ABCMdb

ABCC1 p.Cys265Ser

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Publications

PMID: 19200005 [PubMed] Porcelli L et al: "Intracellular trafficking of MDR transporters and relevance of SNPs."

No. Sentence Comment

241 In particular, the cell lines expressing the variants Cys43Ser-ABCC1, Cys 265Ala-ABCC1 and Cys265Ser-ABCC1 exhibited severely disrupted plasma membrane trafficking [116]. Login to comment

PMID: 12731862 [PubMed] Leslie EM et al: "Functional and structural consequences of cysteine substitutions in the NH2 proximal region of the human multidrug resistance protein 1 (MRP1/ABCC1)."

No. Sentence Comment

54 Mutagenesis was performed according to the manufacturer`s instructions with the following sense mutagenic primers (substituted nucleotides are underlined and introduced or lost restriction sites are in italics) as follows: Cys43Ala (5'-G TGG GTG CCT GCT TTT TAC CTC TGG GCC-3'), Cys43Ser (5'-G TGG GTG CCT TCT TTT TAC CTC-3'), Cys49Ala (5'-C CTC TGG GCC GCA TTC CCC TTC TAC-3') (BsmI), Cys49Ser (5'-C CTC TGG GCC TCT TTC CCC TTC-3'), Cys85Ala (5'-G TGG ATC GTC GCG TGG GCA GAC C-3') (BstUI), Cys85Ser (5'-G TGG ATC GTC AGC TGG GCA GAC C-3'), Cys148Ala (5'-GTA GCC CTA GTG GCT GCC CTA GCC-3') (BglI), Cys148Ser (5'-GTA GCC CTA GTG TCT GCC CTA GCC-3'), Cys190Ala (5'-C GTC TTG TCC GCA TTC TCA GAT CGC-3') (BsmI), Cys190Ser (5'-C GTC TTG TCC TCT TTC TCA GAT CG-3'), Cys208Ala (5'-C CCT AAT CCC GCG CCA GAG TCC AG-3') (BstUI), Cys208Ser (5'-C CCT AAT CCC AGC CCA GAG TCC-3'), Cys265Ala (5'-GTA AAG AAC TGG AAG AAG GAA GCC GCG AAG ACT AGG AAG CAG-3') (BpiI), and Cys265Ser (5'- GG AAG AAG GAA TCC GCC AAG ACT AG-3') (BsmI). Login to comment
109 Thus, the cell lines expressing the TM1 mutant Cys43Ser-MRP1 (Figure 3D) and the CL3 mutants Cys265Ala-MRP1 (Figure 3O) and Cys265Ser-MRP1 (Figure 3P) exhibited severely disrupted plasma membrane trafficking. Login to comment
111 Three of the mutant cell lines with impaired plasma membrane trafficking of MRP1 exhibited filament-like staining (Cys43Ala, Cys43Ser, and Cys49Ser) (Figure 3C,D,F) while the cell lines expressing Cys265Ala and Cys265Ser MRP1 showed a stippled-like staining pattern. Login to comment
112 Finally, Cys265Ser expressing cells had a unique staining pattern, which was stippled and resembled vacuolar staining. Login to comment
130 Table 1: Detection of Tryptic Fragments N1 and N2 of MRP1 in Membranes Prepared from HeLa Cells Stably Expressing CysfAla and CysfSer MRP1 Mutantsa trypsin:protein ratio (w:w)transfected HeLa cell line N1 detected N2 detected WT-MRP1 1:10 000 1:1000 C43A-MRP1 1:100 1:100 C43S-MRP1 1:10 000 1:1000 C49A-MRP1 1:250 1:100 C49S-MRP1 1:10 000 1:500 C85A-MRP1 1:10 000 1:1000 C85S-MRP1 1:1000 1:250 C148A-MRP1 1:250 1:250 C148S-MRP1 1:1000 1:500 C190A-MRP1 1:1000 1:1000 C190S-MRP1 1:1000 1:250 C208A-MRP1 1:10 000 1:250 C208S-MRP1 1:10 000 1:500 C265A-MRP1 1:250 1:10 C265S-MRP1 1:1000 1:250 a The data shown represent a summary of the limited trypsin digests shown in Figures 4 and 5. Login to comment
132 Cys49Ser, Cys190Ala, Cys208Ala, and Cys208Ser also closely matched those of WT-MRP1 except that the N1 fragment did not appear until a trypsin:protein ratio of 1:1000 for Cys190Ala-MRP1 and the N2 fragments of Cys49Ser-MRP1, Cys208Ala-MRP1, and Cys208Ser-MRP1 did not appear until trypsin:protein ratios of 1:500, 1:250, and 1:500, respectively. The remaining CysfSer MRP1 mutants (Cys85Ser, Cys148Ser, Cys190Ser, and Cys265Ser) were more resistant to trypsinolysis than WT-MRP1 but less resistant than their respective Ala partners. Login to comment
133 For all four of these CysfSer mutants, the N1 tryptic fragment appeared at a trypsin:protein ratio of 1:1000 while the N2 fragment appeared at ratios of 1:500 for Cys148Ser and 1:250 for Cys85Ser, Cys190Ser, and Cys265Ser. Login to comment
151 In contrast, unlike Cys265Ala-MRP1, which showed increased activity, Cys265Ser-MRP1 exhibited LTC4 uptake activity similar to WT-MRP1. Login to comment
156 Consistent with their Ala-substituted counterparts, Cys49Ser-MRP1, Cys148Ser- MRP1, and Cys265Ser-MRP1 showed moderately reduced E217 G uptake (34-50%) while uptake by Cys43Ser-MRP1 was increased by 40% relative to WT-MRP1. Login to comment
177 Thus, the arsenite resistance of cells expressing the TM1 Cys43Ser mutant was 2.5-fold lower than the cell line expressing WT-MRP1 whereas cells expressing Cys265Ser MRP1 were approximately 3-fold more resistant to this heavy metal oxyanion (Table 2). Login to comment
