SipA Activation of Caspase-3 Is a Decisive Mediator of Host Cell Survival at Early Stages of Salmonella enterica Serovar Typhimurium Infection.
SipA Activation of Caspase-3 Is a Decisive Mediator of Host Cell Survival at Early Stages of Salmonella enterica Serovar Typhimurium Infection.
复制标题
SipA 激活 Caspase-3 是肠沙门氏菌鼠伤寒血清型感染早期宿主细胞存活的决定性介质。
DOI：
10.1128/iai.00393-17
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发表时间：
2017-09
影响因子：
3.1
通讯作者：
Wall DM
中科院分区：
文献类型：
--
作者：
McIntosh A;Meikle LM;Ormsby MJ;McCormick BA;Christie JM;Brewer JM;Roberts M;Wall DM
沙门氏菌侵袭蛋白A(SIPA)是一种双重功能的效应蛋白，在肠上皮细胞的肌动蛋白聚合和caspase-3激活中发挥作用。到目前为止，尽管它在多种细胞类型中表达，并在感染过程中分泌细胞外，但它在其他细胞类型中的功能仍很不清楚。在这里，我们展示了在巨噬细胞中，SIPA在感染早期诱导caspase-3激活增加。这种激活需要与多种感染相关的SIPA的阈值水平，并且可能是控制受感染巨噬细胞中细菌数量的限制因素。在多形核白细胞中，SipA或其他沙门氏菌致病岛1效应物无论是单独还是在整个细菌存在的情况下都不影响caspase-3的激活。小分子荧光phiLOV标记SIPA，可以通过三型分泌系统，对SipA-phiLOV激活的巨噬细胞caspase-3进行可视化和定量。此外，在体外肠道模型中，可以通过多光子激光扫描显微镜跟踪caspase-3在肠道中的Sipa-phiLOV激活。这使得可以可视化肠上皮受损的区域，并展示了这种荧光标记在体内跟踪单个效应者的潜在用途。
Salmonella invasion protein A (SipA) is a dual-function effector protein that plays roles in both actin polymerization and caspase-3 activation in intestinal epithelial cells. To date its function in other cell types has remained largely unknown despite its expression in multiple cell types and its extracellular secretion during infection. Here we show that in macrophages SipA induces increased caspase-3 activation early in infection. This activation required a threshold level of SipA linked to multiplicity of infection and may be a limiting factor controlling bacterial numbers in infected macrophages. In polymorphonuclear leukocytes, SipA or other Salmonella pathogenicity island 1 effectors had no effect on induction of caspase-3 activation either alone or in the presence of whole bacteria. Tagging of SipA with the small fluorescent phiLOV tag, which can pass through the type three secretion system, allowed visualization and quantification of caspase-3 activation by SipA-phiLOV in macrophages. Additionally, SipA-phiLOV activation of caspase-3 could be tracked in the intestine through multiphoton laser scanning microscopy in an ex vivo intestinal model. This allowed visualization of areas where the intestinal epithelium had been compromised and demonstrated the potential use of this fluorescent tag for in vivo tracking of individual effectors.