PubMed · 9263659
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1997. Membrane permeability.. https://doi.org/10.1016/s0955-0674(97)80038-5
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We sought to identify new susceptibility loci for Alzheimer's disease through a staged association study (GERAD+) and by testing suggestive loci reported by the Alzheimer's Disease Genetic Consortium (ADGC) in a companion paper. We undertook a combined analysis of four genome-wide association datasets (stage 1) and identified ten newly associated variants with P ≤ 1 × 10(-5). We tested these variants for association in an independent sample (stage 2). Three SNPs at two loci replicated and showed evidence for association in a further sample (stage 3). Meta-analyses of all data provided compelling evidence that ABCA7 (rs3764650, meta P = 4.5 × 10(-17); including ADGC data, meta P = 5.0 × 10(-21)) and the MS4A gene cluster (rs610932, meta P = 1.8 × 10(-14); including ADGC data, meta P = 1.2 × 10(-16)) are new Alzheimer's disease susceptibility loci. We also found independent evidence for association for three loci reported by the ADGC, which, when combined, showed genome-wide significance: CD2AP (GERAD+, P = 8.0 × 10(-4); including ADGC data, meta P = 8.6 × 10(-9)), CD33 (GERAD+, P = 2.2 × 10(-4); including ADGC data, meta P = 1.6 × 10(-9)) and EPHA1 (GERAD+, P = 3.4 × 10(-4); including ADGC data, meta P = 6.0 × 10(-10)).
The ATP-dependent transport of natural product drugs, e.g. vincristine, by multidrug resistance-associated protein (MRP1) requires reduced glutathione (GSH), whilst that of anionic substrates does not. The present results suggest, however, that GSH can modulate transport of anionic species. Efflux of fluorescent anionic substrates was measured from adherent MRP1-expressing human multidrug-resistant lung tumour cells, COR-L23/R, and drug-sensitive parental cells. As expected, much greater efflux of calcein, methylfluorescein-glutathione (GS-MF), and 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein (BCECF) was observed from the resistant cells. Unexpectedly, lowering GSH levels in COR-L23/R cells by inhibiting GSH synthesis with buthionine sulfoximine decreased efflux of calcein and of GS-MF (3-fold and 1.6-fold) but not efflux of BCECF. Transport of the anionic conjugate dinitrophenyl-glutathione ([(3)H]DNP-SG) was investigated by following its uptake into inside-out plasma membrane vesicles prepared from the MRP1-expressing cells. At least 90% of the ATP-dependent uptake was blockable by the anti-MRP1 antibody QCRL-3 and 100 microM vincristine inhibited uptake but only in the presence of 1--3 mM GSH, suggesting MRP1 to be the protein primarily responsible for this transport. Agents shown to reduce efflux of calcein from resistant cells, i.e. indomethacin, MK-571, and probenecid, also inhibited [(3)H]DNP-SG uptakes, consistent with MRP1 being responsible for export of calcein. At concentrations achievable within cells, GSSG (70 microM) inhibited uptake whereas GSH (1 and 3 mM) enhanced uptake. We suggest that variations in both GSH and GSSG levels within cells may affect MRP1-mediated anion transport.
The high affinity sulfonylurea receptor 1 (SUR1) is involved in the metabolism of glucose in pancreatic beta-cells. We investigated the impact of the SUR1 intron 16-3t-->c polymorphism on non-insulin-dependent diabetes mellitus (NIDDM) prevalence in a large representative sample of French men and women, 35-64 years old, and explored potential relationships between the SUR1 intron 16 -t-->c polymorphism and sulfonylurea therapy efficiency. This study took place in Lille (northern), Strasbourg (eastern), and Toulouse (southern France). One hundred and twenty-two subjects with NIDDM were registered. We stratified NIDDM subjects according to their medical treatment: sulfonylureas (n = 70) versus other treatments (n = 50). From the three populations, a control group was selected (n = 1,250). Subjects carrying the cc intron 16 genotype had an increased risk of NIDDM [odds ratio (OR) = 1.76, 95% confidence interval (CI) 1.10-2.80; P = 0.017]. Subjects bearing at least one -3c allele and treated with sulfonylurea agents had fasting plasma triglyceride concentrations 35% lower than subjects that were tt homozygous (P = 0.026), whereas no difference could be detected between genotypes in NIDDM subjects treated with other treatments. The SUR1 intron 16 -3t-->c polymorphism was associated with an increased susceptibility to NIDDM in this population study, and seems to modulate the sulfonylurea therapy efficiency on hypertriglyceridemia reduction. This observation may help to better target the various therapies available for treatment of NIDDM.