Acid sphingomyelinase is required for lipid Raft TLR4 complex formation.
Acid sphingomyelinase is required for lipid Raft TLR4 complex formation.
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DOI：
10.1089/sur.2006.050
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发表时间：
2007-02-01
影响因子：
2
通讯作者：
Maier, Ronald V
中科院分区：
文献类型：
--
作者：
Cuschieri, Joseph;Bulger, Eileen;Maier, Ronald V
背景技术背景：脂筏由鞘脂组成，在脂多糖（LPS）暴露期间由于磷酸激酶C（PKC）-zeta激活而对Toll样受体4（TLR 4）组装至关重要。目的：研究LPS诱导的TLR 4的组装和激活是否依赖于脂多糖（LPS）与CD 14结合后酸性鞘磷脂酶产生的鞘脂代谢产物神经酰胺。方法：用LPS、外源性C（2）神经酰胺或两者联合刺激培养的THP-1细胞。选择的细胞进行预处理与酸性鞘磷脂酶抑制剂丙咪嗪或CD 14中和antibody.RESULTS：暴露于LPS导致激活的酸性鞘磷脂酶，神经酰胺的生产，磷酸化PKCzeta，和组装的TLR 4受体内脂筏。随后是MAPK家族产物的激活和肿瘤坏死因子-α的释放。丙咪嗪或CD 14阻断预处理与所有这些LPS诱导的事件的衰减相关。C2神经酰胺和LPS同时处理可逆转丙咪嗪诱导的所有抑制作用，但不能逆转阻断CD 14诱导的抑制作用.结论：LPS与CD 14结合后TLR 4受体的组装和激活需要酸性鞘磷脂酶产生神经酰胺.
BACKGROUND: Lipid rafts, composed of sphingolipids, are critical to Toll-like receptor 4 (TLR4) assembly during lipopolysaccharide (LPS) exposure as a result of phosphokinase C (PKC)-zeta activation. However, the mechanism responsible for these events remains unknown.PURPOSE: We determined whether LPS-induced TLR4 assembly and activation are dependent on the sphingolipid metabolite ceramide, produced by acid sphingomyelinase following the initial binding of LPS to CD14.METHODS: Cultured THP-1 cells were stimulated with LPS, exogenous C(2) ceramide, or both. Selected cells were pretreated with the acid sphingomyelinase inhibitor imipramine or CD14 neutralizing antibody.RESULTS: Exposure to LPS led to activation of acid sphingomyelinase, production of ceramide, phosphorylation of PKCzeta, and assembly of the TLR4 receptor within lipid rafts. This was followed by activation of the MAPK family of products and the liberation of tumor necrosis factor-alpha. Pretreatment with imipramine or CD14 blockade was associated with attenuation of all of these LPS-induced events. Simultaneous treatment with C(2) ceramide and LPS reversed all the inhibitory effects induced by imipramine, but not those associated with CD14 blockade.CONCLUSION: Assembly and activation of the TLR4 receptor following LPS binding to CD14 requires the production of ceramide by acid sphingomyelinase.