Medical Research Unit on Immunochemistry, Specialties Hospital, National Medical Centre Siglo XXI, Mexican Social Security Institute, Mexico City, Mexico.
Parasit Vectors. 2012 Oct 8;5:224. doi: 10.1186/1756-3305-5-224.
Entamoeba histolytica is a protozoan parasite that infects humans and causes amebiasis affecting developing countries. Phagocytosis of epithelial cells, erythrocytes, leucocytes, and commensal microbiota bacteria is a major pathogenic mechanism used by this parasite. A Toll/IL-1R/Resistance (TIR) domain-containing protein is required in phagocytosis in the social ameba Dictyostelium discoideum, an ameba closely related to Entamoeba histolytica in phylogeny. In insects and vertebrates, TIR domain-containing proteins regulate phagocytic and cell activation. Therefore, we investigated whether E. histolytica expresses TIR domain-containing molecules that may be involved in the phagocytosis of erythrocytes and bacteria.
Using in silico analysis we explored in Entamoeba histolytica databases for TIR domain containing sequences. After silencing TIR domain containing sequences in trophozoites by siRNA we evaluated phagocytosis of erythrocytes and bacteria.
We identified an E. histolytica thioredoxin containing a TIR-like domain. The secondary and tertiary structure of this sequence exhibited structural similarity to TIR domain family. Thioredoxin transcripts silenced in E. histolytica trophozoites decreased erythrocytes and E. coli phagocytosis.
TIR domain-containing thioredoxin of E. histolytica could be an important element in erythrocytes and bacteria phagocytosis.
溶组织内阿米巴是一种原生动物寄生虫，感染人类并导致阿米巴病，影响发展中国家。吞噬上皮细胞、红细胞、白细胞和共生微生物细菌是这种寄生虫的主要致病机制。在与溶组织内阿米巴在系统发育上密切相关的社会变形虫盘基网柄菌中，吞噬作用需要 Toll/IL-1R/Resistance（TIR）结构域蛋白。在昆虫和脊椎动物中，TIR 结构域蛋白调节吞噬作用和细胞激活。因此，我们研究了溶组织内阿米巴是否表达可能参与红细胞和细菌吞噬作用的 TIR 结构域蛋白。
我们通过计算机分析在溶组织内阿米巴数据库中探索了 TIR 结构域蛋白。用 siRNA 沉默滋养体中的 TIR 结构域蛋白后，我们评估了红细胞和细菌的吞噬作用。
我们鉴定了一种含有 TIR 样结构域的溶组织内阿米巴硫氧还蛋白。该序列的二级和三级结构表现出与 TIR 结构域家族的结构相似性。在溶组织内阿米巴滋养体中沉默的硫氧还蛋白转录本降低了红细胞和大肠杆菌的吞噬作用。
溶组织内阿米巴的 TIR 结构域含硫氧还蛋白可能是红细胞和细菌吞噬作用的重要因素。
