Lee Young Ah, Kim Kyeong Ah, Min Arim, Shin Myeong Heon
Department of Environmental Medical Biology and Institute of Tropical Medicine, Yonsei University College of Medicine, Seoul 120-752, Korea.
Korean J Parasitol. 2014 Aug;52(4):355-65. doi: 10.3347/kjp.2014.52.4.355. Epub 2014 Aug 29.
The enteric protozoan parasite Entamoeba histolytica is the causative agent of human amebiasis. During infection, adherence of E. histolytica through Gal/GalNAc lectin on the surface of the amoeba can induce caspase-3-dependent or -independent host cell death. Phosphorylinositol 3-kinase (PI3K) and protein kinase C (PKC) in E. histolytica play an important function in the adhesion, killing, or phagocytosis of target cells. In this study, we examined the role of amoebic PI3K and PKC in amoeba-induced apoptotic cell death in Jurkat T cells. When Jurkat T cells were incubated with E. histolytica trophozoites, phosphatidylserine (PS) externalization and DNA fragmentation in Jurkat cells were markedly increased compared to those of cells incubated with medium alone. However, when amoebae were pretreated with a PI3K inhibitor, wortmannin before being incubated with E. histolytica, E. histolytica-induced PS externalization and DNA fragmentation in Jurkat cells were significantly reduced compared to results for amoebae pretreated with DMSO. In addition, pretreatment of amoebae with a PKC inhibitor, staurosporine strongly inhibited Jurkat T cell death. However, E. histolytica-induced cleavage of caspase-3, -6, and -7 were not inhibited by pretreatment of amoebae with wortmannin or staurosporin. In addition, we found that amoebic PI3K and PKC have an important role on amoeba adhesion to host compartment. These results suggest that amebic PI3K and PKC activation may play an important role in caspase-independent cell death in Entamoeba-induced apoptosis.
肠道原生动物寄生虫溶组织内阿米巴是人类阿米巴病的病原体。在感染过程中，溶组织内阿米巴通过其表面的半乳糖/ N - 乙酰半乳糖胺凝集素进行黏附，可诱导半胱天冬酶 - 3依赖性或非依赖性的宿主细胞死亡。溶组织内阿米巴中的磷脂酰肌醇3 - 激酶（PI3K）和蛋白激酶C（PKC）在靶细胞的黏附、杀伤或吞噬过程中发挥重要作用。在本研究中，我们检测了阿米巴PI3K和PKC在溶组织内阿米巴诱导的Jurkat T细胞凋亡性细胞死亡中的作用。当Jurkat T细胞与溶组织内阿米巴滋养体共孵育时，与仅用培养基孵育的细胞相比，Jurkat细胞中磷脂酰丝氨酸（PS）外化和DNA片段化明显增加。然而，当阿米巴在与溶组织内阿米巴共孵育前用PI3K抑制剂渥曼青霉素预处理时，与用二甲基亚砜（DMSO）预处理的阿米巴相比，溶组织内阿米巴诱导的Jurkat细胞中PS外化和DNA片段化显著减少。此外，用PKC抑制剂星形孢菌素预处理阿米巴可强烈抑制Jurkat T细胞死亡。然而，渥曼青霉素或星形孢菌素预处理阿米巴并未抑制溶组织内阿米巴诱导的半胱天冬酶 - 3、 - 6和 - 7的裂解。此外，我们发现阿米巴PI3K和PKC在阿米巴对宿主隔室的黏附中起重要作用。这些结果表明，阿米巴PI3K和PKC的激活可能在溶组织内阿米巴诱导的凋亡中半胱天冬酶非依赖性细胞死亡中起重要作用。
