Association of genes involved in bile acid synthesis with the progression of primary biliary cirrhosis in Japanese patients.
BACKGROUND
Patients with primary biliary cirrhosis (PBC) exhibit a variety of clinical manifestations and patterns of disease progression. The aim of this study was to identify genetic determinants of PBC progression.


METHODS
A total of 52 tag single nucleotide polymorphisms (SNPs) of 11 candidate genes involved in regulating bile acid synthesis were analyzed by polymerase chain reaction (PCR)-restriction fragment length polymorphism, -high resolution melting curve analysis, or -direct DNA sequencing in 315 Japanese patients with PBC.


RESULTS
In this study, four tag SNPs of CYP7A1 (rs1457043, rs8192870, rs3808607, and rs3824260), two tag SNPs of HNF4A (rs6017340 and 6031587), and one SNP of PPARGC1A (rs8192678) showed a significant association with PBC progression. In addition, a dual luciferase assay revealed that the polymorphism of rs3808607 in CYP7A1 altered the expression of CYP7A1 in HepG2. Specifically, the CYP7A1 promoter carrying the risk G allele for PBC progression induced higher expression of CYP7A1 under both the normal and cholestatic conditions in vitro as compared to another promoter carrying the non-risk T allele.


CONCLUSIONS
These results suggested that the genetic variants of CYP7A1 and its transcriptional activators (HNF4A and PPARGC1A) may activate bile acid synthesis, resulting in the accumulation of bile acids in hepatocytes and eventually leading to the predisposition to PBC progression. Thus, the regulation of CYP7A1 expression may represent an attractive therapeutic target for cholestatic liver diseases including PBC.
Department of Pharmacotherapeutics, Nagasaki University Graduate School of Biomedical Sciences, 1-14 Bunkyo-machi, Nagasaki, 852-8521, Japan.
Tatsuo
T
Inamine
Shingo
S
Higa
Fumie
F
Noguchi
Shinji
S
Kondo
Katsuhisa
K
Omagari
Hiroshi
H
Yatsuhashi
Kazuhiro
K
Tsukamoto
Minoru
M
Nakamura
D000368:Aged; D001647:Bile Acids and Salts / Q000096:biosynthesis*; D002790:Cholesterol 7-alpha-Hydroxylase / Q000235:genetics*; D015331:Cohort Studies; D018450:Disease Progression; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D051557:Hepatocyte Nuclear Factor 4 / Q000235:genetics*; D006801:Humans; D007564:Japan; D008105:Liver Cirrhosis, Biliary / Q000175:diagnosis / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D020641:Polymorphism, Single Nucleotide; D017422:Sequence Analysis, DNA; D014157:Transcription Factors / Q000235:genetics*
D001647:Bile Acids and Salts; C496592:HNF4A protein, human; D051557:Hepatocyte Nuclear Factor 4; C486497:PPARGC1A protein, human; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D014157:Transcription Factors; C553219:CYP7A1 protein, human; D002790:Cholesterol 7-alpha-Hydroxylase