2022 Fiscal Year Research-status Report
Role of R-loop in antibody class switching and B cell lymphomagenesis
| Project/Area Number |
21K06015
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| Research Institution | Kyoto University |
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Principal Investigator |
Begum NasimAra 京都大学, 医学研究科, 特定准教授 (80362507)
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| Project Period (FY) |
2021-04-01 – 2024-03-31
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| Keywords | CSR / R-loop / AID / HNRNPU / DNA Repair / NHEJ |
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| Outline of Annual Research Achievements |
We successfully identified HNRNPU as a critical modulator of the R-loop in the IgH and cMyc loci. We confirmed that S-S recombination was impaired in the absence of HNRNPU due to C-NHEJ-mediated repair defect. HNRNPU is required for both CSR and aberrant chromosomal translocation in B cells. Key new findings are summarized below_
(1) Mechanistic study indicates that HNRNPU functions as an R-loop suppressing factor, possibly through binding to the germline transcript (GLT) derived from the IgH locus. (2) Another line of evidence suggests that this binding to GLT depends on HNRNPU’s C-terminal, which explicitly recognizes the G-quadruplex structure.(3) RNase A treatment also dissociates HNRNPU from 53BP1 and Shileldn, suggesting HNRNPU stabilizes the C-NHEJ complex through RNA.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
As we successfully identified an R-loop regulatory candidate protein and confirmed its role specifically in R-loop suppression, experiments necessary for stepwise characterization are proceeding well.
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| Strategy for Future Research Activity |
(A) Based on proteomic analysis of S9.6 IP and HNRNPU IP, we plan to investigate the common factors for R-loop and C-NHEJ complex.
(B) ChIP analysis shows that HNRNPU promotes C-NHEJ factors recruitment to the AID-induced DNA break site. As long non-coding RNAs were detected with HNRNPU and C-NHEJ complex, the next plan is to confirm the specificity and to understand how they help stabilize the DNA repair complex.
(C) The C-terminal intrinsically disordered region (IDR)of HNRNPU is critical for its function in CSR. To fully understand the contribution of this IDR, we will conduct a detailed analysis of RNA/DNA G-quadruplex binding and liquid-liquid phase separation assay.
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Research Products
(4 results)
