Molecular Machinery for Vasotocin-Dependent Transepithelial Water Movement in Amphibians: Aquaporins and Evolution
Molecular Machinery for Vasotocin-Dependent Transepithelial Water Movement in Amphibians: Aquaporins and Evolution
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DOI：
10.1086/bblv229n1p109
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发表时间：
2015-08-01
影响因子：
1.6
通讯作者：
Okada, Reiko
中科院分区：
文献类型：
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作者：
Suzuki, Masakazu;Shibata, Yuki;Okada, Reiko
两栖动物代表了最早适应陆地环境的脊椎动物，并成功地分布在世界各地。腹面皮肤、肾脏和膀胱是成年无尾两栖类重要的生殖调节器官。水通道蛋白，称为水通道蛋白（AQP），在这些器官的跨上皮水吸收/重吸收中发挥关键作用。在无尾两栖类中至少鉴定出43种类型的水通道蛋白;最近的系统发育分析将无尾两栖类水通道蛋白分为16类（AQP 0 -14，16）。无尾两栖类特异性AQPa 2被指定为AQP 6，然后进一步细分为腹侧皮肤型（AQP 6vs; AQPa 2S）和膀胱型（AQP 6 ub; AQPa 2U），腹侧皮肤型的表达仅限于腹侧皮肤，膀胱型的表达基本上在膀胱中表达。对于神经调节器官，AQP 3组成性地位于紧密连接上皮细胞的基底侧质膜。AQP 6vs、AQP 2和/或AQP 6 ub也在这些上皮细胞中表达，并且响应于精氨酸催产素而移位至顶端膜，从而调节水的吸收/重吸收。最近的研究表明，两种亚型的AQP 6vs有助于皮肤水分吸收的蛙类物种。此外，从热带爪蟾Gray，1864中鉴定出AQP 5（AQP 5a）和AQP 5L（AQP 5 b），并且AQP 5定位于脱水爪蟾膀胱腔上皮细胞的顶膜。这一发现表明，AQP 5可能参与了脱水条件下该器官的水重吸收。基于迄今为止报道的信息，我们提出了模型的演变waterabsorbing/ reabsorbing机制在无尾两栖动物的调节器官与水通道蛋白。
Amphibians represent the first vertebrates to adapt to terrestrial environments, and are successfully distributed around the world. The ventral skin, kidney, and urinary bladder are important osmoregulatory organs for adult anuran amphibians. Water channel proteins, called aquaporins (AQPs), play key roles in transepithelial water absorption/reabsorption in these organs. At least 43 types of AQPs were identified in anurans; a recent phylogenetic analysis categorized anuran AQPs among 16 classes (AQP0-14, 16). Anuran-specific AQPa2 was assigned to AQP6, then was further subdivided into the ventral skintype (AQP6vs; AQPa2S), whose expression is confined to the ventral skin, and the urinary bladder-type (AQP6ub; AQPa2U), which is basically expressed in the urinary bladder. For the osmoregulatory organs, AQP3 is constitutively located in the basolateral plasma membrane of tight-junctioned epithelial cells. AQP6vs, AQP2 and/or AQP6ub are also expressed in these epithelial cells and are translocated to the apical membrane in response to arginine vasotocin, thereby regulating water absorption/reabsorption. It was suggested recently that two subtypes of AQP6vs contribute to cutaneous water absorption in Ranid species. In addition, AQP5 (AQP5a) and AQP5L (AQP5b) were identified from Xenopus tropicalis Gray, 1864, and AQP5 was localized to the apical membrane of luminal epithelial cells of the urinary bladder in dehydrated Xenopus. This finding suggested that AQP5 may be involved in water reabsorption from this organ under dehydration. Based on the hitherto reported information, we propose models for the evolution of waterabsorbing/ reabsorbing mechanisms in anuran osmoregulatory organs in association with AQPs.