Toxoplasma gondii Induces Apoptosis via Endoplasmic Reticulum Stress-Derived Mitochondrial Pathway in Human Small Intestinal Epithelial Cell-Line

Transcriptomic analysis of LMH cells in response to the overexpression of a protein of Eimeria tenella encoded by the locus ETH_00028350

A protein of Eimeria tenella (encoded by the locus ETH_00028350) homologous to Toxoplasma gondii dense granule protein 9, designated as EtHGRA9 hereafter, was reported to be expressed in all life cycle stages of E. tenella. However, no data are currently available regarding its functional properties. In the present study, a recombinant vector harboring a 741 bp gene segment encoding the mature form of EtHGRA9 was constructed and transfected into leghorn male hepatoma (LMH) cells. Then, transcriptomic analysis of the transfected LMH cells was carried out by using a high-throughput RNA-seq technology. The LMH cells overexpressing EtHGRA9 was validated by means of Western blotting as well as indirect immunofluorescence staining. The results demonstrated that the expression of 547 genes (275 upregulated genes and 272 downregulated genes) was altered by EtHGRA9. The quantitative real-time polymerase chain reaction (qRT-PCR) validation of the ten genes with differential expression between the two groups was consistent with the transcriptome analysis. According to pathway enrichment analysis for the obtained differentially expressed genes, seven pathways were significantly affected by EtHGRA9, such as cytokine-cytokine receptor interaction, MAPK signaling pathway, and protein processing in endoplasmic reticulum. Our data reveal several possible roles of EtHGRA9 in immune or inflammatory responses, which paves the way for a better understanding of the molecular interplay between E. tenella and its host.

Toxoplasma gondii induces MLTC-1 apoptosis via ERS pathway

Toxoplasma gondii (T. gondii) is a serious intracellular parasite and mammalian infection can damage the reproductive system and lead to apoptosis of Murine Leydig tumor cells (MLTC-1); however, the mechanism is unclear. The testis Leydig cell is the main testosterone synthesis cell in male mammals. We studied the mechanism of T. gondii infection on Leydig cell apoptosis in vitro. MLTC-1 were divided into control and experimental groups. Experiment group cells and tachyzoites were co-cultured, in a 1:20 ratio, for 3, 6, 9, and 12 h. T. gondii entered the cells and caused lesions at 12 h. Flow cytometry showed that the apoptosis rate of the experiment group increased with time and was significantly higher (P < 0.05) than the control group. RT-qPCR and western blot demonstrated that the expression of P53, Caspase-3, and Bax were significantly increased at 12 h (P < 0.05). Bcl-2 expression was significantly increased at 12 h (P < 0.05). The ER stress (ERS) pathway was important in cell apoptosis. RT-qPCR and western blot showed that the expression of CHOP was significantly increased at 12 h (P < 0.05). These data indicate that T. gondii induced MLTC-1 cell apoptosis may occur via the ERS pathway.