Recognition of Defective CFTRdeltaF508 by Quality Control Machines

描述（由申请人提供）：囊性纤维化（CF）是一种致命的肺部疾病，其特征是由肺气道的水化缺陷和慢性细菌感染引起的纤维化组织损伤。大多数CF病例的病因是CFTR的遗传？F508是一种突变型Cl-通道，其在内质网（ER）中的合成位点易于错误折叠和过早蛋白酶体降解。CFTR包含两个跨膜结构域（MSD）、两个核苷酸结合结构域（NBD）和一个调节结构域，这些结构域需要适当组装以实现通道活性。CFTR？F508是合成的，但它的组装在一个未知的中间步骤停止，它被选择降解之前，通过质膜（PM）。CFTR中的装配缺陷？F508可以通过改变细胞折叠环境的化合物来拯救，并且“化学伴侣”正被用作CF药物。R 01 GM 56981的竞争性更新申请旨在通过阐明CFTR中的缺陷步骤来帮助开发CF治疗剂。F508折叠和识别ER质量控制（ERQC）因素，选择CFTR？F508用于降解。初步研究鉴定了一种新的ER膜相关的E3泛素连接酶复合物，其由ERQC因子Derlin-1、跨膜E3 RMA 1、Hsp 40 DNAJ 12和细胞溶质Hsp 70组成，其在上皮中作用以选择CFTR进行降解。在细菌感染的CF肺中，炎性信号强烈诱导RMA 1的表达。因此，过度活动的RMA 1 E3复合物可能会加剧CFTR的缺陷？F508的生物发生，因为蛋白质稳态的额外缺陷，有助于CF的病理。因此，我们建议定义RMA 1 E3行动的机制，在CFTR的选择？F508用于蛋白酶体降解。在此过程中，我们将确定RMA 1 E3客户端的产品组合，这些客户端受到炎症肺上皮细胞中ERQC长期过度激活的负面影响。这些信息将用于开发减弱RMA 1表达和拯救CFTR F508免于过早降解的方法，并限制由慢性炎症应激引起的上皮中蛋白质稳态的损伤。这些研究将有助于开发CF的治疗方法，并提供对先天免疫信号传导过程中蛋白质稳态调节的基本理解。!

DESCRIPTION (provided by applicant): Cystic Fibrosis (CF) is a fatal lung disease characterized by fibrotic tissue damage resultant from defective hydration and chronic bacterial infection of lung airways. The etiology of most CF cases is inheritance of CFTR?F508, a mutant Cl- channel, which is prone to misfolding and premature proteasomal degradation at its site of synthesis in the endoplasmic reticulum (ER). CFTR contains two membrane-spanning domains (MSD), two nucleotide-binding domains (NBD) and a regulatory domain that require proper assembly for channel activity. CFTR?F508is synthesized, but its assembly arrests at an unknown intermediate step and it is selected for degradation prior to passage to the plasma membrane (PM). Assembly defects in CFTR?F508can be rescued by compounds that alter the cellular folding environment and "chemical chaperones" are being pursued as CF drugs. This competitive renewal application for R01 GM56981 seeks to aid in the development of CF therapeutics by elucidating defective steps in CFTR?F508folding and identifying ER quality control (ERQC) factors that select CFTR?F508for degradation. Preliminary studies identify a novel ER membrane associated E3 ubiquitin ligase complex composed of the ERQC factor Derlin-1, the transmembrane E3 RMA1, the Hsp40 DNAJ12and cytosolic Hsp70 that acts in epithelia to select CFTR for degradation. Expression of RMA1 is strongly induced by inflammatory signals in bacterially infected of CF lungs. Thus, over activity of the RMA1 E3 complex may exacerbate defects in CFTR?F508 biogenesis and because additional defects in protein homeostasis that contribute to the pathology of CF. Thus, we propose to define the mechanism for RMA1 E3 action in the selection of CFTR?F508 for proteasomal degradation. During this process we will determine the portfolio of RMA1 E3 clients that are negatively impacted by chronic over activation of ERQC in inflamed lung epithelial cells. This information will be utilized to develop methods to attenuate RMA1 expression and to rescue CFTR F508 from premature degradation and limit damage to protein homeostasis in epithelia resultant from chronic inflammatory stress. These studies will contribute to development of a treatment for CF and provide a basic understanding of regulation of protein homeostasis during innate immune signaling. !