The Extracellular Domain of the β2 Integrin β Subunit (CD18) Is Sufficient for Escherichia coli Hemolysin and Aggregatibacter actinomycetemcomitans Leukotoxin Cytotoxic Activity.
The Extracellular Domain of the β2 Integrin β Subunit (CD18) Is Sufficient for Escherichia coli Hemolysin and Aggregatibacter actinomycetemcomitans Leukotoxin Cytotoxic Activity.
复制标题
β2 整合素 β 亚基 (CD18) 的胞外域足以发挥大肠杆菌溶血素和 Aggregatibacter actinomycetemcomitans 白毒素细胞毒性活性。
DOI：
10.1128/mbio.01459-19
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发表时间：
2019
期刊：
影响因子：
6.4
通讯作者：
Welch,RodneyA
中科院分区：
文献类型：
--
作者：
Ristow,LauraC;Tran,Vy;Schwartz,KevinJ;Pankratz,Lillie;Mehle,Andrew;Sauer,John-Demian;Welch,RodneyA
大肠杆菌溶血素（HlyA）是一种与人类尿路感染严重并发症相关的致孔外毒素。HlyA是毒素重复序列（RTX）家族的原型，该家族包括来自牙周病原体伴放线菌聚集杆菌（Aggregatibacteractinomycetemcomitans）的LtxA。这些毒素的宿主细胞受体的存在和要求是有争议的。我们在人单核细胞U-937的突变体库中进行了无偏正向遗传选择，以寻找参与HlyA细胞毒性的宿主因子。β 2整合素β亚基是最佳候选者。Δ β 2细胞系对HlyA的抗性比野生型U-937细胞高约100倍，但在高浓度下仍对HlyA敏感。类似地，Δ β 2细胞比野生型U-937细胞对LtxA更具抗性，因为Δ β 2细胞即使在> 1，000倍的毒素浓度下也保持LtxA抗性。任何一个β 2整合素α亚基的缺失，甚至所有四个α亚基的缺失，都不会产生对HlyA的耐药性。HlyA和LtxA与β 2亚基结合，但不与α L、α M或α Xin结合。在Δ β 2细胞中，β 2或β 2胞质尾缺失的遗传互补恢复了HlyA和LtxA的敏感性，表明β 2整合素信号传导不是细胞毒性所必需的。最后，β 2突变不会改变对无关的成孔毒素的敏感性，因为野生型或Δ β 2细胞对金黄色葡萄球菌α毒素和奇异变形杆菌HpmA同样敏感。我们的研究表明，两种RTX毒素单独利用β 2整合素β亚基促进细胞毒性，但下游整合素信号传导是不稳定的。重要提示尿路感染是世界范围内最常见的细菌感染之一。尿路致病性大肠杆菌菌株是导致超过80%的社区获得性尿路感染的原因。虽然我们已经知道近世纪，严重的感染源于尿路感染，包括肾脏或血液感染与表达的毒素，溶血素，从尿路致病性大肠杆菌，溶血素的功能，以提高毒力是未知的。我们的研究确定溶血素与β 2整合素（一种人类白色细胞粘附分子）的相互作用是尿路感染的潜在治疗靶点。急诊大肠杆菌溶血素是由多种人类和动物病原体产生的毒素家族（RTX家族）的原型。我们的工作扩展到RTX家族的另一个成员的受体的鉴定和表征，表明这种相互作用可能在整个RTX毒素家族中广泛保守。
The Escherichia coli hemolysin (HlyA) is a pore-forming exotoxin associated with severe complications of human urinary tract infections. HlyA is the prototype of the repeats-in-toxin (RTX) family, which includes LtxA from Aggregatibacter actinomycetemcomitans, a periodontal pathogen. The existence and requirement for a host cell receptor for these toxins are controversial. We performed an unbiased forward genetic selection in a mutant library of human monocytic cells, U-937, for host factors involved in HlyA cytotoxicity. The top candidate was the β2integrin β subunit. Δβ2cell lines are approximately 100-fold more resistant than wild-type U-937 cells to HlyA, but remain sensitive to HlyA at high concentrations. Similarly, Δβ2cells are more resistant than wild-type U-937 cells to LtxA, as Δβ2cells remain LtxA resistant even at >1,000-fold-higher concentrations of the toxin. Loss of any single β2integrin α subunit, or even all four α subunits together, does not confer resistance to HlyA. HlyA and LtxA bind to the β2subunit, but not to αL, αM, or αXin far-Western blots. Genetic complementation of Δβ2cells with either β2or β2with a cytoplasmic tail deletion restores HlyA and LtxA sensitivity, suggesting that β2integrin signaling is not required for cytotoxicity. Finally, β2mutations do not alter sensitivity to unrelated pore-forming toxins, as wild-type or Δβ2cells are equally sensitive to Staphylococcus aureus α-toxin and Proteus mirabilis HpmA. Our studies show two RTX toxins use the β2integrin β subunit alone to facilitate cytotoxicity, but downstream integrin signaling is dispensable.IMPORTANCEUrinary tract infections are one of the most common bacterial infections worldwide. Uropathogenic Escherichia coli strains are responsible for more than 80% of community-acquired urinary tract infections. Although we have known for nearly a century that severe infections stemming from urinary tract infections, including kidney or bloodstream infections are associated with expression of a toxin, hemolysin, from uropathogenic Escherichia coli, how hemolysin functions to enhance virulence is unknown. Our research defines the interaction of hemolysin with the β2integrin, a human white cell adhesion molecule, as a potential therapeutic target during urinary tract infections. The E. coli hemolysin is the prototype for a toxin family (RTX family) produced by a wide array of human and animal pathogens. Our work extends to the identification and characterization of the receptor for an additional member of the RTX family, suggesting that this interaction may be broadly conserved throughout the RTX toxin family.