ABCA4 mutations causing mislocalization are found frequently in patients with severe retinal dystrophies

Wiszniewski, Wojciech; Zaremba, Charles M.; Yatsenko, Alexander N.; Jamrich, Milan; Wensel, Theodore G.; Lewis, Richard A.; Lupski, James R.

doi:10.1093/hmg/ddi310

Cited by 88 publications

(43 citation statements)

References 39 publications

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“…The choice of a transient expression system, which allows convenient production of mutated proteins, is important for future studies of disease-associated mutations. We also chose to work with ABCA4 devoid of purification tags because a case study in transgenic frogs reported mislocalization of the human protein tagged with EGFP to the inner segments of photoreceptors [59]. Selective binding to GNL agarose (Figure 7A) suggested that heterologously expressed human ABCA4 retained the predominantly high-mannose type of N-linked glycosylation found in native bovine ABCA4 [19].…”

Section: Discussionmentioning

confidence: 99%

Expression, purification and structural properties of ABC transporter ABCA4 and its individual domains

Tsybovsky

Palczewski

2014

Protein Expression and Purification

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ABCA4 is a member of the A subfamily of ATP-binding cassette transporters that consists of large integral membrane proteins implicated in inherited human diseases. ABCA4 assists in the clearance of N-retinylidene-phosphatidylethanolamine, a potentially toxic by-product of the visual cycle formed in photoreceptors during light perception. Structural and functional studies of this protein have been hindered by its large size, membrane association, and domain complexity. Although mammalian, insect and bacterial systems have been used for expression of ABCA4 and its individual domains, the structural relevance of resulting proteins to the native transporter has yet to be established. We produced soluble domains of ABCA4 in E. coli and S. cerevisiae and the full-length transporter in HEK293 cells. Electron microscopy and size exclusion chromatography were used to assess the conformational homogeneity and structure of these proteins. We found that isolated ABCA4 domains formed large, heterogeneous oligomers cross-linked with non-specific disulphide bonds. Incomplete folding of cytoplasmic domain 2 was proposed based on fluorescence spectroscopy results. In contrast, full-length human ABCA4 produced in mammalian cells was found structurally equivalent to the native protein obtained from bovine photoreceptors. These findings offer recombinantly expressed full-length ABCA4 as an appropriate object for future detailed structural and functional characterization.

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Section: Discussionmentioning

confidence: 99%

Expression, purification and structural properties of ABC transporter ABCA4 and its individual domains

Tsybovsky

Palczewski

2014

Protein Expression and Purification

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“…The first extracellular loop of ABCA3 shares little sequence homology with other ABC transporters. However, several disease-causing missense mutations of human ABCA1 and ABCA4 in topologically related loops may also lead to mislocalization of the protein (33,34). The (G1221S) mutant in transmembrane domain 11 of ABCA3 is somewhat localized to lysosomes and in some of those lysosomes it appeared to transport NBD-PC.…”

Section: Discussionmentioning

confidence: 99%

Functional and Trafficking Defects in ATP Binding Cassette A3 Mutants Associated with Respiratory Distress Syndrome

Cheong

Madesh

Gonzales

et al. 2006

Journal of Biological Chemistry

182

164

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Silencing of ABCA3 expression also reduced vesicular uptake of surfactant lipids phosphatidylcholine, sphingomyelin, and cholesterol but not phosphatidylethanolamine. We conclude that ABCA3 is required for lysosomal loading of phosphatidylcholine and conversion of lysosomes to lamellar body-like structures. ATP binding cassette (ABC)2 transporters are a superfamily of highly conserved membrane proteins that transport a wide variety of substrates across cell membranes (1). Among the several subfamilies, the ABCA subclass has received considerable attention, because mutations of the ABCA1 gene cause Tangier disease and mutations of the ABCA4 gene cause Stargardt macular dystrophy in humans (2-5). ABCA1 and ABCA4 are proposed to be transmembrane transporters for intracellular cholesterol/phospholipids and N-retinylidene phosphatidylethanolamine, respectively (3-5). ABCA3, a member of the ABCA subfamily with unknown function (6 -10), is predominantly expressed in the lung and localized to the limiting membrane of lamellar bodies in alveolar epithelial type II cells (ATII) in both humans and rats (7,8).In the lung, development of structures for effective pulmonary gas exchange and production of pulmonary surfactant are necessary for successful adaptation to extrauterine life in the newborn infant. These key processes in lung maturation require differentiation of epithelium into ATII cells, the cellular source for surfactant. Pulmonary surfactant is a complex mixture of lipids, primarily phosphatidylcholine (60 -70% of which is dipalmitoylphosphatidylcholine) and specific proteins that line the alveolar surface of the lung, reducing surface tension at the air-liquid interface and preventing collapse of the lung on expiration (11). Surfactant is assembled and stored in lamellar bodies, the secretory organelles of ATII cells (11-13). Two other members of the ABCA subfamily, ABCA1 and ABCA4, have been implicated in lipid transport leading to the hypothesis that ABCA3 transports lipid into the lamellar bodies of ATII cells (7-9). Recently, it has been reported that mutations in ABCA3 are associated with defective assembly of lamellar bodies and fatal respiratory distress syndrome (RDS) in the newborn infant and interstitial lung disease (6, 10).To study the potential role of ABCA3 in RDS, we examined the subcellular trafficking and substrate specificity of ABCA3 in hATII cells and mammalian cell lines using green fluorescent protein (GFP)-tagged protein and fluorescent lipid analogs. Morphological and functional changes secondary to both loss-and gain-of-function experiments demonstrate that ABCA3 selectively transports phosphatidylcholine, sphingomyelin, and cholesterol to lamellar bodies in hATII cells. Our findings indicate that lipid trafficking by ABCA3 across lamellar body membranes is necessary for lamellar body biogenesis as a key step in assembly of lung surfactant in hATII cells.

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“…Therefore, visualization had to rely on an anti ABCA4 antibody and a fluorescent secondary antibody [18]. …”

Section: Introductionmentioning

confidence: 99%

“…Similar studies have been conducted with ABCA4 [18]. The use of specific cell surface antibodies for ABCB1 and ABCG2 has also been reviewed [14].…”

Section: Introductionmentioning

confidence: 99%

Pharmacological correction of misfolding of ABC proteins

Rudashevskaya

Stockner

Trauner

et al. 2014

Drug Discovery Today: Technologies

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The endoplasmic reticulum (ER) quality control system distinguishes between correctly and incorrectly folded proteins to prevent processing of aberrantly folded conformations along the secretory pathway. Non-synonymous mutations can lead to misfolding of ABC proteins and associated disease phenotypes. Specific phenotypes may at least partially be corrected by small molecules, so-called pharmacological chaperones. Screening for folding correctors is expected to open an avenue for treatment of diseases such as cystic fibrosis and intrahepatic cholestasis.

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ABCA4 mutations causing mislocalization are found frequently in patients with severe retinal dystrophies

Cited by 88 publications

References 39 publications

Expression, purification and structural properties of ABC transporter ABCA4 and its individual domains

Expression, purification and structural properties of ABC transporter ABCA4 and its individual domains

Functional and Trafficking Defects in ATP Binding Cassette A3 Mutants Associated with Respiratory Distress Syndrome

Pharmacological correction of misfolding of ABC proteins

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