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Rijo-Ferreira F, Takahashi JS. Circadian rhythms in infectious diseases and symbiosis. Semin Cell Dev Biol 2022; 126:37-44. [PMID: 34625370 PMCID: PMC9183220 DOI: 10.1016/j.semcdb.2021.09.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 09/01/2021] [Accepted: 09/07/2021] [Indexed: 10/20/2022]
Abstract
Timing is everything. Many organisms across the tree of life have evolved timekeeping mechanisms that regulate numerous of their cellular functions to optimize timing by anticipating changes in the environment. The specific environmental changes that are sensed depends on the organism. For animals, plants, and free-living microbes, environmental cues include light/dark cycles, daily temperature fluctuations, among others. In contrast, for a microbe that is never free-living, its rhythmic environment is its host's rhythmic biology. Here, we describe recent research on the interactions between hosts and microbes, from the perspective both of symbiosis as well as infections. In addition to describing the biology of the microbes, we focus specifically on how circadian clocks modulate these host-microbe interactions.
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Affiliation(s)
- Filipa Rijo-Ferreira
- Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX, United States.
| | - Joseph S Takahashi
- Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX, United States; Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, United States.
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2
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Acosta-Rodríguez V, Rijo-Ferreira F, Izumo M, Xu P, Wight-Carter M, Green CB, Takahashi JS. Circadian alignment of early onset caloric restriction promotes longevity in male C57BL/6J mice. Science 2022; 376:1192-1202. [PMID: 35511946 PMCID: PMC9262309 DOI: 10.1126/science.abk0297] [Citation(s) in RCA: 124] [Impact Index Per Article: 62.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Caloric restriction (CR) prolongs lifespan, yet the mechanisms by which it does so remain poorly understood. Under CR, mice self-impose chronic cycles of 2-hour-feeding and 22-hour-fasting, raising the question whether calories, fasting, or time of day are causal. We show that 30%-CR is sufficient to extend lifespan 10%; however, a daily fasting interval and circadian-alignment of feeding act together to extend lifespan 35% in male C57BL/6J mice. These effects are independent of body weight. Aging induces widespread increases in gene expression associated with inflammation and decreases in expression of genes encoding components of metabolic pathways in liver from ad lib fed mice. CR at night ameliorates these aging-related changes. Thus, circadian interventions promote longevity and provide a perspective to further explore mechanisms of aging. Timed caloric restriction at night enhances longevity.
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Affiliation(s)
- Victoria Acosta-Rodríguez
- Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Filipa Rijo-Ferreira
- Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.,Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Mariko Izumo
- Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Pin Xu
- Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Mary Wight-Carter
- Animal Resources Center, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Carla B Green
- Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Joseph S Takahashi
- Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.,Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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3
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Acosta-Rodriguez V, Rijo-Ferreira F, Izumo M, Xu P, Green C, Takahashi J. Circadian Alignment of Feeding Regulates Lifespan Extension by Caloric Restriction. Innov Aging 2021. [PMCID: PMC8969463 DOI: 10.1093/geroni/igab046.442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Caloric restriction (CR) promotes longevity in several species. Classic CR protocols often lead to chronic cycles of 2h-feeding/22h-fasting, raising the question whether calories, fasting or time of day are causal. To address this, we tested an AL control group and five CR protocols with different timing and duration of feeding/fasting cycles. C57BL/6J male mice were subjected to 30% CR as one single meal a day at the beginning of the day or night (classical protocols with < 2h feeding, CR-day and CR-night), or smaller meals distributed for 12h (CR-day-12h and CR-night-12h), or evenly spread out throughout 24h (CR-spread) to abolish the otherwise daily feeding pattern adopted by nocturnal animals. We found that CR alone is sufficient to extend lifespan without fasting. However, the benefits are enhanced if feeding/fasting cycles are present and match their normal nocturnal activity. Circadian alignment of feeding with at least 12h fasting boosts CR-mediated increase on survival in mice, independently body weight. Aging leads to widespread upregulation of inflammation-related genes and downregulation of metabolic pathways in liver from ad lib fed mice; whereas CR at night ameliorates these aging-related changes and preserves circadian oscillations in gene expression. Overall, our results demonstrate that circadian interventions promote longevity and provide a novel perspective for elucidating mechanisms of aging.
