Geldanamycin treatment ameliorates the response to LPS in murine macrophages by decreasing CD14 surface expression
Geldanamycin treatment ameliorates the response to LPS in murine macrophages by decreasing CD14 surface expression
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DOI：
10.1091/mbc.e02-08-0498
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发表时间：
2003-02-01
影响因子：
3.3
通讯作者：
De Maio, A
中科院分区：
文献类型：
--
作者：
Vega, VL;De Maio, A
格尔达霉素（GA）是一种由放线菌产生的抗生素，它能特异性抑制热休克蛋白90家族的功能。用GA处理小鼠巨噬细胞系（J774）导致对大肠杆菌脂多糖（LPS）的反应降低，这可以通过NF-kappaB转运到细胞核和肿瘤坏死因子a （tnf - α）的分泌减少来观察。为了阐明这种作用的机制，我们分析了正式LPS受体CD14的表达。免疫染色显示，经GA处理的细胞表面CD14水平降低，而其他表面受体，如fc - γ受体和肿瘤坏死因子受体（TNF-R1和TNF-R2）的表达不受影响。CD14表面水平的降低不是由于其表达的减少，因为GA处理没有改变CD14稳态mRNA水平或CD14的总细胞池。与环己亚胺孵育相比，GA处理（2-3 h）能更快地内化表面CD14。GA处理后通透化细胞的免疫染色显示，细胞内CD14与内质网（ER）蛋白calnexin共定位的含量较高。这些结果表明，GA处理后CD14表面表达的下降是由于快速内化而没有新的替代。这些作用可能是由于巨噬细胞中GA对Hsp90和Grp94的抑制作用。
Geldanamycin (GA) is an antibiotic produced by Actinomyces, which specifically inhibits the function of the heat shock protein 90 family. Treatment of a murine macrophage cell line (J774) with GA resulted in a reduced response to Escherichia coli lipopolysaccharide (LPS) as visualized by a decrease of NF-kappaB translocation into the nucleus and secretion of tumor necrosis factor a (TNF-alpha). To elucidate the mechanism of this effect, the expression of CD14, the formal LPS receptor, was analyzed. Cells treated with GA showed a reduced level of surface CD14 detected by immunostaining, whereas the expression of other surface receptors, such as FC-gamma receptor and tumor necrosis factor receptors (TNF-R1 and TNF-R2), was unaffected. The reduced surface level of CD14 was not due to a reduction in its expression because CD14 steady state mRNA levels or the total cellular pool of CD14 was not altered by GA treatment. Surface CD14 was more rapidly internalized after GA treatment (2-3 h) than after incubation with cycloheximide. Immunostaining of permeabilized cells after GA treatment revealed a higher intracellular content of CD14 colocalizing with calnexin, an endoplasmic reticulum (ER) protein. These results suggest that the decrease in CD14 surface expression after GA treatment is due to rapid internalization without new replacement. These effects may be due to the inhibition of Hsp90 and Grp94 by GA in macrophages.