Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, China.
Department of Orthopedics, Xuanwu Hospital, Capital Medical University, Beijing, 100053, China.
Neurosci Bull. 2021 Oct;37(10):1381-1396. doi: 10.1007/s12264-021-00737-1. Epub 2021 Jul 2.
Mechanosensitive ion channels (MSCs) are key molecules in the mechano-electrical transduction of arterial baroreceptors. Among them, acid-sensing ion channel 2 (ASIC2) and transient receptor potential vanilloid subfamily member 1 (TRPV1) have been studied extensively and documented to play important roles. In this study, experiments using aortic arch-aortic nerve preparations isolated from rats revealed that both ASIC2 and TRPV1 are functionally necessary, as blocking either abrogated nearly all pressure-dependent neural discharge. However, whether ASIC2 and TRPV1 work in coordination remained unclear. So we carried out cell-attached patch-clamp recordings in HEK293T cells co-expressing ASIC2 and TRPV1 and found that inhibition of ASIC2 completely blocked stretch-activated currents while inhibition of TRPV1 only partially blocked these currents. Immunofluorescence staining of aortic arch-aortic adventitia from rats showed that ASIC2 and TRPV1 are co-localized in the aortic nerve endings, and co-immunoprecipitation assays confirmed that the two proteins form a compact complex in HEK293T cells and in baroreceptors. Moreover, protein modeling analysis, exogenous co-immunoprecipitation assays, and biotin pull-down assays indicated that ASIC2 and TRPV1 interact directly. In summary, our research suggests that ASIC2 and TRPV1 form a compact complex and function synergistically in the mechano-electrical transduction of arterial baroreceptors. The model of synergism between MSCs may have important biological significance beyond ASIC2 and TRPV1.
机械敏感性离子通道（MSCs）是动脉压力感受器机电转导的关键分子。其中，酸敏感离子通道 2（ASIC2）和瞬时受体电位香草醛亚家族成员 1（TRPV1）已被广泛研究，并被证明发挥着重要作用。在这项研究中，使用从大鼠分离的主动脉弓-主动脉神经制备物进行的实验表明，ASIC2 和 TRPV1 都是功能必需的，因为阻断任何一种都几乎消除了所有压力依赖性的神经放电。然而，ASIC2 和 TRPV1 是否协同工作仍不清楚。因此，我们在共表达 ASIC2 和 TRPV1 的 HEK293T 细胞中进行了细胞贴附式膜片钳记录，发现 ASIC2 的抑制完全阻断了拉伸激活电流，而 TRPV1 的抑制仅部分阻断了这些电流。对大鼠主动脉弓-主动脉外膜的免疫荧光染色显示，ASIC2 和 TRPV1 在主动脉神经末梢共定位，共免疫沉淀实验证实这两种蛋白质在 HEK293T 细胞和压力感受器中形成紧密的复合物。此外，蛋白质建模分析、外源性共免疫沉淀实验和生物素下拉实验表明 ASIC2 和 TRPV1 直接相互作用。总之，我们的研究表明，ASIC2 和 TRPV1 形成紧密的复合物，并在动脉压力感受器的机电转导中协同作用。MSCs 之间的协同作用模型可能具有超越 ASIC2 和 TRPV1 的重要生物学意义。
