cCAMP Regulation of Aquaporin 5

描述（由申请方提供）：水通道蛋白（AQP）是水特异性膜通道蛋白。AQP 5位于气道粘膜下腺体、支气管上皮和I型肺泡上皮细胞的顶膜，可能参与气道表面分泌物的产生。AQP 5表达的调节是复杂的，并受到各种应激条件的调节，包括渗透压和病毒感染。与野生型相比，AQP 5敲除小鼠具有减少的气道腺体分泌和增加的支气管收缩。AQP 5表达的变化可能改变分泌，并在气道生理中起重要作用。在培养的肺上皮细胞中，我们观察到短时间暴露于cAMP会降低AQP 5蛋白水平并改变其细胞分布。β-受体激动剂是哮喘治疗的主要药物，可刺激cAMP的形成，导致平滑肌松弛，但对总气道分泌物的影响尚不明确。我们假设β受体激动剂改变AQP 5表达和亚细胞运输，从而改变气道表面液体。我们将研究以下目标。目标1：通过研究蛋白降解机制（包括泛素化变化），确定急性cAMP和β激动剂刺激如何降低AQP 5表达。目标二：使用野生型和突变型AQP 5构建体的免疫荧光测定急性暴露于cAMP和β-激动剂刺激对AQP 5蛋白运输的影响。

DESCRIPTION (provided by applicant): Aquaporins (AQPs) are water specific membrane channel proteins. AQP5, located in the apical membrane of airway submucosal glands, bronchial epithelium, and type I pneumocytes, likely participates in generation of airway surface secretions. Regulation of AQP5 expression is complex and modulated by a variety of stress conditions, including osmolality and viral infections. AQP5 knockout mice have reduced airway gland secretions and increased bronchoconstriction compared to wild type. Changes in AQP5 expression may alter secretions, and play an important role in the airway physiology. In cultured lung epithelial cells, we observed that short-exposures to cAMP decrease AQP5 protein levels and modify its cellular distribution. Beta-agonists, a mainstay of asthma therapy, stimulate the formation of cAMP, and lead to smooth muscle relaxation, but effect on total airway secretions is not defined. We hypothesize that beta-agonists alter AQP5 expression and subcellular trafficking and can thereby alter airway surface liquid. We will investigate the following aims. Aim#1 : To determine how acute cAMP and beta-agonist stimulation decrease AQP5 expression by investigating mechanisms of protein degradation including changes in ubiquitination. Aim#2: To determine the effects of acute exposure to cAMP and beta-agonist stimulation on AQP5 protein trafficking using immunofluorescence of wild-type and mutant AQP5 constructs.