Recognition of Defective CFTRdeltaF508 by Quality Control Machines

描述(申请人提供)：囊性纤维化(CF)是一种致命的肺部疾病，其特征是由于肺部水合作用缺陷和慢性细菌感染导致纤维组织损伤。CFTRF508是一种突变的氯离子通道，在内质网(ER)的合成部位容易发生错误折叠和蛋白酶体过早降解。CFTR包含两个跨膜结构域(MSD)、两个核苷酸结合域(NBD)和一个调节域，需要适当的组装才能实现通道活性。CFTRF508是合成的，但其组装在未知的中间步骤处停滞，并在通过到质膜(PM)之前被选择用于降解。CFTRF508中的组装缺陷可以通过改变细胞折叠环境的化合物来修复，而“化学伴侣”正被用作CF药物。R01 GM56981的这项竞争性续订申请旨在通过阐明CFTR？F508折叠中的缺陷步骤并确定选择CFTR？F508进行降解的ER质量控制(ERQC)因素来帮助CF疗法的开发。初步研究发现了一种新的ER膜相关的E3泛素连接酶复合体，它由ERQC因子derlin-1、跨膜E3 RMA1、Hsp40DNAJ12和胞浆Hsp70组成，作用于上皮细胞选择CFTR进行降解。在细菌性感染的肺组织中，炎症信号强烈诱导RMA1的表达。因此，RMA1 E3复合体的过度活性可能会加剧CFTR？F508生物发生中的缺陷，并因为额外的蛋白质稳态缺陷导致CF的病理。因此，我们建议定义RMA1 E3在选择CFTRF508进行蛋白酶体降解时的作用机制。在这一过程中，我们将确定RMA1 E3客户组合，这些客户受到炎症肺上皮细胞中ERQC长期过度激活的负面影响。这些信息将被用来开发方法来减弱RMA1的表达，将CFTRF508从过早降解中拯救出来，并限制慢性炎症应激对上皮细胞蛋白质稳态的破坏。这些研究将有助于开发一种治疗CF的方法，并提供对先天性免疫信号中蛋白质稳态调节的基本了解。好了！

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. !