title: HIV-1 viral envelope glycoprotein gp120 produces oxidative stress and regulates the functional expression of multidrug resistance protein-1 (Mrp1) in glial cells.
abstract: Brain human immunodeficiency virus type-1 (HIV-1) infection is associated with oxidative stress, which may lead to HIV-1 encephalitis, a chronic neurodegenerative condition. In vitro, oxidative stress can be induced in glial cells by exposure to HIV-1 envelope protein glycoprotein (gp120). Multidrug resistance proteins (Mrps) are known to efflux endogenous substrates (i.e. GSH and GSSG) involved in cellular defense against oxidative stress. Altered GSH/GSSG export may contribute to oxidative damage during HIV-1 encephalitis. At present, it is unknown if gp120 exposure can alter the functional expression of Mrp isoforms. Heat-shock protein 70, inducible nitric oxide synthase, intracellular GSSG, 2',7'-dichlorofluorescein fluorescence, and extracellular nitrite were increased in primary cultures of rat astrocytes triggered with gp120, suggesting an oxidative stress response. RT-PCR and immunoblot analysis demonstrated increased Mrp1 mRNA (2.3-fold) and protein (2.2-fold), respectively, in gp120 treated astrocytes while Mrp4 mRNA or protein expression was not changed. Cellular retention of 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein, an established Mrp substrate, was reduced (twofold) in gp120-treated astrocytes, suggesting increased Mrp-mediated transport. In addition, GSH and GSSG export were enhanced in gp120-triggered cells. These data suggest that gp120 can up-regulate Mrp1, but not Mrp4, functional expression in cultured astrocytes. Our observation of increased GSH/GSSG efflux in response to gp120 treatment implies that Mrp isoforms may be involved in regulating the oxidative stress response in glial cells.
authors.affiliation: Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Patrick T
authors.initials: PT
authors.lastname: Ronaldson
authors.forename: Reina
authors.initials: R
authors.lastname: Bendayan
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis* / Q000235:genetics / Q000502:physiology; D000818:Animals; D002478:Cells, Cultured; D015967:Gene Expression Regulation, Viral / Q000502:physiology*; D015699:HIV Envelope Protein gp120 / Q000502:physiology*; D015658:HIV Infections / Q000378:metabolism* / Q000473:pathology; D006367:HeLa Cells; D006801:Humans; D009457:Neuroglia / Q000378:metabolism* / Q000502:physiology; D018384:Oxidative Stress / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D015854:Up-Regulation / Q000502:physiology
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D015699:HIV Envelope Protein gp120