title: Expression of ATP-binding cassette membrane transporters in rodent and human sertoli cells: relevance to the permeability of antiretroviral therapy at the blood-testis barrier.
abstract: The blood-testis barrier (BTB), composed primarily of Sertoli cells, is responsible for protecting developing germ cells from xenobiotic exposure. ATP-binding cassette (ABC) membrane-associated drug efflux transporters, P-glycoprotein (P-gp), breast cancer resistance protein (BCRP), and the multidrug resistance-associated proteins (Mrps), have been shown to restrict antiretroviral drug permeability at blood-tissue barriers such as the blood-brain barrier. However, it remains unclear whether these transporters are functional at the level of Sertoli cells and can regulate anti-HIV drug permeability at the BTB. This study investigated the functional expression of ABC transporters in a mouse Sertoli cell line system (TM4) and in primary cultures of human Sertoli cells (HSECs). Expression of multidrug resistance Mdr1a/1b/MDR1/P-gp, Mrp1/MRP1, and Mrp4/MRP4 is confirmed by quantitative polymerase chain reaction and immunoblotting analysis in TM4 cells and HSECs. Immunofluorescence studies revealed plasma membrane localization of P-gp, Mrp1/MRP1, and Mrp4/MRP4 in both cell systems. However, Bcrp expression and localization was only detected in rodent cells. Accumulation of 1) rhodamine-6G (R-6G), a fluorescent P-gp substrate, 2) [³H]atazanavir, a HIV protease inhibitor and known P-gp substrate, 3) 2'7'-bis-(2-carboxyethyl)-5-(and-6)carboxyfluorescein (BCECF), a fluorescent Mrp substrate, and 4) [³H]mitoxantrone, a BCRP substrate, by TM4 monolayer cells in the presence of established inhibitors demonstrates that these transporters are functional. In addition, several anti-HIV drugs significantly enhance the accumulation of R-6G, [³H]atazanavir, BCECF, and [³H]mitoxantrone by TM4 cells. This study provides the first evidence of ABC transporter expression and activity in Sertoli cells and suggests that these transporters could play an important role in restricting antiretroviral drug permeability at the BTB.
authors: Graduate Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada.
authors: Kevin R
authors: KR
authors: Robillard
authors: Tozammel
authors: T
authors: Hoque
authors: Reina
authors: R
authors: Bendayan
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis / Q000235:genetics; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000096:biosynthesis* / Q000235:genetics; D000818:Animals; D019380:Anti-HIV Agents / Q000493:pharmacokinetics*; D001814:Blood-Testis Barrier / Q000187:drug effects*; D015153:Blotting, Western; D002460:Cell Line; D002478:Cells, Cultured; D018076:DNA, Complementary / Q000096:biosynthesis / Q000235:genetics; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000096:biosynthesis / Q000235:genetics; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000235:genetics; D010539:Permeability; D016133:Polymerase Chain Reaction; D012313:RNA / Q000096:biosynthesis / Q000302:isolation & purification; D012708:Sertoli Cells / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D019380:Anti-HIV Agents; D018076:DNA, Complementary; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D009363:Neoplasm Proteins; D012313:RNA; C073492:ABCC4 protein, human; C116614:ABCG2 protein, human; C421109:multidrug resistance-associated protein 1