Antisense to MDR1 mRNA reduces P-glycoprotein expression, swelling-activated C1- current and volume regulation in bovine ciliary epithelial cells.
Native ciliary epithelial cells from the ciliary epithelium of the eye exhibit anti-P-glycoprotein (P-gp) immunofluorescence. We have used an antisense 'knock-down' approach to investigate the relationship between P-gp and the volume-activated chloride current (IC1,swell) and its role in volume regulation. An antisense oligonucleotide to the human multidrug resistance (MDR1) gene, taken up by the cells in a dose-dependent manner, reduced P-gp immunofluorescence, inhibited IC1,swell and significantly increased the latency of activation of IC1,swell. Increasing the hypotonic stress did not result in an increased activation of ICl,swell. MDR1 antisense 'knock-down' also reduced the ability of the cells to volume regulate following a hypotonic challenge. These cells are known to express at least two volume-activated chloride channels, and the data suggest that P-gp is involved in the activation pathway of a subset of channels that contribute to whole-cell IC1,swell and participate in volume regulation.
School of Molecular and Medical Biosciences, University of Wales, Cardiff CF1 3US, UK.
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D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics*; D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D002712:Chlorides / Q000378:metabolism*; D002923:Cilia / Q000502:physiology*; D004847:Epithelial Cells / Q000187:drug effects / Q000502:physiology*; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D007038:Hypotonic Solutions; D008564:Membrane Potentials; D020319:Oligodeoxyribonucleotides, Antisense / Q000493:pharmacokinetics / Q000494:pharmacology*; D018408:Patch-Clamp Techniques; D012333:RNA, Messenger / Q000235:genetics*
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D002712:Chlorides; D007038:Hypotonic Solutions; D020319:Oligodeoxyribonucleotides, Antisense; D012333:RNA, Messenger