title: Expression of Cryptosporidium parvum thioredoxin peroxidase in COS-7 cells confers radioprotection.
abstract: Cryptosporidium parvum is one of the most radioresistant organisms identified to date. In a previous study, we found that thioredoxin peroxidase (CpTPx) was significantly upregulated in this species following exposure to high dose (10 kGy) of γ-irradiation. To assess the potential of CpTPx to confer radioprotection in mammalian cells, it was expressed in COS-7 African green monkey kidney cells (CpTPx-COS7). For comparison, the thioredoxin peroxidase of Cryptosporidium muris (CmTPx) was also expressed in these cells (CmTPx-COS7 cells), which has been confirmed to have lesser antioxidant activity than CpTPx in the previous study. Notably, the survival rates of CpTPx-COS7 cells were significantly higher (12-22%) at 72 h after 8 Gy irradiation than CmTPx-COS7 or non-transfected COS-7 (ntCOS-7) counterparts. In addition, CpTPx revealed a 50% of ROS reduction in irradiated CpTPx-COS7 cells, while γ-H2AX DNA damage marker expression was not significantly changed. Furthermore, the amount of apoptosis only increased to about 120% after 2-8 Gy irradiation compared to 200-300% increase observed in ntCOS-7 cells. CmTPx was shown to have antioxidant and DNA damage protection activities; however, these activities were always lower than those of CpTPx. These results suggest that the potent antioxidant and protective activities of CpTPx are well conserved in this cell-based system and that CpTPx contributed to the radioprotection of mammalian cells through its exceptional antioxidant activity.
authors.affiliation: Department of Radiation Oncology & Research Institute of Medical Science, Konkuk University, School of Medicine, Seoul 143-701, South Korea.
authors.forename: Semie
authors.initials: S
authors.lastname: Hong
authors.affiliation: Department of Environmental and Tropical Medicine & Research Institute of Medical Science, Konkuk University, School of Medicine, Seoul 143-701, South Korea.
authors.forename: Jae-Hwan
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Department of Environmental and Tropical Medicine & Research Institute of Medical Science, Konkuk University, School of Medicine, Seoul 143-701, South Korea.
authors.forename: Sejoung
authors.initials: S
authors.lastname: Yoon
authors.affiliation: Department of Environmental and Tropical Medicine & Research Institute of Medical Science, Konkuk University, School of Medicine, Seoul 143-701, South Korea.
authors.forename: Kyoungjin
authors.initials: K
authors.lastname: Kim
authors.affiliation: Department of Environmental and Tropical Medicine & Research Institute of Medical Science, Konkuk University, School of Medicine, Seoul 143-701, South Korea.
authors.forename: Seobo
authors.initials: S
authors.lastname: Sim
authors.affiliation: Department of Radiation Oncology, College of Medicine, Chungbuk National University, Cheongju 361-763, South Korea.
authors.forename: Woo-Yoon
authors.initials: WY
authors.lastname: Park
authors.affiliation: Department of Environmental and Tropical Medicine & Research Institute of Medical Science, Konkuk University, School of Medicine, Seoul 143-701, South Korea. Electronic address: maria205@kku.ac.kr.
authors.forename: Jae-Ran
authors.initials: JR
authors.lastname: Yu
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D019556:COS Cells / Q000201:enzymology* / Q000469:parasitology / Q000528:radiation effects; D002522:Chlorocebus aethiops; D016785:Cryptosporidium parvum / Q000201:enzymology* / Q000528:radiation effects; D005720:Gamma Rays; D015971:Gene Expression Regulation, Enzymologic; D018613:Microscopy, Confocal; D054464:Peroxiredoxins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D014162:Transfection
chemical_list: D000975:Antioxidants; D017382:Reactive Oxygen Species; D054464:Peroxiredoxins
keywords: Cryptosporidium parvum; Radioprotection; Thioredoxin peroxidase