Human kininogen gene is transactivated by the farnesoid X receptor.
Human kininogen belongs to the plasma kallikreinkinin system. High molecular weight kininogen is the precursor for two-chain kinin-free kininogen and bradykinin. It has been shown that the two-chain kinin-free kininogen has the properties of anti-adhesion, anti-platelet aggregation, and anti-thrombosis, whereas bradykinin is a potent vasodilator and mediator of inflammation. In this study we show that the human kininogen gene is strongly up-regulated by agonists of the farnesoid X receptor (FXR), a nuclear receptor for bile acids. In primary human hepatocytes, both the endogenous FXR agonist chenodeoxycholate and synthetic FXR agonist GW4064 increased kininogen mRNA with a maximum induction of 8-10-fold. A more robust induction of kininogen expression was observed in HepG2 cells, where kininogen mRNA was increased by chenodeoxycholate or GW4064 up to 130-140-fold as shown by real time PCR. Northern blot analysis confirmed the up-regulation of kininogen expression by FXR agonists. To determine whether kininogen is a direct target of FXR, we examined the sequence of the kininogen promoter and identified a highly conserved FXR response element (inverted repeat, IR-1) in the proximity of the kininogen promoter (-66/-54). FXR/RXRalpha heterodimers specifically bind to this IR-1. A construct of a minimal promoter with the luciferase reporter containing this IR-1 was transactivated by FXR. Deletion or mutation of this IR-1 abolished FXR-mediated promoter activation, indicating that this IR-1 element is responsible for the promoter transactivation by FXR. We conclude that kininogen is a novel and direct target of FXR, and bile acids may play a role in the vasodilation and anti-coagulation processes.
Zhao
Annie
A
Department of Atherosclerosis and Endocrinology, Bioinformatics, and Molecular Profiling, Merck Research Laboratories, Rahway, New Jersey 07065, USA.
Lew
Jane-L
JL
Huang
Li
L
Yu
Jinghua
J
Zhang
Theresa
T
Hrywna
Yaroslav
Y
Thompson
John R
JR
de Pedro
Nuria
N
Blevins
Richard A
RA
Peláez
Fernando
F
Wright
Samuel D
SD
Cui
Jisong
J
D001665:Binding Sites; D015152:Blotting, Northern; D006528:Carcinoma, Hepatocellular / Q000378:metabolism; D002635:Chenodeoxycholic Acid / Q000494:pharmacology; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000819:agonists / Q000502:physiology*; D017353:Gene Deletion; D005786:Gene Expression Regulation / Q000187:drug effects; D022781:Hepatocytes / Q000378:metabolism; D006801:Humans; D007555:Isoxazoles / Q000494:pharmacology; D007704:Kininogens / Q000235:genetics*; D008113:Liver Neoplasms / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D018160:Receptors, Cytoplasmic and Nuclear; D018168:Receptors, Retinoic Acid / Q000502:physiology; D012091:Repetitive Sequences, Nucleic Acid; D047488:Retinoid X Receptors; D014157:Transcription Factors / Q000819:agonists / Q000502:physiology*; D015533:Transcriptional Activation; D014162:Transfection; D014407:Tumor Cells, Cultured; D000099150:Receptor, Farnesoid X-Activated
D002635:Chenodeoxycholic Acid; D004247:DNA; D004268:DNA-Binding Proteins; D007555:Isoxazoles; D007704:Kininogens; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D018168:Receptors, Retinoic Acid; D047488:Retinoid X Receptors; D014157:Transcription Factors; D000099150:Receptor, Farnesoid X-Activated; C412815:GW 4064