Xenobiotic transporter that may play an important role in the exclusion of xenobiotics from the brain. May be involved in brain-to-blood efflux. Appears to play a major role in the multidrug resistance phenotype of several cancer cell lines. When overexpressed, the transfected cells become resistant to mitoxantrone, daunorubicin and doxorubicin, display diminished intracellular accumulation of daunorubicin, and manifest an ATP-dependent increase in the efflux of rhodamine 123.
Delivery of drugs to the brain is impeded by the activity of efflux pumps expressed by endothelial cells of brain vasculature. The ATP binding cassette (ABC) transporters, among which ABCB1/MDR1 P-glycoprotein and ABCC1/multidrug resistance-associated protein 1 are expressed in brain endothelial cells, participate in drug efflux properties of the blood-brain barrier (BBB). Searches of the EST (expressed sequence tags) database with the conserved ABC domain, conducted to identify other ABC transporters expressed in the BBB, recovered 15 ABC transporter sequences expressed in human brain cDNA libraries. One of these sequences, identical to ABCG2, was highly expressed in cultured human cerebromicrovascular endothelial cells and human brain tissue at both mRNA and protein levels. Overexpression of human ABCG2 in immortalized rat brain endothelial cells resulted in enhanced polarized abluminal to luminal transport of various substrates tested in the in vitro BBB model. Brain vessels extracted from tissue sections of nonmalignant human brain and glioblastoma tumors by laser capture microdissection microscopy and analyzed by real-time polymerase chain reaction showed higher expression of ABCG2 relative to ABCB1/MDR1 and ABCC1/MRP1. ABCG2 was up-regulated in both glioblastoma vessels and parenchymal tissue. These studies suggest a role for brain endothelial ABCG2 transporter in modulating drug delivery to the brain and in conferring drug resistance to glioblastomas.
We characterized a new human ATP-binding cassette (ABC) transporter gene that is highly expressed in the placenta. The gene, ABCP, produces two transcripts that differ at the 5' end and encode the same 655-amino acid protein. The predicted protein is closely related to the Drosophila white and yeast ADP1 genes and is a member of a subfamily that includes several multidrug resistance transporters. ABCP, white, and ADP1 all have a single ATP-binding domain at the NH2 terminus and a single COOH-terminal set of transmembrane segments. ABCP maps to human chromosome 4q22, between the markers D4S2462 and D4S1557, and the murine gene (Abcp) is located on chromosome 6 28-29 cM from the centromere. ABCP defines a new syntenic segment between human chromosome 4 and mouse chromosome 6. The abundant expression of this gene in the placenta suggests that the protein product has an important role in transport of specific molecule(s) into or out of this tissue.
Interacting selectively and non-covalently with any protein or protein complex (a complex of two or more proteins that may include other nonprotein molecules).
Evidence
1:
Inferred from Physical InteractionIntAct
We previously showed that the 44-kDa serine/threonine kinase Pim-1 (Pim-1L) can protect prostate cancer cells from apoptosis induced by chemotherapeutic drugs (Xie, Y., Xu, K., Dai, B., Guo, Z., Jiang, T., Chen, H., and Qiu, Y. (2006) Oncogene 25, 70-78). To further explore the mechanisms of Pim-1L-mediated resistance to chemotherapeutic drugs in prostate cancer cells, we employed a yeast two-hybrid screening to identify cellular proteins that were associated with Pim-1L, and we found the ABC transporter BCRP/ABCG2 as one of the potential interacting partners of Pim-1L. We also showed that the expression level of Pim-1L and BCRP was up-regulated in mitoxantrone and docetaxel-resistant prostate cancer cell lines. Pim-1L was co-localized with BCRP on the plasma membrane and induced phosphorylation of BCRP at threonine 362. Knocking-down Pim-1L expression in the drug-resistant prostate cancer cells abolished multimer formation of endogenous BCRP and resensitized the resistant cells to chemotherapeutic drugs suggesting that BCRP phosphorylation induced by Pim-1L was essential for its functionality. This is further corroborated by our finding that the plasma membrane localization and drug-resistant activity of BCRP were compromised by T362A mutation. Our data suggest that Pim-1L may protect prostate cancer cells from apoptosis, at least in part, through regulation of transmembrane drug efflux pump. These findings may provide a potential therapeutic approach by disrupting Pim-1 signaling to reverse BCRP-mediated multidrug resistance.
