∆F508 CFTR interactome remodelling promotes rescue of cystic fibrosis

Abstract

Summary Deletion of phenylalanine 508 of the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) is the major cause of Cystic Fibrosis (CF), one of the most common inherited childhood diseases. The mutated CFTR anion channel is not fully glycosylated and shows minimal activity in bronchial epithelial cells of CF patients. Low temperature or inhibition of histone deacetylases (HDACi) can partially rescue ΔF508 CFTR cellular processing defects and function. A favorable change of ΔF508 CFTR protein-protein interactions was proposed as mechanism of rescue, however CFTR interactome dynamics during temperature-shift and HDACi rescue are unknown. Here, we report the first comprehensive analysis of the wt and ΔF508 CFTR interactome and its dynamics during temperature shift and HDACi. By using a novel deep proteomic analysis method (CoPIT), we identified 638 individual high-confidence CFTR interactors and discovered a mutation-specific interactome, which is extensively remodeled upon rescue. Detailed analysis of the interactome remodeling identified key novel interactors, whose loss promoted enhanced CFTR channel function in primary CF epithelia or which were critical for normal CFTR biogenesis. Our results demonstrate that global remodeling of ΔF508 CFTR interactions is crucial for rescue, and provide comprehensive insight into the molecular disease mechanisms of CF caused by deletion of F508.

Combination of Correctors Rescues CFTR Transmembrane-Domain Mutants by Mitigating their Interactions with Proteostasis

“…Each specific protein uses only a subset of the proteostasis network components in a cellular environment, which include chaperones/co-chaperones, as well as folding, trafficking, and degradation factors. CFTR bearing ΔF508 has a prolonged association with proteostasis components at the ER, and these components target the CFTR for ubiquitination and degradation [1, 2]. CFTR bearing G85E, E92K, L1077P, or M1101K connects to a proteostasis network similar to that observed in previous studies for ΔF508, which might explain the similarities in their degradation.…”

“…The wt-CFTR and ΔF508 interact differently with proteostasis components that enable wt-CFTR maturation and preclude ΔF508 exit from the ER [2]. We explored the binding of proteins involved in ERAD to CFTR constructs bearing G85E, E92K, L1077P, or M1101K, and also asked whether correctors may modulate their interactomes to rescue CFTR.…”

“…During CFTR translation, multiple chaperones/co-chaperones orchestrate the protein's folding at the endoplasmic reticulum (ER); folding is followed by glycosylation in the Golgi apparatus and trafficking to the cell surface [1, 2]. The most prevalent CFTR mutant is a deletion of phenylalanine at position 508 (ΔF508) that reduces the thermal stability of NBD1 and affects CFTR's interdomain interactions.…”

“…Misfolded proteins cause human diseases as a result of their engagement with protein homeostasis (proteostasis) networks that assess the proteins’ poor quality and target them for degradation [1, 2]. In cystic fibrosis (CF), mutations in the CF transmembrane conductance regulator (CFTR) gene often lead to misfolded CFTR protein that malfunctions [3].…”

A Critical View on ABC Transporters and Their Interacting Partners in Auxin Transport

“…Another interesting observation was the tendency of fullsize ABC transporters to interact with one another and with secondary active transporters. In another interesting report, by comparison of the CFTR and CFTR 508 interactome, key interactors involved in rescue of channel function were identified (Pankow et al 2015).…”