Program Director/Principal Investigator (Last. First, Middle): T h o m a S , P h i l i p J . PROJECT SUMMARY (See instmctions): The original application for competitive renewal of the R01 grant that was selected for a MERIT award proposed three alms to address three fundamental questions relevant to the mechanisms by which CFTR forms Its functional, native structure and how this process Is altered by disease-causing mutations. How does AF508 interfere with NBD1 folding? Does AF508 significantly modify the interaction of the folded NBD1 with other domains? What interactions with quality control proteins are critical? During the first four and a half years of MERIT support we have answered the first two questions In an exploitable way. These results indicate that CFTR folding is a hierarchical process and provide a clear explanation for the efficacy "ceiling" for extant compounds that correct folding of the AF508 mutant. They also suggest a means to a mechanism-based approai^h for the discovery new compounds that work in synergy with extant correctors or novel compounds that circumvent the "ceiling". These approaches are already being employed by a number of drug discovery efforts. Finally, using a powerful specific photo-crosslinking method, differential interactions of proteins with mutant and wild type nascent chains translated in vitro have revealed a previously unappreciated mechanism for preemptive quality control. The system involves proteins that lead to the degradation of the mRNA coding for the mutant protein, thereby reducing the production of protein bound to misfold. This mechanism prevents the accumulation of potentially cytotoxic misfoided proteins without spending energy for futile translation and subsequent ATP dependent proteolysis by the proteasome. We are now requesting continued support of the MERIT award to extend the analyses successfully applied to AF508 in Aim 1 and 2 to additional CF-causing mutations and to define and characterize the mechanisms responsible for preemptive quality control system discovered during execution of Aim 3. We thank the institute for selecting our study for MERIT support that allowed pursuit of the long term discovery effort of Aim 3 that has now revealed novel and unexpected biology. Such a path would not have been feasible under the time constraints of a R01.
Most cases of cystic fibrosis, a common fatal genetic disease, are caused by mutations that interfere with the assembly of the cystic fibrosis transmembrane conductance regulator (CFTR) protein. The studies proposed will elucidate the details of how the disease-causing mutations interfere with this process. Understanding the assembly process, and, thus, the detailed molecular pathology, will provide important information for developing targeted therapeutics for cystic fibrosis.
|Karamyshev, Andrey L; Patrick, Anna E; Karamysheva, Zemfira N et al. (2014) Inefficient SRP interaction with a nascent chain triggers a mRNA quality control pathway. Cell 156:146-57|
|Sosnay, Patrick R; Siklosi, Karen R; Van Goor, Fredrick et al. (2013) Defining the disease liability of variants in the cystic fibrosis transmembrane conductance regulator gene. Nat Genet 45:1160-7|
|Peters, Kathryn W; Okiyoneda, Tsukasa; Balch, William E et al. (2011) CFTR Folding Consortium: methods available for studies of CFTR folding and correction. Methods Mol Biol 742:335-53|
|Schmidt, Andre; Mendoza, Juan L; Thomas, Philip J (2011) Biochemical and biophysical approaches to probe CFTR structure. Methods Mol Biol 741:365-76|
|Patrick, Anna E; Karamyshev, Andrey L; Millen, Linda et al. (2011) Alteration of CFTR transmembrane span integration by disease-causing mutations. Mol Biol Cell 22:4461-71|
|Lewis, Karen A; Yaeger, Arynn; DeMartino, George N et al. (2010) Accelerated formation of alpha-synuclein oligomers by concerted action of the 20S proteasome and familial Parkinson mutations. J Bioenerg Biomembr 42:85-95|
|Hoelen, Hanneke; Kleizen, Bertrand; Schmidt, Andre et al. (2010) The primary folding defect and rescue of ýýF508 CFTR emerge during translation of the mutant domain. PLoS One 5:e15458|
|Zhu, Li; Millen, Linda; Mendoza, Juan L et al. (2010) A unique redox-sensing sensor II motif in TorsinA plays a critical role in nucleotide and partner binding. J Biol Chem 285:37271-80|
|Dorwart, Michael R; Shcheynikov, Nikolay; Baker, Jennifer M R et al. (2008) Congenital chloride-losing diarrhea causing mutations in the STAS domain result in misfolding and mistrafficking of SLC26A3. J Biol Chem 283:8711-22|