Extensive sphingolipid depletion does not affect lipid raft integrity or lipid raft localization and efflux function of the ABC transporter MRP1

Karin Klappe , Anne-Jan Dijkhuis , Ina Hummel , Annie van Dam , Pavlina T Ivanova , Stephen B Milne , David S Myers , H Alex Brown , Hjalmar Permentier , Jan W Kok (1)

1 Cell Biology

We show that highly efficient depletion of sphingolipids in two different cell lines does not abrogate the ability to isolate lubrol-based detergent-resistant membranes (DRMs) or detergent-free lipid rafts from these cells. Compared to control, DRM/detergent-free lipid raft fractions contain equal amounts of protein, cholesterol and phospholipid, while the classical DRM/lipid raft markers Src, caveolin-1 (Cav-1) and flotillin display the same gradient distribution. DRMs/detergent-free lipid rafts themselves are severely depleted of sphingolipids. The fatty acid profile of the remaining sphingolipids as well as that of the glycerophospholipids shows several differences compared to control, most prominently an increase of highly saturated C16 species. The glycerophospholipid headgroup composition is unchanged in sphingolipid depleted cells and cell-derived detergent-free lipid rafts. Sphingolipid depletion does not alter the localization of multidrug resistance-related protein 1 (MRP1) in DRMs/detergent-free lipid rafts or MRP1-mediated efflux of carboxyfluorescein. We conclude that extensive sphingolipid depletion does not affect lipid raft integrity in two cell lines and does not affect the function of the lipid raft-associated protein MRP1.

Mots clés: Life Sciences

Karin Klappe, Anne-Jan Dijkhuis, Ina Hummel, Annie van Dam, Pavlina T Ivanova, et al.. Extensive sphingolipid depletion does not affect lipid raft integrity or lipid raft localization and efflux function of the ABC transporter MRP1. Biochemical Journal, 2010, 430 (3), pp.519-529. ⟨10.1042/BJ20091882⟩. ⟨hal-00512004⟩