Abnormal subcellular localization of AQP5 and downregulated AQP5 protein in parotid glands of streptozotocin-induced diabetic rats.
Abnormal subcellular localization of AQP5 and downregulated AQP5 protein in parotid glands of streptozotocin-induced diabetic rats.
复制标题
DOI：
10.1016/j.bbagen.2011.01.013
复制
发表时间：
2011-05
期刊：
影响因子：
--
通讯作者：
Di Wang;Zhenfang Yuan;N. Inoue;Gota Cho;M. Shono;Y. Ishikawa
中科院分区：
文献类型：
--
作者：
Di Wang;Zhenfang Yuan;N. Inoue;Gota Cho;M. Shono;Y. Ishikawa
方法采用Western blotting、real-time PCR和免疫细胞化学方法，对40例正常人唾液腺组织中AQP 5蛋白和mRNA的表达进行检测。AQP 5蛋白水平测定顶端质膜（APM）和洗涤剂不溶性馏分制备链脲佐菌素糖尿病大鼠腮腺。尽管增加AQP 5 mRNA，AQP 5蛋白水平降低，在糖尿病腮腺与对照组相比。免疫组织化学研究表明，AQP 5，在未受刺激的条件下，共定位与flotillin-2和GM 1的弥漫性模式在顶端的腺泡和导管细胞的细胞质中的控制和糖尿病大鼠。静脉注射毒蕈碱受体激动剂西维美林后10 min，对照组大鼠腮腺腺泡和导管细胞APM中的AQP 5、flotilin-2和GM 1显著增加，而糖尿病大鼠则无此现象。注射后60分钟，AQP 5在两种大鼠的顶端细胞质中以弥漫性模式定位。用西维美林处理腮腺组织10分钟增加对照大鼠而不是糖尿病大鼠中AQP 5的Triton X-100溶解度。结论唾液腺内AQP 5蛋白表达下调及MKA诱导的AQP 5转位缺失可能是糖尿病大鼠口干的原因。一般意义头孢美林在胰岛素治疗下对糖尿病口干症有疗效。
BACKGROUNDThe mechanisms underlying diabetic xerostomia have not been clarified in relation with aquaporin-5 (AQP5) subcellular localization in salivary glands.METHODSWestern blotting, real-time PCR, and immunocytochemistry were used to analyse AQP5 protein levels and mRNA expression. AQP5 protein levels were measured in the apical plasma membrane (APM) and detergent-insoluble fraction prepared from streptozotocin-diabetic rat parotid glands.RESULTSDespite an increase in AQP5 mRNA, AQP5 protein levels were decreased in diabetic parotid glands compared with controls. Immunohistochemical studies indicated that AQP5, under unstimulated conditions, colocalised with flotillin-2 and GM1 with a diffuse pattern in the apical cytoplasm of acinar and duct cells in both control and diabetic rats. Ten minutes after intravenous injection of muscarinic agonist cevimeline, AQP5 was dramatically increased together with flotillin-2 and GM1 in the APM of parotid acinar and duct cells of control but not diabetic rats. Sixty minutes after injection, AQP5 was located in a diffuse pattern in the apical cytoplasm in both rats. Treatment of the parotid tissues with cevimeline for 10min increased the Triton X-100 solubility of AQP5 in control but not diabetic rats. Administration of insulin to diabetic rats tended to restore the cevimeline-induced translocation of AQP5.CONCLUSIONLack of AQP5 translocation in the salivary gland in response to a muscarinic agonist and downregulation of AQP5 protein might lead to diabetic xerostomia. General significance Cevimeline is useful to cure diabetic xerostomia under insulin administration.