RAG2 involves the Igκ locus demethylation during B cell development. (August 2017)

• Record Type: Journal Article
• Authors: Wu, Caijun; Dong, Yanying; Zhao, Xiaohui; Zhang, Ping; Zheng, Mingzhe; Zhang, Hua; Li, Shichang; Jin, Yaofeng; Ma, Yunfeng; Ren, Huixun; Ji, Yanhong
• Is Part Of: Molecular immunology. Volume 88(2017:Aug.)
• Page Start: 125
• Page End: 134
• Publication Date: 2017-08
• Subjects: B lymphocytes -- V(D)J recombination -- RAG2 -- Igκ locus -- DNA methylation; Immunochemistry -- Periodicals; Molecular biology -- Periodicals; Immunochemistry -- Periodicals; Allergy and Immunology -- Periodicals; Molecular Biology -- Periodicals; Immunochimie -- Périodiques; Biologie moléculaire -- Périodiques; Immunochemistry; Molecular biology; Periodicals; Electronic journals; 571.96
• DOI: 10.1016/j.molimm.2017.06.026
• Languages: English
• ISSNs: 0161-5890

Abstract

Highlights: Wild-type RAG2 involves the Igκ locus demethylation in a RAG1-independent manner at pre-B cell stage of B lymphocyte development. RAG2's residues 350–383 region is responsible for endogenous Igκ locus demethylation. DNA methylation status does not guide the Igκ gene assembly in our working model. Abstract: The genes encoding the immunoglobulin κ light chain are assembled during B cell development by V(D)J recombination. For efficient rearrangement, the Igκ locus must undergo a series of epigenetic changes. One such epigenetic mark is DNA methylation. The mechanism that the Igκ locus is selectively demethylated at the pre-B cell stage has not previously been characterized. Here, we employed bisulfite DNA-modification assays to analyze the methylation status of the Igκ locus in primary pre-B cells from RAG-deficient mice with pre-rearranged Igh knock-in allele. We observed that the Igκ locus was hypermethylated in RAG2-deficient pre-B cells but hypomethylated in RAG1-deficient pre-B cells, indicating that wild-type (WT) RAG2 involves the Igκ locus demethylation in a RAG1-independent manner prior to rearrangement. We generated a series of RAG2 mutants between residue 350 and 383. We showed that these mutants mediated the Igκ rearrangement but failed to regulate the Igκ gene demethylation. We further analyzed that these mutants could increase RAG recombinase activity in vivo . We conclude that residues 350–383 region are responsible for endogenous Igκ locus demethylation at pre-B cells. We propose that WT RAG2 has an intrinsic function to regulate the Igκ locus demethylation.