title: Expression of multidrug resistance-associated protein (MRP) in human retinal pigment epithelial cells and its interaction with BAPSG, a novel aldose reductase inhibitor.
abstract: OBJECTIVE
  The objective of this study was to determine the expression and activity of multidrug resistance-associated protein (MRP) in the retinal pigment epithelial (RPE) cells and to further assess whether BAPSG, a novel anionic aldose reductase inhibitor, interacts with MRP.
  
  
  METHODS
  Functional and biochemical evidence for MRP was obtained in a human retinal pigment epithelial (ARPE-19) cell line and primary cultures of human retinal pigment epithelial (HRPE) cells. Fluorescein accumulation and efflux in the presence and absence of MRP inhibitors was used to obtain functional evidence for MRP. Western blots and RT-PCR were used to obtain biochemical evidence for MRP1. The influence of MRP inhibitors on BAPSG accumulation and efflux in ARPE-19 cells was determined to understand its interaction with MRP.
  
  
  RESULTS
  MRP inhibitors increased fluorescein accumulation and reduced efflux in RPE cells. Both cell types exhibited a 190-kDa western blot band corresponding to MRP1 protein and a 287 bp RT-PCR band corresponding to MRP1 mRNA. MRP inhibitors reduced BAPSG efflux and increased its accumulation in ARPE-19 cells.
  
  
  CONCLUSIONS
  MRP is functionally and biochemically active in human RPE cells. Anionic BAPSG is a likely substrate for MRP.
authors.affiliation: Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha 68198-6025, USA.
authors.forename: J V
authors.initials: JV
authors.lastname: Aukunuru
authors.forename: G
authors.initials: G
authors.lastname: Sunkara
authors.forename: N
authors.initials: N
authors.lastname: Bandi
authors.forename: W B
authors.initials: WB
authors.lastname: Thoreson
authors.forename: U B
authors.initials: UB
authors.lastname: Kompella
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis* / Q000378:metabolism; D000449:Aldehyde Reductase / Q000037:antagonists & inhibitors*; D000963:Antimetabolites / Q000494:pharmacology; D015153:Blotting, Western; D002460:Cell Line; D003080:Cold Temperature; D004791:Enzyme Inhibitors / Q000378:metabolism* / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D019793:Fluorescein / Q000737:chemistry; D005998:Glycine / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D007202:Indicators and Reagents; D010857:Pigment Epithelium of Eye / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013450:Sulfones / Q000378:metabolism* / Q000494:pharmacology; D013778:Tetrazolium Salts; D013844:Thiazoles
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000963:Antimetabolites; D004791:Enzyme Inhibitors; D007202:Indicators and Reagents; D012333:RNA, Messenger; D013450:Sulfones; D013778:Tetrazolium Salts; D013844:Thiazoles; C062604:N-(((4-benzoylamino)phenyl)sulfonyl)glycine; D000449:Aldehyde Reductase; C022616:thiazolyl blue; D005998:Glycine; D019793:Fluorescein