Regulated CIC CI Channels in CI Secretion in CF

描述(申请人提供)：囊性纤维化跨膜调节剂(CFTR)是一种CI通道。在囊性纤维化(CF)中，CI转运减少是因为CFTR被错误运输，或者具有不同的成熟度、稳定性或单位电导。其他离子通道的功能调节在CF中也是异常的，呼吸道细胞增加了炎症和细菌感染。这项建议的长期目标是通过激活另一种氯通道CIC2来降低囊性纤维化的严重程度。CIC2CI通道与CFTR在同一呼吸道上皮细胞中被发现，并且CIC2的激活物在体内发挥作用，已经被确定。未发现CIC2mRNA在CF中表达上调。然而，在合作研究中，使用基因组方法发现Kir4.2K通道的mRNA在几种CF小鼠模型的肺中上调。克隆和表达的通道是PKA激活的。这种K通道可能有助于通过残存的F508CFTR和包括CIC2在内的其他CI通道促进CI的转运。这一建议中需要解决的关键问题是，通过直接激活CIC2(或通过激活K通道间接激活)激活CI转运蛋白是否足以补偿在CF中观察到的其他功能的损失。其具体目的是：1)确定CIC2功能是否可以通过药理学和分子生物学方法分离出来；2)通过药理学和分子生物学方法，确定CIC2在与呼吸道微环境相似的条件下培养的呼吸道细胞模型中的作用。3)确定CIC2激活对CI转运缺陷的纠正是否会影响其他与CF相关的功能变化。将研究Na转运(ENaC)功能、钙激活CI通道(CLCA2)功能以及炎症和细菌敏感性的标记物；4)确定Kir4.2K通道上调和激活在CF中的作用。这也将从CI转运、Na转运、CLCA2功能、炎症和细菌敏感性方面进行研究。

DESCRIPTION (provided by applicant): The cystic fibrosis transmembrane regulator (CFTR) is a CI channel. In cystic fibrosis (CF), CI transport is reduced because the CFTR is mis-trafficked, or has different maturation, stability, or unit conductance. Regulation of the function of other ion channels is also aberrant in CF, and airway cells have increased inflammation and bacterial infection. The long-term goal of this proposal is to reduce the severity of cystic fibrosis by activation of another chloride channel, CIC2. CIC2 CI channels are found in the same airway epithelia as CFTR, and activators of CIC2 that function in vivo, have been identified. CIC2 mRNA has not been shown to be up-regulated in CF. However, in collaborative studies, the mRNA for the Kir4.2 K channel was found to be up-regulated in the lung of several murine models of CF using genomic approaches. The cloned and expressed channel is PKA-activated. This K channel may help promote CI transport by residual F508CFTR and other CI channels including CIC2. The key questions to be addressed in this proposal are whether activation of CI transport by activation of CIC2 directly (or indirectly through activation of this K channel) will be sufficient to compensate for loss of other functions observed in CF. The Specific Aims are to: 1) Establish whether CIC2 function can be separated from CFTR function by using pharmacological and molecular biological approaches; 2) Define the role of CIC2 in airway cell models cultured in conditions similar to the airway microenvironment by using pharmacological and molecular biological approaches. 3) Define whether correction of the CI transport defect by CIC2 activation affects other CF-related changes in function. Na transport (ENaC) function, Ca-activated CI channel (CLCA2) function, and markers of inflammation and bacterial susceptibility will be studied; and 4) Define the role of up-regulation and activation of Kir4.2 K channel in CF. This will also be studied in terms of CI transport, Na transport, CLCA2 function, inflammation and bacterial susceptibility.