Objectives: The multidrug resistance-associated protein 3/ATP-binding cassette transmembrane transporter subfamily C member 3 (MRP3/ABCC3) plays an important role in exporting endogenous and xenobiotic anionic substrates, including glucuronide conjugates of xenobiotics, from hepatocytes into the blood circulation. This excretory function of ABCC3 becomes very apparent particularly under cholestatic conditions, since ABCC3 is induced when the biliary excretion pathway is impaired. In this study, we analyzed the functional properties of 11 nonsynonymous single nucleotide polymorphisms (SNPs) in the ABCC3 gene found in the public SNP database.
Methods: HeLa and Sf9 insect cells were used to analyze the protein expression and transport function, respectively.
Results: After transient transfection of cDNA into HeLa cells, it was found that R1381S ABCC3 exhibits intracellular accumulation of immature protein, the localization of which was mostly merged with a marker for the endoplasmic reticulum. Two kinds of SNPs type ABCC3 (S346F and S607N) lost their transport activity for [H]estradiol-17beta-D-glucuronide in membrane vesicles from Sf9 cells infected with the recombinant baculoviruses, although the band length and the amount of protein expression remained normal. In contrast, the cellular localization, protein expression and function of other eight kinds of SNPs type ABCC3 (G11D, R99Q, V765L, P920S, R923Q, R1286G, R1348C, and Q1365R ABCC3) remained normal.
Conclusion: The results of this study suggest that the possession of R1381S, S346F, and S607N types of ABCC3 sequences may be a possible risk factor for the acquisition of hepatotoxicity, due to their poor ability to transport toxic compounds across the sinusoidal membrane.