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A nuclear factor of high mobility group box protein in Toxoplasma gondii. PLoS One 2014; 9:e111993. [PMID: 25369210 PMCID: PMC4219823 DOI: 10.1371/journal.pone.0111993] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 10/08/2014] [Indexed: 01/28/2023] Open
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.
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Keyel PA. How is inflammation initiated? Individual influences of IL-1, IL-18 and HMGB1. Cytokine 2014; 69:136-45. [PMID: 24746243 DOI: 10.1016/j.cyto.2014.03.007] [Citation(s) in RCA: 130] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 02/27/2014] [Accepted: 03/24/2014] [Indexed: 12/17/2022]
Abstract
Pro-inflammatory cytokines are crucial for fighting infection and establishing immunity. Recently, other proteins, such as danger-associated molecular patterns (DAMPs), have also been appreciated for their role in inflammation and immunity. Following the formation and activation of multiprotein complexes, termed inflammasomes, two cytokines, IL-1β and IL-18, along with the DAMP High Mobility Group Box 1 (HMGB1), are released from cells. Although these proteins all lack classical secretion signals and are released by inflammasome activation, they each lead to different downstream consequences. This review examines how various inflammasomes promote the release of IL-1β, IL-18 and HMGB1 to combat pathogenic situations. Each of these effector molecules plays distinct roles during sterile inflammation, responding to viral, bacterial and parasite infection, and tailoring the innate immune response to specific threats.
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Affiliation(s)
- Peter A Keyel
- Department of Biological Sciences, Texas Tech University, Biology Rm 108, Box 43131, Lubbock, TX 79409-3131, United States.
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Cribb P, Perozzi M, Villanova GV, Trochine A, Serra E. Characterization of TcHMGB, a high mobility group B family member protein from Trypanosoma cruzi. Int J Parasitol 2011; 41:1149-56. [PMID: 21854779 DOI: 10.1016/j.ijpara.2011.06.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Revised: 06/03/2011] [Accepted: 06/25/2011] [Indexed: 11/17/2022]
Abstract
High mobility group B (HMGB) proteins are highly abundant non-histone chromatin proteins that play important roles in the execution and control of many nuclear functions. Based on homology searches, we identified the coding sequence for the TcHMGB protein, an HMGB family member from Trypanosoma cruzi. TcHMGB has two HMG box domains, similar to mammalian HMGBs, but lacks the typical C-terminal acidic tail. Instead, it contains a 110 amino acid long N-terminal domain. The TcHMGB N-terminal domain is conserved between the TriTryp sequences (70-80% similarity) and seems to be characteristic of kinetoplastid HMGBs. Despite these differences, TcHMGB maintains HMG box architectural functions: we demonstrated that the trypanosomatid HMGB binds distorted DNA structures such as cruciform DNA in gel shift assays. TcHMGB is also able to bend linear DNA as determined by T4 ligase circularization assays, similar to other HMGB family members. Immunofluorescence and western blot assays showed that TcHMGB is a nuclear protein expressed in all life cycle stages. Protein levels, however, seem to vary throughout the life cycle, which may be related to previously described changes in heterochromatin distribution and transcription rates.
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Affiliation(s)
- Pamela Cribb
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, Rosario CP2000, Argentina
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Characterization of an Entamoeba histolytica high-mobility-group box protein induced during intestinal infection. EUKARYOTIC CELL 2008; 7:1565-72. [PMID: 18658254 DOI: 10.1128/ec.00123-08] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The unicellular eukaryote Entamoeba histolytica is a human parasite that causes amebic dysentery and liver abscess. A genome-wide analysis of gene expression modulated by intestinal colonization and invasion identified an upregulated transcript that encoded a putative high-mobility-group box (HMGB) protein, EhHMGB1. We tested if EhHMGB1 encoded a functional HMGB protein and determined its role in control of parasite gene expression. Recombinant EhHMGB1 was able to bend DNA in vitro, a characteristic of HMGB proteins. Core conserved residues required for DNA bending activity in other HMGB proteins were demonstrated by mutational analysis to be essential for EhHMGB1 activity. EhHMGB1 was also able to enhance the binding of human p53 to its cognate DNA sequence in vitro, which is expected for an HMGB1 protein. Confocal microscopy, using antibodies against the recombinant protein, confirmed its nuclear localization. Overexpression of EhHMGB1 in HM1:IMSS trophozoites led to modulation of 33 transcripts involved in a variety of cellular functions. Of these, 20 were also modulated at either day 1 or day 29 in the mouse model of intestinal amebiasis. Notably, four transcripts with known roles in virulence, including two encoding Gal/GalNAc lectin light chains, were modulated in response to EhHMGB1 overexpression. We concluded that EhHMGB1 was a bona fide HMGB protein with the capacity to recapitulate part of the modulation of parasite gene expression seen during adaptation to the host intestine.