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Affiliation(s)
| | | | - Mariko Izumo
- UT Southwestern Medical Center, Dallas, Texas, United States
| | - Pin Xu
- Icahn School of Medicine at Mount Sinai, New York, New York, United States
| | - Carla Green
- UT Southwestern Medical Center, Dallas, Texas, United States
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Machado H, Bizarra-Rebelo T, Costa-Sequeira M, Trindade S, Carvalho T, Rijo-Ferreira F, Rentroia-Pacheco B, Serre K, Figueiredo LM. Trypanosoma brucei triggers a broad immune response in the adipose tissue. PLoS Pathog 2021; 17:e1009933. [PMID: 34525131 PMCID: PMC8476018 DOI: 10.1371/journal.ppat.1009933] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 09/27/2021] [Accepted: 08/31/2021] [Indexed: 12/13/2022] Open
Abstract
Adipose tissue is one of the major reservoirs of Trypanosoma brucei parasites, the causative agent of sleeping sickness, a fatal disease in humans. In mice, the gonadal adipose tissue (AT) typically harbors 2–5 million parasites, while most solid organs show 10 to 100-fold fewer parasites. In this study, we tested whether the AT environment responds immunologically to the presence of the parasite. Transcriptome analysis of T. brucei infected adipose tissue revealed that most upregulated host genes are involved in inflammation and immune cell functions. Histochemistry and flow cytometry confirmed an increasingly higher number of infiltrated macrophages, neutrophils and CD4+ and CD8+ T lymphocytes upon infection. A large proportion of these lymphocytes effectively produce the type 1 effector cytokines, IFN-γ and TNF-α. Additionally, the adipose tissue showed accumulation of antigen-specific IgM and IgG antibodies as infection progressed. Mice lacking T and/or B cells (Rag2-/-, Jht-/-), or the signature cytokine (Ifng-/-) displayed a higher parasite load both in circulation and in the AT, demonstrating the key role of the adaptive immune system in both compartments. Interestingly, infections of C3-/- mice showed that while complement system is dispensable to control parasite load in the blood, it is necessary in the AT and other solid tissues. We conclude that T. brucei infection triggers a broad and robust immune response in the AT, which requires the complement system to locally reduce parasite burden. African trypanosomiasis is a neglected disease with significant socio-economic burden in sub-Saharan Africa. The protozoan parasite Trypanosoma brucei, a causative agent of African trypanosomiasis, can be found in the blood and extra-vascular spaces of the infected host. For an unknown reason, T. brucei accumulates in adipose tissue (AT) in very high numbers. Here we used a multidisciplinary approach to assess whether an immune response was mounted in AT during a T. brucei infection. We found that as infection progresses, a broad variety of immune cells and antibodies accumulate in the AT. We also found that this broad immune response is partially able to control parasite numbers in the AT. Our study provides evidence that T. brucei parasites present in the AT are subjected to immune surveillance. The reason why T. brucei accumulates to such a high extent in AT remains to be elucidated.
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Affiliation(s)
- Henrique Machado
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Tiago Bizarra-Rebelo
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Mariana Costa-Sequeira
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Sandra Trindade
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Tânia Carvalho
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Filipa Rijo-Ferreira
- Department of Neuroscience, Peter O’Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Barbara Rentroia-Pacheco
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Karine Serre
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
- * E-mail: (KS); (LMF)
| | - Luisa M. Figueiredo
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
- * E-mail: (KS); (LMF)
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Acosta-Rodríguez VA, Rijo-Ferreira F, Green CB, Takahashi JS. Importance of circadian timing for aging and longevity. Nat Commun 2021; 12:2862. [PMID: 34001884 PMCID: PMC8129076 DOI: 10.1038/s41467-021-22922-6] [Citation(s) in RCA: 79] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 03/29/2021] [Indexed: 12/21/2022] Open
Abstract
Dietary restriction (DR) decreases body weight, improves health, and extends lifespan. DR can be achieved by controlling how much and/or when food is provided, as well as by adjusting nutritional composition. Because these factors are often combined during DR, it is unclear which are necessary for beneficial effects. Several drugs have been utilized that target nutrient-sensing gene pathways, many of which change expression throughout the day, suggesting that the timing of drug administration is critical. Here, we discuss how dietary and pharmacological interventions promote a healthy lifespan by influencing energy intake and circadian rhythms. Circadian clocks link physiologic processes to environmental conditions and a mismatch between internal and external rhythms has negative effects on organismal health. In this review, the authors discuss the interactions between circadian clocks and dietary interventions targeted to promote healthy aging.
