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The multidrug resistance-associated protein transporter ABCC1 (MRP1) is an integral plasma membrane protein involved in the multidrug resistance phenotype. It actively expels a number of cytotoxic molecules from cells. To gain insight into the modulation of the functional properties of this integral membrane protein by cholesterol, a main component of the lipid bilayer, we used multidrug-resistant GLC4⁄ADR cells, | ễFEBS Journal Perturbation of membrane microdomains in GLC4 multidrug-resistant lung cancer cells - modification of ABCC1 MRP1 localization and functionality Carole Marbeuf-Gueye Verene Stierle Paiwan Sudwan Milena Salerno and Arlette Garnier-Suillerot Laboratoire Biophysique Moleculaire Cellulaire et Tissulaire BioMoCeTi UMR CNRS 7033 Universite Paris 13 et Paris 6 Bobigny France Keywords ABCC1 functionality ABCC1 localization membrane cholesterollevel multidrug resistance raft Correspondence M. Salerno Laboratoire BioMoCeTi CNRS UMR 7033 UFR SMBH 74 rue Marcel Cachin 93017 Bobigny Cedex France Fax 33 1 48 38 88 88 Tel 33 1 48 38 77 48 E-mail m.salerno@smbh.univ-paris13.fr Received 20 November 2006 revised 20 December 2006 accepted 10 January 2007 doi 10.1111 j.1742-4658.2007.05688.x The multidrug resistance-associated protein transporter ABCC1 MRP1 is an integral plasma membrane protein involved in the multidrug resistance phenotype. It actively expels a number of cytotoxic molecules from cells. To gain insight into the modulation of the functional properties of this integral membrane protein by cholesterol a main component of the lipid bilayer we used multidrug-resistant GLC4 ADR cells which overexpress MRP1. Upon altering the plasma membrane cholesterol content of these cells membrane localization and the activity of MRP1 were analyzed. A detergent-free methodology was used to separate light and heavy plasma membrane fractions. Our data show that MRP1 was exclusively found in light fractions known as L0 phase membrane microdomains together with 23 of gangliosides GM1 and 40 of caveolin-1. Depletion of the membrane cholesterol level to 40 by treatment with the cholesterol-chelating agent methyl-b-cyclodextrin did not modify MRP1 activity as evidenced either by the rate of efflux of pirarubicin or that of glutathione. Further cholesterol depletion below 40 yielded both a partial shift of MRP1 to the high-density fraction and a decrease of its functionality. Taken
