Rescuing Trafficking Mutants of the ATP-binding Cassette Protein, ABCA4, with Small Molecule Correctors as a Treatment for Stargardt Eye Disease

Sabirzhanova, Inna; Lopes‐Pacheco, Miquéias; Rapino, Daniele; Grover, Rahul; Handa, James T.; Guggino, William B.; Cebotaru, Liudmila

doi:10.1074/jbc.m115.647685

Cited by 44 publications

(50 citation statements)

References 40 publications

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“…We could not prove the assumption that the mutant protein might have retained in the ER due to protein misfolding as previously described for trafficking defects (Cheong et al., ; Engelbrecht et al., ), since there was no apparent colocalization with Calnexin. In combination with the highly diffuse ABCA3‐HA labeling pattern throughout the whole cell, this leads to the conclusion that the mutant ABCA3‐HA protein might have somehow retained within the cytoplasm, similar as previously described for the ABCA4 (Sabirzhanova et al., ) and ABCC7 transporter (Du et al., ). An alternative explanation could be that this diffuse staining pattern is due to HA‐containing ABCA3 remnants within the cytoplasm after protein degradation in the ER or any other form of transport out of the ER, for example.…”

Section: Discussionsupporting

confidence: 80%

ABCA3 missense mutations causing surfactant dysfunction disorders have distinct cellular phenotypes

Schindlbeck¹,

Wittmann²,

Höppner³

et al. 2018

Human Mutation

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Mutations in the ATP-binding cassette subfamily A member 3 (ABCA3) gene are the most common monogenetic cause of surfactant dysfunction disorders in newborns and interstitial lung diseases in children and young adults. Although the effect of mutations resulting in truncated or incomplete proteins can be predicted, the consequences of missense variants cannot be as easily. Our aim was to investigate the intracellular handling and disturbance of the cellular surfactant system in a stable cell model with several different clinically relevant ABCA3 missense mutations. We found that the investigated missense mutations within the ABCA3 gene affect surfactant homeostasis in different ways: first by disrupting intracellular ABCA3 protein localization (c.643C > A, p.Q215K; c.2279T > G, p.M760R), second by impairing the lipid transport of ABCA3 protein (c.875A > T, p.E292V; c.4164G > C, p.K1388N), and third by yet undetermined mechanisms predisposing for the development of interstitial lung diseases despite correct localization and normal lipid transport of the variant ABCA3 protein (c.622C > T, p.R208W; c.863G > A, p.R288K; c.2891G > A, p.G964D). In conclusion, we classified cellular consequences of missense ABCA3 sequence variations leading to pulmonary disease of variable severity. The corresponding molecular pathomechanisms of such ABCA3 variants may specifically be addressed by targeted treatments.

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Section: Discussionsupporting

confidence: 80%

ABCA3 missense mutations causing surfactant dysfunction disorders have distinct cellular phenotypes

Schindlbeck¹,

Wittmann²,

Höppner³

et al. 2018

Human Mutation

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“…The pHTomato assay could be exploited for other protein trafficking diseases, the only requirement being a suitable extracellular domain to which the pHTomato can be tagged. One obvious protein, related to CFTR, whose cellular localization is an important determinant of disease severity is ABCA4, an ABC transporter mutated in Stargardt disease (Sabirzhanova et al ., ).…”

Section: Discussionmentioning

confidence: 97%

Improved fluorescence assays to measure the defects associated with F508del‐CFTR allow identification of new active compounds

Langron

Simone

Delalande

et al. 2017

British J Pharmacology

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Background and Purpose Cystic fibrosis (CF) is a debilitating disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which codes for a Clˉ/HCO3ˉ channel. F508del, the most common CF‐associated mutation, causes both gating and biogenesis defects in the CFTR protein. This paper describes the optimization of two fluorescence assays, capable of measuring CFTR function and cellular localization, and their use in a pilot drug screen. Experimental Approach HEK293 cells expressing YFP‐F508del‐CFTR, in which halide sensitive YFP is tagged to the N‐terminal of CFTR, were used to screen a small library of compounds based on the VX‐770 scaffold. Cells expressing F508del‐CFTR‐pHTomato, in which a pH sensor is tagged to the fourth extracellular loop of CFTR, were used to measure CFTR plasma membrane exposure following chronic treatment with the novel potentiators. Key Results Active compounds with efficacy ~50% of VX‐770, micromolar potency, and structurally distinct from VX‐770 were identified in the screen. The F508del‐CFTR‐pHTomato assay suggests that the hit compound MS131A, unlike VX‐770, does not decrease membrane exposure of F508del‐CFTR. Conclusions and Implications Most known potentiators have a negative influence on F508del‐CFTR biogenesis/stability, which means membrane exposure needs to be monitored early during the development of drugs targeting CFTR. The combined use of the two fluorescence assays described here provides a useful tool for the identification of improved potentiators and correctors. The assays could also prove useful for basic scientific investigations on F508del‐CFTR, and other CF‐causing mutations.

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“…A major challenge is to find pharmacological treatments for the severe forms of these diseases. It has been reported that molecules designed to rescue trafficking defective CFTR (cystic fibrosis transmembrane conductance regulator) mutants can also be effective toward other adenosine triphosphate (ATP)‐binding cassette (ABC) transporters . For ABCB4, we have shown that variations, which impair ABCB4 folding in the endoplasmic reticulum, lead to premature degradation and could be rescued in vitro by treatments with cyclosporin A or C .…”

mentioning

confidence: 99%

“…It has been reported that molecules designed to rescue trafficking defective CFTR (cystic fibrosis transmembrane conductance regulator) mutants can also be effective toward other adenosine triphosphate (ATP)-binding cassette (ABC) transporters. (11) For ABCB4, we have shown that variations, which impair ABCB4 folding in the endoplasmic reticulum, lead to premature degradation and could be rescued in vitro by treatments with cyclosporin A or C. (12,13) Two other chemical chaperones, 4-phenylbutyric acid and curcumin, have been recently proposed to rescue ABCB4 variants that impaired traffic. (14) However, the majority of variations affect PC secretion activity of ABCB4, (13) and no pharmacological treatment has been proposed for these mutations yet.…”

mentioning

confidence: 99%

Functional defect of variants in the adenosine triphosphate–binding sites of ABCB4 and their rescue by the cystic fibrosis transmembrane conductance regulator potentiator, ivacaftor (VX‐770)

et al. 2016

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ABCB4 (MDR3) is an adenosine triphosphate (ATP)‐binding cassette (ABC) transporter expressed at the canalicular membrane of hepatocytes, where it mediates phosphatidylcholine (PC) secretion. Variations in the ABCB4 gene are responsible for several biliary diseases, including progressive familial intrahepatic cholestasis type 3 (PFIC3), a rare disease that can be lethal in the absence of liver transplantation. In this study, we investigated the effect and potential rescue of ABCB4 missense variations that reside in the highly conserved motifs of ABC transporters, involved in ATP binding. Five disease‐causing variations in these motifs have been identified in ABCB4 (G535D, G536R, S1076C, S1176L, and G1178S), three of which are homologous to the gating mutations of cystic fibrosis transmembrane conductance regulator (CFTR or ABCC7; i.e., G551D, S1251N, and G1349D), that were previously shown to be function defective and corrected by ivacaftor (VX‐770; Kalydeco), a clinically approved CFTR potentiator. Three‐dimensional structural modeling predicted that all five ABCB4 variants would disrupt critical interactions in the binding of ATP and thereby impair ATP‐induced nucleotide‐binding domain dimerization and ABCB4 function. This prediction was confirmed by expression in cell models, which showed that the ABCB4 mutants were normally processed and targeted to the plasma membrane, whereas their PC secretion activity was dramatically decreased. As also hypothesized on the basis of molecular modeling, PC secretion activity of the mutants was rescued by the CFTR potentiator, ivacaftor (VX‐770). Conclusion: Disease‐causing variations in the ATP‐binding sites of ABCB4 cause defects in PC secretion, which can be rescued by ivacaftor. These results provide the first experimental evidence that ivacaftor is a potential therapy for selected patients who harbor mutations in the ATP‐binding sites of ABCB4. (Hepatology 2017;65:560‐570)

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Rescuing Trafficking Mutants of the ATP-binding Cassette Protein, ABCA4, with Small Molecule Correctors as a Treatment for Stargardt Eye Disease

Cited by 44 publications

References 40 publications

ABCA3 missense mutations causing surfactant dysfunction disorders have distinct cellular phenotypes

ABCA3 missense mutations causing surfactant dysfunction disorders have distinct cellular phenotypes

Improved fluorescence assays to measure the defects associated with F508del‐CFTR allow identification of new active compounds

Functional defect of variants in the adenosine triphosphate–binding sites of ABCB4 and their rescue by the cystic fibrosis transmembrane conductance regulator potentiator, ivacaftor (VX‐770)

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