Molecular Modification of Transient Receptor Potential Canonical 6 Channels Modulates Calcium Dyshomeostasis in a Mouse Model Relevant to Malignant Hyperthermia.
Molecular Modification of Transient Receptor Potential Canonical 6 Channels Modulates Calcium Dyshomeostasis in a Mouse Model Relevant to Malignant Hyperthermia.
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DOI：
10.1097/aln.0000000000003635
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发表时间：
2020-12
期刊：
影响因子：
8.8
通讯作者：
Jose R. Lopez;A. Uryash;J. Adams;P. Hopkins;P. Allen
中科院分区：
文献类型：
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作者：
Jose R. Lopez;A. Uryash;J. Adams;P. Hopkins;P. Allen
背景药物调节先前已表明瞬时受体电位经典(TRPC)通道在恶性高热的发病机制中发挥重要作用。这项研究测试了这样的假设：在与恶性高热相关的小鼠模型中，基因抑制 TRPC6 的功能可以部分改善肌肉阳离子稳态失调和对氟烷的反应。方法本研究使用钙和钠选择性微电极和蛋白质印迹，检查了在 20 只 RYR1-p.R163C 和 20 只野生型小鼠以及同等数量的非表达对照中过度表达肌肉特异性非传导显性失活 TRPC6 通道的效果。结果 与野生型肌肉相比，RYR1-p.R163C 小鼠肌肉的细胞内钙和钠水平长期升高。非传导 TRPC6 通道的转基因表达将细胞内钙从 331 ± 34 nM（平均值 ± SD）降低至 190 ± 27 nM（P < 0.0001），钠从 15 ± 1 mM 降低至 11 ± 1 mM（P < 0.0001）。其表达将 RYR1-p.R163C 肌纤维中 TRPC6 特异性激活剂贯叶金丝桃素的细胞内 Ca2+ 增加从 52%（348 ± 37 nM 至 537 ± 70 nM）降低至 14%（185 ± 11 nM 至 210 ± 44 nM）。 TRPC3 和 TRPC6 表达的蛋白质印迹分析显示，TRPC6 的显性失活转基因过度表达导致预期的 TRPC6 增加，以及 TRPC3 表达的补偿性增加。尽管肌肉特异性显性失活 TRPC6 的表达能够调节氟烷暴露期间细胞内钙的增加并延长寿命（35 ± 5 分钟与 15 ± 3 分钟；P < 0.0001），但在氟烷暴露 20 分钟后，钙开始缓慢而稳定地增加，最终导致死亡。结论 这些数据支持之前的发现，即 TRPC 通道在引起与 RYR1 变异相关的细胞内钙和钠稳态失调中发挥重要作用，而 RYR1 变异是恶性高热的致病因素。然而，他们还表明，单独调节 TRPC 通道不足以防止暴露于挥发性麻醉剂恶性高热引发剂的致命作用。编辑的观点
BACKGROUND Pharmacologic modulation has previously shown that transient receptor potential canonical (TRPC) channels play an important role in the pathogenesis of malignant hyperthermia. This study tested the hypothesis that genetically suppressing the function of TRPC6 can partially ameliorate muscle cation dyshomeostasis and the response to halothane in a mouse model relevant to malignant hyperthermia. METHODS This study examined the effect of overexpressing a muscle-specific nonconducting dominant-negative TRPC6 channel in 20 RYR1-p.R163C and 20 wild-type mice and an equal number of nonexpressing controls, using calcium- and sodium-selective microelectrodes and Western blots. RESULTS RYR1-p.R163C mouse muscles have chronically elevated intracellular calcium and sodium levels compared to wild-type muscles. Transgenic expression of the nonconducting TRPC6 channel reduced intracellular calcium from 331 ± 34 nM (mean ± SD) to 190 ± 27 nM (P < 0.0001) and sodium from 15 ± 1 mM to 11 ± 1 mM (P < 0.0001). Its expression lowered the increase in intracellular Ca2+ of the TRPC6-specific activator hyperforin in RYR1-p.R163C muscle fibers from 52% (348 ± 37 nM to 537 ± 70 nM) to 14% (185 ± 11 nM to 210 ± 44 nM). Western blot analysis of TRPC3 and TRPC6 expression showed the expected increase in TRPC6 caused by overexpression of its dominant-negative transgene and a compensatory increase in expression of TRPC3. Although expression of the muscle-specific dominant-negative TRPC6 was able to modulate the increase in intracellular calcium during halothane exposure and prolonged life (35 ± 5 min vs. 15 ± 3 min; P < 0.0001), a slow, steady increase in calcium began after 20 min of halothane exposure, which eventually led to death. CONCLUSIONS These data support previous findings that TRPC channels play an important role in causing the intracellular calcium and sodium dyshomeostasis associated with RYR1 variants that are pathogenic for malignant hyperthermia. However, they also show that modulating TRPC channels alone is not sufficient to prevent the lethal effect of exposure to volatile anesthetic malignant hyperthermia-triggering agents. EDITOR’S PERSPECTIVE