MDA5媒介の炎症の原因となるのは,アルウ・デュプレックスRNAに対する自己耐性障害である
Sadeem Ahmad1, Xin Mu1, Fei Yang1
1Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA.
Cell
|February 4, 2018
まとめ
MDA5受容体の異常な活性化により,Aluレトロエレメントからの細胞 dsRNAによるアイカルディ・グティエール症候群 (AGS) のような免疫障害が発生する. MDA5のAGS変種は,これらの自己dsRNAを認識し,免疫系の調節障害を引き起こします.
科学分野:
- 免疫学
- 分子生物学
- 遺伝学
背景:
- MDA5のような先天的な免疫受容体の異常な活性化は,アイカルディ・グーティエール症候群 (Aicardi-Goutières syndrome,AGS) などの免疫疾患と関連しています.
- MDA5はウイルス双鎖RNA (dsRNA) のセンサーであり,抗ウイルス免疫反応の開始に不可欠です.
- 細胞のdsRNAに対する自己耐性喪失は,不適切な免疫活性化を誘発する.
研究 の 目的:
- エイカルディ・グーティエール症候群における構成MDA5活性化に伴うメカニズムを調査する.
- MDA5活性化におけるAluレトロエレメントとその派生dRNAの役割を決定する.
- MDA5の自己/非自己差別に対する細胞環境の影響を調査する.
主な方法:
- 新しいRNase-保護/RNA-シーケンシング (RNA-seq) の開発と応用.
- 細胞のAlu-dsRNAを含む異なるdsRNA構造のMDA5フィラメント形成の分析
- MDA5 オリゴメリゼーションに対する細胞RNA濃度の影響の調査.
主要な成果:
- AGSにおける構成的なMDA5活性化は,Aluレトロエレメントから生じる細胞 dsRNAに対する耐性喪失によって引き起こされる.
- AGSで発見された変異したMDA5変異体は,dSRNAの構造的不規則性に対する感受性が低下し,Alu- dSRNAのフィラメントアセンブリを可能にします.
- RNAが豊富な細胞環境は,異常なMDA5オリゴメリゼーションを抑制することが判明し,文脈依存の免疫センシングを示しています.
結論:
- dsRNAを認識するMDA5の効率の向上は,自己認識を犠牲にして,自己免疫疾患に寄与する.
- Alu-dsRNAは霊長類の免疫系を形作る ウイルスのような内生的な要素として機能します
- 細胞のdsRNAとレトロエレメントによるMDA5の調節を理解することで,免疫ホメオスタシスと疾患の病原性についての洞察が得られます.
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