title: Inflammation Modulates RLIP76/RALBP1 Electrophile-Glutathione Conjugate Transporter and Housekeeping Genes in Human Blood-Brain Barrier Endothelial Cells.
abstract: Endothelial cells are often present at inflammation sites. This is the case of endothelial cells of the blood-brain barrier (BBB) of patients afflicted with neurodegenerative disorders such as Alzheimer's, Parkinson's, or multiple sclerosis, as well as in cases of bacterial meningitis, trauma, or tumor-associated ischemia. Inflammation is a known modulator of gene expression through the activation of transcription factors, mostly NF-κB. RLIP76 (a.k.a. RALBP1), an ATP-dependent transporter of electrophile-glutathione conjugates, modulates BBB permeability through the regulation of tight junction function, cell adhesion, and exocytosis. Genes and pathways regulated by RLIP76 are transcriptional targets of tumor necrosis factor alpha (TNF-α) pro-inflammatory molecule, suggesting that RLIP76 may also be an inflammation target. To assess the effects of TNF-α on RLIP76, we faced the problem of choosing reference genes impervious to TNF-α. Since such genes were not known in human BBB endothelial cells, we subjected these to TNF-α, and measured by quantitative RT-PCR the expression of housekeeping genes commonly used as reference genes. We find most to be modulated, and analysis of several inflammation datasets as well as a metaanalysis of more than 5000 human tissue samples encompassing more than 300 cell types and diseases show that no single housekeeping gene may be used as a reference gene. Using three different algorithms, however, we uncovered a reference geneset impervious to TNF-α, and show for the first time that RLIP76 expression is induced by TNF-α and follows the induction kinetics of inflammation markers, suggesting that inflammation can influence RLIP76 expression at the BBB. We also show that MRP1 (a.k.a. ABCC1), another electrophile-glutathione transporter, is not modulated in the same cells and conditions, indicating that RLIP76 regulation by TNF-α is not a general property of glutathione transporters. The reference geneset uncovered herein should aid in future gene expression studies in inflammatory conditions of the BBB.
authors.affiliation: Department for Medicinal Chemistry, Institute of Pharmaceutical Chemistry, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria; Department of Biomedical Imaging and Image-guided Therapy, Vienna General Hospital (AKH), Medical University of Vienna, Waehringer-Guertel 18-20, 1090 Vienna, Austria.
authors.forename: Barbara
authors.initials: B
authors.lastname: Bennani-Baiti
authors.affiliation: Karl Chiari Lab for Orthopaedic Biology, Department of Orthopaedics, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria.
authors.forename: Stefan
authors.initials: S
authors.lastname: Toegel
authors.affiliation: Department of Pharmaceutical Technology and Biopharmaceutics, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria.
authors.forename: Helmut
authors.initials: H
authors.lastname: Viernstein
authors.affiliation: Department for Medicinal Chemistry, Institute of Pharmaceutical Chemistry, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria.
authors.forename: Ernst
authors.initials: E
authors.lastname: Urban
authors.affiliation: Department for Medicinal Chemistry, Institute of Pharmaceutical Chemistry, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria.
authors.forename: Christian R
authors.initials: CR
authors.lastname: Noe
authors.affiliation: The B2 Scientific Group, Werdertorgasse 12/3/6, 1010 Vienna, Austria.
authors.forename: Idriss M
authors.initials: IM
authors.lastname: Bennani-Baiti
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D015415:Biomarkers / Q000378:metabolism; D001812:Blood-Brain Barrier / Q000473:pathology*; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D020690:GTPase-Activating Proteins / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D020043:Genes, Essential; D056726:Genetic Association Studies; D005978:Glutathione / Q000378:metabolism*; D006801:Humans; D007249:Inflammation / Q000235:genetics* / Q000473:pathology; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D051381:Rats; D012984:Software; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D018528:ATP-Binding Cassette Transporters; D015415:Biomarkers; D020690:GTPase-Activating Proteins; D016328:NF-kappa B; C095637:RALBP1 protein, human; D014409:Tumor Necrosis Factor-alpha; D005978:Glutathione