2005 Fiscal Year Final Research Report Summary
Molecular mechanism of class switch recombination and somatic hypermutation.
| Project/Area Number |
16590401
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Immunology
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| Research Institution | Kyoto University |
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Principal Investigator |
SHINKURA Reiko Kyoto University, Graduate School of Medicine, Lecturer, 医学研究科, 寄付講座講師 (50362471)
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| Project Period (FY) |
2004 – 2005
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| Keywords | antibody / AID / class switch recombination / somatic hypermutation / humoral immune response |
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| Research Abstract |
Activation-induced cytidine deaminase (AID) is the essential molecule for class switch recombination (CSR) and somatic hypermutation (SHM). CSR is a region-specific recombination that takes place between switch (S) regions. SHM introduces point mutations in the variable (V) region. We are asking two following questions.
1. How does AID regulate differentially CSR and SHM?
We have shown that mutants with alterations in the C-terminal region of AID retain normal SHM activity but almost completely lose CSR activity. In addition, we found that mutations in the N-terminal region of AID resulted in specific loss of SHM activity but retained CSR activity. Those mutations do not locate in the cytidine deaminase motif of AID, indicating that CSR and SHM activities of AID are regulated differentially through the interaction of CSR- or SHM-specific cofactors with C-terminus or N-terminus of AID, respectively. For in vivo study, we will generate the AID knock-in mice those express the N- or C-terminal AID mutants instead of wild-type AID.
2. What is the target of AID?
AID is important for the initiation of DNA cleavage in S region. However, how AID initiates DNA cleavage is still controversial. All other researchers except for us believe that AID deaminates cytocine on DNA, resulting in DNA double strand breakage in collaboration with UNG. However, we think that AID is an RNA editing enzyme, which edits mRNA to encode the putative endonuclease, resulting in DNA cleavage. We synthesized and purified AID by in vitro transcription/translation system. In vitro synthesized AID showed the cytidine deaminase activity on single-stranded DNA, whereas deaminase-deficient AID mutant did not. It indicates that in vitro synthesized AID has cytidine deaminase activity on DNA. Next, using this AID protein, we are going to show that AID edits RNA, too.
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Research Products
(6 results)
