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Transcriptional regulation of human UDP‐glucuronosyltransferase 2B4 (UGT2B4) by sulfotransferase deficiency
Author(s) -
Barrett Kathleen,
Fang Hailin,
Kocarek Thomas A,
RungeMorris Melissa
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.1102.1
Subject(s) - gene knockdown , transfection , farnesoid x receptor , luciferase , chemistry , reporter gene , downregulation and upregulation , microbiology and biotechnology , biology , transcription factor , nuclear receptor , gene expression , gene , biochemistry
We previously found that UGT2B4 expression is up‐regulated in HepG2 cells with reduced sulfotransferase activity as achieved by stable knockdown of 3′‐phosphoadenosine 5′‐phosphosulfate synthases 1 and 2 (PAPSS1/2). Since UGT2B4 is reportedly regulated by the bile acid‐sensing nuclear receptor FXR, we investigated whether PAPSS1/2 knockdown‐inducible UGT2B4 expression is mediated through FXR. When a luciferase reporter plasmid containing 2Kb of the UGT2B4–5′‐flanking sequence was transiently transfected into PAPSS1/2 knockdown HepG2 (shPAPSS) cells, luciferase activity was significantly (~4‐fold) higher than it was after transfection into control cells. Treatment of shPAPSS cells with an FXR agonist (GW4064 or chenodeoxycholic acid) or transfection with an FXR expression plasmid increased reporter activity (~2‐to 5‐fold), demonstrating the FXR responsiveness of 2Kb‐UGT2B4‐Luc. However, knockdown of FXR in shPAPSS cells had no effect on 2Kb‐UGT2B4‐Luc activity, and mutation of a previously reported FXR response element at nt ‐1180 reduced reporter activity by only ~20%. These results indicate that the information conferring transcriptional up‐regulation of UGT2B4 in response to PAPSS1/2 knockdown is contained within the first 2Kb of the UGT2B4 5′‐flanking region but that FXR is not responsible for this transcriptional activation. This work was supported by NIH grant ES005823.