title: Regulation of multidrug resistance protein 1 by tumor necrosis factor alpha in cultured glial cells: involvement of nuclear factor-kappaB and c-Jun N-terminal kinase signaling pathways.
abstract: Pharmacotherapy of brain HIV-1 infection may be limited by ABC transporters [i.e., P-glycoprotein (P-gp), multidrug resistance protein 1 (Mrp1)] that export antiretroviral drugs from HIV-1 brain cellular targets (i.e., astrocytes, microglia). Using an in vitro astrocyte model of an HIV-1 associated inflammatory response, our laboratory has shown that cytokines [i.e., tumor necrosis factor alpha (TNF-alpha), interleukin (IL)-1 beta, IL-6], which are secreted in response to HIV-1 envelope glycoprotein gp120 exposure, can decrease P-gp functional expression; however, it is unknown whether these same cytokines can alter expression and/or activity of other ABC transporters (i.e., Mrp1). In primary cultures of rat astrocytes, Mrp1 expression was increased by TNF-alpha (2.7-fold) but was not altered by IL-1 beta or IL-6. Cellular retention of 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein, an Mrp substrate, was reduced in TNF-alpha-treated astrocytes, suggesting increased Mrp-mediated transport. Pharmacologic inhibition of nuclear factor-kappaB (NF-kappaB) signaling with SN50 prevented both TNF-alpha release and Mrp1 expression changes in astrocytes triggered with gp120; however, SN50 did not attenuate Mrp1 expression in cells triggered with TNF-alpha. In contrast, Mrp1 functional expression was not altered in the presence of gp120 or TNF-alpha when astrocyte cultures were pretreated with 1,9-pyrazoloanthrone (SP600125), an established c-Jun N-terminal kinase (JNK) inhibitor. SP600125 did not affect TNF-alpha release from cultured astrocytes triggered with gp120. Mrp1 mRNA expression was increased after treatment with gp120 (1.6-fold) or TNF-alpha (1.7-fold), suggesting altered Mrp1 gene transcription. These data suggest that gp120 and TNF-alpha can up-regulate Mrp1 expression in cultured astrocytes. Furthermore, our results imply that both NF-kappaB and JNK signaling are involved in Mrp1 regulation during an HIV-1 associated inflammatory response.
authors.affiliation: Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, ON, Canada.
authors.forename: Patrick T
authors.initials: PT
authors.lastname: Ronaldson
authors.forename: Tamima
authors.initials: T
authors.lastname: Ashraf
authors.forename: Reina
authors.initials: R
authors.lastname: Bendayan
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000378:metabolism*; D002478:Cells, Cultured; D015699:HIV Envelope Protein gp120 / Q000494:pharmacology; D015497:HIV-1 / Q000472:pathogenicity; D006367:HeLa Cells; D006801:Humans; D053583:Interleukin-1beta / Q000494:pharmacology; D015850:Interleukin-6 / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases / Q000502:physiology*; D020935:MAP Kinase Signaling System / Q000502:physiology*; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000032:analysis / Q000235:genetics*; D016328:NF-kappa B / Q000502:physiology*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D015699:HIV Envelope Protein gp120; D053583:Interleukin-1beta; D015850:Interleukin-6; D048031:JNK Mitogen-Activated Protein Kinases; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D016328:NF-kappa B; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; C514793:gp120 protein, Human immunodeficiency virus 1; C421109:multidrug resistance-associated protein 1