scholarly journals A recurrent ABCC2 p.G693R mutation resulting in loss of function of MRP2 and hyperbilirubinemia in Dubin-Johnson syndrome in China

2020 ◽  
Author(s):  
Lina Wu ◽  
Yanmeng Li ◽  
Yi Song ◽  
Donghu Zhou ◽  
Siyu Jia ◽  
...  
Keyword(s):  
Cellular Localization ◽  
Organic Anion ◽  
Autosomal Recessive Disorder ◽  
Anion Transport ◽  
Causative Mutation ◽  
Loss Of Function ◽  
Organic Anion Transport ◽  
Transport Activity ◽  
Johnson Syndrome ◽  
Anion Transport Activity

Abstract Background: Dubin-Johnson syndrome (DJS) is a rare autosomal recessive disorder characterized by predominantly conjugated hyperbilirubinemia that is caused by pathogenic mutations in the adenosine triphosphate-binding cassette subfamily C member 2 ( ABCC2 ) gene, which encodes multidrug resistance-associated protein 2 (MRP2). However, little is known about the causative mutation of DJS in China. Recently, we have reported ABCC2 p.G693R mutation in two unrelated cases. In the present study, we investigated the pathogenicity of the ABCC2 p.G693R mutation in DJS in China. Methods: Clinical and genetic analysis was conducted for the two patients with the ABCC2 p.G693R mutation. Whole exome sequencing for mutations in other known hyperbilirubinemia-related genes was conducted for the cases with ABCC2 p.G693R. Expression and cellular localization of the mutant MRP2 p.G693R were analyzed by Western blotting and immunofluorescence assay, respectively. Organic anion transport activity was evaluated by the analysis of glutathione-conjugated-monochlorobimane. Results: The two DJS patients with ABCC2 p.G693R mutation, which was conserved among different species, showed typical hyperbilirubinemia phenotype. No pathogenic mutation was identified in the other known hyperbilirubinemia related genes. Functional studies in three cell lines showed that the expression, localization and the organic anion transport activity were significantly compromised by MRP2 p.G693R mutation compared with wild-type MRP2. Conclusions: The recurrent ABCC2 p.G693R mutation is associated with loss of function of the MRP2 protein and may result in hyperbilirubinemia in DJS in China.

scholarly journals A novel ABCC2 p.G693R mutation resulting in loss of function of MRP2: a recurrent cause of hyperbilirubinemia in Dubin-Johnson syndrome in China

2019 ◽  
Author(s):  
Lina Wu ◽  
Yanmeng Li ◽  
Yi Song ◽  
Donghu Zhou ◽  
Siyu Jia ◽  
...  
Keyword(s):  
Cellular Localization ◽  
Organic Anion ◽  
Autosomal Recessive Disorder ◽  
Anion Transport ◽  
Causative Mutation ◽  
Loss Of Function ◽  
Organic Anion Transport ◽  
Transport Activity ◽  
Johnson Syndrome ◽  
Anion Transport Activity

Abstract Background Dubin-Johnson syndrome (DJS) is a rare autosomal recessive disorder characterized by predominantly conjugated hyperbilirubinemia that is caused by pathogenic mutations in the adenosine triphosphate-binding cassette subfamily C member 2 ( ABCC2 ) gene, which encodes multidrug resistance-associated protein 2 (MRP2). However, little is known about the causative mutation of DJS in China. Recently, we have reported a novel ABCC2 p.G693R mutation in two unrelated cases. In the present study, we investigated the pathogenicity of the ABCC2 p.G693R mutation in DJS in China.Methods Clinical and genetic analysis was conducted for the two patients with the ABCC2 p.G693R mutation. Whole exome sequencing for mutations in other known hyperbilirubinemia-related genes was conducted for the cases with ABCC2 p.G693R. Expression and cellular localization of the mutant MRP2 p.G693R were analyzed by Western blotting and immunofluorescence assay, respectively. Organic anion transport activity was evaluated by the analysis of glutathione-conjugated-monochlorobimane.Results The two DJS patients with ABCC2 p.G693R mutation, which was conserved among different species, showed typical hyperbilirubinemia phenotype. No pathogenic mutation was identified in the other known hyperbilirubinemia related genes. Functional studies in three cell lines showed that the expression, localization and the organic anion transport activity were significantly compromised by MRP2 p.G693R mutation compared with wild-type MRP2.Conclusions The ABCC2 p.G693R mutation is associated with loss of function of the MRP2 protein, which may represent one of the major etiological factors of hyperbilirubinemia in DJS in China.

Redistribution of canalicular organic anion transport activity in isolated and cultured rat hepatocytes

Hepatology ◽  
1995 ◽  
Vol 21 (6) ◽  
pp. 1649-1657 ◽  
Author(s):  
Han Roelofsen ◽  
Conny T. M. Bakker ◽  
Berry Schoemaker ◽  
Marc Heijn ◽  
Peter L. M. Jansen ◽  
...  
Keyword(s):  
Organic Anion ◽  
Rat Hepatocytes ◽  
Anion Transport ◽  
Organic Anion Transport ◽  
Transport Activity ◽  
Cultured Rat Hepatocytes ◽  
Anion Transport Activity

Impaired hepatocanalicular organic anion transport in endotoxemic rats

1995 ◽  
Vol 269 (3) ◽  
pp. G427-G434 ◽  
Author(s):  
H. Roelofsen ◽  
B. Schoemaker ◽  
C. Bakker ◽  
R. Ottenhoff ◽  
P. L. Jansen ◽  
...  
Keyword(s):  
Organic Anion ◽  
Liver Perfusion ◽  
Isolated Hepatocytes ◽  
Anion Transport ◽  
Organic Anion Transport ◽  
Transport Activity ◽  
Efflux Rate ◽  
And Control ◽  
Dose Dependent ◽  
Isolated Liver

