Depletion of recombination-specific cofactors by the C-terminal mutant of the activation-induced cytidine deaminase causes the dominant negative effect on class switch recombination
| Autor: | Nasim A. Begum, Afzal Husain, Maki Kobayashi, Tasuku Honjo, Azza Al Ismail |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
0301 basic medicine
Hyper IgM syndrome Immunology Mutant Somatic hypermutation medicine.disease_cause Cell Line Mice 03 medical and health sciences Cytidine Deaminase medicine Activation-induced (cytidine) deaminase Animals Immunology and Allergy Genetics Mutation biology Chemistry General Medicine Cytidine deaminase medicine.disease Immunoglobulin Class Switching Null allele Molecular biology 030104 developmental biology Immunoglobulin class switching biology.protein |
| Zdroj: | International Immunology. 29:525-537 |
| ISSN: | 1460-2377 0953-8178 |
| DOI: | 10.1093/intimm/dxx061 |
| Popis: | Activation-induced cytidine deaminase (AID) is essential for class-switch recombination (CSR) and somatic hypermutation (SHM) of immunoglobulin genes. Studies on in vitro mutagenized AID as well as its mutations in human patients with hyper-IgM (HIGM)-syndrome type II revealed that C-terminal AID mutations were defective in CSR whereas their DNA cleavage and SHM activities remained intact. The C-terminal mutants of AID were speculated to exert the dominant negative effect on wild-type (WT) AID whereas its mechanism remains unknown. We generated the JP41 (R190X) mutation in one allele and a null mutation on the other allele in a mouse B cell line (CH12F3-2A) using CRISPR/Cas9 genome-editing tools and studied the effect of JP41 expression on the function of exogenously introduced WT AID fused with estrogen receptor (AIDER) in AIDJP41/∆/AIDER CH12F3-2A cells. We found that JP41 expression strongly suppressed not only CSR but also Igh/c-Myc chromosomal translocations by AIDER. We showed that the dominant negative effect is not evident at the DNA cleavage step but obvious at both deletional and inversional recombination steps. We also confirmed the dominant negative effect of other C-terminal mutants, JP8Bdel (R183X) and P20 (34-aa insertion at residue 182) in AID-deficient spleen B cells. Finally, we showed that the expression of JP41 reduced the binding of AIDER with its cofactors (hnRNP L, SERBP1 and hnRNP U). Together, these data indicate that dominant negative effect of JP41 on CSR is likely due to the depletion of the CSR-specific RNA-binding proteins from WT AID. |
| Databáze: | OpenAIRE |
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