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Affiliation(s)
- Victoria A Acosta-Rodríguez
- Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Filipa Rijo-Ferreira
- Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA.,Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Carla B Green
- Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Joseph S Takahashi
- Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA. .,Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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Abstract
Sleeping sickness is caused by a eukaryotic unicellular parasite known to infect wild animals, cattle, and humans. It causes a fatal disease that disrupts many rhythmic physiological processes, including daily rhythms of hormonal secretion, temperature regulation, and sleep, all of which are under circadian (24-h) control. In this review, we summarize research on sleeping sickness parasite biology and the impact it has on host health. We also consider the possible evolutionary advantages of sleep and circadian deregulation for the parasite.
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Affiliation(s)
- Filipa Rijo-Ferreira
- Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX, United States.,Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Joseph S Takahashi
- Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX, United States.,Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, United States
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Abstract
Biological rhythms appear to be an elegant solution to the challenge of coordinating activities with the consequences of the Earth's daily and seasonal rotation. The genes and molecular mechanisms underpinning circadian clocks in multicellular organisms are well understood. In contrast, the regulatory mechanisms and fitness consequences of biological rhythms exhibited by parasites remain mysterious. Here, we explore how periodicity in parasite traits is generated and why daily rhythms matter for parasite fitness. We focus on malaria (Plasmodium) parasites which exhibit developmental rhythms during replication in the mammalian host's blood and in transmission to vectors. Rhythmic in-host parasite replication is responsible for eliciting inflammatory responses, the severity of disease symptoms, and fueling transmission, as well as conferring tolerance to anti-parasite drugs. Thus, understanding both how and why the timing and synchrony of parasites are connected to the daily rhythms of hosts and vectors may make treatment more effective and less toxic to hosts.
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Affiliation(s)
- Kimberley F Prior
- Institute of Evolutionary Biology & Institute of Immunology and Infection Research, University of Edinburgh, Edinburgh, UK.
| | - Filipa Rijo-Ferreira
- Department of Neuroscience, Peter O'Donnell Jr. Brain Institute & Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Patricia A Assis
- Department of Medicine, University of Massachusetts Medical School, Worcester, MA, USA
| | - Isabella C Hirako
- Department of Medicine, University of Massachusetts Medical School, Worcester, MA, USA; Laboratório de Imunopatologia, Fundação Oswaldo Cruz - Minas, Belo Horizonte, MG, Brazil
| | - David R Weaver
- Department of Neurobiology & NeuroNexus Institute, University of Massachusetts Medical School, Worcester, MA, USA
| | - Ricardo T Gazzinelli
- Department of Medicine, University of Massachusetts Medical School, Worcester, MA, USA; Laboratório de Imunopatologia, Fundação Oswaldo Cruz - Minas, Belo Horizonte, MG, Brazil
| | - Sarah E Reece
- Institute of Evolutionary Biology & Institute of Immunology and Infection Research, University of Edinburgh, Edinburgh, UK
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Rijo-Ferreira F, Acosta-Rodriguez VA, Abel JH, Kornblum I, Bento I, Kilaru G, Klerman EB, Mota MM, Takahashi JS. The malaria parasite has an intrinsic clock. Science 2020; 368:746-753. [PMID: 32409471 PMCID: PMC7409452 DOI: 10.1126/science.aba2658] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 02/11/2020] [Accepted: 04/06/2020] [Indexed: 01/08/2023]
Abstract
Malarial rhythmic fevers are the consequence of the synchronous bursting of red blood cells (RBCs) on completion of the malaria parasite asexual cell cycle. Here, we hypothesized that an intrinsic clock in the parasite Plasmodium chabaudi underlies the 24-hour-based rhythms of RBC bursting in mice. We show that parasite rhythms are flexible and lengthen to match the rhythms of hosts with long circadian periods. We also show that malaria rhythms persist even when host food intake is evenly spread across 24 hours, suggesting that host feeding cues are not required for synchrony. Moreover, we find that the parasite population remains synchronous and rhythmic even in an arrhythmic clock mutant host. Thus, we propose that parasite rhythms are generated by the parasite, possibly to anticipate its circadian environment.
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Affiliation(s)
- Filipa Rijo-Ferreira
- Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA.
