Goebel Jens, Forrest Kathy, Morford Lorri, Roszman Thomas L
Department of Pediatrics, Section of Pediatric Nephrology, Kentucky Clinic Building, University Medical Center, University of Kentucky, Lexington, KY 40536-0284, USA.
J Leukoc Biol. 2002 Jul;72(1):199-206.
We studied whether cytokine receptors (Rs) on T cells associate with lipid microdomains ("rafts"). Low-dose phytohemagglutinin (PHA)-stimulated human T cells were separated into cytoplasmic, membrane, and raft fractions by buoyant density centrifugation. Examination of these fractions for the presence of interleukin (IL)-2- and -15R chains and associated signaling molecules by Western blotting revealed marked, selective enrichment of the IL-2/15R beta-chain in rafts before IL-2 stimulation. After IL-2 stimulation, a substantial amount of the beta-chain was found in the membrane fraction. This partial translocation was also observed for the beta-chain-associated molecules JAK-1, p56(lck), and grb-2. Finally, raft disruption with methyl-beta-cyclodextrin (MBCD) attenuated IL-2-induced tyrosine phosphorylation events and selectively decreased the surface expression of the IL-2/15R beta-chain detected by flow cytometry. These results show that the IL-2/15R beta-chain is enriched in rafts obtained from low-dose, PHA-stimulated T cells, that IL-2 binding alters this enrichment, and that this enrichment may be functionally relevant as a possible mechanism to ensure cytokine selectivity and specificity.
我们研究了T细胞上的细胞因子受体（Rs）是否与脂质微区（“筏”）相关联。通过浮力密度离心将低剂量植物血凝素（PHA）刺激的人T细胞分离为细胞质、膜和筏组分。通过蛋白质免疫印迹法检测这些组分中白细胞介素（IL）-2和-15R链以及相关信号分子的存在，结果显示在IL-2刺激之前，筏中IL-2/15Rβ链有显著的选择性富集。IL-2刺激后，在膜组分中发现了大量的β链。β链相关分子JAK-1、p56(lck)和grb-2也观察到了这种部分易位。最后，用甲基-β-环糊精（MBCD）破坏筏减弱了IL-2诱导的酪氨酸磷酸化事件，并选择性降低了通过流式细胞术检测到的IL-2/15Rβ链的表面表达。这些结果表明，IL-2/15Rβ链在从低剂量PHA刺激的T细胞获得的筏中富集，IL-2结合改变了这种富集，并且这种富集可能在功能上相关，作为确保细胞因子选择性和特异性的一种可能机制。