The ATP-binding cassette transporter ABCG1 mediates the transport of excess cholesterol from macrophages and other cell types to high density lipoprotein (HDL) but not to lipid-depleted apolipoprotein AI. Several splice variants which may have different functions have been identified in mammals. In the current study, we characterized the human splice variant ABCG1(666), which differs from full-length ABCG1(678) by absence of an internal segment of 12 amino acids (VKQTKRLKGLRK). Accordingly spliced ABCG1 transcripts were detected in macrophages and liver in approximately twofold higher amounts than the alternatively spliced ABCG1 form encoding full-length ABCG1. We used transient and stable expression of ABCG1(666) fusion proteins to characterize glycosylation, subcellular localization, molecular interaction and functions of this ABCG1 variant. It could be demonstrated that ABCG1(666) is located at the cell surface and has the ability to form cholesterol transport competent homodimers which affect cellular cholesterol export in a similar manner as previously characterized forms of ABCG1. Our results support that ABCG1(666) may in fact be the most prominent form of functional ABCG1 expressed in the human.
We characterized a new human ATP-binding cassette (ABC) transporter gene that is highly expressed in the placenta. The gene, ABCP, produces two transcripts that differ at the 5' end and encode the same 655-amino acid protein. The predicted protein is closely related to the Drosophila white and yeast ADP1 genes and is a member of a subfamily that includes several multidrug resistance transporters. ABCP, white, and ADP1 all have a single ATP-binding domain at the NH2 terminus and a single COOH-terminal set of transmembrane segments. ABCP maps to human chromosome 4q22, between the markers D4S2462 and D4S1557, and the murine gene (Abcp) is located on chromosome 6 28-29 cM from the centromere. ABCP defines a new syntenic segment between human chromosome 4 and mouse chromosome 6. The abundant expression of this gene in the placenta suggests that the protein product has an important role in transport of specific molecule(s) into or out of this tissue.
Proc. Natl. Acad. Sci. U.S.A. 95, 15665-15670 (1998)[PubMed:9861027]
MCF-7/AdrVp is a multidrug-resistant human breast cancer subline that displays an ATP-dependent reduction in the intracellular accumulation of anthracycline anticancer drugs in the absence of overexpression of known multidrug resistance transporters such as P glycoprotein or the multidrug resistance protein. RNA fingerprinting led to the identification of a 2.4-kb mRNA that is overexpressed in MCF-7/AdrVp cells relative to parental MCF-7 cells. The mRNA encodes a 655-aa [corrected] member of the ATP-binding cassette superfamily of transporters that we term breast cancer resistance protein (BCRP). Enforced expression of the full-length BCRP cDNA in MCF-7 breast cancer cells confers resistance to mitoxantrone, doxorubicin, and daunorubicin, reduces daunorubicin accumulation and retention, and causes an ATP-dependent enhancement of the efflux of rhodamine 123 in the cloned transfected cells. BCRP is a xenobiotic transporter that appears to play a major role in the multidrug resistance phenotype of MCF-7/AdrVp human breast cancer cells.
Proc. Natl. Acad. Sci. U.S.A. 95, 15665-15670 (1998)[PubMed:9861027]
MCF-7/AdrVp is a multidrug-resistant human breast cancer subline that displays an ATP-dependent reduction in the intracellular accumulation of anthracycline anticancer drugs in the absence of overexpression of known multidrug resistance transporters such as P glycoprotein or the multidrug resistance protein. RNA fingerprinting led to the identification of a 2.4-kb mRNA that is overexpressed in MCF-7/AdrVp cells relative to parental MCF-7 cells. The mRNA encodes a 655-aa [corrected] member of the ATP-binding cassette superfamily of transporters that we term breast cancer resistance protein (BCRP). Enforced expression of the full-length BCRP cDNA in MCF-7 breast cancer cells confers resistance to mitoxantrone, doxorubicin, and daunorubicin, reduces daunorubicin accumulation and retention, and causes an ATP-dependent enhancement of the efflux of rhodamine 123 in the cloned transfected cells. BCRP is a xenobiotic transporter that appears to play a major role in the multidrug resistance phenotype of MCF-7/AdrVp human breast cancer cells.
