Disease relevance of ABCG1

• We now show that ABCG1, which we identified by differential display RT-PCR in foamy macrophages, is overexpressed in macrophages from patients with Tangier disease compared to control macrophages [1].
• Using promoter-luciferase reporter assays in the myeloid cell lines THP-1 and RAW246.7 and the hepatoma cell line HepG2 we could demonstrate the functionality of the ABCG1 promoter and the minimal sequence requirements for gene expression [2].
• These studies clarify the mechanism of transcriptional upregulation of the ABCG1 gene by oxysterols in macrophages and liver, two key tissues where ABCG1 expression may affect cholesterol balance and atherogenesis [3].
• To elucidate the potential physiological role of ABCG1, we have initiated a series of studies overexpressing ABCG1, using an adenovirus vector (rABCG1-Adv) in C57BL mice [4].
• The human ATP-binding cassette superfamily G (White) member 2 (ABCG2) gene and its murine homologue breast cancer resistance protein 1 (Bcrp1) are recently described ATP-binding cassette transporters associated with drug resistance in tumor cell lines, including the MCF-7 cell line, selected for its resistance to mitoxantrone (MCF-7/MitoR) [5].

Psychiatry related information on ABCG1

• A single haplotype was shared by all affected individuals and informative crossovers indicated that the elusive gene that confers susceptibility to narcolepsy is likely to be located between markers D21S267 and ABCG1, in a 5.15 Mb region of 21q [6].
• Screening ABCG1, the human homologue of the Drosophila white gene, for polymorphisms and association with bipolar affective disorder [7].
• BACKGROUND: White-matter hyperintensities are commonly found on magnetic resonance imaging (MRI) of elderly people with or without dementia [8].
• SETTING: Weill-Cornell Medical Center, White Plains, NY; University of Minnesota, Minneapolis; and Stanford University, Stanford, Calif.Patients One hundred twenty-two patients meeting DSM-IV criteria for anorexia nervosa [9].
• However, a meta-analytic synthesis of 261 comparisons, based largely on self-esteem scales and involving more than half a million respondents, revealed higher scores for Black than for White children, adolescents, and young adults [10].

High impact information on ABCG1

• Human Multidrug Resistance ABCB and ABCG Transporters: Participation in a Chemoimmunity Defense System [11].
• Cord levels of C peptide in infants of diabetic mothers were elevated at the earliest gestational age studied (less than 34 weeks) and were directly related to the severity of maternal diabetes, as assessed by the White classification [12].
• Row over White House moves to ban fetal tissue research [13].
• Biotechnology regulation: White House holds the ring [14].
• A uranium-lead zircon age for a volcanic ash interstratified with fossil-bearing, shallow marine siliciclastic rocks in the Zimnie Gory section of the White Sea region indicates that a diverse assemblage of body and trace fossils occurred before 555.3 +/- 0.3 million years ago [15].

Chemical compound and disease context of ABCG1

• In this study, we performed detailed molecular analyses of a series of C. albicans isolates from an MT patient who developed disseminated candidiasis caused by an azole-resistant strain 2 weeks after initiation of fluconazole prophylaxis (K. A. Marr, T. C. White, J. A. H. vanBurik, and R. A. Bowden, Clin. Infect. Dis. 25:908-910, 1997) [16].
• Serum samples were collected from 20 healthy White and 33 Black infants before and after immunisation with three doses of diphtheria-pertussis-tetanus vaccine and with one dose of Haemophilus influenzae type b polyribose phosphate vaccine and meningococcal group A and group C polysaccharide vaccines [17].
• In an attempt to resolve this apparent disagreement, we exposed White Carneau pigeons to drinking water containing calcium (100 ppm), magnesium (30 ppm), lead (0.8 ppm), or cadmium (0.6 ppm) and used a 2(4)-factorial design to measure the effects of these elements in atherosclerosis and hypertension [18].
• The relationship of the increased urinary excretion of steroid hormones in Black South African men, a low-risk group fed a Western diet, and the decreased excretion in Black and White North American men, high-risk groups fed a vegetarian diet, to the development of prostatic cancer remains to be clarified [19].
• Human choriocarcinoma cells (JAR) synthesize the alpha and beta subunits of the glycoprotein hormone chorionic gonadotropin (hCG) (R.W. Ruddon, C.A. Hanson, A. H. Bryan, G.J. Putterman, E.L. White, F. Perini, K. S. Meade, and P.H. Aldenderfer (1980) J. Biol. Chem. 255, 1000-1007) [20].

Biological context of ABCG1

• Treatment of macrophages with an liver X receptor activator results in up-regulation of ABCG1 and increases cholesterol efflux to HDL [21].
• RNA interference reduced the expression of ABCG1 in liver X receptor-activated macrophages and caused a parallel decrease in cholesterol efflux to HDL [21].
• PURPOSE OF REVIEW: This review briefly discusses the ATP-binding cassette transporter G (ABCG) family members and emphasizes recent studies that identify ABCG1 as a key regulator of cellular lipid homeostasis [22].
• ZNF202m1 expression in HepG2 cells dose-dependently repressed the promotor activities of ABCA1 and ABCG1 [23].
• Role of ABCG1 and other ABCG family members in lipid metabolism [24].

