Cloning and functional expression of a second new aquaporin abundantly expressed in testis
Cloning and functional expression of a second new aquaporin abundantly expressed in testis
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DOI：
10.1006/bbrc.1997.7219
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发表时间：
1997-08-28
影响因子：
3.1
通讯作者：
Sasaki, S
中科院分区：
文献类型：
--
作者：
Ishibashi, K;Kuwahara, M;Sasaki, S
从老鼠的睾丸中发现了一个新的水渠成员。该基因被称为水通道蛋白8 (AQP8)，编码一个263个氨基酸的蛋白，包含MIP家族蛋白的保守NPA基序。AQP8与其他水通道蛋白氨基酸序列同源性较高（35%），与植物水通道AQP-gamma TIP氨基酸序列同源性最高（39%），提示AQP8是哺乳动物水通道蛋白中的独特成员。AQP8在爪蟾卵母细胞中的表达可刺激其渗透水通透性（P-f）达到8.5倍。0.3 mM氯化汞对P-f的增加有55%的抑制作用，巯基乙醇则相反。模拟水渗透性的Arrhenius活化能较低（5.1 kcal/mol）。AQP8不促进甘油运输。Northern blot分析显示，一个1.5 kb的AQP8转录本在睾丸中大量存在，在肝脏中少量存在。睾丸原位杂交显示AQP8 mRNA在精子发生的各个阶段，从原代精母细胞到精小管中的精细胞均有表达。与先前克隆的AQP7一起，AQP8也可能在精子发生中发挥重要作用。睾丸中两种水通道蛋白存在的出乎意料的复杂性可能需要进一步分析水通道蛋白在生殖生物学中的作用。(C) 1997学术出版社。
A new member of water channels has been identified from rat testis. This gene, termed aquaporin 8 (AQP8), encoded a 263-amino-acid protein that contained the conserved NPA motifs of MIP family proteins. AQP8 has amino acid sequence identity with other aquaporins (similar to 35%) and highest with a plant water channel, AQP-gamma TIP (39%), suggesting that AQP8 is a unique member in mammalian aquaporins. The expression of AQP8 in Xenopus oocytes stimulated the osmotic water permeability (P-f) 8.5 folds. The increase of P-f was inhibited with 0.3 mM mercury chloride by 55%, which was reversed with mercaptoethanol. The Arrhenius activation energy for the stimulated water permeability was low (5.1 kcal/mol). AQP8 did not facilitate glycerol transport. Northern blot analysis revealed a 1.5-kb transcript of AQP8 abundantly in testis and slightly in liver. In situ hybridization of testis revealed the expression of AQP8 mRNA in all stages of spermatogenesis from primary spermatocytes to spermatids in seminiferous tubules. Together with previously cloned AQP7, AQP8 may also play an important role in spermatogenesis. The unexpected complexity of the presence of two aquaporins in testis may call for the further analysis of the role of aquaporins in the reproduction biology. (C) 1997 Academic Press.