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Briquet S, Boschet C, Gissot M, Tissandié E, Sevilla E, Franetich JF, Thiery I, Hamid Z, Bourgouin C, Vaquero C. High-mobility-group box nuclear factors of Plasmodium falciparum. EUKARYOTIC CELL 2006; 5:672-82. [PMID: 16607015 PMCID: PMC1459676 DOI: 10.1128/ec.5.4.672-682.2006] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In eukaryotes, the high-mobility-group (HMG) nuclear factors are highly conserved throughout evolution and are divided into three families, including HGMB, characterized by an HMG box domain. Some HMGB factors are DNA structure specific and preferentially interact with distorted DNA sequences, trigger DNA bending, and hence facilitate the binding of nucleoprotein complexes that in turn activate or repress transcription. In Plasmodium falciparum, two HMGB factors were predicted: PfHMGB1 and PfHMGB2. They are small proteins, under 100 amino acids long, encompassing a characteristic HMG box domain closely related to box B of metazoan factors, which comprises two HMG box domains, A and B, in tandem. Computational analyses supported the conclusion that the Plasmodium proteins were genuine architectural HMGB factors, and in vitro analyses performed with both recombinant proteins established that they were able to interact with distorted DNA structures and bend linear DNA with different affinities. These proteins were detected in both asexual- and gametocyte-stage cells in Western blotting experiments and mainly in the parasite nuclei. PfHMGB1 is preferentially expressed in asexual erythrocytic stages and PfHMGB2 in gametocytes, in good correlation with transcript levels of expression. Finally, immunofluorescence studies revealed differential subcellular localizations: both factors were observed in the nucleus of asexual- and sexual-stage cells, and PfHMGB2 was also detected in the cytoplasm of gametocytes. In conclusion, in light of differences in their levels of expression, subcellular localizations, and capacities for binding and bending DNA, these factors are likely to play nonredundant roles in transcriptional regulation of Plasmodium development in erythrocytes.
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Affiliation(s)
- Sylvie Briquet
- INSERM, U511, Université Pierre et Marie Curie, Paris VI, Centre Hospitalo-Universitaire de la Pitié-Salpêtrière, Paris, France, Biologie et Génétique du Paludisme, CEPIA (Centre de Production et d'Infection des Anophèles), Institut Pasteur, Paris, France
- Corresponding author. Mailing address: INSERM, U511, Université Pierre et Marie Curie, Paris VI, Centre Hospitalo-Universitaire de la Pitié-Salpêtrière, 91 boulevard de l'Hôpital, 75013 Paris, France. Phone: 33 (0) 1 40 77 81 14. Fax: 33 (0) 1 45 83 88 58. E-mail for Sylvie Briquet: . E-mail for Catherine Vaquero:
| | - Charlotte Boschet
- INSERM, U511, Université Pierre et Marie Curie, Paris VI, Centre Hospitalo-Universitaire de la Pitié-Salpêtrière, Paris, France, Biologie et Génétique du Paludisme, CEPIA (Centre de Production et d'Infection des Anophèles), Institut Pasteur, Paris, France
| | - Mathieu Gissot
- INSERM, U511, Université Pierre et Marie Curie, Paris VI, Centre Hospitalo-Universitaire de la Pitié-Salpêtrière, Paris, France, Biologie et Génétique du Paludisme, CEPIA (Centre de Production et d'Infection des Anophèles), Institut Pasteur, Paris, France
| | - Emilie Tissandié
- INSERM, U511, Université Pierre et Marie Curie, Paris VI, Centre Hospitalo-Universitaire de la Pitié-Salpêtrière, Paris, France, Biologie et Génétique du Paludisme, CEPIA (Centre de Production et d'Infection des Anophèles), Institut Pasteur, Paris, France
