Cystic fibrosis (CF) is a lethal autosomal recessive inherited disease caused by mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR), which functions as a cAMP- dependent Cl channel at the apical membrane of epithelial cells, including those lining the airways. A critical issue in CF disease is the inability of the most common CFTR mutation, deletion of the phenylalanine residue at position 508 (?F508CFTR), to achieve the native, folded state required for its export from the endoplasmic reticulum (ER) and traffic to the epithelial cell apical membrane. Instead, ?F508CFTR protein is exclusively retained in the ER and degraded by the ubiquitin-proteasome system. Our understanding of CFTR biogenesis in its early stages is incomplete. Recent studies show that Derlin and its associated proteins play a critical role in ubiquitin mediated CFTR degradation. Our preliminary data suggest that the Derlin complex effectively degrades wt and ?F508 CFTR and that specific components of Derlin complex preferentially regulate ?F508CFTR degradation. Our hypothesis is that the Derlin complex is a key regulator of the early steps in CFTR biogenesis. The goal for this proposal is to identify components of the Derlin complex that recognize and extract CFTR from the ER, and to identify the basis for their selective degradation of ?F508CFTR. We will test four specific aims: (1) to define the role of Derlin complex in CFTR degradation;(2) to examine the role of lysine-linkage of polyubiquitin chains in CFTR biogenesis;(3) to identify the processes mediating CFTR retrotranslocation from the ER to the cytosol;and (4) to evaluate the ubiquitin E3 ligases that evoke ubiquitin- mediated CFTR degradation. Successful completion of this proposal will advance our understanding of early checkpoints in ?F508 CFTR biogenesis and provide a roadmap for identifying novel potential therapeutic targets to restore ?F508 maturation and function.
Cystic fibrosis (CF) is caused by mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR). One of the most common mutation, deletion of the phenylalanine residue at position 508 (DeltaF508CFTR), leads to defect in the protein transport to the cell surface and results in the protein prematurely digested. This project is designed to understand how the defective protein gets premature digestion. The outcome of this project will provide a roadmap for identifying novel potential therapeutic targets to restore DeltaF508 function.
|Trescott, Laura; Holcomb, Joshua; Spellmon, Nicholas et al. (2015) Targeting the Root Cause of Cystic Fibrosis. Curr Drug Targets 16:933-44|
|Holcomb, Joshua; Spellmon, Nicholas; Trescott, Laura et al. (2015) PDZ Structure and Implication in Selective Drug Design against Cystic Fibrosis. Curr Drug Targets 16:945-50|
|Hou, Xia; Lewis, Kenneth T; Wu, Qingtian et al. (2014) Proteome of the porosome complex in human airway epithelia: interaction with the cystic fibrosis transmembrane conductance regulator (CFTR). J Proteomics 96:82-91|
|Zaman, Khalequz; Bennett, Deric; Fraser-Butler, Maya et al. (2014) S-Nitrosothiols increases cystic fibrosis transmembrane regulator expression and maturation in the cell surface. Biochem Biophys Res Commun 443:1257-62|
|Wu, Jianchun; Jiang, Hai; Luo, Shouqing et al. (2013) Caspase-mediated cleavage of C53/LZAP protein causes abnormal microtubule bundling and rupture of the nuclear envelope. Cell Res 23:691-704|
|Lee, Jin-Sook; Hou, Xia; Bishop, Nicole et al. (2013) Aquaporin-assisted and ER-mediated mitochondrial fission: a hypothesis. Micron 47:50-8|
|Wu, Yanning; Wang, Shuo; Farooq, Shukkur M et al. (2012) A chemokine receptor CXCR2 macromolecular complex regulates neutrophil functions in inflammatory diseases. J Biol Chem 287:5744-55|
|Marozkina, Nadzeya V; Yemen, Sean; Borowitz, Molly et al. (2010) Hsp 70/Hsp 90 organizing protein as a nitrosylation target in cystic fibrosis therapy. Proc Natl Acad Sci U S A 107:11393-8|