Repression of rac2 mRNA expression by Anaplasma phagocytophila is essential to the inhibition of superoxide production and bacterial proliferation
Repression of rac2 mRNA expression by Anaplasma phagocytophila is essential to the inhibition of superoxide production and bacterial proliferation
复制标题
DOI：
10.4049/jimmunol.169.12.7009
复制
发表时间：
2002-12-15
影响因子：
4.4
通讯作者：
Fikrig, E
中科院分区：
文献类型：
--
作者：
Carlyon, JA;Chan, WT;Fikrig, E
人粒细胞埃立克体病的病原体无浆体吞噬细胞病是一种侵袭中性粒细胞的新型细菌病原体，可在HL-60细胞中培养。感染的中性粒细胞和HL-60细胞不能产生超氧阴离子(O-2(-))，这部分归因于吞噬假单胞菌抑制Gp91(Phox)的转录，gp91是NADPH氧化酶的组成部分。基因芯片和RT-PCR分析表明，在感染的HL-60细胞中，编码NADPH氧化酶活性的关键成分rac2基因的转录水平下调。定量RT-PCR结果显示，在维甲酸诱导分化的HL-60细胞中，Rac2mRNA的表达降低了7倍，在中性粒细胞中的表达降低了50倍。感染的HL-60细胞不表达rac2蛋白。在激活NADPH氧化酶的能力上，rac1和rac2是可以互换的。表达CMV即刻早期启动子myc标记的rac1和gp91(Phox)的HL-60细胞在感染120h后仍能产生O-2(-)。吞噬细胞的增殖在这些细胞中受到严重抑制。这些结果直接将rac2和gp91(Phox)转录的抑制归因于吞噬弧菌感染细胞中NADPH氧化酶活性的丧失，并证明了NADPH对细菌细胞内生存的重要性。
Anaplasma phagocytophila, the etiologic agent of human granulocytic ehrlichiosis, is an emerging bacterial pathogen that invades neutrophils and can be cultivated in HL-60 cells. Infected neutrophils and HL-60 cells fail to produce superoxide anion (O-2(-)), which is partially attributable to the fact that A. phagocytophila inhibits transcription of gp91(phox), an integral component of NADPH oxidase. cDNA microarray and RT-PCR analyses demonstrated that transcription of the gene encoding Rac2, a key component in NADPH oxidase activation, was down-regulated in infected HL-60 cells. Quantitative RT-PCR demonstrated that rac2 mRNA expression was reduced 7-fold in retinoic acid-differentiated HL-60 cells and 50-fold in neutrophils following A. phagocytophila infection. Rac2 protein expression was absent in infected HL-60 cells. Rac1 and Rac2 are interchangeable in their abilities to activate NADPH oxidase. HL-60 cells transfected to express myc-tagged rac1 and gp91(phox) from the CMV immediate early promoter maintained the ability to generate O-2(-) 120 h postinfection. A. phagocytophila proliferation was severely inhibited in these cells. These results directly attribute the inhibition of rac2 and gp91(phox) transcription to the loss of NADPH oxidase activity in A. phagocytophila-infected cells and demonstrate its importance to bacterial intracellular survival.