The Mechanism of R-loop resolution in male germ cells and its effects on spermatogenesis and next generation.

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K20655
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0702:Biology at cellular to organismal levels, and related fields
• Research Institution: Kyoto University
• Principal Investigator: Shiromoto Yusuke 京都大学, 医学研究科, 特定助教 (40912259)
• Project Period (FY): 2021-08-30 – 2023-03-31
• Keywords: 精巣 / 精子幹細胞 / R-loop / DNA損傷

Outline of Final Research Achievements

In this study, we established germline stem cells (GS cells) lacking Adar1, an R-loop resolution factor, and analyzed their DNA:RNA hybrid levels and gene expression. The DNA:RNA hybrid levels of whole genome in the cells were not affected by Adar1 knockout. On the other hand, the expression of p16INK4a, a senescence marker, was elevated in Adar1 knockout cells. This result suggests that Adar1 may contribute to cellular senescence in GS cells.
A screening for ADAR1-related factors in cultured cells identified ATM, TDP1, and XPF as candidate factors that function in regulation of R-loop. Further analysis is needed on the function of Adar1 in R-loop resolution by ATM, TDP1, and XPF in germ cells. Testis-specific Adar1-deficient mice have been generated and are currently being analyzed for effects on spermatogenesis and their offspring.

Free Research Field

核酸発生生物学

Academic Significance and Societal Importance of the Research Achievements

生殖細胞は次代に遺伝情報を伝達する細胞であり、その異常は次世代に受け継がれる。R-loop解消因子であるADAR1を欠損するGS細胞では細胞内全体のDNA:RNAハイブリッド量やインプリント遺伝子のDNAのメチルに変化は認められなかったが、ADAR1がTDP1などと協調して機能する可能性が示唆された。これらの成果はR-loop解消機構の理解に加え、カンプトテシンなどR-loopを誘導する抗がん剤に対する細胞の生存機構の理解にも繋がり、安全な薬剤使用に貢献できる。
ADAR1欠損GS細胞において老化マーカーであるp16の発現が上昇したことから、老化による男性不妊症の原因解明に繋がる可能性がある。