Functional implications of the influence of ABCA1 on lipid microenvironment at the plasma membrane: a biophysical study.
The ABCA1 transporter orchestrates cellular lipid homeostasis by promoting the release of cholesterol to plasmatic acceptors. The molecular mechanism is, however, unknown. We report here on the biophysical analysis in living HeLa cells of the ABCA1 lipid microenvironment at the plasma membrane. The modifications of membrane attributes induced by ABCA1 were assessed at both the outer and inner leaflet by monitoring either the lifetime of membrane inserted fluorescent lipid analogues by fluorescence lifetime imaging microscopy (FLIM) or, respectively, the membrane translocation of cationic sensors. Analysis of the partitioning of dedicated probes in plasma membrane blebs vesiculated from these cells allowed visualization of ABCA1 partitioning into the liquid disordered-like phase and corroborated the idea that ABCA1 destabilizes the lipid arrangement at the membrane. Specificity was demonstrated by comparison with cells expressing an inactive transporter. The physiological relevance of these modifications was finally demonstrated by the reduced membrane mobility and function of transferrin receptors under the influence of an active ABCA1. Collectively, these data assess that the control of both transversal and lateral lipid distribution at the membrane is the primary function of ABCA1 and positions the effluxes of cholesterol from cell membranes downstream to the redistribution of the sterol into readily extractable membrane pools.
Zarubica
Ana
A
Centre d'Immunologie de Marseille Luminy, Institut National de la Santè et de la Recherche Médicale, Centre National de la Recherche Scientifique, Université de la Méditerranée, Parc Scientifique de Luminy case 906, 13288 Marseille, Cedex 09 France.
Plazzo
Anna Pia
AP
Stöckl
Martin
M
Trombik
Tomasz
T
Hamon
Yannick
Y
Müller
Peter
P
Pomorski
Thomas
T
Herrmann
Andreas
A
Chimini
Giovanna
G
D064286:ATP Binding Cassette Transporter 1; D018528:ATP-Binding Cassette Transporters / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D036681:Fluorescence Recovery After Photobleaching; D006367:HeLa Cells; D006801:Humans; D050356:Lipid Metabolism; D008055:Lipids / Q000737:chemistry*; D021962:Membrane Microdomains / Q000737:chemistry / Q000378:metabolism; D008564:Membrane Potentials / Q000502:physiology; D008856:Microscopy, Fluorescence / Q000379:methods; D008969:Molecular Sequence Data; D011990:Receptors, Transferrin / Q000378:metabolism
C577836:ABCA1 protein, human; D064286:ATP Binding Cassette Transporter 1; D018528:ATP-Binding Cassette Transporters; D008055:Lipids; D011990:Receptors, Transferrin