• Molecules and Cells
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• v.45 no.8
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• pp.575-587
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• 2022

Human ABCB6 is an ATP-binding cassette transporter that regulates heme biosynthesis by translocating various porphyrins from the cytoplasm into the mitochondria. Here we report the cryo-electron microscopy (cryo-EM) structures of human ABCB6 with its substrates, coproporphyrin III (CPIII) and hemin, at 3.5 and 3.7 Å resolution, respectively. Metal-free porphyrin CPIII binds to ABCB6 within the central cavity, where its propionic acids form hydrogen bonds with the highly conserved Y550. The resulting structure has an overall fold similar to the inward-facing apo structure, but the two nucleotide-binding domains (NBDs) are slightly closer to each other. In contrast, when ABCB6 binds a metal-centered porphyrin hemin in complex with two glutathione molecules (1 hemin: 2 glutathione), the two NBDs end up much closer together, aligning them to bind and hydrolyze ATP more efficiently. In our structures, a glycine-rich and highly flexible "bulge" loop on TM helix 7 undergoes significant conformational changes associated with substrate binding. Our findings suggest that ABCB6 utilizes at least two distinct mechanisms to fine-tune substrate specificity and transport efficiency.

• The Korean Journal of Physiology and Pharmacology
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• v.17 no.6
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• pp.525-530
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• 2013

Multidrug resistance 3 (MDR3) is expressed on the canalicular membrane of the hepatocytes and plays an important role in protecting the liver from bile acids. Altered ABCB4 gene expression can lead to a rare hepatic disease, low phospholipid-associated cholelithiasis (LPAC). In this study, we characterized 3 ABCB4 mutations in LPAC patients using various in vitro assay systems. We first measured the ability of each mutant to transport paclitaxel and then the mechanisms by which these mutations might change MDR3 transport activity were determined using immunoblotting, cell surface protein biotinylation, and immunofluorescence. Through a membrane vesicular transport assay, we observed that the uptake of paclitaxel was significantly reduced in membrane vesicles expressing 2 ABCB4 mutations, F165I and S320F. Both mutants showed significantly decreased total and cell surface MDR3 expression. These data suggest two missense mutations of ABCB4 may alter function of MDR3 and ultimately can be determined as LPAC-causing mutations.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.22 no.2
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• pp.201-206
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• 2019

Benign recurrent intrahepatic cholestasis (BRIC), a rare cause of cholestasis, is characterized by recurrent episodes of cholestasis without permanent liver damage. BRIC type 2 (BRIC2) is an autosomal recessive disorder caused by ABCB11 mutations. A 6-year-old girl had recurrent episodes of jaundice. At two months of age, jaundice and hepatosplenomegaly developed. Liver function tests showed cholestatic hepatitis. A liver biopsy revealed diffuse giant cell transformation, bile duct paucity, intracytoplasmic cholestasis, and periportal fibrosis. An ABCB11 gene study revealed novel compound heterozygous mutations, including c.2075+3A>G in IVS17 and p.R1221K. Liver function test results were normal at 12 months of age. At six years of age, steatorrhea, jaundice, and pruritus developed. Liver function tests improved following administration of phenylbutyrate and rifampicin. Her younger brother developed jaundice at two months of age and his genetic tests revealed the same mutations as his sister. This is the first report of BRIC2 confirmed by ABCB11 mutations in Korean siblings.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.23 no.6
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• pp.558-566
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• 2020

Purpose: Progressive familial intrahepatic cholestasis (PFIC) is a rare genetic autosomal recessive disease caused by mutations in ATP8B1, ABCB11 or ABCB4. Mutational analysis of these genes is a reliable approach to identify the disorder. Methods: We collected and analyzed relevant data related to clinical diagnosis, biological investigation, and molecular determination in nine children carrying these gene mutations, who were from unrelated families in South China. Results: Of the nine patients (five males, four females) with PFIC, one case of PFIC1, four cases of PFIC2, and four cases of PFIC3 were diagnosed. Except in patient no. 8, jaundice and severe pruritus were the major clinical signs in all forms. γ-glutamyl transpeptidase was low in patients with PFIC1/PFIC2, and remained mildly elevated in patients with PFIC3. We identified 15 different mutations, including nine novel mutations (p.R470HfsX8, p.Q794X and p.I1170T of ABCB11 gene mutations, p.G319R, p.A1047P, p.G1074R, p.T830NfsX11, p.A1047PfsX8 and p.N1048TfsX of ABCB4 gene mutations) and six known mutations (p.G446R and p.F529del of ATP8B1 gene mutations, p.A588V, p.G1004D and p.R1057X of ABCB11 gene mutations, p.P479L of ABCB4 gene mutations). The results showed that compared with other regions, these three types of PFIC genes had different mutational spectrum in China. Conclusion: The study expands the genotypic spectrum of PFIC. We identified nine novel mutations of PFIC and our findings could help in the diagnosis and treatment of this disease.

