Talk abstracts
Talk on Tuesday 11:15-11:30am submitted by Jack Wellmerling
Targeting the EGFR-ERK axis to stabilize CFTR in cystic fibrosis
Jack Wellmerling (Biophysics Graduate Program, Ohio State University), Sheng-Wei Chang (Department of Veterinary Biosciences, Ohio State University), Estelle Cormet-Boyaka (Department of Veterinary Biosciences, Ohio State University)
Abstract:
Cystic Fibrosis (CF) is a life-limiting autosomal recessive disorder associated with chronic lung infection and inflammation caused by mutation in the gene encoding the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR). CFTR is a chloride channel responsible for maintaining adequate airway hydration. The most common CFTR mutation, F508del, results in severely reduced CFTR activity through impaired protein trafficking, channel gating, and plasma membrane stability. CFTR modulators and potentiators, which address trafficking and gating, respectively, have been developed. However, membrane stability of F508del CFTR remains an issue. Our laboratory has previously demonstrated that activation of Extracellular-Regulated Kinase (ERK) leads to CFTR degradation [1]. We report that ERK signaling is constitutively active in CF airway epithelial cells due to signaling by the Epidermal Growth Factor Receptor (EGFR). Compared to controls, CF cells produce and shed the EGFR ligand Transforming Growth Factor-Alpha in excess. Our data show that this axis plays a role in regulation of F508del-CFTR. Next, we assessed the feasibility of improving CFTR membrane stability with the osmoprotectant ectoine. Ectoine stabilizes macromolecules through the biophysical principle of preferential exclusion, and has previously been shown to attenuate EGFR signaling by preventing its loss from lipid rafts and subsequent intracellular translocation [2]. We show that ectoine suppresses ERK signaling in primary human airway epithelial cells from F508del-homozygous CF donors. Using cycloheximide chase, we show that ectoine increases the membrane half-life of pharmacologically rescued CFTR in a human CF bronchial epithelial cell line by 122%. Finally, we show by trans-epithelial short-circuit current measurements that ectoine increases CFTR-mediated chloride transport beyond what is accomplished by modulator alone, suggesting it may be beneficial for CF patients on modulator therapy.
References:
1: Xu X, Balsiger R, Tyrrell J, Boyaka PN, Tarran R, Cormet-Boyaka E. Cigarette
smoke exposure reveals a novel role for the MEK/ERK1/2 MAPK pathway in regulation
of CFTR. Biochim Biophys Acta. 2015 Jun;1850(6):1224-32. doi:
10.1016/j.bbagen.2015.02.004.
2: Peuschel H, Sydlik U, Grether-Beck S, Felsner I, Stöckmann D, Jakob S, Kroker
M, Haendeler J, Gotić M, Bieschke C, Krutmann J, Unfried K. Carbon nanoparticles
induce ceramide- and lipid raft-dependent signalling in lung epithelial cells: a
target for a preventive strategy against environmentally-induced lung
inflammation. Part Fibre Toxicol. 2012 Dec 10;9:48. doi: 10.1186/1743-8977-9-48.
Keywords: Cystic Fibrosis, EGFR, ERK