The effect of endotoxin on hepatocyte nuclear factor 1 nuclear protein binding: potential implications on CYP2E1 expression in the rat
| Autor: | Samuel M. Poloyac, Robert A. Blouin, Amy L. Roe, Steven I. Shedlofsky, Georgette Howard |
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| Rok vydání: | 2001 |
| Předmět: |
Lipopolysaccharides
Male Lipopolysaccharide Blotting Western Pharmaceutical Science Electrophoretic Mobility Shift Assay Enzyme-Linked Immunosorbent Assay Stimulation Biology digestive system Gene Expression Regulation Enzymologic Rats Sprague-Dawley chemistry.chemical_compound Gene expression Animals Electrophoretic mobility shift assay Hepatocyte Nuclear Factor 1-alpha Nuclear protein Hepatocyte Nuclear Factor 1-beta Cell Nucleus Pharmacology Acute-phase protein Nuclear Proteins Cytochrome P-450 CYP2E1 CYP2E1 Molecular biology Rats DNA-Binding Proteins Endotoxins Hepatocyte nuclear factors Liver chemistry Hepatocyte Nuclear Factor 1 embryonic structures Microsomes Liver Protein Binding Transcription Factors |
| Zdroj: | Journal of Pharmacy and Pharmacology. 53:1365-1371 |
| ISSN: | 2042-7158 0022-3573 |
| DOI: | 10.1211/0022357011777864 |
| Popis: | The purpose of this study was to determine if changes in nuclear protein binding of hepatocyte nuclear factor 1 (HNF-1) occur after lipopolysaccharide (LPS) administration. In addition, the time-course of alterations in CYP2E1 regulation were evaluated. Rats were injected with 2.0 mg LPS and euthanized over a 72-h period. Nuclear protein binding to a consensus HNF-1 oligonucleotide was assessed by the electrophoretic mobility shift assay. CYP2E1 activity was analysed using chlorzoxazone as a substrate (6OH-CLZ), and CYP2E1 protein concentration was determined by enzyme-linked immunosorbent assay. Endotoxin treatment resulted in decreased nuclear protein binding to an HNF-1 element as early as 1 h after treatment and returned to control levels by 72 h. This reduced binding persisted for 24 h and returned to control values 48 h after LPS administration. In addition, the reduction in binding was primarily attributable to a HNF-1α immunoreactive protein. The observed reduction in HNF-1 binding was followed in the time-course by decreases in CYP2E1 activity and protein content with maximal decreases to 50 and 67% of control, respectively, at 48 h after LPS administration. Endotoxin is a potent inducer of the acute phase response (APR). The APR stimulation by endotoxin administration reduced HNF-1α binding and decreased the expression of CYP2E1 in the rat liver. The time-course of alterations in HNF-1 and CYP2E1 lend support to the possibility that HNF-1α may play a role in the down-regulation of genes that require HNF-1α for their constitutive expression. These data serve as an important precedent for future studies evaluating the direct association of decreased HNF-1α binding and reduced gene expression after LPS administration. |
| Databáze: | OpenAIRE |
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