| | - Elisa Sevilla
- INSERM, U511, Université Pierre et Marie Curie, Paris VI, Centre Hospitalo-Universitaire de la Pitié-Salpêtrière, Paris, France, Biologie et Génétique du Paludisme, CEPIA (Centre de Production et d'Infection des Anophèles), Institut Pasteur, Paris, France
| | - Jean-François Franetich
- INSERM, U511, Université Pierre et Marie Curie, Paris VI, Centre Hospitalo-Universitaire de la Pitié-Salpêtrière, Paris, France, Biologie et Génétique du Paludisme, CEPIA (Centre de Production et d'Infection des Anophèles), Institut Pasteur, Paris, France
| | - Isabelle Thiery
- INSERM, U511, Université Pierre et Marie Curie, Paris VI, Centre Hospitalo-Universitaire de la Pitié-Salpêtrière, Paris, France, Biologie et Génétique du Paludisme, CEPIA (Centre de Production et d'Infection des Anophèles), Institut Pasteur, Paris, France
| | - Zuhal Hamid
- INSERM, U511, Université Pierre et Marie Curie, Paris VI, Centre Hospitalo-Universitaire de la Pitié-Salpêtrière, Paris, France, Biologie et Génétique du Paludisme, CEPIA (Centre de Production et d'Infection des Anophèles), Institut Pasteur, Paris, France
| | - Catherine Bourgouin
- INSERM, U511, Université Pierre et Marie Curie, Paris VI, Centre Hospitalo-Universitaire de la Pitié-Salpêtrière, Paris, France, Biologie et Génétique du Paludisme, CEPIA (Centre de Production et d'Infection des Anophèles), Institut Pasteur, Paris, France
| | - Catherine Vaquero
- INSERM, U511, Université Pierre et Marie Curie, Paris VI, Centre Hospitalo-Universitaire de la Pitié-Salpêtrière, Paris, France, Biologie et Génétique du Paludisme, CEPIA (Centre de Production et d'Infection des Anophèles), Institut Pasteur, Paris, France
- Corresponding author. Mailing address: INSERM, U511, Université Pierre et Marie Curie, Paris VI, Centre Hospitalo-Universitaire de la Pitié-Salpêtrière, 91 boulevard de l'Hôpital, 75013 Paris, France. Phone: 33 (0) 1 40 77 81 14. Fax: 33 (0) 1 45 83 88 58. E-mail for Sylvie Briquet: . E-mail for Catherine Vaquero:
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Abstract
The nuclear chromatin of trypanosomes is organised in the form of nucleosome filaments. When soluble chromatin is prepared under suitable conditions, a regular array of nucleosomes can be shown by electron microscopy. Chromatin of blood stream as well as procyclic culture forms of Trypanosoma brucei brucei and of T. cruzi shows limited compaction at salt concentrations increasing from 1 to 100 mM. No 30 nm fibres, typical for higher eukaryotes, are formed. Digestion of the nuclear chromatin with micrococcal nuclease and analysis of the histone proteins with various techniques reveal that the basic organisation of the trypanosome chromatin is similar but not identical as compared to that of higher eukaryotes. Distinct differences are present with respect to biochemical properties of the histones as well as to their interaction with the DNA. The primary structure of the histones also differs significantly from that found in other lower and higher eukaryotes. The function of the recently described H1-like proteins in trypanosomes is currently being investigated. The differences that have already been found in the structure and compaction of the trypanosome chromatin compared to that of higher eukaryotes lead us to expect differences of gene expression which, in turn, might offer targets for the control of trypanosomiasis.
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Affiliation(s)
- H Hecker
- Swiss Tropical Institute, Basel, Switzerland
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