title: Nicotinic acid induces apolipoprotein A-I gene expression in HepG2 and Caco-2 cell lines.
abstract: The objective was to test the effect of nicotinic acid on apolipoprotein A-I (apo A-I) gene expression in hepatic (HepG2) and intestinal (Caco-2) cell lines. HepG2 and Caco-2 cells were treated with 0.1, 0.3, 1.0, 3.0, and 10 mmol/L of nicotinic acid; and apo A-I concentrations in conditioned media were measured with Western blots. Relative apo A-I messenger RNA (mRNA) levels, normalized to glyceraldehyde-3-phosphate dehydrogenase mRNA, were measured with quantitative real-time polymerase chain reaction method. The nicotinic acid response element in the apo A-I promoter was identified using a series of apo A-I reporter plasmids containing deletion constructs of the promoter. In other experiments, HepG2 cells were also transfected with the apo A-I reporter plasmid and the hepatocyte nuclear factors 3α and β expression plasmids. The apo A-I levels in conditioned media from HepG2 cells, apo A-I mRNA levels, and apo A-I promoter activity increased significantly following treatment with 1.0, 3.0, and 10 mmol/L nicotinic acid. Nicotinic acid-induced promoter activity required a region of the apo A-I gene located between -170 and -186 base pairs. Exogenous overexpression of the hepatocyte nuclear factors 3α and β had no additive effect on apo A-I promoter. Apolipoprotein A-I concentrations in conditioned media and the apo A-I promoter activity were also significantly increased in Caco-2 intestinal cells. Nicotinic acid may increase apo A-I protein synthesis in the liver and small intestine. Induction of apo A-I gene by nicotinic acid requires a nicotinic acid responsive element in the apo A-I promoter.
authors.affiliation: Division of Endocrinology, Department of Medicine, University of Florida College of Medicine, Jacksonville, FL 32209, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Haas
authors.forename: Abdul-Razzak
authors.initials: AR
authors.lastname: Alamir
authors.forename: Senan
authors.initials: S
authors.lastname: Sultan
authors.forename: Joe M
authors.initials: JM
authors.lastname: Chehade
authors.forename: Norman C N
authors.initials: NC
authors.lastname: Wong
authors.forename: Arshag D
authors.initials: AD
authors.lastname: Mooradian
mesh_terms: D016632:Apolipoprotein A-I / Q000096:biosynthesis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D018938:Caco-2 Cells; D015870:Gene Expression; D056945:Hep G2 Cells; D051541:Hepatocyte Nuclear Factor 3-alpha / Q000378:metabolism; D051542:Hepatocyte Nuclear Factor 3-beta / Q000378:metabolism; D006801:Humans; D009525:Niacin / Q000494:pharmacology*; D010957:Plasmids; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D012045:Regulatory Sequences, Nucleic Acid; D020218:Response Elements / Q000187:drug effects / Q000235:genetics; D014162:Transfection
chemical_list: D016632:Apolipoprotein A-I; C496499:FOXA1 protein, human; C496502:FOXA2 protein, human; D051541:Hepatocyte Nuclear Factor 3-alpha; D012333:RNA, Messenger; D051542:Hepatocyte Nuclear Factor 3-beta; D009525:Niacin