Revaluation of the role of cholesterol in stabilizing rafts implicated in T cell receptor signaling.
T lymphocytes contain two kinetic pools of cholesterol extractable with methyl-beta-cyclodextrin (m-beta-CD): a fast pool (31.5%, t1/2=17 s) and a slow pool (68.5%, t1/2=15 min). Purification of detergent-resistant membranes (DRMs) shows that the fast pool corresponds to buoyant cholesterol. Cholesterol extraction of the fast pool (i.e. cholesterol from rafts) still allows the buoyancy of signaling proteins and their phosphorylation under CD3 stimulation. Cholesterol depletion of the slow pool (i.e. cholesterol from membranes other than rafts) is accompanied by the extraction of the whole raft followed by the inhibition of CD3-induced tyrosine-phosphorylations. Cholesterol oxidase (COase) allows a specific oxidation of raft cholesterol into cholestenone. Cholestenone leaves the DRMs and accumulates as Triton X-100-soluble material. Specific cholesterol-rich raft disruption by COase does not inhibit the activation of either Jurkat cells or T CD4+ lymphocytes. Our study challenges the real role of cholesterol-rich rafts in CD3/TCR signaling and suggests that a cholesterol-poor subtype of rafts is involved in signal transmission via the TCR.
Rouquette-Jazdanian
Alexandre K
AK
Institut National de la Santé et de la Recherche Médicale (INSERM) Unit 576, IFR 50, Hôpital de l'Archet I, 151 Route de Saint Antoine de Ginestière, B.P. 79, 06202 Nice Cedex 3, France.
Pelassy
Claudette
C
Breittmayer
Jean-Philippe
JP
Aussel
Claude
C
D000328:Adult; D017252:CD3 Complex / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects / Q000502:physiology*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002784:Cholesterol / Q000378:metabolism / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D019169:Jurkat Cells; D021962:Membrane Microdomains / Q000187:drug effects / Q000502:physiology*; D010084:Oxidation-Reduction; D051966:Phospholipase C gamma / Q000378:metabolism; D010766:Phosphorylation; D011948:Receptors, Antigen, T-Cell / Q000187:drug effects / Q000502:physiology*; D012016:Reference Values; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors; D014443:Tyrosine / Q000378:metabolism; D047392:beta-Cyclodextrins / Q000494:pharmacology
D017252:CD3 Complex; D011948:Receptors, Antigen, T-Cell; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D014443:Tyrosine; D002784:Cholesterol; D051966:Phospholipase C gamma