Ataluren in cystic fibrosis: development, clinical studies and where are we now?

Abidin, Noreen Zainal; Haq, Iram; Gardner, Aaron; Brodlie, Malcolm

doi:10.1080/14656566.2017.1359255

Cited by 54 publications

(36 citation statements)

References 47 publications

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“…To date, ~200 disease‐causing mutations in this integral membrane ion channel have been identified, including some in NBD2 . Among these mutations is a truncation in NBD2 (W1282X), which results in a poorly expressed yet potentially correctable mutant protein, as well as a point mutation (N1303K) that appears to stabilize the protein . Based on the fact that the W1282X truncation resides in a central core of the NBD2—and because of the highly hydrophobic nature of ApoB, which is targeted for ERAD under lipid‐poor conditions—we hypothesized that these substrates would be aggregation prone and thus Hsp104‐dependent ERAD substrates in yeast.…”

Section: Introductionmentioning

confidence: 99%

Hsp104 facilitates the endoplasmic‐reticulum–associated degradation of disease‐associated and aggregation‐prone substrates

et al. 2019

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Misfolded proteins in the endoplasmic reticulum (ER) are selected for ER-associated degradation (ERAD). More than 60 disease-associated proteins are substrates for the ERAD pathway due to the presence of missense or nonsense mutations. In yeast, the Hsp104 molecular chaperone disaggregates detergent-insoluble ERAD substrates, but the spectrum of diseaseassociated ERAD substrates that may be aggregation prone is unknown. To determine if Hsp104 recognizes aggregation-prone ERAD substrates associated with human diseases, we developed yeast expression systems for a hydrophobic lipid-binding protein, apolipoprotein B (ApoB), along with a chimeric protein harboring a nucleotide-binding domain from the cystic fibrosis transmembrane conductance regulator (CFTR) into which disease-causing mutations were introduced. We discovered that Hsp104 facilitates the degradation of ER-associated ApoB as well as a truncated CFTR chimera in which a premature stop codon corresponds to a disease-causing mutation. Chimeras containing a wild-type version of the CFTR domain or a different mutation were stable and thus Hsp104 independent. We also discovered that the detergent solubility of the unstable chimera was lower than the stable chimeras, and Hsp104 helped retrotranslocate the unstable chimera from the ER, consistent with disaggregase activity. To determine why the truncated chimera was unstable, we next performed molecular dynamics simulations and noted significant unraveling of the CFTR nucleotide-binding domain. Because human cells lack Hsp104, Additional Supporting Information may be found in the online version of this article.Lynley M. Doonan, Christopher J. Guerriero, and G. Michael Preston contributed equally to this work.Significance statement: Misfolded proteins can aggregate, which impairs cellular homeostasis and can give rise to disease. Although yeast express an enzyme that dissolves aggregates, humans lack this protein. We show that human aggregation-prone proteins associated with the endoplasmic reticulum are substrates for the yeast disaggregase. These data suggest that a human analog of the yeast disaggregase exists or that another mechanism removes aggregates associated with the endoplasmic reticulum.these data indicate that an alternate disaggregase or mechanism facilitates the removal of aggregation-prone, disease-causing ERAD substrates in their native environments.

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Section: Introductionmentioning

confidence: 99%

Hsp104 facilitates the endoplasmic‐reticulum–associated degradation of disease‐associated and aggregation‐prone substrates

et al. 2019

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“…65 The second phase 3 study, specifically in this subgroup, failed to confirm benefit. Hence further development of ataluren was stopped in CF, [66][67][68] although the drug is still further used and evaluated in patients with muscular dystrophy.…”

Section: Read-through Agentsmentioning

confidence: 99%

Treating the Underlying Cystic Fibrosis Transmembrane Conductance Regulator Defect in Patients with Cystic Fibrosis