178 Representative chemosensitivity assays illustrating the sodium arsenite resistance of cell lines expressing the Cys43Ser and Cys265Ser MRP1 mutants are shown in Figure 7. Login to comment
179 The HeLa cell lines expressing Cys43Ser-MRP1 and Cys265Ser-MRP1 that showed changes in arsenite resistance were also tested for their sensitivity to the anticancer drugs vincristine and doxorubicin. Login to comment
181 The Cys43Ala, Cys43Ser, Cys265Ala, and Cys265Ser MRP1 mutant expressing cell lines were 6.5-, 2.6-, 7.1-, and 5.1-fold resistant to doxorubicin, respectively, levels of resistance that did not differ significantly from the ~5-fold resistance observed with cells expressing WT-MRP1 (Figure 8A). Login to comment
182 In contrast, the cell line expressing Cys43Ser-MRP1 was only 5-fold resistant to vincristine while the cell lines expressing Cys43Ala, Cys265Ala, and Cys265Ser-MRP1 were 21-, 19-, and 13-fold resistant, respectively, levels of resistance comparable to those observed in cells expressing WT-MRP1 (15-fold resistant) (Figure 8B). Login to comment
192 Table 2: Sensitivity of Stably Transfected HeLa Cells Expressing Wild-Type and Cys-Substituted MRP1 to Sodium Arsenite and Potassium Antimony Tartrate relative resistancea transfected HeLa cell line Na+ arsenite K+ antimony tartrate WT-MRP1 3.6 ( 1.3 (1) (n ) 6) 2.0 ( 0.5 (1) (n ) 7) C43A-MRP1 4.3 ( 0.7 (1.2) (n ) 3) 2.0 ( 0.4 (1) (n ) 3) C43S-MRP1 1.4 ( 0.5 (0.4)b (n ) 6) 2.8 ( 1.1 (1.4) (n ) 4) C49A-MRP1 4.0 ( 1.6 (1.1) (n ) 5) 2.6 ( 0.7 (1.3) (n ) 4) C49S-MRP1 3.0 ( 1.5 (0.8) (n ) 4) 3.0 ( 0.6 (1.5) (n ) 4) C190A-MRP1 3.8 ( 0.4 (1) (n ) 4) 4.0 ( 1.2 (2) (n ) 3) C190S-MRP1 2.9 ( 0.4 (0.8) (n ) 4) 2.7 ( 0.4 (1.4) (n ) 3) C208A-MRP1 3.0 ( 0.6 (0.8) (n ) 3) 2.4 ( 0.6 (1.2) (n ) 3) C208S-MRP1 4.2 ( 0.8 (1.2) (n ) 3) 3.8 ( 0.7 (1.9) (n ) 3) C265A-MRP1 2.5 ( 0.2 (0.7) (n ) 4) 2.3 ( 0.6 (0.9) (n ) 3) C265S-MRP1 10.2 ( 0.4 (2.8)b (n ) 5) 4.0 ( 1.7 (2) (n ) 3) a The resistance of stably transfected HeLa cells was determined using a tetrazolium-based cytotoxicity assay. The relative resistance factors were obtained by dividing the IC50 values for wild-type or Cys mutant MRP1 transfected cells by the IC50 values for empty vector control transfected cells and were normalized for differences in MRP1 expression levels. Login to comment
197 In addition, several Cys mutants did not appear fully routed to the plasma membrane, with the most severely disrupted pattern of subcellular localization being observed with the TM1 mutant Cys43Ser and the CL3 mutants Cys265Ala and Cys265Ser. Login to comment
210 All Cys-substituted proteins were present to a certain extent in the plasma membrane of the FIGURE 7: Resistance of HeLa cells expressing Cys43Ser and Cys265Ser mutant MRP1 to sodium arsenite. Login to comment
211 HeLa cell lines stably transfected with the pcDNA3.1(-) vector (O), pcDNA3.1(-)- MRP1K (b), and (A) pcDNA3.1(-)C43S-MRP1K (9) or (B) pcDNA3.1(-)-C265S-MRP1K (9) were exposed to sodium arsenite for 72 h at 37 °C at the concentrations indicated, and then, cell viability was measured using a tetrazolium assay. The results shown are those of a typical experiment in which each data point represents the mean (SD of quadruplicate determinations. Login to comment
213 Data are not normalized for MRP1 expression; however, Cys265Ser-MRP1 and Cys43Ser-MRP1 were expressed at levels comparable to, and 1.5-fold higher than, WT-MRP1, respectively. Login to comment
214 Consequently, normalization of the data would not affect the relative resistance of Cys265Ser-MRP1 and would only further emphasize the decreased arsenite resistance of Cys43Ser-MRP1. Login to comment
237 In addition to their limited effects on organic anion transport function, the mutation of Cys residues in MSD1 and CL3 Cys had no effect on the ability of MRP1 to confer resistance to heavy metal-centered oxyanions with just two exceptions (Cys43Ser-MRP1 and Cys265Ser-MRP1). Login to comment
253 Thus, one possible explanation for the increased arsenite resistance of Cys265Ser-MRP1 is that arsenite could be forming a complex with the mutant protein that is not held with as high affinity as WT-MRP1. Login to comment
255 Another possible explanation is that substitution of Cys265 with Ser but not Ala results in a conformational change within CL3 that indirectly increases the efficiency with which arsenite interacts with the protein. Login to comment