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Victoria A Acosta-Rodriguez
- Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - John H Abel
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA
- Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Boston, MA, USA
- Division of Sleep Medicine, Harvard Medical School, Boston, MA, USA
| | - Izabela Kornblum
- Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Ines Bento
- Instituto de Medicina Molecular, João Lobo Antunes, Faculdade de Medicina Universidade de Lisboa, Lisbon, Portugal
| | - Gokhul Kilaru
- Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Elizabeth B Klerman
- Division of Sleep Medicine, Harvard Medical School, Boston, MA, USA
- Department of Neurology, Massachusetts General Hospital, Boston, MA, USA
- Division of Sleep and Circadian Disorders, Brigham and Women's Hospital, Boston, MA, USA
| | - Maria M Mota
- Instituto de Medicina Molecular, João Lobo Antunes, Faculdade de Medicina Universidade de Lisboa, Lisbon, Portugal
| | - Joseph S Takahashi
- Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA.
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
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Matthews KA, Senagbe KM, Nötzel C, Gonzales CA, Tong X, Rijo-Ferreira F, Bhanu NV, Miguel-Blanco C, Lafuente-Monasterio MJ, Garcia BA, Kafsack BFC, Martinez ED. Disruption of the Plasmodium falciparum Life Cycle through Transcriptional Reprogramming by Inhibitors of Jumonji Demethylases. ACS Infect Dis 2020; 6:1058-1075. [PMID: 32272012 PMCID: PMC7748244 DOI: 10.1021/acsinfecdis.9b00455] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
![]()
Little
is known about the role of the three Jumonji C (JmjC) enzymes
in Plasmodium falciparum (Pf). Here,
we show that JIB-04 and other established inhibitors of mammalian
JmjC histone demethylases kill asexual blood stage parasites and are
even more potent at blocking gametocyte development and gamete formation.
In late stage parasites, JIB-04 increased levels of trimethylated
lysine residues on histones, suggesting the inhibition of P. falciparum Jumonji demethylase activity. These epigenetic
defects coincide with deregulation of invasion, cell motor, and sexual
development gene programs, including gene targets coregulated by the
PfAP2-I transcription factor and chromatin-binding factor, PfBDP1.
Mechanistically, we demonstrate that PfJmj3 converts 2-oxoglutarate
to succinate in an iron-dependent manner consistent with mammalian
Jumonji enzymes, and this catalytic activity is inhibited by JIB-04
and other Jumonji inhibitors. Our pharmacological studies of Jumonji
activity in the malaria parasite provide evidence that inhibition
of these enzymatic activities is detrimental to the parasite.
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Affiliation(s)
- Krista A. Matthews
- Department of Pharmacology, The University of Texas Southwestern Medical Center, 6000 Harry Hines Blvd., Dallas, Texas 75390, United States
| | - Kossi M. Senagbe
- Hamon Center for Therapeutic Oncology Research, The University of Texas Southwestern Medical Center, 6000 Harry Hines Blvd., Dallas, Texas 75390, United States
| | - Christopher Nötzel
- Department of Microbiology & Immunology, Weill Cornell Medicine, 1300 York Avenue, W-705, New York, New York 10065, United States
- Biochemistry, Cell & Molecular Biology Graduate Program, Weill Cornell Medicine, 1300 York Avenue, W-705, New York, New York 10065, United States
| | - Christopher A. Gonzales
- Hamon Center for Therapeutic Oncology Research, The University of Texas Southwestern Medical Center, 6000 Harry Hines Blvd., Dallas, Texas 75390, United States
| | - Xinran Tong
- Department of Microbiology & Immunology, Weill Cornell Medicine, 1300 York Avenue, W-705, New York, New York 10065, United States
| | - Filipa Rijo-Ferreira
- Department of Neuroscience, The University of Texas Southwestern Medical Center, 6000 Harry Hines Blvd., Dallas, Texas 75390, United States
| | - Natarajan V. Bhanu
- Epigenetics Program, Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, 3400 Civic Center Blvd., Bldg. 421, Philadelphia, Pennsylvania 19104, United States
| | - Celia Miguel-Blanco
- Tres Cantos Medicines Development Campus, GlaxoSmithKline, P.T.M. Severo Ochoa, Tres Cantos, Madrid 28760, Spain
| | | | - Benjamin A. Garcia
- Epigenetics Program, Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, 3400 Civic Center Blvd., Bldg. 421, Philadelphia, Pennsylvania 19104, United States
| | - Björn F. C. Kafsack
- Department of Microbiology & Immunology, Weill Cornell Medicine, 1300 York Avenue, W-705, New York, New York 10065, United States
