The Apoptotic Role of Metacaspase in Toxoplasma gondii
The Apoptotic Role of Metacaspase in Toxoplasma gondii
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Metacaspase 在弓形虫中的凋亡作用
DOI：
10.3389/fmicb.2015.01560
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发表时间：
2016-01-19
影响因子：
5.2
通讯作者：
Liu, Qun
中科院分区：
文献类型：
--
作者：
Li, Muzi;Wang, Hui;Liu, Qun
弓形虫是一种主要的机会致病菌，在一系列动物物种和人类中传播。在T.用凋亡诱导剂处理弓形虫，但该途径的分子机制尚不清楚。后半胱天冬酶是半胱天冬酶样半胱氨酸蛋白酶，其可以在其中不存在半胱天冬酶的植物、真菌和原生动物中发现。后半胱氨酸天冬氨酸蛋白酶是多功能蛋白酶，参与类骨化性细胞死亡、不溶性蛋白聚集体清除和细胞增殖。探讨T.弓形虫后半胱天冬酶（TgMCA）参与寄生虫的凋亡，我们构建了TgMCA突变株。Western blot分析表明，TgMCA的自蛋白水解过程与其他一些物种的metacaspase相同。间接免疫荧光试验（IFA）显示，TgMCA在细胞外环境中分散于胞质中，并重新定位于细胞核中，表明其功能在细胞核中执行。凋亡寄生虫的数量显着减少TgMCA敲除菌株和TgMCA过表达菌株处理后，细胞外缓冲液，如末端脱氧核苷酸转移酶dUTP缺口末端标记（TUNEL）测定。TgMCA的缺乏并不影响寄生虫的体外繁殖和体内毒力，这表明它可能是多余的寄生虫繁殖。但过表达TgMCA可抑制体外培养的胞内寄生虫生长。TgMCA敲除菌株在细胞外缓冲液中显示出比亲本和过表达系更大的活力。在这项研究中，我们证明了TgMCA有助于T。刚地。
Toxoplasma gondii is a major opportunistic pathogen that spreads in a range of animal species and human beings. Quite a few characterizations of apoptosis have been identified in T. gondii treated with apoptosis inducers, but the molecular mechanisms of the pathway are not clearly understood. Metacaspases are caspase-like cysteine proteases that can be found in plants, fungi, and protozoa in which caspases are absent. Metacaspases are multifunctional proteases involved in apoptosis-like cell death, insoluble protein aggregate clearance, and cell proliferation. To investigate whether T. gondii metacaspase (TgMCA) is involved in the apoptosis of the parasites, we generated TgMCA mutant strains. Western blot analysis indicated that the autoproteolytic processing of TgMCA was the same as that for metacaspases of some other species. Indirect immunofluorescence assay (IFA) showed that TgMCA was dispersed throughout the cytoplasm and relocated to the nucleus when the parasites were exposed to the extracellular environment, which indicated the execution of its function in the nucleus. The number of apoptosis parasites was significantly diminished in the TgMCA knockout strain and increased in the TgMCA overexpression strain after treatment with extracellular buffer, as determined by the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. The lack of TgMCA did not affect the parasite propagation in vitro and virulence in vivo, suggesting that it is probably redundant in parasite propagation. But overexpression of TgMCA reduced the intracellular parasites growth in vitro. The TgMCA knockout strain showed more viability in extracellular buffer compared to the parental and overexpression lines. In this study, we demonstrated that TgMCA contributes to the apoptosis of T. gondii.