由人类GIPR拼接变体介导的信号传导的分子基础
Fenghui Zhao1,2, Kaini Hang3,4, Qingtong Zhou5,6
1The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
概括
葡萄糖依赖型胰岛素型多受体 (GIPR) 的变异拼接变体通过占据连接体结合口袋来构成性地抑制其信号传递. 这些发现揭示了新形式的连接体独立偏差信号在代谢受体功能.
科学领域:
- 生物化学 生物化学
- 分子生物学分子生物学
- 结构生物学 结构生物学
背景情况:
- 葡萄糖依赖性胰岛素型多受体 (GIPR) 是葡萄糖恒温的关键调节器,也是代谢障碍的治疗点.
- GIPR表现出众多的拼接变体 (SV),其序列变化可能会影响其功能.
- 了解GIPR SVs对于开发有效的代谢疗法至关重要.
研究的目的:
- 为了研究N端改变的GIPR拼接变体 (SV1和SV2) 的结构和功能后果.
- 阐明这些SVs对内源性介导的GIPR信号传递的影响,包括联结和信号传导.
- 使用冷电子显微镜探索观察到的功能变化背后的机制.
主要方法:
- 通过冷电子显微镜 (cryo-EM) 确定了两个N端改变的GIPR拼接变体 (SV1和SV2) 的结构.
- 在HEK293T细胞中与野生型GIPR共同表达的SVs,以评估连接体结合,受体表达,cAMP积累和β-arrestin招募.
- 分析了细胞表面定位和信号传导通路.
主要成果:
- N端改变的GIPR SVs (SV1,SV2) 并没有结合GIP激素,也没有独立地引起信号.
- 这两种SV都抑制了野生类型GIPR的联体结合和cAMP积累.
- SV1特别减少了GIPR介导的β-止素2反应,表明了一个偏差的信号配置.
- 透露的冷EM结构显示,SV1和SV2采用了占据连接体结合口袋的形状,解释了它们失去结合的原因.
结论:
- 改变N端的GIPR拼接变体表现出构成性,连接体独立的偏向信号.
- 这些SVs的功能是先占据连接体结合口袋,破坏正常的GIPR激活.
- 这一发现扩大了对偏差信号传递的理解,超越了联体特异性机制,包括内在受体构造.
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