- Biochemistry, Cell & Molecular Biology Graduate Program, Weill Cornell Medicine, 1300 York Avenue, W-705, New York, New York 10065, United States
| | - Elisabeth D. Martinez
- Department of Pharmacology, The University of Texas Southwestern Medical Center, 6000 Harry Hines Blvd., Dallas, Texas 75390, United States
- Hamon Center for Therapeutic Oncology Research, The University of Texas Southwestern Medical Center, 6000 Harry Hines Blvd., Dallas, Texas 75390, United States
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Carvalho T, Trindade S, Pimenta S, Santos AB, Rijo-Ferreira F, Figueiredo LM. Trypanosoma brucei triggers a marked immune response in male reproductive organs. PLoS Negl Trop Dis 2018; 12:e0006690. [PMID: 30110342 PMCID: PMC6093638 DOI: 10.1371/journal.pntd.0006690] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Accepted: 07/16/2018] [Indexed: 12/16/2022] Open
Abstract
African trypanosomiasis is caused by the protozoan parasite Trypanosoma brucei, transmitted between mammals by the bite of a tsetse. It has been recently shown that parasites accumulate in large numbers in various organs and tissues, including the mouse testis. Whether parasites are protected from the immune system in the male reproductive organ or can be transmitted through sexual route remains unknown. Here we show that parasites can be detected by fine needle aspiration cytology of the male reproductive system in mice, and histopathological analysis revealed that T. brucei accumulates in the stroma of the epididymis, epididymal adipose tissue and fibrous tunics of the testis. No parasites were found in the lumen of intact epididymal ducts or seminiferous tubules of the testis, indicating that the large majority of the parasites are not located in immune-privileged sites. In fact, these parasites are associated with marked inflammatory cell infiltration, parasite degeneration, and severe tissue damage and rupture of epididymal ducts, which may be related with reduced fertility. Overall, we show that just like in the bloodstream and most other tissues, in the male reproductive organs, T. brucei are exposed to a strong immune response. The detection of a very high number of parasites in this organ and its accessibility opens the possibility of using fine needle aspiration cytology as a complementary diagnostic tool in Animal African Trypanosomiasis.
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Affiliation(s)
- Tânia Carvalho
- Instituto de Medicina Molecular–João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Sandra Trindade
- Instituto de Medicina Molecular–João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Sílvia Pimenta
- Instituto de Medicina Molecular–João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Ana B. Santos
- Instituto de Medicina Molecular–João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Filipa Rijo-Ferreira
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| | - Luísa M. Figueiredo
- Instituto de Medicina Molecular–João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
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11
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Rijo-Ferreira F, Carvalho T, Afonso C, Sanches-Vaz M, Costa RM, Figueiredo LM, Takahashi JS. Sleeping sickness is a circadian disorder. Nat Commun 2018; 9:62. [PMID: 29302035 PMCID: PMC5754353 DOI: 10.1038/s41467-017-02484-2] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Accepted: 12/04/2017] [Indexed: 12/15/2022] Open
Abstract
Sleeping sickness is a fatal disease caused by Trypanosoma brucei, a unicellular parasite that lives in the bloodstream and interstitial spaces of peripheral tissues and the brain. Patients have altered sleep/wake cycles, body temperature, and endocrine profiles, but the underlying causes are unknown. Here, we show that the robust circadian rhythms of mice become phase advanced upon infection, with abnormal activity occurring during the rest phase. This advanced phase is caused by shortening of the circadian period both at the behavioral level as well as at the tissue and cell level. Period shortening is T. brucei specific and independent of the host immune response, as co-culturing parasites with explants or fibroblasts also shortens the clock period, whereas malaria infection does not. We propose that T. brucei causes an advanced circadian rhythm disorder, previously associated only with mutations in clock genes, which leads to changes in the timing of sleep. African sleeping sickness is well known for the alterations of sleeping patterns, but it is not known how circadian biology is altered by the causative pathogen Trypanosoma brucei. Here the authors show T. brucei causes a disorder of the cellular circadian clock that is unrelated to the immune response to the parasite.
