 protein also inhibited cell proliferation of Ba/F3 cells. These findings strongly suggest that three key genes, namely cyclin A2, CXCR4, and IGFBP-4 may play a role in the downstream of the BCL-6 signaling pathway during B-lymphoid differentiation.
Insights
The BCL-6 gene, implicated in non-Hodgkin's lymphomas, regulates cyclin A2, CXCR4, and IGFBP-4 gene expression. This BCL-6 signaling pathway also inhibits pro-B cell proliferation, suggesting its role in B-lymphoid differentiation.
Area of Science:
- Molecular Biology
- Genetics
- Cancer Biology
Background:
- The BCL-6 gene, a zinc-finger transcriptional repressor, is frequently involved in chromosomal translocations in non-Hodgkin's lymphomas (NHLs).
- The precise biological functions and downstream targets of the BCL-6 protein remain largely uncharacterized.
Purpose of the Study:
- To investigate the cellular responses and identify target genes regulated by the BCL-6 signaling pathway.
- To elucidate the role of BCL-6 in B-lymphoid differentiation.
Main Methods:
- Established Ba/F3 pro-B cells with an inducible human BCL-6 transgene.
- Utilized cDNA array hybridization and Northern blot analysis to assess gene expression changes.
- Monitored cell proliferation rates.
Main Results:
- Induced BCL-6 protein downregulated the expression of cyclin A2, chemokine receptor CXCR4, and insulin-like growth factor binding protein-4 (IGFBP-4).
- Northern blot analysis confirmed the downregulation of these target genes by BCL-6.
- BCL-6 induction led to the inhibition of Ba/F3 cell proliferation.
Conclusions:
- Cyclin A2, CXCR4, and IGFBP-4 are key downstream targets of the BCL-6 signaling pathway.
- The BCL-6 signaling pathway plays a significant role in regulating B-lymphoid differentiation and cell proliferation.