Cloning and functional characterization of the amphibian mesotocin receptor, a member of the oxytocin/vasopressin receptor superfamily
Cloning and functional characterization of the amphibian mesotocin receptor, a member of the oxytocin/vasopressin receptor superfamily
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DOI：
10.1111/j.1432-1033.1996.0759p.x
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发表时间：
1996-05-01
期刊：
影响因子：
--
通讯作者：
Fahrenholz, F
中科院分区：
文献类型：
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作者：
Akhundova, A;Getmanova, E;Fahrenholz, F
催产素是一种催产素样激素，存在于从肺鱼到有袋动物的大多数陆生脊椎动物中，包括所有非哺乳动物的四足动物（两栖动物、爬行动物和鸟类）。它在脊椎动物中的分布最广，仅次于在所有非哺乳类脊椎动物中发现的催产素和在硬骨鱼中发现的异催产素。本文报道了蟾蜍膀胱中催产素受体（MTR）cDNA的克隆及其功能鉴定。克隆的cDNA编码389个氨基酸的多肽，其显示出与硬骨鱼异催产素受体和哺乳动物催产素受体的最大相似性，所述催产素受体在参与配体结合的细胞外环中具有突变。当在COSM 6细胞中表达时，MTR表现出以下配体亲和力的相对顺序：中催产素>催产素=催产素>加压素>醇1、异催产素、醇2。注射MTR cRNA到非洲爪蟾卵母细胞中诱导膜氯电流响应于中催产素，这表明中催产素受体与磷酸肌醇/钙途径的偶联。该反应被催产素拮抗剂抑制，但不被对V-2加压素受体特异的加压素拮抗剂抑制。北方杂交和反转录PCR结果表明，MTR mRNA不仅存在于蟾蜍膀胱中，而且存在于蟾蜍的肾脏、肌肉和脑组织中。结果表明，中催产素及其受体的各种功能，特别是包括参与水和盐的运输的调节。
Mesotocin is the oxytocin-like hormone found in most terrestrial vertebrates from lungfishes to marsupials, which includes all non-mammalian tetrapods (amphibians, reptiles, and birds). It has the largest distribution in vertebrates after vasotocin found in all non-mammalian vertebrates and isotocin identified in bony fishes. In this study, we report the cloning and functional characterization of the cDNA for the mesotocin receptor (MTR) from the urinary bladder of the toad Bufo marinus. The cloned cDNA encodes a polypeptide of 389 amino acids that shows the greatest similarity to the teleost fish isotocin receptor and to mammalian oxytocin receptors with mutations in extracellular loops which are involved in ligand binding. When expressed in COSM6 cells, MTR exhibits the following relative order of ligand affinity: mesotocin > vasotocin = oxytocin > vasopressin > hydrin 1, isotocin, hydrin 2. Injection of MTR cRNA into Xenopus laevis oocytes induces membrane chloride currents in response to mesotocin, which indicates the coupling of the mesotocin receptor to the inositol phosphate/calcium pathway. This response is inhibited by an oxytocin antagonist, but not by a vasopressin antagonist specific for V-2 vasopressin receptors. MTR mRNA is not only found in toad urinary bladder, but also in kidney, muscle, and brain tissue of the toad as revealed by Northern blot analysis and reverse-transcriptase PCR. The results suggest a variety of functions for mesotocin and its receptor including, in particular, an involvement in the regulation of water and salt transport.