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Affiliation(s)
- Filipa Rijo-Ferreira
- Graduate Program in Areas of Basic and Applied Biology, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, 4099-002, Porto, Portugal.,Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028, Lisboa, Portugal.,Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX, 75390-9111, USA.,Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, 75390-9111, USA
| | - Tânia Carvalho
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028, Lisboa, Portugal
| | - Cristina Afonso
- Champalimaud Neuroscience Programme, Champalimaud Centre for the Unknown, 1400-038, Lisbon, Portugal
| | - Margarida Sanches-Vaz
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028, Lisboa, Portugal
| | - Rui M Costa
- Champalimaud Neuroscience Programme, Champalimaud Centre for the Unknown, 1400-038, Lisbon, Portugal
| | - Luísa M Figueiredo
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028, Lisboa, Portugal.
| | - Joseph S Takahashi
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX, 75390-9111, USA. .,Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, 75390-9111, USA.
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12
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Affiliation(s)
- Filipa Rijo-Ferreira
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- Howard Hughes Medical Institute, The University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Joseph S. Takahashi
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- Howard Hughes Medical Institute, The University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- * E-mail: (JST); (LMF)
| | - Luisa M. Figueiredo
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
- * E-mail: (JST); (LMF)
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13
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Rijo-Ferreira F, Pinto-Neves D, Barbosa-Morais NL, Takahashi JS, Figueiredo LM. Trypanosoma brucei metabolism is under circadian control. Nat Microbiol 2017; 2:17032. [PMID: 28288095 PMCID: PMC5398093 DOI: 10.1038/nmicrobiol.2017.32] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 02/09/2017] [Indexed: 12/16/2022]
Abstract
The Earth's rotation forced life to evolve under cyclic day and night environmental changes. To anticipate such daily cycles, prokaryote and eukaryote free-living organisms evolved intrinsic clocks that regulate physiological and behavioural processes. Daily rhythms have been observed in organisms living within hosts, such as parasites. Whether parasites have intrinsic molecular clocks or whether they simply respond to host rhythmic physiological cues remains unknown. Here, we show that Trypanosoma brucei, the causative agent of human sleeping sickness, has an intrinsic circadian clock that regulates its metabolism in two different stages of the life cycle. We found that, in vitro, ∼10% of genes in T. brucei are expressed with a circadian rhythm. The maximum expression of these genes occurs at two different phases of the day and may depend on a post-transcriptional mechanism. Circadian genes are enriched in cellular metabolic pathways and coincide with two peaks of intracellular adenosine triphosphate concentration. Moreover, daily changes in the parasite population lead to differences in suramin sensitivity, a drug commonly used to treat this infection. These results demonstrate that parasites have an intrinsic circadian clock that is independent of the host, and which regulates parasite biology throughout the day.
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Affiliation(s)
- Filipa Rijo-Ferreira
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal.,Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9111, USA.,Graduate Program in Areas of Basic and Applied Biology, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, 4099-002 Porto, Portugal
| | - Daniel Pinto-Neves
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Nuno L Barbosa-Morais
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Joseph S Takahashi
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9111, USA.,Howard Hughes Medical Institute, The University of Texas Southwestern Medical Center, Dallas, Texas 75390-9111, USA
| | - Luisa M Figueiredo
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
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14
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Leija C, Rijo-Ferreira F, Kinch LN, Grishin NV, Nischan N, Kohler JJ, Hu Z, Phillips MA. Pyrimidine Salvage Enzymes Are Essential for De Novo Biosynthesis of Deoxypyrimidine Nucleotides in Trypanosoma brucei. PLoS Pathog 2016; 12:e1006010. [PMID: 27820863 PMCID: PMC5098729 DOI: 10.1371/journal.ppat.1006010] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 10/18/2016] [Indexed: 01/17/2023] Open
Abstract
The human pathogenic parasite Trypanosoma brucei possess both de novo and salvage routes for the biosynthesis of pyrimidine nucleotides. Consequently, they do not require salvageable pyrimidines for growth. Thymidine kinase (TK) catalyzes the formation of dTMP and dUMP and is one of several salvage enzymes that appear redundant to the de novo pathway. Surprisingly, we show through analysis of TK conditional null and RNAi cells that TK is essential for growth and for infectivity in a mouse model, and that a catalytically active enzyme is required for its function. Unlike humans, T. brucei and all other kinetoplastids lack dCMP deaminase (DCTD), which provides an alternative route to dUMP formation. Ectopic expression of human DCTD resulted in full rescue of the RNAi growth phenotype and allowed for selection of viable TK null cells. Metabolite profiling by LC-MS/MS revealed a buildup of deoxypyrimidine nucleosides in TK depleted cells. Knockout of cytidine deaminase (CDA), which converts deoxycytidine to deoxyuridine led to thymidine/deoxyuridine auxotrophy. These unexpected results suggested that T. brucei encodes an unidentified 5'-nucleotidase that converts deoxypyrimidine nucleotides to their corresponding nucleosides, leading to their dead-end buildup in TK depleted cells at the expense of dTTP pools. Bioinformatics analysis identified several potential candidate genes that could encode 5'-nucleotidase activity including an HD-domain protein that we show catalyzes dephosphorylation of deoxyribonucleotide 5'-monophosphates. We conclude that TK is essential for synthesis of thymine nucleotides regardless of whether the nucleoside precursors originate from the de novo pathway or through salvage. Reliance on TK in the absence of DCTD may be a shared vulnerability among trypanosomatids and may provide a unique opportunity to selectively target a diverse group of pathogenic single-celled eukaryotes with a single drug.
