Differential effect of ABCB1 haplotypes on promoter activity

Jordan T. Speidel, Meixiang Xu, Sherif Abdel-Rahman

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Objective Promoter single-nucleotide polymorphisms (SNPs) of the ABCB1 gene, encoding the placental efflux transporter P-glycoprotein, can affect its expression and alter xenobiotic transfer from the maternal to the fetal circulation. Because SNPs are arranged in specific combinations as defined haplotypes, the aims of this study were to: (i) determine the placental haplotype structure of the ABCB1 promoter and (ii) determine the differential effect of these haplotypes on placental ABCB1 promoter activity. Materials and methods DNA samples from 100 healthy placentas were PCR-amplified and sequenced to identify existing SNPs in the proximal ABCB1 promoter. The haplotype structure encompassing these SNPs was inferred by PHASE analysis. Luciferase reporter constructs representing these haplotypes were generated and transfected into human placental 3A cells and their effect on ABCB1 promoter activity was determined using a dual-luciferase assay. Results We identified 12 ABCB1 promoter SNPs. These SNPs were predicted by PHASE to segregate into 28 haplotypes with frequencies ranging between 0.019 and 0.88. We found 12 of these haplotypes in our population in addition to two haplotypes not predicted by PHASE. We also generated two haplotypes to determine individual SNP effects for a total of 16 studied. Compared with the ancestral haplotype, three haplotypes significantly up-regulated (107-266% increase; P<0.05), one significantly down-regulated (95.4% decrease; P<0.01), and 12 had no statistically significant effect on ABCB1 promoter activity. Discussion and conclusion Our data show that the effect of SNPs on promoter activity depends on their presence in a specific haplotype. This indicates that haplotypes, rather than individual SNPs, could play a significant role in regulating placental P-glycoprotein expression and affect placental transfer and fetal exposure to xenobiotics.

Original languageEnglish (US)
Pages (from-to)69-77
Number of pages9
JournalPharmacogenetics and Genomics
Volume28
Issue number3
DOIs
StatePublished - Jan 1 2018

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Haplotypes
Single Nucleotide Polymorphism
P-Glycoprotein
Xenobiotics
Luciferases
Placenta
Mothers
Polymerase Chain Reaction

Keywords

  • ABCB1
  • P-glycoprotein
  • promoter haplotypes
  • single-nucleotide polymorphisms

ASJC Scopus subject areas

  • Molecular Medicine
  • Molecular Biology
  • Genetics
  • Genetics(clinical)

Cite this

Differential effect of ABCB1 haplotypes on promoter activity. / Speidel, Jordan T.; Xu, Meixiang; Abdel-Rahman, Sherif.

In: Pharmacogenetics and Genomics, Vol. 28, No. 3, 01.01.2018, p. 69-77.

Research output: Contribution to journalArticle

Speidel, Jordan T. ; Xu, Meixiang ; Abdel-Rahman, Sherif. / Differential effect of ABCB1 haplotypes on promoter activity. In: Pharmacogenetics and Genomics. 2018 ; Vol. 28, No. 3. pp. 69-77.
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