A naturally occurring point mutation in the rat aquaporin 5 gene, influencing its protein production by and secretion of water from salivary glands.
A naturally occurring point mutation in the rat aquaporin 5 gene, influencing its protein production by and secretion of water from salivary glands.
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DOI：
10.1152/ajpgi.00449.2005
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发表时间：
2006-12
期刊：
影响因子：
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通讯作者：
K. Murdiastuti;N. Purwanti;M. Karabasil;Xuefei Li;C. Yao;T. Akamatsu;N. Kanamori;K. Hosoi
中科院分区：
文献类型：
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作者：
K. Murdiastuti;N. Purwanti;M. Karabasil;Xuefei Li;C. Yao;T. Akamatsu;N. Kanamori;K. Hosoi
在Sprague-Dawley大鼠的下颌下腺（SMG）的膜部分中观察到水通道蛋白5（AQP 5）表达水平的两倍以上的多样性（Murdiastuti K，三木O，Yao C，Parvin MN，Kosugi-Tanaka C，Akamatsu T，Kanamori N，和Hojiak K. Pflügers Arch 445：405-412，2002）。在本研究中，在高AQP 5生产者和低AQP 5生产者中重复兄弟和姐妹大鼠之间的繁殖，以获得近交后代。使用第3代至第18代的高产和低产大鼠进行实验。通过蛋白质印迹法，在腮腺和泪腺，和肺中的AQP 5蛋白质的水平在低生产者中都很低，而在高生产者中都很高，这意味着该水通道的基因的遗传变异。尽管有这种暗示，但通过北方印迹法，两组之间的AQP 5 mRNA水平几乎相同，表明这种多样性与转录调控无关。对两组SMG的AQP 5 cDNA进行测序。结果表明，低水平生产者的AQP 5基因在第308位发生了点突变（G308 A），导致第三跨膜区的（103）Gly被（103）Asp取代，而Kozak区未发现突变。这种突变的存在也通过基因组DNA的评估得到证实。该突变可能导致AQP 5的异常膜插入或无效运输，因为具有该突变的大鼠在SMG腺泡细胞中显示出极低的AQP 5膜表达，并且其唾液腺的水分泌减少。
A greater than twofold diversity in the expression level of aquaporin 5 (AQP5) has been observed in the membrane fraction of the submandibular gland (SMG) in Sprague-Dawley rats (Murdiastuti K, Miki O, Yao C, Parvin MN, Kosugi-Tanaka C, Akamatsu T, Kanamori N, and Hosoi K. Pflügers Arch 445: 405-412, 2002). In the present study, breeding between brother and sister rats was repeated within high AQP5 producers and low ones to obtain inbred offspring. High- and low-producer rats from 3rd to 18th generations were used for experiments. By Western blotting, levels of AQP5 proteins in the parotid and lacrimal glands, and lungs were all low in low producers, whereas they were all high in high producers, implying genetic variations of the gene for this water channel. Despite this implication, AQP5 mRNA levels were almost the same between the two groups by Northern blotting, suggesting the irrelevance of transcriptional regulation for this diversity. AQP5 cDNAs from the SMGs of the two groups were sequenced. The nucleotide sequence of AQP5 cDNA from low producers indicated the existence of a point mutation at nt 308 (G308A), leading to a replacement of (103)Gly with (103)Asp in the third transmembrane domain, but no alteration was detected in the Kozak area. The existence of such a mutation was confirmed by the assessment of genomic DNA also. This mutation may have resulted in an abnormal membrane insertion or ineffective trafficking of AQP5, since the rats having this mutation showed extremely low membrane expression of AQP5 in the SMG acinar cells and decreased water secretion from their salivary glands.