Molecular characterization and structural implications of 25 new ABCB4 mutations in progressive familial intrahepatic cholestasis type 3 (PFIC3)

Degiorgio, D.; Colombo, Carla; Seia, Manuela; Porcaro, Luigi; Costantino, Lucy; Zazzeron, L.; Bordo, Domenico; Coviello, Domenico

doi:10.1038/sj.ejhg.5201908

Cited by 88 publications

(86 citation statements)

References 28 publications

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“…9 The pathogenetic potential of both mutations is suggested by segregation analysis. The p.(L481R) mutation was identified in three out of seven affected siblings belonging to family A, whereas the already characterized p.(Y403H) mutation 6,14 was identified in four affected members belonging to other two families. According to what is generally described, [13][14][15] the genotypes reported here show that (i) two mutant ABCB4 alleles are associated with severe early-onset of intrahepatic cholestasis characterized by a rapid course toward terminal liver failure.…”

Section: Discussionmentioning

confidence: 89%

“…Although MDR3 defects are rare, 6 several findings suggest that MDR3-floppase dysfunction has a substantial direct and indirect influence on human cholestatic morbidity. Recently, Groen et al 25 have shown a functional interdependence between MDR3-floppase activity (that promotes outward translocation of inner leaflet PC) and ATP8B1-flippase activity (that promotes inward translocation of outer leaflet phosphatidylserine); only the concerted activities of both transporters allow the necessary balance of phospholipids through the bilayer of the hepatocanalicular membrane.…”

Section: Discussionmentioning

confidence: 99%

“…Families B and C have been described previously. 14 Genetic analysis, DNA cloning and site-directed mutagenesis Genomic DNA samples were isolated from blood lymphocytes and mutation analysis was performed as previously described; 6 the NCBI transcript sequence used as reference to describe our nucleotide changes was the ABCB4 isoform A, NM_000443. To exclude that the new nucleotide change identified in family A was a nonpathogenetic polymorphism, we searched this variant in 224 chromosomes of 112 healthy Caucasians 14 and in the NCBI-SNP database (http://www.ncbi.nlm.nih.gov/SNP).…”

Section: Materials and Methods Subjectsmentioning

confidence: 99%

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Two ABCB4 point mutations of strategic NBD-motifs do not prevent protein targeting to the plasma membrane but promote MDR3 dysfunction

et al. 2013

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The ABCB4 gene encodes for MDR3, a protein that translocates phosphatidylcholine from the inner to the outer leaflet of the hepatocanalicular membrane; its deficiency favors the formation of 'toxic bile'. Several forms of hepatobiliary diseases have been associated with ABCB4 mutations, but the detrimental effects of most mutations on the encoded protein needs to be clarified. Among subjects with cholangiopathies who were screened for mutations in ABCB4 by direct sequencing, we identified the new mutation p.(L481R) in three brothers. According to our model of tertiary structure, this mutation affects the Q-loop, whereas the p.(Y403H) mutation, that we already described in two other families, involves the A-loop. This study was aimed at analyzing the functional relevance of these two ABCB4 mutations: MDR3 expression and lipid content in the culture supernatant were evaluated in cell lines stably transfected with the ABCB4 wild-type clone and corresponding mutants. No differences of expression were observed between wild-type and mutant gene products. Instead, both mutations caused a reduction of phosphatidylcholine secretion compared with the wild-type transfected cell lines. On the contrary, cholesterol (Chol) release, after 1 and 3 mM sodium taurocholate stimulation, was higher in the mutant-transfected cell lines than that in the wild-type and was particularly enhanced in cells transfected with the p.Y403H-construct.In summary, our data show that both mutations do not seem to affect protein expression, but are able to reduce the efflux of phosphatidylcholine associated with increase of Chol, thereby promoting the formation of toxic bile.

