title: Hepatic response to chronic hypoxia in experimental rat model through HIF-1 alpha, activator protein-1 and NF-kappa B.
abstract: Chronic liver diseases are commonly associated with tissue hypoxia that may cause inflammation, oxidative stress, liver cell injury and increased nuclear transcriptional regulation. The hepatic response to chronic hypoxia at the molecular level has not yet been clearly understood until now. The aim of this study is to investigate whether nuclear transcription factors [hypoxia-inducible factor-1 (HIF-1α), activator protein-1 (AP-1), nuclear factor-kappa B (NF-κB)] exhibit activity changes during hepatic response to chronic hypoxia. Blood and liver samples were collected from adult Sprague-Dawley rats living in atmospheric air or 10% oxygen for four weeks. Levels of serum alanine aminotransferase (ALT), 8-isoprostane and nitrotyrosine were measured. The activities of nuclear transcription factors and the expression of downstream genes (iNOS, eNOS, ET-1 and VEGF) were measured using RT-PCR, Western blotting and Gel shift analysis. Results showed that serum ALT level, 8-isoprostane level and formation of nitrotyrosine were within normal range at all time-points. In the hypoxic liver, DNA-binding activities of HIF-1α, NF-κB and AP-1 increased significantly. Expression levels of iNOS, VEGF and ET-1 progressively increased from day 7 to day 28. eNOS was also elevated in the hypoxic liver. In conclusion, our study suggests that increased activity of HIF-1α, AP-1 and NF-κB may partly play a significant role in the hepatic response to oxidative stress and liver injury under chronic hypoxia. The increased expression of VEGF, ET-1, iNOS and eNOS may be partly due to the compensatory mechanism in the vascular beds of the liver in response to chronic hypoxia.
authors: Department of Health Technology and Informatics, Hong Kong Polytechnic University, Hong Kong SAR.
authors: Thomas Y H
authors: TY
authors: Lau
authors: Jia
authors: J
authors: Xiao
authors: Emily C
authors: EC
authors: Liong
authors: Linchuan
authors: L
authors: Liao
authors: Tung Ming
authors: TM
authors: Leung
authors: Amin A
authors: AA
authors: Nanji
authors: Man Lung
authors: ML
authors: Fung
authors: George L
authors: GL
authors: Tipoe
mesh_terms: D000410:Alanine Transaminase / Q000097:blood; D000818:Animals; D015415:Biomarkers / Q000097:blood; D015153:Blotting, Western; D002908:Chronic Disease; D015237:Dinoprost / Q000031:analogs & derivatives / Q000097:blood; D004195:Disease Models, Animal; D024202:Electrophoretic Mobility Shift Assay; D019332:Endothelin-1 / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D000860:Hypoxia / Q000235:genetics / Q000378:metabolism*; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D008297:Male; D016328:NF-kappa B / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000235:genetics / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000235:genetics / Q000378:metabolism; D018384:Oxidative Stress; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D014443:Tyrosine / Q000031:analogs & derivatives / Q000097:blood; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism
chemical_list: D015415:Biomarkers; D019332:Endothelin-1; C497444:Hif1a protein, rat; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D016328:NF-kappa B; D012333:RNA, Messenger; D018808:Transcription Factor AP-1; D042461:Vascular Endothelial Growth Factor A; C467498:vascular endothelial growth factor A, rat; C075750:8-epi-prostaglandin F2alpha; C002744:3-nitrotyrosine; D014443:Tyrosine; D015237:Dinoprost; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496318:Nos2 protein, rat; C496316:Nos3 protein, rat; D000410:Alanine Transaminase