Upstream stimulatory factor 2 is implicated in the progression of biliary atresia by regulation of hepcidin expression.
BACKGROUND
Hepcidin is downregulated during the progression of biliary atresia (BA), but the mechanism is still unknown.


METHODS
We analyzed single nucleotide polymorphism of rs7251432 and 916145 within hepcidin and its upstream, USF2 gene, respectively, in 52 patients of BA and 96 healthy controls. Liver tissues were obtained from 10 patients with early and late stage of BA, 10 patients with choledochal cyst, and 4 normal controls to study upstream stimulatory factor 2 (USF2) messenger RNA (mRNA) and protein expressions. Chromatin immunoprecipitation assay and USF2-specific short interference RNA (siRNA) were used in human HepG2 cells to show that USF2 can regulate hepcidin expression.


RESULTS
C and CC allele frequencies of rs916145 of USF2 were significantly higher in patients with BA than in healthy controls. There was also significantly higher USF2 protein nuclear translocation in the early stage of BA than in the late stage, which was compatible with higher hepcidin mRNA expression in the early stage of BA. Chromatin immunoprecipitation assay demonstrated physiologic bindings of USF2 to the hepcidin promoter in HepG2 cells. USF2 siRNA also significantly knocked down hepcidin mRNA expression.


CONCLUSIONS
The study demonstrates that C allele of rs916145 in USF2 gene has more frequency for developing BA, and decreased USF2 protein nuclear translocation might partly play a role in the decreased hepcidin expression in the cholestatic liver injury of the late stage of BA.
Huang
Ying-Hsien
YH
Department of Pediatrics, Chang Gung Memorial Hospital-Kaoshiung Medical Center, Niao-Sung Hsiang, Kaohsiung, Taiwan 833, ROC
Huang
Chao-Cheng
CC
Chuang
Jiin-Haur
JH
Hsieh
Chie-Sung
CS
Lee
Shin-Ye
SY
Chen
Chao-Long
CL
D021581:Active Transport, Cell Nucleus; D000483:Alleles; D023181:Antimicrobial Cationic Peptides / Q000096:biosynthesis / Q000235:genetics*; D001656:Biliary Atresia / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D002675:Child, Preschool; D015529:Choledochal Cyst / Q000378:metabolism; D047369:Chromatin Immunoprecipitation; D018450:Disease Progression; D005260:Female; D005786:Gene Expression Regulation; D005787:Gene Frequency; D055785:Gene Knockdown Techniques; D022781:Hepatocytes / Q000378:metabolism; D064451:Hepcidins; D006801:Humans; D007223:Infant; D008297:Male; D020641:Polymorphism, Single Nucleotide; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D051720:Upstream Stimulatory Factors / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*
D023181:Antimicrobial Cationic Peptides; C578702:HAMP protein, human; D064451:Hepcidins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C497184:USF2 protein, human; D051720:Upstream Stimulatory Factors