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Affiliation(s)
- Christopher Leija
- Department of Pharmacology University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
| | - Filipa Rijo-Ferreira
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
- Department of Neuroscience, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
- Graduate Program in Areas of Basic and Applied Biology, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Lisa N. Kinch
- Department of Biophysics, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
| | - Nick V. Grishin
- Department of Biophysics, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
| | - Nicole Nischan
- Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
| | - Jennifer J. Kohler
- Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
| | - Zeping Hu
- Children’s Medical Center Research Institute, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
| | - Margaret A. Phillips
- Department of Pharmacology University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
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15
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Trindade S, Rijo-Ferreira F, Carvalho T, Pinto-Neves D, Guegan F, Aresta-Branco F, Bento F, Young SA, Pinto A, Van Den Abbeele J, Ribeiro RM, Dias S, Smith TK, Figueiredo LM. Trypanosoma brucei Parasites Occupy and Functionally Adapt to the Adipose Tissue in Mice. Cell Host Microbe 2016; 19:837-48. [PMID: 27237364 PMCID: PMC4906371 DOI: 10.1016/j.chom.2016.05.002] [Citation(s) in RCA: 221] [Impact Index Per Article: 27.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 03/21/2016] [Accepted: 04/30/2016] [Indexed: 11/17/2022]
Abstract
Trypanosoma brucei is an extracellular parasite that causes sleeping sickness. In mammalian hosts, trypanosomes are thought to exist in two major niches: early in infection, they populate the blood; later, they breach the blood-brain barrier. Working with a well-established mouse model, we discovered that adipose tissue constitutes a third major reservoir for T. brucei. Parasites from adipose tissue, here termed adipose tissue forms (ATFs), can replicate and were capable of infecting a naive animal. ATFs were transcriptionally distinct from bloodstream forms, and the genes upregulated included putative fatty acid β-oxidation enzymes. Consistent with this, ATFs were able to utilize exogenous myristate and form β-oxidation intermediates, suggesting that ATF parasites can use fatty acids as an external carbon source. These findings identify the adipose tissue as a niche for T. brucei during its mammalian life cycle and could potentially explain the weight loss associated with sleeping sickness. T. brucei parasites accumulate in the adipose tissue early after mouse infection Adipose tissue forms (ATFs) can replicate and are capable of infecting naive mice ATFs are transcriptionally distinct and upregulate genes for fatty acid metabolism ATFs can actively uptake exogenous myristate and form β-oxidation intermediates
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Affiliation(s)
- Sandra Trindade
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1990-375 Lisboa, Portugal
| | - Filipa Rijo-Ferreira
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1990-375 Lisboa, Portugal; Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390-9111, USA; Graduate Program in Areas of Basic and Applied Biology, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, 4099-002 Porto, Portugal
| | - Tânia Carvalho
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1990-375 Lisboa, Portugal
| | - Daniel Pinto-Neves
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1990-375 Lisboa, Portugal
| | - Fabien Guegan
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1990-375 Lisboa, Portugal
| | - Francisco Aresta-Branco
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1990-375 Lisboa, Portugal
| | - Fabio Bento
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1990-375 Lisboa, Portugal
| | - Simon A Young
- Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, UK
| | - Andreia Pinto
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1990-375 Lisboa, Portugal
| | - Jan Van Den Abbeele
- Department of Biomedical Sciences, Unit of Veterinary Protozoology, Institute of Tropical Medicine Antwerp, B-2000 Antwerp, Belgium; Department of Physiology, Laboratory of Zoophysiology, University of Ghent, B-9000 Ghent, Belgium
| | - Ruy M Ribeiro
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA; Guest Professor, Faculdade de Medicina, Universidade de Lisboa, 1990-375 Lisboa, Portugal
| | - Sérgio Dias
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1990-375 Lisboa, Portugal
| | - Terry K Smith
- Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, UK
| | - Luisa M Figueiredo
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1990-375 Lisboa, Portugal.
