Article | Published:

Lineage-specific functions of Bcl-6 in immunity and inflammation are mediated by distinct biochemical mechanisms

Nature Immunology volume 14, pages 380388 (2013) | Download Citation

Abstract

The transcription factor Bcl-6 orchestrates germinal center (GC) reactions through its actions in B cells and T cells and regulates inflammatory signaling in macrophages. Here we found that genetic replacement with mutated Bcl6 encoding Bcl-6 that cannot bind corepressors to its BTB domain resulted in disruption of the formation of GCs and affinity maturation of immunoglobulins due to a defect in the proliferation and survival of B cells. In contrast, loss of function of the BTB domain had no effect on the differentiation and function of follicular helper T cells or that of other helper T cell subsets. Bcl6-null mice had a lethal inflammatory phenotype, whereas mice with a mutant BTB domain had normal healthy lives with no inflammation. The repression of inflammatory responses by Bcl-6 in macrophages was accordingly independent of the repressor function of the BTB domain. Bcl-6 thus mediates its actions through lineage-specific biochemical functions.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Accessions

Primary accessions

Gene Expression Omnibus

References

  1. 1.

    et al. Alterations of a zinc finger-encoding gene, BCL-6, in diffuse large-cell lymphoma. Science 262, 747–750 (1993).

  2. 2.

    et al. BCL-6 protein is expressed in germinal-center B cells. Blood 86, 45–53 (1995).

  3. 3.

    , , , & Control of inflammation, cytokine expression, and germinal center formation by BCL-6. Science 276, 589–592 (1997).

  4. 4.

    et al. The BCL-6 proto-oncogene controls germinal-centre formation and Th2-type inflammation. Nat. Genet. 16, 161–170 (1997).

  5. 5.

    et al. Disruption of the Bcl6 gene results in an impaired germinal center formation. J. Exp. Med. 186, 439–448 (1997).

  6. 6.

    et al. Bcl-6 mediates the germinal center B cell phenotype and lymphomagenesis through transcriptional repression of the DNA-damage sensor ATR. Nat. Immunol. 8, 705–714 (2007).

  7. 7.

    , & BCL6 represses CHEK1 and suppresses DNA damage pathways in normal and malignant B-cells. Blood Cells Mol. Dis. 41, 95–99 (2008).

  8. 8.

    et al. BCL6 repression of EP300 in human diffuse large B cell lymphoma cells provides a basis for rational combinatorial therapy. J. Clin. Invest. 120, 4569–4582 (2010).

  9. 9.

    & The BCL6 proto-oncogene suppresses p53 expression in germinal-centre B cells. Nature 432, 635–639 (2004).

  10. 10.

    , , , & BCL6 interacts with the transcription factor Miz-1 to suppress the cyclin-dependent kinase inhibitor p21 and cell cycle arrest in germinal center B cells. Nat. Immunol. 6, 1054–1060 (2005).

  11. 11.

    Follicular helper CD4 T cells (TFH). Annu. Rev. Immunol. 29, 621–663 (2011).

  12. 12.

    , , , & Follicular helper T cells as cognate regulators of B cell immunity. Curr. Opin. Immunol. 21, 266–273 (2009).

  13. 13.

    et al. The transcriptional repressor Bcl-6 directs T follicular helper cell lineage commitment. Immunity 31, 457–468 (2009).

  14. 14.

    et al. Bcl6 mediates the development of T follicular helper cells. Science 325, 1001–1005 (2009).

  15. 15.

    et al. Bcl6 and Blimp-1 are reciprocal and antagonistic regulators of T follicular helper cell differentiation. Science 325, 1006–1010 (2009).

  16. 16.

    et al. Bcl6 and Maf cooperate to instruct human follicular helper CD4 T cell differentiation. J. Immunol. 188, 3734–3744 (2012).

  17. 17.

    , & Effectors and memories: Bcl-6 and Blimp-1 in T and B lymphocyte differentiation. Nat. Immunol. 11, 114–120 (2010).

  18. 18.

    et al. BCL-6 regulates chemokine gene transcription in macrophages. Nat. Immunol. 1, 214–220 (2000).

  19. 19.

    et al. Bcl-6 and NF-κB cistromes mediate opposing regulation of the innate immune response. Genes Dev. 24, 2760–2765 (2010).

  20. 20.

    et al. Corepressor SMRT binds the BTB/POZ repressing domain of the LAZ3/BCL6 oncoprotein. Proc. Natl. Acad. Sci. USA 94, 10762–10767 (1997).

  21. 21.

    & The BCL-6 POZ domain and other POZ domains interact with the co-repressors N-CoR and SMRT. Oncogene 17, 2473–2484 (1998).

  22. 22.

    , , & BCoR, a novel corepressor involved in BCL-6 repression. Genes Dev. 14, 1810–1823 (2000).

  23. 23.

    et al. Mechanism of SMRT corepressor recruitment by the BCL6 BTB domain. Mol. Cell 12, 1551–1564 (2003).

  24. 24.

    et al. Structure of a BCOR corepressor peptide in complex with the BCL6 BTB domain dimer. Mol. Cell 29, 384–391 (2008).

  25. 25.

