6-mercaptopurine and 9-(2-phosphonyl-methoxyethyl) adenine (PMEA) transport altered by two missense mutations in the drug transporter gene ABCC4

6533b824fe1ef96bd1280a22

RESEARCH PRODUCT

6-mercaptopurine and 9-(2-phosphonyl-methoxyethyl) adenine (PMEA) transport altered by two missense mutations in the drug transporter gene ABCC4

Alice Habermeier Peter Nürnberg Thomas Lang Ellen I. Closs Christine Fischer Mohammad R. Toliat Sherif Mehralivand Martin F. Fromm Ulrich M. Zanger Daniel Janke Ulrike Gradhand Peter Fritz Leszek Wojnowski Ute Gödtel-armbrust Dennis Strand Matthias Schwab

subject

Recombinant Fusion Proteins Green Fluorescent Proteins Mutation Missense Organophosphonates Xenopus ATP-binding cassette transporter ABCC4 Biology Green fluorescent protein Xenopus laevis Genetics Animals Humans Missense mutation Genetics (clinical)DNA Primers chemistry.chemical_classification Base Sequence Mercaptopurine Adenine Wild type biology.organism_classification Molecular biology Transmembrane protein Amino acid chemistry Biochemistry Mutagenesis Site-Directed biology.protein Multidrug Resistance-Associated Proteins

description

Multiple drug resistance protein 4 (MRP4, ABCC4) belongs to the C subfamily of the ATP-binding cassette (ABC) transporter superfamily and participates in the transport of diverse antiviral and chemotherapeutic agents such as 6-mercaptopurine (6-MP) and 9-(2-phosphonyl methoxyethyl) adenine (PMEA). We have undertaken a comprehensive functional characterization of protein variants of MRP4 found in Caucasians and other ethnicities. A total of 11 MRP4 missense genetic variants (nonsynonymous SNPs), fused to green fluorescent protein (GFP), were examined in Xenopus laevis oocytes for their effect on expression, localization, and function of the transporter. Radiolabeled 6-MP and PMEA were chosen as transport substrates. All MRP4 protein variants were found to be expressed predominantly in the oocyte membrane. A total of four variants (Y556C, E757 K, V776I, and T1142 M) exhibited a 20% to 40% reduced expression level compared to the wild type. Efflux studies showed that 6-MP is transported by MRP4 in unmodified form. Compared to wild-type MRP4, the transmembrane variant V776I, revealed a significant lower activity in 6-MP transport, while the amino acid exchange Y556C in the WalkerB motif displayed significantly higher transport of PMEA. The transport properties of the other variants were comparable to wild-type MRP4. Our study shows that Xenopus oocytes are well suited to characterize MRP4 and its protein variants. Carriers of the rare MRP4 variants Y556C and V776I may have altered disposition of MRP4 substrates. Hum Mutat 29(5), 659–669, 2008. © 2008 Wiley-Liss, Inc.

year	journal	country	edition	language
2008-02-27	Human Mutation

https://doi.org/10.1002/humu.20694