Lipopolysaccharide-induced down-regulation of organic anion transporting polypeptide 4 (Oatp4; Slc21a10) is independent of tumor necrosis factor-alpha, Interleukin-1beta, interleukin-6, or inducible nitric oxide synthase.
Organic anion transporting polypeptide 4 (Oatp4; Slc21a10) is expressed almost exclusively in liver, where it mediates uptake of a variety of compounds, including bile acids, as well as other endo- and xenobiotics, across hepatic sinusoidal membranes in a Na+-independent manner. Lipopolysaccharide (LPS) has been shown to decrease Oatp4 mRNA levels in a dose- and time-dependent manner in Toll-like receptor 4 (TLR4)-normal (C3H/OuJ) mice, but not in TLR4-mutant (C3H/HeJ) mice. Moreover, after LPS administration, serum concentrations of tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and interleukin-6 (IL-6) are markedly lower in TLR4-mutant mice than in TLR4-normal mice. Thus, TLR4 is considered an upstream mediator of LPS-induced decrease in mouse Oatp4 mRNA. LPS is thought to alter liver gene expression through LPS-induced cytokines or nitric oxide (NO). TNF receptor p55 (TNFRp55) and type I IL-1 receptor (IL-1RI) mediate the biological functions of TNF-alpha and IL-1beta, respectively. Therefore, to determine whether endogenous cytokines or NO are mediators of LPS-induced down-regulation of Oatp4, Oatp4 mRNA levels were determined in mice deficient in the TNFRp55, IL-1RI, IL-6, or inducible nitric oxide synthase (iNOS) after LPS administration. Mice homozygous for a targeted deletion of genes for TNFRp55, IL-1RI, IL-6, or iNOS exhibited similar decreases in Oatp4 mRNA levels as wild-type mice after LPS administration. Moreover, in mouse hepatoma cells, treatment with TNF-alpha, IL-1beta, or IL-6 individually or in combination did not suppress activity of mouse Oatp4 promoter (-4.8 kb to +30). Therefore, LPS-induced down-regulation of Oatp4 appears to be independent of TNF-alpha, IL-1beta, IL-6, or iNOS.
Li
Ning
N
Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, Kansas City, Kansas 66160, USA.
Klaassen
Curtis D
CD
D000818:Animals; D045744:Cell Line, Tumor; D016207:Cytokines / Q000378:metabolism* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D006720:Homozygote; D007375:Interleukin-1 / Q000378:metabolism / Q000494:pharmacology; D015850:Interleukin-6 / Q000378:metabolism / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000633:toxicity*; D008099:Liver / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D027381:Liver-Specific Organic Anion Transporter 1; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II; D029362:Organic Anion Transporters, Sodium-Independent / Q000096:biosynthesis*; D011401:Promoter Regions, Genetic / Q000187:drug effects; D011956:Receptors, Cell Surface / Q000235:genetics; D011994:Recombinant Proteins / Q000494:pharmacology; D013997:Time Factors; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism / Q000494:pharmacology
D016207:Cytokines; D007375:Interleukin-1; D015850:Interleukin-6; D008070:Lipopolysaccharides; D027381:Liver-Specific Organic Anion Transporter 1; D008562:Membrane Glycoproteins; D029362:Organic Anion Transporters, Sodium-Independent; D011956:Receptors, Cell Surface; D011994:Recombinant Proteins; C498887:Slco1b2 protein, mouse; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014409:Tumor Necrosis Factor-alpha; C440499:lipopolysaccharide, Escherichia coli O111 B4; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse