Rouquette-Jazdanian Alexandre K, Pelassy Claudette, Breittmayer Jean-Philippe, Aussel Claude
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.
Cell Signal. 2006 Jan;18(1):105-22. doi: 10.1016/j.cellsig.2005.03.024. Epub 2005 May 31.
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.
T淋巴细胞含有两个可被甲基-β-环糊精（m-β-CD）提取胆固醇的动力学池：一个快速池（31.5%，半衰期=17秒）和一个缓慢池（68.5%，半衰期=15分钟）。耐去污剂膜（DRM）的纯化表明，快速池对应于漂浮胆固醇。快速池的胆固醇提取（即来自脂筏的胆固醇）仍能使信号蛋白保持漂浮状态，并在CD3刺激下发生磷酸化。缓慢池的胆固醇耗竭（即来自脂筏以外膜的胆固醇）伴随着整个脂筏的提取，随后抑制CD3诱导的酪氨酸磷酸化。胆固醇氧化酶（COase）可使脂筏胆固醇特异性氧化为胆甾烯酮。胆甾烯酮离开DRM并作为Triton X-100可溶性物质积累。COase对富含胆固醇的脂筏进行特异性破坏不会抑制Jurkat细胞或T CD4+淋巴细胞的激活。我们的研究对富含胆固醇的脂筏在CD3/TCR信号传导中的实际作用提出了质疑，并表明一种胆固醇含量低的脂筏亚型参与了通过TCR的信号传递。
