PTIP promotes chromatin changes critical for immunoglobulin class switch recombination.

Science (New York, N.Y.) 2010 Aug 20

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Programmed genetic rearrangements in lymphocytes require transcription at antigen receptor genes to promote accessibility for initiating double-strand break (DSB) formation critical for DNA recombination and repair. Here, we showed that activated B cells deficient in the PTIP component of the MLL3 (mixed-lineage leukemia 3)-MLL4 complex display impaired trimethylation of histone 3 at lysine 4 (H3K4me3) and transcription initiation of downstream switch regions at the immunoglobulin heavy-chain (Igh) locus, leading to defective immunoglobulin class switching. We also showed that PTIP accumulation at DSBs contributes to class switch recombination (CSR) and genome stability independently of Igh switch transcription. These results demonstrate that PTIP promotes specific chromatin changes that control the accessibility of the Igh locus to CSR and suggest a nonredundant role for the MLL3-MLL4 complex in altering antibody effector function.

Citation

Jeremy A Daniel, Margarida Almeida Santos, Zhibin Wang, Chongzhi Zang, Kristopher R Schwab, Mila Jankovic, Darius Filsuf, Hua-Tang Chen, Anna Gazumyan, Arito Yamane, Young-Wook Cho, Hong-Wei Sun, Kai Ge, Weiqun Peng, Michel C Nussenzweig, Rafael Casellas, Gregory R Dressler, Keji Zhao, André Nussenzweig. PTIP promotes chromatin changes critical for immunoglobulin class switch recombination. Science (New York, N.Y.). 2010 Aug 20;329(5994):917-23