Anatomical context of ABCG1

• Immunocytochemical and flow cytometric analyses revealed that ABCG1 is expressed on the cell surface and in intracellular compartments of cholesterol-laden macrophages [25].
• ABCG1, another LXR target gene involved in cholesterol efflux to HDL, also showed diminished expression in NPC1(-/-) fibroblasts and increased expression upon LXR agonist treatment [26].
• Treatment of Caco-2 cells with bile acids, which activate farnesoid X receptor and subsequently induce SHP, leads to the repression of the human ABCG1 gene, an established LXR target gene [27].
• To determine if such HDL reduction correlates with a change in ABCA1 or ABCG1 expression, their expressions were measured in THP-1 monocytes and mice treated with LPS [28].
• The ABCG1 gene is induced in endothelial cells by cholesterol, whereas ABCA1 is not [29].

Associations of ABCG1 with chemical compounds

• Inhibition of ABCG1 protein expression using an antisense strategy resulted in reduced HDL(3)-dependent efflux of cholesterol and choline-phospholipids [25].
• Bacterial lipopolysaccharide induces expression of ABCA1 but not ABCG1 via an LXR-independent pathway [28].
• The verapamil treatment resulted in rapid increase in ABCA1 protein and its mRNA, but not the ABCG1 mRNA, another target gene product of the nuclear receptor liver X receptor (LXR) [30].
• Actinomycin D prevented the increase in ABCA1 and ABCG1 mRNA levels and the increase in cholesterol efflux induced by the ligands [31].
• Regulation of gene expression of ATP-binding cassette transporter (ABC)A1 and ABCG1 by liver X receptor/retinoid X receptor (LXR/RXR) ligands was investigated in the human intestinal cell line CaCo-2 [31].

Physical interactions of ABCG1

• Our results demonstrating a regulator function for ABCG1 in cholesterol and phospholipid transport define a biologic activity for ABC transporters in macrophages [25].
• Peptides 147-154aa of La/SSB and 139-146aa of the MBP were attached on tetrameric sequential oligopeptide carriers and used for immunizations of New Zealand White rabbits [32].
• We studied pH-dependent conformational changes in alpha1-acid glycoprotein using both binding of cationic fluorescent probe Quinaldine Red with protein molecule and changes in distance between tryptophan from binding site of the protein and Calcofluor White on glycan surface using FRET [33].

Regulatory relationships of ABCG1

• HDL from CETP-deficient subjects shows enhanced ability to promote cholesterol efflux from macrophages in an apoE- and ABCG1-dependent pathway [34].
• Interestingly in this study, the linkage evidence on 11 p at the SUR locus was somewhat enhanced (lod score went up from 1.7 to 2.0) in a prehypertensive (BP >or= 135/80 mm Hg) subset of 40 White families suggesting a pleiotropic gene for BP and RHR with interactions [35].
• The prevalence of the homozygous IGF1 (CA)(19) genotype was much lower in Black controls (21%) than White controls (46%), which may, in part, explain the increased prostate cancer incidence in Black versus White men [36].
• We examined the prevalence and predictors of BRCA1 and BRCA2 mutations in 1,628 women with breast cancer and 674 women without breast cancer who participated in a multicenter population-based case-control study of Black and White women, 35 to 64 years of age [37].
• New Zealand White rabbits that received intra-articular injections of Ad.RSVIL-1ra expressed transgenic IL-1ra in synoviocytes, and secretion was detected for at least 4 weeks post-infection [38].

Other interactions of ABCG1

• These studies indicate that ABCG1 and ABCG4 promote cholesterol efflux from cells to HDL [21].
• We demonstrate here that the full-length ZNF202m1 isoform binds to GnT repeats within the promotors of ABCA1 (-229/-210) and ABCG1 (-572/-552) [23].
• Two other ABCG transporters, ABCG5 and ABCG8, mutations of which cause sitosterolemia, have been identified [39].
• Except for ABCG2, the members of the ABCG family play an important role in efflux transport of cholesterol [40].
• Upregulation of ABCA1, ABCG1, and apoE expression during monocyte differentiation and foam cell formation was accompanied by a simultaneous downregulation of both ZNF202 mRNA isoforms m1 and m3 [41].

Analytical, diagnostic and therapeutic context of ABCG1

• In addition, a combination of in situ hybridization and indirect immunofluorescence microscopy revealed that ABCG1 is expressed in foamy macrophages within the atherosclerotic plaque [1].
• On examination by confocal laser scanning microscopy, ABCG1 was present in perinuclear structures within the cell [1].
• We screened all 15 exons and 700 bases of the 5' flanking region of ABCG1 for mutations, using Denaturing High Performance Liquid Chromatography (DHPLC) [7].
• We performed a prospective cohort study among 184 unrelated White CH patients [42].
• Endometrial expression of SR-BI in White composite gilts (n = 3-4 each) was determined by Northern blotting on Days 10, 13, and 15 cyclic gilts and Days 10, 13, 15, 20, 30, and 40 pregnant gilts [43].

References