Any process that results in a change in state or activity of a cell or an organism (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of a drug stimulus. A drug is a substance used in the diagnosis, treatment or prevention of a disease.
Proc. Natl. Acad. Sci. U.S.A. 95, 15665-15670 (1998)[PubMed:9861027]
MCF-7/AdrVp is a multidrug-resistant human breast cancer subline that displays an ATP-dependent reduction in the intracellular accumulation of anthracycline anticancer drugs in the absence of overexpression of known multidrug resistance transporters such as P glycoprotein or the multidrug resistance protein. RNA fingerprinting led to the identification of a 2.4-kb mRNA that is overexpressed in MCF-7/AdrVp cells relative to parental MCF-7 cells. The mRNA encodes a 655-aa [corrected] member of the ATP-binding cassette superfamily of transporters that we term breast cancer resistance protein (BCRP). Enforced expression of the full-length BCRP cDNA in MCF-7 breast cancer cells confers resistance to mitoxantrone, doxorubicin, and daunorubicin, reduces daunorubicin accumulation and retention, and causes an ATP-dependent enhancement of the efflux of rhodamine 123 in the cloned transfected cells. BCRP is a xenobiotic transporter that appears to play a major role in the multidrug resistance phenotype of MCF-7/AdrVp human breast cancer cells.
The directed movement of substances (such as macromolecules, small molecules, ions) into, out of or within a cell, or between cells, or within a multicellular organism by means of some agent such as a transporter or pore.
We characterized a new human ATP-binding cassette (ABC) transporter gene that is highly expressed in the placenta. The gene, ABCP, produces two transcripts that differ at the 5' end and encode the same 655-amino acid protein. The predicted protein is closely related to the Drosophila white and yeast ADP1 genes and is a member of a subfamily that includes several multidrug resistance transporters. ABCP, white, and ADP1 all have a single ATP-binding domain at the NH2 terminus and a single COOH-terminal set of transmembrane segments. ABCP maps to human chromosome 4q22, between the markers D4S2462 and D4S1557, and the murine gene (Abcp) is located on chromosome 6 28-29 cM from the centromere. ABCP defines a new syntenic segment between human chromosome 4 and mouse chromosome 6. The abundant expression of this gene in the placenta suggests that the protein product has an important role in transport of specific molecule(s) into or out of this tissue.
The chemical reactions and pathways involving urate, the anion of uric acid, 2,6,8-trioxypurine, the end product of purine metabolism in certain mammals and the main excretory product in uricotelic animals.
Evidence
1:
Inferred from Mutant PhenotypeUniProtKB
BACKGROUND: High serum uric acid levels are associated with gout, atherosclerosis and cardiovascular disease. Three genes (SLC2A9, ABCG2, and SLC17A3) were reported to be involved in the regulation of uric acid levels. RESEARCH: Design and Methods: SNPs rs2231142 (ABCG2) and rs1165205 (SLC17A3) were genotyped in three cohorts (n=4492) and combined with previously genotyped SNPs within SLC2A9 (rs6855911, rs7442295, rs6449213, rs12510549). RESULTS: Each copy of the minor allele decreased uric acid levels by 0.30-0.38 mg/dL for SLC2A9 (p values: 10(-20)-10(-36)) and increased levels by 0.34 mg/dL for ABCG2 (p=1.1x10(-16)). SLC17A3 influenced uric acid levels only modestly. Together the SNPs showed graded associations with uric acid levels of 0.111 mg/dL per risk allele (p=3.8x10(-42)). In addition, we observed a sex-specific interaction of age with the association of SLC2A9 SNPs with uric acid levels, where increasing age strengthened the association of SNPs in women and decreased the association in men. CONCLUSIONS: Genetic variants within SLC2A9,ABCG2 and SLC17A3 show highly significant associations with uric acid levels, and for SNPs within SLC2A9 this association is strongly modified by age and sex.
