Monomethylarsenic Diglutathione Transport by the Human Multidrug Resistance Protein 1 (MRP1/ABCC1)

Abstract

ABSTRACT:The ATP-binding cassette (ABC) transporter protein multidrug resistance protein 1 (MRP1; ABCC1) plays an important role in the cellular efflux of the high-priority environmental carcinogen arsenic as a triglutathione

A Novel Pathway for Arsenic Elimination: Human Multidrug Resistance Protein 4 (MRP4/ABCC4) Mediates Cellular Export of Dimethylarsinic Acid (DMAV) and the Diglutathione Conjugate of Monomethylarsonous Acid (MMAIII)

“…Digested cells were diluted 1:1 with deionized distilled water and filtered through 0.45-mm syringe filters (Whatman, Toronto, ON, Canada). The total concentration of arsenic in samples was determined by inductively coupled plasma mass spectrometry (ICP-MS) (Agilent 7500; Yokogawa Analytical Systems, Hachioji, Japan) using the standard addition method as described previously (Kalivas, 1987;Carew et al, 2011). Samples were introduced directly into the nebulizer of the ICP-MS.…”

“…Cytotoxicity Testing. The cytotoxicity of six arsenic species was measured using HEK-V4, HEK-MRP3, HEK-MRP4-1E16, and HEK-MRP5 (G418 selected) or HEK-MCV and HEK-MRP4-MC4 (hygromycin selected) stable cell lines as previously described (Carew et al, 2011). Briefly, cells were seeded in 96-well plates at 1 Â 10 4 cells/well and grown for 24 hours.…”

“…MMA(GS) 2 was synthesized from MMA III and GSH as described previously (Kala et al, 2000;Carew et al, 2011). Briefly, MMA III (final concentration of 50 mM) was combined with GSH (final concentration of 75 mM) in degassed Trissucrose buffer and incubated under a nitrogen atmosphere for .30 minutes at 4°C.…”

“…Pelleted membrane vesicles were washed twice with 1 ml ice-cold Tris-sucrose buffer, then digested in 250 ml concentrated nitric acid for 48 hours, diluted 1:1 with deionized distilled water, and filtered with 0.45-mm syringe filters (Whatman). The total concentration of arsenic in each sample was determined by ICP-MS using the standard addition method as described previously (Kalivas, 1987;Carew et al, 2011). ATP-dependent transport was determined by subtracting transport in the presence of AMP from transport in the presence of ATP.…”

“…MRP1 (ABCC1) plays an important role in the cellular efflux of As(GS) 3 and MMA(GS) 2 (Leslie et al, 2004;Carew et al, 2011). In vivo studies of Mrp2 (Abcc2)-deficient (TR 2 ) Wistar rats show that Mrp2 is responsible for the biliary excretion of As(GS) 3 and MMA(GS) 2 (Kala et al, 2000).…”