Regulated CIC CI Channels in CI Secretion in CF

描述（由申请人提供）：囊性纤维化跨膜调节因子（CFTR）是一种CI通道。 在囊性纤维化（CF）中，CI转运减少，因为CFTR被错误运输，或具有不同的成熟度、稳定性或单位电导。 CF中其他离子通道功能的调节也异常，气道细胞的炎症和细菌感染增加。 该提案的长期目标是通过激活另一个氯离子通道CIC 2来降低囊性纤维化的严重程度。 在与CFTR相同的气道上皮中发现了CIC 2 Cl通道，并且已经鉴定了在体内起作用的CIC 2的激活剂。 CIC 2 mRNA在CF中未显示上调。 然而，在合作研究中，发现Kir4.2 K通道的mRNA在使用基因组方法的几种CF小鼠模型的肺中上调。 克隆和表达的通道是PKA激活的。 该K通道可以帮助促进通过残余F508 CFTR和包括CIC 2的其他Cl通道的Cl运输。 在该提议中要解决的关键问题是通过直接激活CIC 2（或通过激活该K通道间接激活）来激活Cl转运是否足以补偿在CF中观察到的其他功能的丧失。 具体目标是：1）通过使用药理学和分子生物学方法确定CIC 2功能是否可以与CFTR功能分离; 2）通过使用药理学和分子生物学方法确定CIC 2在与气道微环境相似的条件下培养的气道细胞模型中的作用。3)定义通过CIC 2激活纠正CI转运缺陷是否影响其他CF相关的功能变化。 将研究Na转运（ENaC）功能、Ca激活的Cl通道（CLCA 2）功能以及炎症和细菌易感性的标志物;以及4）确定Kir4.2 K通道在CF中的上调和激活的作用。这也将在Cl转运、Na转运、CLCA 2功能、炎症和细菌易感性方面进行研究。

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.