Saban Research Institute of Childrens Hospital Los Angeles, Department of Pediatrics, University of Southern California, USA.
Future Microbiol. 2011 Aug;6(8):953-66. doi: 10.2217/fmb.11.65.
We investigate how the α7 nicotinic acetylcholine receptor (α7 nAChR), an essential regulator of inflammation, contributes to the α7 agonist nicotine-enhanced Escherichia coli K1 invasion of human brain microvascular endothelial cells (HBMECs) through lipid rafts/caveolae-mediated signaling.
MATERIALS & METHODS: α7 nAChR-mediated signaling and bacterial invasion were defined by lipid raft fractionation, immunofluorescence microscopy and siRNA knockdown.
Nicotine-enhanced bacterial invasion was dose-dependently inhibited by two raft-disrupting agents, nystatin and filipin. Significant accumulation of the lipid raft marker GM3 was observed in HBMEC induced by E. coli K1 and nicotine. The recruitment of α7 nAChR and related signaling molecules, including vimentin, and Erk1/2, to caveolin-1 enriched lipid rafts was increased upon treatment with E44 or E44 plus nicotine. Erk1/2 activation (phosphorylation), which is required for α7 nAChR-mediated signaling and E44 invasion, was associated with lipid rafts and nicotine-enhanced bacterial infection. Furthermore, E44 invasion, E44/nicotine-induced activation of Erk1/2 and clustering of α7 nAChR and caveolin-1 was specifically blocked by both siRNAs.
α7 nAChR-mediated signaling through lipid rafts/caveolae is required for nicotine-enhanced E. coli K1 invasion of HBMEC.
我们研究了α7 烟碱型乙酰胆碱受体（α7 nAChR）作为炎症的重要调节剂，如何通过脂筏/小窝介导的信号通路促进α7 激动剂尼古丁增强的大肠杆菌 K1 侵袭人脑微血管内皮细胞（HBMEC）。
通过脂筏分离、免疫荧光显微镜和 siRNA 敲低来定义 α7 nAChR 介导的信号转导和细菌侵袭。
两种破坏脂筏的试剂——制霉菌素和 Filipin，可剂量依赖性地抑制尼古丁增强的细菌侵袭。大肠杆菌 K1 和尼古丁诱导的 HBMEC 中观察到脂质筏标志物 GM3 的显著积累。用 E44 或 E44 加尼古丁处理后，α7 nAChR 和相关信号分子（包括波形蛋白和 Erk1/2）向富含 caveolin-1 的脂筏募集增加。α7 nAChR 介导的信号转导和 E44 侵袭所需的 Erk1/2 激活（磷酸化）与脂筏和尼古丁增强的细菌感染有关。此外，E44 侵袭、E44/尼古丁诱导的 Erk1/2 激活以及 α7 nAChR 和 caveolin-1 的聚集，均被两种 siRNA 特异性阻断。
通过脂筏/小窝的α7 nAChR 介导的信号转导是尼古丁增强大肠杆菌 K1 侵袭 HBMEC 所必需的。
