Krüppel-Like Factor 9 Promotes Hepatic Cytochrome P450 2D6 Expression during Pregnancy in CYP2D6-Humanized Mice

Abstract

Cytochrome P450 2D6 (CYP2D6), a major drug-metabolizing enzyme, is responsible for metabolism of approximately 25% of marketed drugs. Clinical evidence indicates that metabolism of CYP2D6 substrates is increased during pregnancy, but the underlying mechanisms remain unclear. To identify transcription factors potentially responsible for CYP2D6 induction during pregnancy, a panel of genes differentially expressed in the livers of pregnant versus nonpregnant CYP2D6-humanized (tg-CYP2D6) mice was compiled via microarray experiments followed by realtime quantitative reverse-transcription polymerase chain reaction (qRT-PCR) verification. As a result, seven transcription factorsactivating transcription factor 5 (ATF5), early growth response 1 (EGR1), forkhead box protein A3 (FOXA3), JUNB, Krüppel-like factor 9 (KLF9), KLF10, and REV-ERBa-were found to be up-regulated in liver during pregnancy. Results from transient transfection and promoter reporter gene assays indicate that KLF9 itself is a weak transactivator of CYP2D6 promoter but significantly enhances CYP2D6 promoter transactivation by hepatocyte nuclear factor 4 (HNF4a), a known transcriptional activator of CYP2D6 expression. The results from deletion and mutation analysis of CYP2D6 promoter activity identified a KLF9 putative binding motif at -22/-14 region to be critical in the potentiation of HNF4a-induced transactivation of CYP2D6. Electrophoretic mobility shift assays revealed a direct binding of KLF9 to the putative KLF binding motif. Results from chromatin immunoprecipitation assay showed increased recruitment of KLF9 to CYP2D6 promoter in the livers of tg-CYP2D6 mice during pregnancy. Taken together, our data suggest that increased KLF9 expression is in part responsible for CYP2D6 induction during pregnancy via the potentiation of HNF4a transactivation of CYP2D6.

Treatment With Antipsychotics in Pregnancy: Changes in Drug Disposition

“…CYP2D6 expression and activity also increase during pregnancy,4, 5, 6, 16 and for other CYP2D6 substrates a 2–13‐fold increase in clearance has been described 17. A previously published case series described aripiprazole plasma concentrations in three pregnancies in two women 9.…”

Hepatocyte nuclear factor (HNF) 4α transactivation of cytochrome P450 (Cyp) 2d40 promoter is enhanced during pregnancy in mice

“…Previously, we have shown that SHP represses and KLF9 potentiates HNF4α transactivation of CYP2D6 promoter [13, 18]. To examine whether SHP and KLF9 modulate HNF4α transactivation of Cyp2d40 promoter (similarly to CYP2D6 promoter), we performed promoter reporter assays in HEK293T cells.…”

“…HNF4α is a nuclear receptor known to play a critical role in regulating expression of liver-specific genes, including drug-metabolizing enzymes [14–17]. Our studies also demonstrated that the increased HNF4α transactivation of CYP2D6 promoter is in part attributed to two transcription factors, namely small heterodimer partner (SHP, NR0B2) and Krüppel-like Factor 9 (KLF9), whose hepatic expression is differentially regulated during pregnancy [13, 18]. SHP, a member of nuclear receptor superfamily, lacks the DNA-binding domain [19] and interacts with HNF4α to function as a transcriptional repressor [20, 21].…”

“…During pregnancy, hepatic SHP expression decreases, and this leads to de-repression of CYP2D6 promoter [13]. On the other hand, KLF9 transactivates CYP2D6 promoter in synergy with HNF4α [18]. During pregnancy, hepatic KLF9 expression increases, further potentiating HNF4α transactivation of CYP2D6 promoter [18].…”

“…On the other hand, KLF9 transactivates CYP2D6 promoter in synergy with HNF4α [18]. During pregnancy, hepatic KLF9 expression increases, further potentiating HNF4α transactivation of CYP2D6 promoter [18]. Importantly, these results provide a potential platform to identify and characterize mouse Cyp2d homologs that are regulated similarly as CYP2D6.…”