To investigate the mechanism of sepsis-associated hyperbilirubinemia we have studied hepatocanalicular transport of organic anions in a rat model of endotoxemia. Rats were injected intravenously with lipopolysaccharides (LPS), and at different times after injection, canalicular transport of 2,4-dinitrophenyl-S-glutathione (GS-DNP), as a model organic anion, was measured in perfused livers and isolated hepatocytes. In isolated liver perfusion experiments the initial biliary GS-DNP secretion rate was found to be significantly decreased 18 h after injection with 2 mg/kg LPS. In isolated hepatocytes from these rats, GS-DNP efflux rate was also significantly decreased (193.0 +/- 67 and 448.3 +/- 53 nmol.min-1.g dry wt-1 in endotoxemic and normal hepatocytes, respectively). Inhibition of GS-DNP effluxin isolated endotoxemic hepatocytes was dose dependent and reached a maximum with 0.25 mg/kg LPS. Inhibition was maximal at 12 h after LPS injection. Transport activity gradually returned to normal in 4-5 days after endotoxemia was induced. Dexamethasone pretreatment partially reversed the inhibition of GS-DNP transport in isolated endotoxemic hepatocytes. The phorbol ester phorbol 12-myristate 13-acetate increased GS-DNP efflux by 73 +/- 16 and 24 +/- 8% in endotoxemic and control hepatocytes, respectively, but could not restore the transport activity of endotoxemic hepatocytes to control levels. These results show that canalicular organic anion transport is decreased in the endotoxemic liver; this may play a role in the frequently observed hyperbilirubinemia during sepsis.

scholarly journals Characteristics of bile salt uptake into skate hepatocytes

1994 ◽  
Vol 299 (3) ◽  
pp. 665-670 ◽  
Author(s):  
G Fricker ◽  
V Dubost ◽  
K Finsterwald ◽  
J L Boyer
Keyword(s):  
Substrate Specificity ◽  
Bile Salt ◽  
Transport System ◽  
Bile Salts ◽  
Organic Anion ◽  
Anion Transport ◽  
Organic Anion Transport ◽  
Salt Uptake ◽  
Anion Transport System ◽  
Alpha 7

The substrate specificity for the transporter that mediates the hepatic uptake of organic anions in freshly isolated hepatocytes of the elasmobranch little skate (Raja erinacea) was determined for bile salts and bile alcohols. The Na(+)-independent transport system exhibits a substrate specificity, which is different from the specificity of Na(+)-dependent bile salt transport in mammals. Unconjugated and conjugated di- and tri-hydroxylated bile salts inhibit uptake of cholyltaurine and cholate competitively. Inhibition is significantly greater with unconjugated as opposed to glycine- or taurine-conjugated bile salts. However, the number of hydroxyl groups in the steroid moiety of the bile salts has only minor influences on the inhibition by the unconjugated bile salts. Since the transport system seems to represent an archaic organic-anion transport system, other anions, such as dicarboxylates, amino acids and sulphate, were also tested, but had no inhibitory effect on bile salt uptake. To clarify whether bile alcohols, the physiological solutes in skate bile, share this transport system, cholyltaurine transport was studied after addition of 5 beta-cholestane-3 beta,5 alpha,6 beta-triol, 5 alpha-cholestan-3 beta-ol and 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha-triol. These bile alcohols inhibit cholyltaurine uptake non-competitively. In contrast, uptake of 5 beta-cholestane-3 alpha,7 alpha,12 alpha-triol, which is Na(+)-independent, is not inhibited by cholyltaurine. The findings further characterize a Na(+)-independent organic-anion transport system in skate liver cells, which is not shared by bile alcohols and has preference for unconjugated lipophilic bile salts.

scholarly journals Preference of Proteomonas Sulcata Anion Channelrhodopsin for Nitrate Revealed Using a pH Electrode Method

2021 ◽  
Author(s):  
Chihiro Kikuchi ◽  
Hina Kurane ◽  
Takuma Watanabe ◽  
Makoto Demura ◽  
Takashi Kikukawa ◽  
...  
Keyword(s):  
Transmembrane Helix ◽  
Anion Transport ◽  
Yeast Cells ◽  
Ion Pump ◽  
Transport Activity ◽  
Electrode Method ◽  
Anion Transport Activity ◽  
Living Organisms ◽  
Stable Forms ◽  
Ph Electrode

Abstract Ion channel proteins are physiologically important molecules in living organisms. Their molecular functions have been investigated using electrophysiological methods, which enable quantitative, precise and advanced measurements and thus require complex instruments and experienced operators. For simpler and easier measurements, we measured the anion transport activity of light-gated anion channelrhodopsins (ACRs) using a pH electrode method, which has already been established for ion pump rhodopsins. Using that method, we successfully measured the anion transport activity and its dependence on the wavelength of light, i.e. its action spectra, and on the anion species, i.e. its selectivity or preference, of several ACRs expressed in yeast cells. In addition, we identified the strong anion transport activity and the preference for NO3- of an ACR from a marine cryptophyte algae Proteomonas sulcata, named PsuACR_353. Such a preference was discovered for the first time in microbial pump- or channel-type rhodopsins. Nitrate is one of the most stable forms of nitrogen and is used as a nitrogen source by most organisms including plants. Therefore, PsuACR_353 may play a role in NO3- transport and might take part in NO3--related cellular functions in nature. Measurements of a mutant protein revealed that a Thr residue in the 3rd transmembrane helix, which corresponds to Cys102 in GtACR1, contributed to the preference for NO3-. These findings will be helpful to understand the mechanisms of anion transport, selectivity and preference of PsuACR_353.

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