CCR5 internalisation and signalling have different dependence on membrane lipid raft integrity
CCR5 internalisation and signalling have different dependence on membrane lipid raft integrity
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DOI：
10.1016/j.cellsig.2008.05.014
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发表时间：
2008-09-01
影响因子：
4.8
通讯作者：
Mueller, Anja
中科院分区：
文献类型：
--
作者：
Cardaba, Clara Moyano;Kerr, Jason S.;Mueller, Anja
趋化因子受体CCR5是人类免疫缺陷病毒进入细胞的共同受体。CCR5已被证明是以富含胆固醇和鞘磷脂的膜微域为靶点，称为脂筏或小窝。胆固醇是CCL4与CCR5结合和保持受体构象完整性所必需的。Filipin治疗会导致小窝蛋白-1从膜上丢失，从而导致小窝的崩溃。我们在这里发现，膜胆固醇与非利磷脂的隔离并不影响受体信号传递，但观察到了配体诱导的CCR5内化的丢失。用甲基-β-环糊精(MCD)提取的胆固醇减少了通过CCR5的信号传递(通过细胞内钙离子的释放来衡量)，并完全取消了对Forsklin刺激的cAMP积累的抑制，而对内化没有影响。百日咳毒素(PTX)可抑制通过GOD G蛋白转导的细胞内钙释放。胆固醇的耗尽破坏了细胞膜上的微区，并将CCR5/G蛋白偶联转换为PTX不依赖的G蛋白。我们的结论是，膜上的胆固醇是通过GαI G蛋白亚基传递CCR5信号所必需的，而脂筏的完整性并不是有效地内化CCR5所必需的，但它对于通过GαI G蛋白正确的CCR5信号转导是至关重要的。(C)2008 Elsevier Inc.保留所有权利。
The chemokine receptor, CCR5, acts as a co-receptor for human immunodeficiency virus entry into cells. CCR5 has been shown to be targeted to cholesterol- and sphingolipid-rich membrane microdomains termed lipid rafts or caveolae. Cholesterol is essential for CCL4 binding to CCR5 and for keeping the conformational integrity of the receptor. Filipin treatment leads to loss of caveolin-1 from the membrane and therefore to a collapse of the caveolae. We have found here that sequestration of membrane cholesterol with filipin did not affect receptor signalling, however a loss of ligand-induced internalisation of CCR5 was observed. Cholesterol extraction with methyl-beta-cyclodextrin (MCD) reduced signalling through CCR5 as measured by release of intraceltular Ca2+ and completely abolished the inhibition of forskolin-stimulated cAMP accumulation with no effect on internalisation. Pertussis toxin (PTX) treatment inhibited the intracellular release of calcium that is transduced via God G-proteins. Depletion of cholesterol destroyed microdomains in the membrane and switched CCR5/G-protein coupling to a PTX-independent G-protein. We conclude that cholesterol in the membrane is essential for CCR5 signalling via the G alpha i G-protein subunit, and that integrity of lipid rafts is not essential for effective CCR5 internalisation however it is crucial for proper CCR5 signal transduction via G alpha i G-proteins. (C) 2008 Elsevier Inc. All rights reserved.