    , , & BCL-6, a POZ/zinc-finger protein, is a sequence-specific transcriptional repressor. Proc. Natl. Acad. Sci. USA 93, 6947–6952 (1996).

  26. 26.

    et al. MTA3 and the Mi-2/NuRD complex regulate cell fate during B lymphocyte differentiation. Cell 119, 75–86 (2004).

  27. 27.

    et al. CtBP is an essential corepressor for BCL6 autoregulation. Mol. Cell Biol. 28, 2175–2186 (2008).

  28. 28.

    et al. The BCL6 transcriptional program features repression of multiple oncogenes in primary B cells and is deregulated in DLBCL. Blood 113, 5536–5548 (2009).

  29. 29.

    et al. Integrated biochemical and computational approach identifies BCL6 direct target genes controlling multiple pathways in normal germinal center B cells. Blood 115, 975–984 (2010).

  30. 30.

    , , & Suppression of signal transducer and activator of transcription 3-dependent B lymphocyte terminal differentiation by BCL-6. J. Exp. Med. 192, 1841–1848 (2000).

  31. 31.

    et al. Transcriptional repression of Stat6-dependent interleukin-4-induced genes by BCL-6: specific regulation of iepsilon transcription and immunoglobulin E switching. Mol. Cell Biol. 19, 7264–7275 (1999).

  32. 32.

    et al. Sequential transcription factor targeting for diffuse large B-cell lymphomas. Cancer Res. 68, 3361–3369 (2008).

  33. 33.

    , & Transcriptional repressor BCL6 controls Th17 responses by controlling gene expression in both T cells and macrophages. J. Immunol. 184, 4123–4132 (2010).

  34. 34.

    , , & T helper type 2 inflammatory disease in the absence of interleukin 4 and transcription factor STAT6. Proc. Natl. Acad. Sci. USA 95, 13823–13828 (1998).

  35. 35.

    et al. BCL-6 negatively regulates macrophage proliferation by suppressing autocrine IL-6 production. Blood 105, 1777–1784 (2005).

  36. 36.

    , & Acetylation inactivates the transcriptional repressor BCL6. Nat. Genet. 32, 606–613 (2002).

  37. 37.

    , & Point mutations in BCL6 DNA-binding domain reveal distinct roles for the six zinc fingers. Biochem. Biophys. Res. Commun. 300, 391–396 (2003).

  38. 38.

    et al. FoxO3a and BCR-ABL regulate cyclin D2 transcription through a STAT5/BCL6-dependent mechanism. Mol. Cell Biol. 24, 10058–10071 (2004).

  39. 39.

    et al. A peptomimetic inhibitor of BCL6 with potent antilymphoma effects in vitro and in vivo. Blood 113, 3397–3405 (2009).

  40. 40.

    et al. Specific peptide interference reveals BCL6 transcriptional and oncogenic mechanisms in B-cell lymphoma cells. Nat. Med. 10, 1329–1335 (2004).

  41. 41.

    et al. A small-molecule inhibitor of BCL6 kills DLBCL cells in vitro and in vivo. Cancer Cell 17, 400–411 (2010).

  42. 42.

    et al. Germinal center B cell and T follicular helper cell development initiates in the interfollicular zone. Immunity 34, 947–960 (2011).

  43. 43.

    et al. Comparison of germinal center markers CD10, BCL6 and human germinal center-associated lymphoma (HGAL) in follicular lymphomas. Diagn. Pathol. 6, 97 (2011).

  44. 44.

    et al. ICOS receptor instructs T follicular helper cell versus effector cell differentiation via induction of the transcriptional repressor Bcl6. Immunity 34, 932–946 (2011).

  45. 45.

    et al. The Bcl6-SMRT/NCoR cistrome represses inflammation to attenuate atherosclerosis. Cell Metab. 15, 554–562 (2012).

  46. 46.

    , & Transcriptional regulation by competing transcription factor modules. PLoS Comput. Biol. 2, e164 (2006).

Download references

Acknowledgements

We thank H. Ye (Albert Einstein College of Medicine) for Bcl6−/− mice; W. Pear (University of Pennsylvania) for the MIGR1 expression vector; and D. Wen and S. Rafii for assistance in generating Bcl6BTBMUT mice. Supported by the US National Cancer Institute (R01 104348 to A.M.), the Burroughs Wellcome Foundation and Chemotherapy Foundation (A.M.) and the March of Dimes (A.M.), and facilitated by the Sackler Center for Biomedical and Physical Sciences at Weill Cornell Medical College.

Author information

Affiliations

  1. Division of Hematology and Oncology, Weill Cornell Medical College, New York, New York, USA.

    • Chuanxin Huang
    • , Katerina Hatzi
    •  & Ari Melnick

Authors

  1. Search for Chuanxin Huang in:

  2. Search for Katerina Hatzi in:

  3. Search for Ari Melnick in:

Contributions

C.H. designed and did most of the experiments; K.H. did and analyzed ChIP-seq experiments; and A.M. conceived of the project and wrote the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Ari Melnick.

Supplementary information

PDF files

  1. 1.

    Supplementary Text and Figures

    Supplementary Figures 1–8 and Tables 1–3

About this article

Publication history

Received

Accepted

Published

DOI

https://doi.org/10.1038/ni.2543

Further reading