通过MDA5变体保护自身免疫性疾病的分子基础
Rahul Singh1, Joe D Joiner2, Alba Herrero Del Valle3
1Molecular Immunity Unit, Department of Medicine, University of Cambridge, MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK; Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), Department of Medicine, University of Cambridge, Cambridge CB2 0AW, UK; Department of Pathology, University of Cambridge, Cambridge CB2 1QP, UK.
Cell reports
|June 1, 2025
概括
MDA5 (黑色素瘤分化相关基因5) 的自身免疫保护变异抑制其RNA传感. 一些变种会损害RNA结合或增加ATPase活性,从而降低免疫反应.
科学领域:
- 免疫学 免疫学 免疫学
- 分子生物学分子生物学
- 结构生物学 结构生物学
背景情况:
- 黑色素瘤分化相关基因5 (MDA5) 对于识别病毒双链RNA (dsRNA) 是至关重要的.
- MDA5的功能依赖于合作性丝状形成和依赖ATP的校对,用于敏感和特定的dsRNA检测.
- MDA5的遗传变异与自身免疫性疾病的保护有关,但增加了感染风险,但它们对RNA传感的确切影响尚不清楚.
研究的目的:
- 调查自身免疫保护MDA5变种如何影响其分子结构和RNA感应活动.
- 阐明特定的MDA5变种影响免疫信号通路的机制.
主要方法:
- 使用冷电子显微镜 (cryo-EM) 来确定与dsRNA结合的MDA5变体的结构.
- 评估了MDA5变体的RNA结合能力和ATPase活性.
- 在MDA5变种存在的情况下测量了对皮科纳病毒感染和细胞因子诱导的干扰素反应.
主要成果:
- 发现罕见的变种E627*和I923V可以降低对皮科纳病毒感染的干扰素反应.
- E627* 变种没有表现出RNA结合,而I923V 显示出过度活跃的ATPase,导致过早的dsRNA解离.
- 低温EM结构显示,I923V具有较小的RNA结合接口和过度的校对活动.
- 基因相关的R843H和T946A变异没有影响细胞因子诱导,这表明间接的疾病机制.
结论:
- 自免疫保护的MDA5变体可以通过各种机制抑制MDA5依赖的信号传递,包括受损的RNA结合和改变的ATPase活性.
- 这些发现澄清了特定的MDA5遗传变异如何影响先天免疫反应以及对感染和炎症的易感性.
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