Discovery of naturally occurring splice variants of the rat histamine H3 receptor that act as dominant-negative isoforms
Discovery of naturally occurring splice variants of the rat histamine H3 receptor that act as dominant-negative isoforms
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DOI：
10.1124/mol.105.019299
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发表时间：
2006-04-01
影响因子：
3.6
通讯作者：
Leurs, R
中科院分区：
文献类型：
--
作者：
Bakker, RA;Lozada, AF;Leurs, R
我们先前描述了三种功能性大鼠组胺H-3受体（rH（3）R）同种型的cDNA克隆，以及它们相应mRNA的不同脑表达模式和所得rH（3A）、rH（3B）和rH（3C）受体同种型的信号传导特性（Mol Pharmacol 59：1-8）。在目前的报告中，我们描述了cDNA克隆，mRNA定位在大鼠中枢神经系统中，和药理学特性的三个额外的rH（3）R剪接变体（rH（3D），rH（3E），和rH（3F）），不同于以前发表的亚型，因为它们导致一个额外的选择性剪接事件。这些新的H3 R同种型缺乏第七跨膜（TM）螺旋，并含有替代的、puronically胞外的C末端（6 TM-rH（3）同种型）。在COS-7细胞中异源表达后，对于6 TM-rH（3）同种型，不能检测到应用各种H3 R配体时的放射性配体结合或功能反应。与rH（3A）受体（rH（3A）R）相反，使用血凝素抗体检测rH（3D）同种型显示rH 3D同种型主要保持在细胞内。然而，rH（3D-F）剪接变体的表达调节7 TM H3 R同种型的细胞表面表达水平和随后的功能反应。rH（3A）R和rH（3）D同种型的共表达导致rH（3A）R的细胞内滞留和rH（3A）R功能的降低。最后，我们表明，在大鼠脑中，H3 R mRNA的表达水平与惊厥戊四唑治疗后调制，这表明，rH（3）R异构体在此描述，因此代表了一种新的生理机制，用于控制组胺能系统的活动。
We described previously the cDNA cloning of three functional rat histamine H-3 receptor (rH(3)R) isoforms as well as the differential brain expression patterns of their corresponding mRNAs and signaling properties of the resulting rH(3A), rH(3B), and rH(3C) receptor isoforms (Mol Pharmacol 59:1-8). In the current report, we describe the cDNA cloning, mRNA localization in the rat central nervous system, and pharmacological characterization of three additional rH(3)R splice variants (rH(3D), rH(3E), and rH(3F)) that differ from the previously published isoforms in that they result from an additional alternative-splicing event. These new H3R isoforms lack the seventh transmembrane (TM) helix and contain an alternative, putatively extracellular, C terminus (6TM-rH(3) isoforms). After heterologous expression in COS-7 cells, radioligand binding or functional responses upon the application of various H3R ligands could not be detected for the 6TM-rH(3) isoforms. In contrast to the rH(3A) receptor (rH(3A)R), detection of the rH(3D) isoform using hemagglutinin antibodies revealed that the rH3D isoform remains mainly intracellular. The expression of the rH(3D-F) splice variants, however, modulates the cell surface expression-levels and subsequent functional responses of the 7TM H3R isoforms. Coexpression of the rH(3A)R and the rH(3)D isoforms resulted in the intracellular retention of the rH(3A)R and reduced rH(3A)R functionality. Finally, we show that in rat brain, the H3R mRNA expression levels are modulated upon treatment with the convulsant pentylenetetrazole, suggesting that the rH(3)R isoforms described herein thus represent a novel physiological mechanism for controlling the activity of the histaminergic system.