Decreased expression levels of rat liver glutathione S-transferase A2 and albumin during the acute phase response are mediated by HNF1 (hepatic nuclear factor 1) and IL6DEX-NP.
The acute phase response is characterized by positive and negative regulation of many liver proteins including GSTs (glutathione S-transferases) and albumin. The expression of albumin and some GSTs are dependent on HNF1 (hepatic nuclear factor 1). Interleukin 6 plus dexamethasone induce a nuclear protein (IL6DEX-NP) in rat hepatocytes in vitro that binds to a promoter element adjacent to the HNF1 site of rGSTA2 and decreases its expression. We determined how HNF1 and IL6DEX-NP regulate rGSTA2 and albumin expression in rats during the acute phase response after LPS (lipopolysaccharide) treatment. Expression of rGSTA2 and albumin mRNA decreased 3 h after LPS treatment and remained low for 48 h. Transcription rates showed a similar pattern but albumin transcription was less affected. HNF1 and IL6DEX-NP binding to the rGSTA2 promoter was present in control livers but was absent at 3 and 6 h after LPS. By 12 h, HNF1 and IL6DEX-NP binding to the rGSTA2 promoter reappeared and increased to above normal at 48 h. The patterns of HNF1 and IL6DEX-NP binding to the albumin promoter were similar. Affinity of IL6DEX-NP for the albumin promoter was less than that for the rGSTA2 promoter and changes in the transcription rates were consistent with the difference. Early decreases in rGSTA2 and albumin during the acute phase response are due to decreased binding of HNF1. Later persistent decreases in transcriptional rate of rGSTA2 and to a lesser extent albumin are due to increased IL6DEX-NP binding. IL6DEX-NP appears to be an important negative regulator of gene expression in vitro and in vivo.
Whalen
Richard
R
Liver Research Institute, University of Arizona School of Medicine, AHSC 245136, 1501 N. Campbell Ave., Tucson, AZ 85724-5136, U.S.A. rwhalen@u.arizona.edu
Voss
Susan H
SH
Boyer
Thomas D
TD
D000210:Acute-Phase Reaction / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism* / Q000503:physiopathology; D000418:Albumins / Q000096:biosynthesis* / Q000235:genetics; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D004268:DNA-Binding Proteins; D003907:Dexamethasone / Q000276:immunology*; D005982:Glutathione Transferase / Q000096:biosynthesis* / Q000235:genetics; D051537:Hepatocyte Nuclear Factor 1; D051538:Hepatocyte Nuclear Factor 1-alpha; D051539:Hepatocyte Nuclear Factor 1-beta; D022781:Hepatocytes / Q000737:chemistry; D015850:Interleukin-6 / Q000502:physiology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008099:Liver / Q000201:enzymology* / Q000503:physiopathology; D008297:Male; D009687:Nuclear Proteins / Q000378:metabolism / Q000502:physiology*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*; D014158:Transcription, Genetic / Q000187:drug effects
D000418:Albumins; D004268:DNA-Binding Proteins; D051538:Hepatocyte Nuclear Factor 1-alpha; C496489:Hnf1a protein, rat; D015850:Interleukin-6; D008070:Lipopolysaccharides; D009687:Nuclear Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; D051537:Hepatocyte Nuclear Factor 1; D051539:Hepatocyte Nuclear Factor 1-beta; D003907:Dexamethasone; D005982:Glutathione Transferase