Article abstract


Nature Immunology 8, 1132 - 1139 (2007)
Published online: 9 September 2007 | doi:10.1038/ni1508

Genotoxic stress regulates expression of the proto-oncogene Bcl6 in germinal center B cells

Ryan T Phan1,3, Masumichi Saito1, Yukiko Kitagawa1, Anthony R Means2 & Riccardo Dalla-Favera1


Antigen-specific B cells are selected in germinal centers, the structure in which these cells proliferate while accomplishing genome-remodeling processes such as class-switch recombination and somatic hypermutation. These events are associated with considerable genotoxic stress, which cells tolerate through suppression of DNA-damage responses by Bcl-6, a transcription factor required for the formation of germinal centers. Here we show that the expression of Bcl-6 is regulated by DNA damage through a signaling pathway that promotes Bcl-6 degradation. After DNA damage accumulated, the kinase ATM promoted Bcl-6 phosphorylation, leading to its interaction with the isomerase Pin1 and its degradation by the ubiquitin-proteasome system. Because Bcl-6 is required for the maintenance of germinal centers, our findings suggest that the extent of genotoxic stress controls the fate of germinal center B cells by means of Bcl-6.

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  1. Institute for Cancer Genetics, the Departments of Pathology and Genetics & Development, and the Herbert Irving Comprehensive Cancer Center, Columbia University, New York, New York 10032, USA.
  2. Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA.
  3. Present address: CBR Institute for Biomedical Research, Children's Hospital, Harvard University Medical School, Boston, Massachusetts 02115, USA.

Correspondence to: Riccardo Dalla-Favera1 e-mail: rd10@columbia.edu

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