CTCF結合要素は,クロマチンスキャン中にRAG基板のアクセシビリティを媒介する.
Suvi Jain1, Zhaoqing Ba1, Yu Zhang1
1Howard Hughes Medical Institute; Program in Cellular and Molecular Medicine, Boston Children's Hospital, and Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.
Cell
|May 29, 2018
まとめ
CTCF結合要素 (CBEs) は,抗体V(D) J再結合部位の近くで,V(D) J再結合効率を高めています. これは予期せぬクロマチンのアクセシビリティ機能によって,特にIGCR1制御領域が不活性であるときに起こります.
科学分野:
- 免疫学
- 分子生物学
- 遺伝学
背景:
- 抗体重鎖変数領域 (V(D) J) エクソンアセンブリは,RAGエンドヌクレアースによってV(D) J再結合センター (RC) で開始される.
- IGCR1制御領域は,CTCF結合要素 (CBEs) によって固定されたクロマチンのループを通じて,上流のV〜HセグメントからD,J〜H,RC要素を隔離することによって,DJ〜Hの中間形成を促進します.
研究 の 目的:
- V(H) セグメントが DJ(H) RC に V(H) から DJ(H) への再配置にアクセスするメカニズムを調査する.
- V(H) セグメントのアクセシビリティと再結合の可能性におけるCBEの役割を明らかにする.
主な方法:
- V (H) リコンビネーション信号配列 (RSS) の下流に位置するCBEの機能を調査した.
- 分析されたV (H) からD (H) の再配置効率は,機能的なIGCR1の存在と欠如によって決定される.
- RAGエンドヌクレアゼ媒介のクロマチンスキャンとループエクストルーションのモデルを使用した.
主要な成果:
- V(H) -RSSの下流のCBEは,RSSの機能だけでなく,関連するV(H) セグメントの再結合可能性を大幅に高めます.
- このCBE媒介の強化は,特にIGCR1の不活性化で顕著であり,予期せぬクロマチンのアクセシビリティを高める機能を明らかにします.
- IGCR1が存在しない場合,CBEsは,線形RAGスキャン中に遭遇したD-近接V (H) セグメント間の相互作用を安定させ,それらの好ましい再配置を促進します.
結論:
- CBEは,V (H) セグメントのアクセシビリティを促進し,V (D) Jのリコンビネーションを強化する上で重要な役割を果たしています.
- 発見は,特にIGCR1機能が損なわれた状況下で,CBEsがDJHへのアクセスを容易にする新しいメカニズムを明らかにしています.
- これは,クロマチンのアクセシビリティの調節を通じて抗体遺伝子の再配置を調節するCBEsの予期せぬ役割を強調しています.
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