The Helicobacter pylori vacuolating cytotoxin (VacA) is an intracellular, mitochondrial-targeting exotoxin that rapidly causes mitochondrial dysfunction and fragmentation. Although VacA targeting of mitochondria has b...The Helicobacter pylori vacuolating cytotoxin (VacA) is an intracellular, mitochondrial-targeting exotoxin that rapidly causes mitochondrial dysfunction and fragmentation. Although VacA targeting of mitochondria has been reported to alter overall cellular metabolism, there is little known about the consequences of extended exposure to the toxin. Here, we describe studies to address this gap in knowledge, which have revealed that mitochondrial dysfunction and fragmentation are followed by a time-dependent recovery of mitochondrial structure, mitochondrial transmembrane potential, and cellular ATP levels. Cells exposed to VacA also initially demonstrated a reduction in oxidative phosphorylation, as well as increase in compensatory aerobic glycolysis. These metabolic alterations were reversed in cells with limited toxin exposure, congruent with the recovery of mitochondrial transmembrane potential and the absence of cytochrome c release from the mitochondria. Taken together, these results are consistent with a model that mitochondrial structure and function are restored in VacA-intoxicated cells.展开更多
目的 :研究幽门螺杆菌空泡毒素作为单一毒力决定簇对真核细胞的作用。方法 :用 PCR扩增vac A基因片段 ,克隆入真核表达载体 p EGFP- N 1,构建重组质粒 p EGFP- vac A,转染 He L a细胞 ,通过相差显微镜和电子显微镜观察细胞形态与结构的...目的 :研究幽门螺杆菌空泡毒素作为单一毒力决定簇对真核细胞的作用。方法 :用 PCR扩增vac A基因片段 ,克隆入真核表达载体 p EGFP- N 1,构建重组质粒 p EGFP- vac A,转染 He L a细胞 ,通过相差显微镜和电子显微镜观察细胞形态与结构的变化。结果 :重组质粒转染 He L a细胞 2 4 h,10 %～ 2 0 %细胞的胞质内出现明显空泡 ,其中少数细胞发生凋亡改变。结论 :成功构建了用于真核表达的重组 vac A质粒 ,转染真核细胞后 ,观察 Vac A作用导致的细胞形态结构的变化 ,为研究 Vac展开更多
文摘The Helicobacter pylori vacuolating cytotoxin (VacA) is an intracellular, mitochondrial-targeting exotoxin that rapidly causes mitochondrial dysfunction and fragmentation. Although VacA targeting of mitochondria has been reported to alter overall cellular metabolism, there is little known about the consequences of extended exposure to the toxin. Here, we describe studies to address this gap in knowledge, which have revealed that mitochondrial dysfunction and fragmentation are followed by a time-dependent recovery of mitochondrial structure, mitochondrial transmembrane potential, and cellular ATP levels. Cells exposed to VacA also initially demonstrated a reduction in oxidative phosphorylation, as well as increase in compensatory aerobic glycolysis. These metabolic alterations were reversed in cells with limited toxin exposure, congruent with the recovery of mitochondrial transmembrane potential and the absence of cytochrome c release from the mitochondria. Taken together, these results are consistent with a model that mitochondrial structure and function are restored in VacA-intoxicated cells.