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Section: Discussionmentioning

confidence: 89%

Section: Discussionmentioning

confidence: 99%

Section: Materials and Methods Subjectsmentioning

confidence: 99%

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Two ABCB4 point mutations of strategic NBD-motifs do not prevent protein targeting to the plasma membrane but promote MDR3 dysfunction

et al. 2013

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“…Since the identification of ABCB4-associated diseases, a growing number of mutations have been reported. [16][17][18] However, it remains unclear how mutations identified from genetics studies affect ABCB4 expression. If it is clear that frame-shift mutations introduce premature stop codons and lead to nonfunctional truncated mutants, missense mutations may affect the protein in different ways.…”

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confidence: 99%

A missense mutation in ABCB4 gene involved in progressive familial intrahepatic cholestasis type 3 leads to a folding defect that can be rescued by low temperature

et al. 2008

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Progressive familial intrahepatic cholestasis type 3 (PFIC3) is a rare liver disease characterized by early onset of cholestasis that leads to cirrhosis and liver failure before adulthood. PFIC3 may be improved by chronic administration of ursodeoxycholic acid, although in many cases liver transplantation is the only therapy. The disease is caused by mutations of the adenosine triphosphate (ATP)-binding cassette, sub-family B, member 4 (ABCB4) [multidrug resistance 3 (MDR3)] gene encoding a specific hepatocellular canalicular transporter involved in biliary phosphatidylcholine secretion. Several mutations have been reported; however, the effect of individual mutations has not been investigated. ABCB4 is highly homologous to ATP-binding cassette, sub-family B, member 1 (ABCB1) (MDR1), the multidrug transporter responsible for drug resistance of cancer cells. We have studied the effect of mutation I541F localized to the first nucleotide-binding domain, which is highly conserved between ABCB4 and ABCB1. Plasmids encoding the wild-type human ABCB4 or rat ABCB1-green fluorescing protein (GFP) construct, and corresponding I541F-mutants, were expressed in hepatocellular carcinoma, human (HepG2) and Madin-Darby canine kidney (MDCK) cells. Expression studies showed that ABCB4 was localized at the bile canalicular membrane in HepG2 cells and at the apical surface in MDCK cells, whereas the I541F mutant was intracellular. In MDCK cells, ABCB1-I541F also accumulated intracellularly in compartments, which were identified as the endoplasmic reticulum and cis-Golgi, and remained partially endoH-sensitive. After shifting cells to 27°C, ABCB1-I541F was expressed at the apical cell surface in a mature and active form. Similarly, ABCB4 was significantly trafficked to the membrane of bile canaliculi in HepG2 cells. Conclusion: Mutation I541F causes mislocalization of both ABCB4 and ABCB1. Intracellular retention of ABCB4-I541F can explain the disease in PFIC3 patients bearing this mutation. The observation that plasma membrane expression and activity can be rescued by low temperature opens perspectives to develop novel therapies for the treatment of PFIC3. (HEPATOLOGY 2009;49:1218-1227

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“…[2][3][4] Mutations of ABCB4 can be found in the NHLBI ESP Exome Variant Server database (http://evs.gs.washington.edu/EVS/).…”

Section: Mutational Spectrummentioning

confidence: 99%

Clinical utility gene card for: Progressive familial intrahepatic cholestasis type 3

Gonzalès¹,

Spraul

Jacquemin³

2013

Eur J Hum Genet

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Molecular characterization and structural implications of 25 new ABCB4 mutations in progressive familial intrahepatic cholestasis type 3 (PFIC3)

Cited by 88 publications

References 28 publications

Two ABCB4 point mutations of strategic NBD-motifs do not prevent protein targeting to the plasma membrane but promote MDR3 dysfunction

Two ABCB4 point mutations of strategic NBD-motifs do not prevent protein targeting to the plasma membrane but promote MDR3 dysfunction

A missense mutation in ABCB4 gene involved in progressive familial intrahepatic cholestasis type 3 leads to a folding defect that can be rescued by low temperature

Clinical utility gene card for: Progressive familial intrahepatic cholestasis type 3

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