5-HT3 Receptor Brain-Type B-Subunits are Differentially Expressed in Heterologous Systems.
5-HT3 Receptor Brain-Type B-Subunits are Differentially Expressed in Heterologous Systems.
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DOI：
10.1021/acschemneuro.5b00080
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发表时间：
2015-07-15
影响因子：
5
通讯作者：
Lummis SC
中科院分区：
文献类型：
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作者：
Corradi J;Thompson AJ;McGonigle I;Price KL;Bouzat C;Lummis SC
已鉴定出五种不同 5-HT3 受体亚基的基因。大多数亚基具有多种亚基，但 B 亚基的两种亚基，即脑型 1 (Br1) 和脑型 2 (Br2) 特别令人感兴趣，因为它们似乎在人脑中大量表达，其中 5-HT3B 亚基 RNA 由约 75% 5-HT3Br2、24% 5-HT3Br1 和 <1% 5-HT3B 组成。在这里，我们使用两电极电压钳、放射性配体结合、荧光、全细胞和单通道膜片钳研究来表征 5-HT3Br1 和 5-HT3Br2 亚基对异源表达的 5-HT3 受体的功能和药理学的作用。数据显示，5-HT3Br1转录变体与5-HT3A亚基共表达时，会改变5-HT3受体的EC50、nH和单通道电导，但对竞争性拮抗剂的效力没有影响；因此，5-HT3ABr1受体具有与5-HT3AB受体相同的特征。 5-HT3AB 和 5-HT3ABr1 受体反应的形状存在一些差异，这可能是由于后者中同聚 5-HT3A 与异聚 5-HT3ABr1 受体的比例较高，因为与 5-HT3B 亚基相比，5-HT3Br1 的表达效率较低。相反，5-HT3Br2 亚基似乎不会与卵母细胞或 HEK293 细胞中的 5-HT3A 亚基形成功能通道，并且该亚基的作用尚未确定。
Genes for five different 5-HT3 receptor subunits have been identified. Most of the subunits have multiple isoforms, but two isoforms of the B subunits, brain-type 1 (Br1) and brain-type 2 (Br2) are of particular interest as they appear to be abundantly expressed in human brain, where 5-HT3B subunit RNA consists of approximately 75% 5-HT3Br2, 24% 5-HT3Br1, and <1% 5-HT3B. Here we use two-electrode voltage-clamp, radioligand binding, fluorescence, whole cell, and single channel patch-clamp studies to characterize the roles of 5-HT3Br1 and 5-HT3Br2 subunits on function and pharmacology in heterologously expressed 5-HT3 receptors. The data show that the 5-HT3Br1 transcriptional variant, when coexpressed with 5-HT3A subunits, alters the EC50, nH, and single channel conductance of the 5-HT3 receptor, but has no effect on the potency of competitive antagonists; thus, 5-HT3ABr1 receptors have the same characteristics as 5-HT3AB receptors. There were some differences in the shapes of 5-HT3AB and 5-HT3ABr1 receptor responses, which were likely due to a greater proportion of homomeric 5-HT3A versus heteromeric 5-HT3ABr1 receptors in the latter, as expression of the 5-HT3Br1 compared to the 5-HT3B subunit is less efficient. Conversely, the 5-HT3Br2 subunit does not appear to form functional channels with the 5-HT3A subunit in either oocytes or HEK293 cells, and the role of this subunit is yet to be determined.