title: HNF-4alpha Negatively Regulates Hepcidin Expression Through BMPR1A in HepG2 Cells.
abstract: Hepcidin synthesis is reported to be inadequate according to the body iron store in patients with non-alcoholic fatty liver disease (NAFLD) undergoing hepatic iron overload (HIO). However, the underlying mechanisms remain unclear. We hypothesize that hepatocyte nuclear factor-4α (HNF-4α) may negatively regulate hepcidin expression and contribute to hepcidin deficiency in NAFLD patients. The effect of HNF-4α on hepcidin expression was observed by transfecting specific HNF-4α small interfering RNA (siRNA) or plasmids into HepG2 cells. Both direct and indirect mechanisms involved in the regulation of HNF-4α on hepcidin were detected by real-time PCR, Western blotting, chromatin immunoprecipitation (chIP), and reporter genes. It was found that HNF-4α suppressed hepcidin messenger RNA (mRNA) and protein expressions in HepG2 cells, and this suppressive effect was independent of the potential HNF-4α response elements. Phosphorylation of SMAD1 but not STAT3 was inactivated by HNF-4α, and the SMAD4 response element was found essential to HNF-4α-induced hepcidin reduction. Neither inhibitory SMADs, SMAD6, and SMAD7 nor BMPR ligands, BMP2, BMP4, BMP6, and BMP7 were regulated by HNF-4α in HepG2 cells. BMPR1A, but not BMPR1B, BMPR2, ActR2A, ActR2B, or HJV, was decreased by HNF-4α, and HNF4α-knockdown-induced stimulation of hepcidin could be entirely blocked when BMPR1A was interfered with at the same time. In conclusion, the present study suggests that HNF-4α has a suppressive effect on hepcidin expression by inactivating the BMP pathway, specifically via BMPR1A, in HepG2 cells.
authors.affiliation: Military Hygiene Department, Faculty of Naval Medicine, Second Military Medical University, No. 800 Xiangyin Road, Shanghai, 200433, China.|Department of Clinical Nutrition, Changhai Hospital, Second Military Medical University, Shanghai, China.
authors.forename: Wencai
authors.initials: W
authors.lastname: Shi
authors.affiliation: Military Hygiene Department, Faculty of Naval Medicine, Second Military Medical University, No. 800 Xiangyin Road, Shanghai, 200433, China.
authors.forename: Heyang
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Clinical Nutrition, Changhai Hospital, Second Military Medical University, Shanghai, China.
authors.forename: Xuan
authors.initials: X
authors.lastname: Zheng
authors.affiliation: Military Hygiene Department, Faculty of Naval Medicine, Second Military Medical University, No. 800 Xiangyin Road, Shanghai, 200433, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Jiang
authors.affiliation: Military Hygiene Department, Faculty of Naval Medicine, Second Military Medical University, No. 800 Xiangyin Road, Shanghai, 200433, China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Xu
authors.affiliation: Military Hygiene Department, Faculty of Naval Medicine, Second Military Medical University, No. 800 Xiangyin Road, Shanghai, 200433, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Shen
authors.affiliation: Military Hygiene Department, Faculty of Naval Medicine, Second Military Medical University, No. 800 Xiangyin Road, Shanghai, 200433, China. linlimin115@126.com.
authors.forename: Min
authors.initials: M
authors.lastname: Li
mesh_terms: D052005:Bone Morphogenetic Protein Receptors, Type I / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015536:Down-Regulation; D056945:Hep G2 Cells; D051557:Hepatocyte Nuclear Factor 4 / Q000235:genetics / Q000378:metabolism*; D064451:Hepcidins / Q000096:biosynthesis* / Q000235:genetics*; D006801:Humans; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: C496592:HNF4A protein, human; D051557:Hepatocyte Nuclear Factor 4; D064451:Hepcidins; D012333:RNA, Messenger; C498211:BMPR1A protein, human; D052005:Bone Morphogenetic Protein Receptors, Type I
keywords: BMPR1A; HNF-4α·hepcidin; pSMAD1/5/8