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

Il-mi Okazaki; Katsuya Okawa; Maki Kobayashi; Kiyotsugu Yoshikawa; Shimpei Kawamoto; Hitoshi Nagaoka; Reiko Shinkura; Yoko Kitawaki; Hisaaki Taniguchi; Tohru Natsume; Shun-Ichiro Iemura; Tasuku Honjo

doi:10.1073/pnas.1104423108

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

Proc Natl Acad Sci U S A. 2011 May 10;108(19):7920-5. doi: 10.1073/pnas.1104423108. Epub 2011 Apr 25.

Authors

Il-mi Okazaki¹, Katsuya Okawa, Maki Kobayashi, Kiyotsugu Yoshikawa, Shimpei Kawamoto, Hitoshi Nagaoka, Reiko Shinkura, Yoko Kitawaki, Hisaaki Taniguchi, Tohru Natsume, Shun-Ichiro Iemura, Tasuku Honjo

Affiliation

¹ Department of Immunology and Genomic Medicine, Frontier Technology Center, Horizontal Medical Research Organization, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan.

Abstract

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.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

AICDA (Activation-Induced Cytidine Deaminase)
Animals
B-Lymphocytes / immunology
B-Lymphocytes / metabolism
Base Sequence
Cell Line
Cytidine Deaminase / chemistry
Cytidine Deaminase / genetics
Cytidine Deaminase / metabolism
DNA Primers / genetics
Gene Knockdown Techniques
Histones / metabolism
Humans
Immunoglobulin Class Switching*
Mice
Molecular Chaperones / antagonists & inhibitors
Molecular Chaperones / genetics
Molecular Chaperones / metabolism
Mutant Proteins / chemistry
Mutant Proteins / genetics
Mutant Proteins / metabolism
Protein Interaction Domains and Motifs
Recombinant Proteins / chemistry
Recombinant Proteins / genetics
Recombinant Proteins / metabolism
Sequence Deletion
Somatic Hypermutation, Immunoglobulin*
Transcription Factors / antagonists & inhibitors
Transcription Factors / genetics
Transcription Factors / metabolism*
Two-Hybrid System Techniques

Substances

DNA Primers
Histones
Molecular Chaperones
Mutant Proteins
Recombinant Proteins
SUPT6H protein, human
Supt6 protein, mouse
Transcription Factors
AICDA (Activation-Induced Cytidine Deaminase)
Cytidine Deaminase