Cuyx

Boeck

2019

Semin Respir Crit Care Med

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Detailed knowledge of how mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene disturb the trafficking or function of the CFTR protein and the use of high-throughput drug screens have allowed novel therapeutic strategies for cystic fibrosis (CF). The main goal of treatment is slowly but surely shifting from symptomatic management to targeting the underlying CFTR defect to halt disease progression and even to prevent occurrence of CF complications. CFTR potentiators for patients with class III mutations, mutation R117H (and in United States also for patients with specific residual function mutations) and the combination of a CFTR modulator plus a potentiator for patients homozygous for F508del, are the two classes of modulators that are in use in the clinic. Approval of these therapeutics has progressively expanded to include both younger patients and a wider range of CFTR mutations. For a significant proportion of patients with CF, current treatment is however still insufficient or unavailable.This review provides an overview of the clinical trial results and the real-life efficacy data of approved CFTR modulators. In addition, we discuss the entire pipeline of CFTR modulators: novel potentiators and correctors, amplifiers, stabilizers, and read-through agents. Furthermore, we discuss other strategies to improve CFTR function like nonsense-mediated decay inhibitors, modified transfer ribonucleic acids, antisense oligonucleotides, and genetic therapies.CFTR modulators are already changing the face of CF and the pipeline of new therapies continues to be exciting.

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“…PTC-'readthrough' can bypass the PTC, leading to partial or full expression of functional protein [15]. Several readthrough agents have been described, including the antibiotic gentamycin and ataluren, a drug in development for Duchenne muscular dystrophy [16] and that has also been trialled in cystic fibrosis [17].…”

Section: Introductionmentioning

confidence: 99%

High-content screening for rare respiratory diseases: readthrough therapy in primary ciliary dyskinesia

Lee

Cardinale

Nigro

et al. 2020

Preprint

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We describe primary cell culture of nasal epithelial cells from patients with primary ciliary dyskinesia including differentiatiation of these to a ciliary phenotype and high-content screening in miniaturised air-liquid interface cultures. Running title:High-content screening in miniaturised ALI culture Abbreviations: PCD = Primary ciliary dyskinesia RGMC = reduced generation of motile cilia ALI = air-liquid interface BEBM = bronchial epithelial basal cell medium BEGM = bronchial epithelial cell growth medium ROCK = Rho-associated protein kinase CBF = ciliary beat frequency NMD = nonsense-mediated decay IDA = inner dynein arm ODA = outer dynein arm MTD-L-IDA = microtubules disorganisation with lack of dynein arm AbstractDevelopment of therapeutic approaches for rare respiratory diseases is hampered by the lack of systems that allow medium-to-high-throughput screening of fully differentiated respiratory epithelium from affected patients. This is a particular problem for primary ciliary dyskinesia (PCD), a rare genetic disease caused by mutations in genes that adversely affect ciliary movement and consequently mucociliary transport. Primary cell culture of basal epithelial cells from nasal brush biopsies, followed by ciliated differentiation at air-liquid interface (ALI) has proven to be a useful tool in PCD diagnostics but the technique's broader utility, including in pre-clinical PCD research, has been limited by the number of basal cells that it is possible to expand from such biopsies. Here, we describe a high-content, imagingbased screening method, enabled by extensive expansion of PCD patient basal cells and their culture into differentiated human respiratory epithelium in miniaturised 96-well transwell format ALI cultures. Analyses of ciliary beat pattern, beat frequency and ultrastructure indicate that a range of different PCD defects are retained in these cultures. We perform a proof-of-principle personalized investigation in reduced generation of motile cilia (RGMC), a rare and very severe form of PCD, in this case caused by a homozygous nonsense mutation (c.441C>A; p.Cys147*) in the MCIDAS gene. The screening system allowed multiple drugs inducing translational readthrough to be evaluated alone or in combination with inhibitors of nonsense-mediated decay. Restoration of basal body formation in the patient's nasal epithelial cells was seen in vitro, suggesting a novel avenue for drug evaluation and development in PCD.

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Ataluren in cystic fibrosis: development, clinical studies and where are we now?

Cited by 54 publications

References 47 publications

Hsp104 facilitates the endoplasmic‐reticulum–associated degradation of disease‐associated and aggregation‐prone substrates

Hsp104 facilitates the endoplasmic‐reticulum–associated degradation of disease‐associated and aggregation‐prone substrates

Treating the Underlying Cystic Fibrosis Transmembrane Conductance Regulator Defect in Patients with Cystic Fibrosis

High-content screening for rare respiratory diseases: readthrough therapy in primary ciliary dyskinesia

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