• 대한임상약리학회:학술대회논문집
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• 2005.12a
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• pp.6-6
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• 2005

• Archives of Pharmacal Research
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• v.29 no.12
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• pp.1132-1139
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• 2006

Single nucleotide polymorph isms (SNPs) in the MDR1 gene that are responsible for drug efflux can cause toxicity. Therefore, this study determined the SNPs of the Korean MDR1 gene, and analyzed the haplotypes and a linkage disequilibrium (LD) of the SNPs determined. The frequency of 9 SNPs from the MDR1 gene was determined by PCR-RFLP analyses of 100 to 500 healthy individuals. The frequcies of the SNPs were C3435T (47.7%), G2677T (37.6%), G2677A (4.4%), T1236C (21.7%), T129C (8%), A2956G (2.5%), T307C (1.5%), A41aG (9.2%), C145G (0%), and G4030C (0%). Analyses of the haplotype structure and an estimation of the LD of the combined polymorph isms demonstrated that the frequency of the 1236T-2677G-3435T haplotype is much higher in Koreans (14.1%) than in Chinese and western black Africans and the C3435T SNP in Koreans appears to have LD with T129C in Koreans for the first time. These results provide insight into the genetic variation of MDR1 in Koreans, and demonstrated the possibility of a new LD in this gene.

• Journal of Life Science
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• v.32 no.9
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• pp.712-720
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• 2022

The purpose of this study was to investigate the efficacy of rat corneal-derived epithelial cells as an in vitro model to evaluate the harmfulness of the cornea caused by particulate matter 2.5 (PM_2.5). To establish an experimental model for the effect of PM_2.5 on corneal epithelial cells, it was confirmed that primary cultured cells isolated from rat eyes were corneal epithelial cells through pan-cytokeratin staining. Our results showed that PM_2.5 treatment reduced cell viability of primary rat corneal epithelial (RCE) cells, which was associated with the induction of apoptosis. PM_2.5 treatment also increased the generation of reactive oxygen species due to mitochondrial dysfunction. In addition, the production of nitric oxide and inflammatory cytokines was increased in PM_2.5-treated RCE cells. Furthermore, through heatmap analysis showing various expression profiling between PM_2.5-exposed and unexposed RCE cells, we proposed five genes, including BLNK, IL-1RA, Itga2b, ABCb1a and Ptgs2, as potential targets for clinical treatment of PM-related ocular diseases. These findings indicate that the primary RCE cell line is a useful in vitro model system for the study of PM_2.5-mediated pathological mechanisms and that PM2.5-induced oxidative and inflammatory responses are key factors in PM2.5-induced ocular surface disorders.

• Journal of Physiology & Pathology in Korean Medicine
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• v.38 no.1
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• pp.22-26
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• 2024

The purpose of this study was to identify the applicability, main compounds, and target genes of Cnidii Fructus (CF) in the treatment of gastritis using network pharmacology. The compounds in CF were searched in Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP) and a database of medicinal materials and chemical compounds in Northeast Asian traditional medicine (TM-MC). The target gene information of the compounds was collected from pubchem and cross-compared with the gastritis-related target gene information collected from Genecard to derive the target genes. Gene ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were performed on the derived target genes. Afterwards, network analysis between compounds and disease target genes was performed using cytoscape. We identified 121 active compounds and 139 target genes associated with gastritis. Pathways derived from the GO biological process and KEGG pathway DB primarily focus on target genes related to inflammation (IL-6, IL-8, TNF production, NF-κB transcription factor activity, and NF-κB signaling pathway) and cell death (PI3K-Akt, FoxO). Major targets for CF treatment of gastritis include TP53, TNF, BCL2, EGFR, NFKB1, ABCB1, PPARG, PTGS2, IL6, IL1B, and SOD1, along with major compounds such as coumarin, osthol, hexadecanoic acid, oleic acid, linoleic acid, and stigmasterol. This study provided CF's applicability for gastritis, related compounds, and target information. Evaluating CF's effectiveness in a preclinical gastritis model suggests its potential use in clinical practice for digestive system diseases.

• Journal of Veterinary Science
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• v.22 no.1
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• pp.4.1-4.13
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• 2021

Background: Microsporum canis is a zoonotic disease that can cause dermatophytosis in animals and humans. Objectives: In clinical practice, ketoconazole (KTZ) and other imidazole drugs are commonly used to treat M. canis infection, but its molecular mechanism is not completely understood. The antifungal mechanism of KTZ needs to be studied in detail. Methods: In this study, one strain of fungi was isolated from a canine suffering with clinical dermatosis and confirmed as M. canis by morphological observation and sequencing analysis. The clinically isolated M. canis was treated with KTZ and transcriptome sequencing was performed to identify differentially expressed genes in M. canis exposed to KTZ compared with those unexposed thereto. Results: At half-inhibitory concentration (½MIC), compared with the control group, 453 genes were significantly up-regulated and 326 genes were significantly down-regulated (p < 0.05). Quantitative reverse transcription polymerase chain reaction analysis verified the transcriptome results of RNA sequencing. Gene ontology enrichment analysis and Kyoto Encyclopedia of Genes and Genomes enrichment analysis revealed that the 3 pathways of RNA polymerase, steroid biosynthesis, and ribosome biogenesis in eukaryotes are closely related to the antifungal mechanism of KTZ. Conclusions: The results indicated that KTZ may change cell membrane permeability, destroy the cell wall, and inhibit mitosis and transcriptional regulation through CYP51, SQL, ERG6, ATM, ABCB1, SC, KER33, RPA1, and RNP genes in the 3 pathways. This study provides a new theoretical basis for the effective control of M. canis infection and the effect of KTZ on fungi.