title: A nuclear factor of high mobility group box protein in Toxoplasma gondii.
abstract: High mobility group box 1 (HMGB1) is a nuclear factor that usually binds DNA and modulates gene expression in multicellular organisms. Three HMGB1 orthologs were predicted in the genome of Toxoplasma gondii, an obligate intracellular protozoan pathogen, termed TgHMGB1a, b and c. Phylogenetic and bioinformatic analyses indicated that these proteins all contain a single HMG box and which shared in three genotypes. We cloned TgHMGB1a, a 33.9 kDa protein that can stimulates macrophages to release TNF-α, and, we demonstrated that the TgHMGB1a binds distorted DNA structures such as cruciform DNA in electrophoretic mobility shift assays (EMSA). Immunofluorescence assay indicated TgHMGB1a concentrated in the nucleus of intracellular tachyzoites but translocated into the cytoplasm while the parasites release to extracellular. There were no significant phenotypic changes when the TgHMGB1a B box was deleted, while transgenic parasites that overexpressed TgHMGB1a showed slower intracellular growth and caused delayed death in mouse, further quantitative RT-PCR analyses showed that the expression levels of many important genes, including virulence factors, increased when TgHMGB1a was overexpressed, but no significant changes were observed in TgHMGB1a B box-deficient parasites. Our findings demonstrated that TgHMGB1a is indeed a nuclear protein that maintains HMG box architectural functions and is a potential proinflammatory factor during the T.gondii infection. Further studies that clarify the functions of TgHMGB1s will increase our knowledge of transcriptional regulation and parasite virulence, and might provide new insight into host-parasite interactions for T. gondii infection.
authors.affiliation: Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, National Animal Protozoa Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
authors.affiliation: Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, National Animal Protozoa Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Lei
authors.affiliation: Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, National Animal Protozoa Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Liu
authors.affiliation: Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, National Animal Protozoa Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, China.
authors.forename: Muzi
authors.initials: M
authors.lastname: Li
authors.affiliation: Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, National Animal Protozoa Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, China.
authors.forename: Huizhu
authors.initials: H
authors.lastname: Nan
authors.affiliation: Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, National Animal Protozoa Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, China.
authors.forename: Qun
authors.initials: Q
authors.lastname: Liu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D017124:Conserved Sequence; D045566:DNA, Cruciform / Q000737:chemistry; D016054:DNA, Protozoan / Q000737:chemistry; D005260:Female; D015870:Gene Expression; D024243:HMGB1 Protein / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D006790:Host-Parasite Interactions; D006801:Humans; D008264:Macrophages / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D021381:Protein Transport; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D014122:Toxoplasma / Q000235:genetics* / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D045566:DNA, Cruciform; D016054:DNA, Protozoan; D024243:HMGB1 Protein; D015800:Protozoan Proteins; D014409:Tumor Necrosis Factor-alpha