Naturally occurring variations in the human 5-HT3A gene profoundly impact 5-HT3 receptor function and expression
Naturally occurring variations in the human 5-HT3A gene profoundly impact 5-HT3 receptor function and expression
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DOI：
10.1097/fpc.0b013e3280117269
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发表时间：
2007-04-01
影响因子：
2.6
通讯作者：
Brauner-Osborne, Hans
中科院分区：
文献类型：
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作者：
Krzywkowski, Karen;Jensen, Anders A.;Brauner-Osborne, Hans
血清素[5-羟色胺（5-HT）]门控离子通道5-HT3参与了术后和放疗/化疗诱导的恶心/呕吐和肠易激综合征的介导。它也被认为在各种精神疾病中发挥作用。在人类5-HT3A基因中发现了五种自然发生的单核苷酸多态性，导致氨基酸变化。方法和结果我们利用荧光细胞法研究了这些多态性对5-HT3A受体的功能影响。值得注意的是，变体A33T、S253N和M257I表现出3-64%的5- ht诱导的最大反应，而R344H和P391R表现出类似野生型的功能。所有变异均显示出5-HT和3种5-HT3拮抗剂的野生型样效力。此外，在[H-3] gr65630结合试验中，所有变异的K-d值与野生型受体相似。与野生型相比，A33T、M2571和R344H的表面表达量降低了2-4倍，但总表达量相近。最后，野生型5-HT3A或5-HT3B亚基与5-HT3A变体A33T、S253N或M257I共表达导致混合或异源受体，其特征是与野生型受体相比，对5-HT的最大反应显著降低。结论5-HT3A基因的3个多态性导致受体功能受损，野生型5-HT3A或5-HT3B均不能恢复其功能。尽管总表达水平与野生型相似，但其中三种变异受体的表面表达水平降低，表明这些变异影响受体的生物发生和/或运输。这些严重的单核苷酸多态性效应为鉴定新的5-HT3A基因疾病病因带来了希望。
Background The serotonin [5-hydroxytryptamine (5-HT)]-gated ion channel 5-HT3 is involved in the mediation of postoperative and radiotherapy/chemotherapy-induced nausea/emesis and in irritable bowel syndrome. It has also been suggested to play a role in various psychiatric diseases. Five naturally occurring single nucleotide polymorphisms leading to amino acid changes have been identified in the human 5-HT3A gene.Methods and results We investigated the functional effects of these polymorphisms on the 5-HT3A receptor using fluorescence-based cellular assays. Notably, variants A33T, S253N, and M257I displayed 5-HT-induced maximal responses of 3-64% of the wild-type response, whereas R344H and P391R exhibited wild-type-like function. All variants displayed wild-type-like potencies of 5-HT and three 5-HT3 antagonists. Furthermore, all variants displayed K-d values similar to that of the wild-type receptor in a [H-3]GR65630-binding assay. The surface expression of A33T, M2571, and R344H was reduced 2-4-fold compared with the wild-type, despite similar total expression levels. Finally, coexpression of wild-type 5-HT3A or 5-HT3B subunits with 5-HT3A variants A33T, S253N, or M257I resulted in mixed or heteromeric receptors, characterized by significantly reduced maximal responses to 5-HT compared with the wild-type receptors.Conclusions Three polymorphisms of the 5-HT3A gene gave rise to functionally impaired receptors whose function could not be rescued by either wild-type 5-HT3A or 5-HT3B. Three of the variant receptors were surface-expressed at reduced levels in spite of total expression levels similar to wild-type, indicating that these variants affect receptor biogenesis and/or trafficking. These severe single nucleotide polymorphism effects hold promise for identification of new 5-HT3A gene-disease causalities.