|
1
|
Tsukumo SI, Subramani PG, Seija N, Tabata M, Maekawa Y, Mori Y, Ishifune C, Itoh Y, Ota M, Fujio K, Di Noia JM, Yasutomo K. AFF3, a susceptibility factor for autoimmune diseases, is a molecular facilitator of immunoglobulin class switch recombination. SCIENCE ADVANCES 2022; 8:eabq0008. [PMID: 36001653 PMCID: PMC9401627 DOI: 10.1126/sciadv.abq0008] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Accepted: 07/08/2022] [Indexed: 06/15/2023]
Abstract
Immunoglobulin class switch recombination (CSR) plays critical roles in controlling infections and inflammatory tissue injuries. Here, we show that AFF3, a candidate gene for both rheumatoid arthritis and type 1 diabetes, is a molecular facilitator of CSR with an isotype preference. Aff3-deficient mice exhibit low serum levels of immunoglobulins, predominantly immunoglobulin G2c (IgG2c) followed by IgG1 and IgG3 but not IgM. Furthermore, Aff3-deficient mice show weak resistance to Plasmodium yoelii infection, confirming that Aff3 modulates immunity to this pathogen. Mechanistically, the AFF3 protein binds to the IgM and IgG1 switch regions via a C-terminal domain, and Aff3 deficiency reduces the binding of AID to the switch regions less efficiently. One AFF3 risk allele for rheumatoid arthritis is associated with high mRNA expression of AFF3, IGHG2, and IGHA2 in human B cells. These findings demonstrate that AFF3 directly regulates CSR by facilitating the recruitment of AID to the switch regions.
Collapse
Affiliation(s)
- Shin-ichi Tsukumo
- Department of Immunology and Parasitology, Graduate School of Medicine, Tokushima University, Tokushima, Japan
- Department of Interdisciplinary Research on Medicine and Photonics, Institute of Post-LED Photonics, Tokushima University, Tokushima, Japan
| | - Poorani Ganesh Subramani
- Institut de Recherches Cliniques de Montréal, Montréal, QC, Canada
- Department of Medicine and Division of Experimental Medicine, McGill University, Montréal, QC, Canada
| | - Noé Seija
- Institut de Recherches Cliniques de Montréal, Montréal, QC, Canada
- Molecular Biology Programs, Department of Medicine, University of Montreal, Montréal, QC, Canada
| | - Mizuho Tabata
- Department of Parasitology and Infectious Diseases, Gifu University Graduate School of Medicine, Gifu, Japan
| | - Yoichi Maekawa
- Department of Parasitology and Infectious Diseases, Gifu University Graduate School of Medicine, Gifu, Japan
| | - Yuya Mori
- Division of Pathogenesis and Disease Regulation, Department of Pathology, Shiga University of Medical Science, Shiga, Japan
| | - Chieko Ishifune
- Department of Immunology and Parasitology, Graduate School of Medicine, Tokushima University, Tokushima, Japan
| | - Yasushi Itoh
- Division of Pathogenesis and Disease Regulation, Department of Pathology, Shiga University of Medical Science, Shiga, Japan
| | - Mineto Ota
- Department of Allergy and Rheumatology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
- Department of Functional Genomics and Immunological Diseases, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Keishi Fujio
- Department of Allergy and Rheumatology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Javier M. Di Noia
- Institut de Recherches Cliniques de Montréal, Montréal, QC, Canada
- Department of Medicine and Division of Experimental Medicine, McGill University, Montréal, QC, Canada
- Molecular Biology Programs, Department of Medicine, University of Montreal, Montréal, QC, Canada
| | - Koji Yasutomo
- Department of Immunology and Parasitology, Graduate School of Medicine, Tokushima University, Tokushima, Japan
- Department of Interdisciplinary Research on Medicine and Photonics, Institute of Post-LED Photonics, Tokushima University, Tokushima, Japan
- The Research Cluster Program on Immunological Diseases, Tokushima University, Tokushima, Japan
| |
Collapse
|
|
2
|
Abstract
Activation-induced cytidine deaminase (AID) initiates somatic hypermutation of immunoglobulin (Ig) gene variable regions and class switch recombination (CSR) of Ig heavy chain constant regions. Two decades of intensive research has greatly expanded our knowledge of how AID functions in peripheral B cells to optimize antibody responses against infections, while maintaining tight regulation of AID to restrain its activity to protect B cell genomic integrity. The many exciting recent advances in the field include: 1) the first description of AID's molecular structure, 2) remarkable advances in high throughput approaches that precisely track AID targeting genome-wide, and 3) the discovery that the cohesion-mediate loop extrusion mechanism [initially discovered in V(D)J recombination studies] also governs AID-medicated CSR. These advances have significantly advanced our understanding of AID's biochemical properties in vitro and AID's function and regulation in vivo. This mini review will discuss these recent discoveries and outline the challenges and questions that remain to be addressed.
Collapse
|