Evidence
2:
Inferred from Mutant PhenotypeUniProtKB
BACKGROUND: Hyperuricaemia, a highly heritable trait, is a key risk factor for gout. We aimed to identify novel genes associated with serum uric acid concentration and gout. METHODS: Genome-wide association studies were done for serum uric acid in 7699 participants in the Framingham cohort and in 4148 participants in the Rotterdam cohort. Genome-wide significant single nucleotide polymorphisms (SNPs) were replicated in white (n=11 024) and black (n=3843) individuals who took part in the study of Atherosclerosis Risk in Communities (ARIC). The SNPs that reached genome-wide significant association with uric acid in either the Framingham cohort (p<5.0 x 10(-8)) or the Rotterdam cohort (p<1.0 x 10(-7)) were evaluated with gout. The results obtained in white participants were combined using meta-analysis. FINDINGS: Three loci in the Framingham cohort and two in the Rotterdam cohort showed genome-wide association with uric acid. Top SNPs in each locus were: missense rs16890979 in SLC2A9 (p=7.0 x 10(-168) and 2.9 x 10(-18) for white and black participants, respectively); missense rs2231142 in ABCG2 (p=2.5 x 10(-60) and 9.8 x 10(-4)), and rs1165205 in SLC17A3 (p=3.3 x 10(-26) and 0.33). All SNPs were direction-consistent with gout in white participants: rs16890979 (OR 0.59 per T allele, 95% CI 0.52-0.68, p=7.0 x 10(-14)), rs2231142 (1.74, 1.51-1.99, p=3.3 x 10(-15)), and rs1165205 (0.85, 0.77-0.94, p=0.002). In black participants of the ARIC study, rs2231142 was direction-consistent with gout (1.71, 1.06-2.77, p=0.028). An additive genetic risk score of high-risk alleles at the three loci showed graded associations with uric acid (272-351 mumol/L in the Framingham cohort, 269-386 mumol/L in the Rotterdam cohort, and 303-426 mumol/L in white participants of the ARIC study) and gout (frequency 2-13% in the Framingham cohort, 2-8% in the Rotterdam cohort, and 1-18% in white participants in the ARIC study). INTERPRETATION: We identified three genetic loci associated with uric acid concentration and gout. A score based on genes with a putative role in renal urate handling showed a substantial risk for gout.
Elevated serum uric acid levels cause gout and are a risk factor for cardiovascular disease and diabetes. To investigate the polygenetic basis of serum uric acid levels, we conducted a meta-analysis of genome-wide association scans from 14 studies totalling 28,141 participants of European descent, resulting in identification of 954 SNPs distributed across nine loci that exceeded the threshold of genome-wide significance, five of which are novel. Overall, the common variants associated with serum uric acid levels fall in the following nine regions: SLC2A9 (p = 5.2x10(-201)), ABCG2 (p = 3.1x10(-26)), SLC17A1 (p = 3.0x10(-14)), SLC22A11 (p = 6.7x10(-14)), SLC22A12 (p = 2.0x10(-9)), SLC16A9 (p = 1.1x10(-8)), GCKR (p = 1.4x10(-9)), LRRC16A (p = 8.5x10(-9)), and near PDZK1 (p = 2.7x10(-9)). Identified variants were analyzed for gender differences. We found that the minor allele for rs734553 in SLC2A9 has greater influence in lowering uric acid levels in women and the minor allele of rs2231142 in ABCG2 elevates uric acid levels more strongly in men compared to women. To further characterize the identified variants, we analyzed their association with a panel of metabolites. rs12356193 within SLC16A9 was associated with DL-carnitine (p = 4.0x10(-26)) and propionyl-L-carnitine (p = 5.0x10(-8)) concentrations, which in turn were associated with serum UA levels (p = 1.4x10(-57) and p = 8.1x10(-54), respectively), forming a triangle between SNP, metabolites, and UA levels. Taken together, these associations highlight additional pathways that are important in the regulation of serum uric acid levels and point toward novel potential targets for pharmacological intervention to prevent or treat hyperuricemia. In addition, these findings strongly support the hypothesis that transport proteins are key in regulating serum uric acid levels.
Protein involved in the transport of a molecule (metabolite, protein, etc), a ion or an electron across cell membranes, inside the cell or in a tissue fluid.
A reference proteome is a set of protein sequences derived from a complete proteome which constitutes a defined standard for a particular user community. Reference proteomes are manually defined according to a number of criteria. They cover the proteomes of well- studied model organisms and other proteomes of interest for biomedical and biotechnological research. Reference proteomes have been selected to provide broad coverage of the tree of life, and constitute a representative cross-section of the taxonomic diversity to be found within UniProtKB.
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