Histone chaperone Spt6 is required for class switch recombination but not somatic hypermutation

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 108; no. 19; pp. 7920 - 7925
• Main Authors: Okazaki, Il-mi, Okawa, Katsuya, Kobayashi, Maki, Yoshikawa, Kiyotsugu, Kawamoto, Shimpei, Nagaoka, Hitoshi, Shinkura, Reiko, Kitawaki, Yoko, Taniguchi, Hisaaki, Natsume, Tohru, Iemura, Shun-Ichiro, Honjo, Tasuku
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 10.05.2011; National Acad Sciences
• Subjects: 3T3 cells; AIDS; Animals; artificial cells; B lymphocytes; B-Lymphocytes - immunology; B-Lymphocytes - metabolism; Base Sequence; Biological Sciences; Cell Line; Cells; cytidine deaminase; Cytidine Deaminase - chemistry; Cytidine Deaminase - genetics; Cytidine Deaminase - metabolism; DNA; DNA cleavage; DNA Primers - genetics; fibroblasts; Gene expression regulation; Gene Knockdown Techniques; Genetic mutation; Genetics; histones; Histones - metabolism; Humans; Immunoglobulin Class Switching; loci; Mass spectrometry; Mice; Molecular Chaperones - antagonists & inhibitors; Molecular Chaperones - genetics; Molecular Chaperones - metabolism; Molecules; Mutant Proteins - chemistry; Mutant Proteins - genetics; Mutant Proteins - metabolism; NIH 3T3 cells; precipitin tests; Protein Interaction Domains and Motifs; Proteins; Recombinant Proteins - chemistry; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; screening; Sequence Deletion; Small interfering RNA; Somatic Hypermutation, Immunoglobulin; Substrates; Transcription Factors - antagonists & inhibitors; Transcription Factors - genetics; Transcription Factors - metabolism; Two-Hybrid System Techniques; Yeast; Yeasts
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.1104423108

Activation-induced cytidine deaminase (AID) is shown to be essential and sufficient to induce two genetic alterations in the Ig loci: class switch recombination (CSR) and somatic hypermutation (SHM). However, it is still unknown how a single-molecule AID differentially regulates CSR and SHM. Here we identified Spt6 as an AID-interacting protein by yeast two-hybrid screening and immunoprecipitation followed by mass spectrometry. Knockdown of Spt6 resulted in severe reduction of CSR in both the endogenous Ig locus in B cells and an artificial substrate in fibroblast cells. Conversely, knockdown of Spt6 did not reduce but slightly enhanced SHM in an artificial substrate in B cells, indicating that Spt6 is required for AID to induce CSR but not SHM. These results suggest that Spt6 is involved in differential regulation of CSR and SHM by AID.