Impact of ABCC2 haplotypes on transcriptional and posttranscriptional gene regulation and function.
ABCC2 (MRP2) is an important export pump, expressed at tissue barriers. The genetic variants -24C>T, 1249G>A and 3972C>T are leading to inter-individual differences of bioavailability of various endogenous and exogenous compounds. Considering ABCC2 haplotypes, we investigated DNA-protein binding properties, mRNA secondary structure, mRNA stability, protein expression and transport activity in various cell lines and analyzed the bioavailability of talinolol in 24 healthy Caucasian volunteers; -24C>T had no clear influence on DNA-protein binding and the mRNA stability did not differ significantly. In transfected HEK293T/17 cells, haplotypes H9 (CGT), H10 (TGC) and H12 (TGT) had significantly lower protein expression, whereas H2 (CAC) exhibited significantly increased protein expression compared to the wild type (H1, CGC): 32.7 ± 8.8, 73.1 ± 6.3; 44.0 ± 15.5 and 115.2 ± 8.2%, respectively. This corresponded with efflux rates of the fluorescent dye glutathione-methylfluorescein in vitro and by trend with talinolol bioavailability in vivo. In conclusion our results show a haplotype-dependent influence on transport capacity of ABCC2, which seems to be mainly based on posttranscriptional modification of protein expression rather than transport rates.
Laechelt
S
S
Institute of Experimental and Clinical Pharmacology, University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany.
Turrini
E
E
Ruehmkorf
A
A
Siegmund
W
W
Cascorbi
I
I
Haenisch
S
S
D000319:Adrenergic beta-Antagonists / Q000493:pharmacokinetics; D000328:Adult; D000818:Animals; D001682:Biological Availability; D018938:Caco-2 Cells; D002461:Cell Line, Transformed; D004285:Dogs; D005260:Female; D005786:Gene Expression Regulation; D014644:Genetic Variation; D057809:HEK293 Cells; D006239:Haplotypes; D006801:Humans; D008297:Male; D026901:Membrane Transport Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D020641:Polymorphism, Single Nucleotide; D011412:Propanolamines / Q000493:pharmacokinetics; D011485:Protein Binding; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D014162:Transfection; D055815:Young Adult
D000319:Adrenergic beta-Antagonists; D026901:Membrane Transport Proteins; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D011412:Propanolamines; D012333:RNA, Messenger; C000715087:ABCC2 protein, human; C011550:talinolol