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16
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Li Q, Leija C, Rijo-Ferreira F, Chen J, Cestari I, Stuart K, Tu BP, Phillips MA. GMP synthase is essential for viability and infectivity of Trypanosoma brucei despite a redundant purine salvage pathway. Mol Microbiol 2015; 97:1006-20. [PMID: 26043892 DOI: 10.1111/mmi.13083] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/04/2015] [Indexed: 12/28/2022]
Abstract
The causative agent of human African trypanosomiasis, Trypanosoma brucei, lacks de novo purine biosynthesis and depends on purine salvage from the host. The purine salvage pathway is redundant and contains two routes to guanosine-5'-monophosphate (GMP) formation: conversion from xanthosine-5'-monophosphate (XMP) by GMP synthase (GMPS) or direct salvage of guanine by hypoxanthine-guanine phosphoribosyltransferase (HGPRT). We show recombinant T. brucei GMPS efficiently catalyzes GMP formation. Genetic knockout of GMPS in bloodstream parasites led to depletion of guanine nucleotide pools and was lethal. Growth of gmps null cells was only rescued by supraphysiological guanine concentrations (100 μM) or by expression of an extrachromosomal copy of GMPS. Hypoxanthine was a competitive inhibitor of guanine rescue, consistent with a common uptake/metabolic conversion mechanism. In mice, gmps null parasites were unable to establish an infection demonstrating that GMPS is essential for virulence and that plasma guanine is insufficient to support parasite purine requirements. These data validate GMPS as a potential therapeutic target for treatment of human African trypanosomiasis. The ability to strategically inhibit key metabolic enzymes in the purine pathway unexpectedly bypasses its functional redundancy by exploiting both the nature of pathway flux and the limited nutrient environment of the parasite's extracellular niche.
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Affiliation(s)
- Qiong Li
- Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, 6001 Forest Park Rd, Dallas, TX, 75390-9041, USA
| | - Christopher Leija
- Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, 6001 Forest Park Rd, Dallas, TX, 75390-9041, USA
| | - Filipa Rijo-Ferreira
- Department of Neuroscience, University of Texas Southwestern Medical Center at Dallas, 6001 Forest Park Rd, Dallas, TX, 75390-9041, USA.,Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal.,Graduate Program in Areas of Basic and Applied Biology, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Jun Chen
- Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, 6001 Forest Park Rd, Dallas, TX, 75390-9041, USA
| | - Igor Cestari
- Seattle Biomedical Research Institute, 307 Westlake Avenue North, Suite 500, Seattle, WA, 98109-5219, USA
| | - Kenneth Stuart
- Seattle Biomedical Research Institute, 307 Westlake Avenue North, Suite 500, Seattle, WA, 98109-5219, USA
| | - Benjamin P Tu
- Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, 6001 Forest Park Rd, Dallas, TX, 75390-9041, USA
| | - Margaret A Phillips
- Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, 6001 Forest Park Rd, Dallas, TX, 75390-9041, USA
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17
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Pena AC, Pimentel MR, Manso H, Vaz-Drago R, Pinto-Neves D, Aresta-Branco F, Rijo-Ferreira F, Guegan F, Pedro Coelho L, Carmo-Fonseca M, Barbosa-Morais NL, Figueiredo LM. Trypanosoma brucei histone H1 inhibits RNA polymerase I transcription and is important for parasite fitness in vivo. Mol Microbiol 2014; 93:645-63. [PMID: 24946224 PMCID: PMC4285223 DOI: 10.1111/mmi.12677] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/15/2014] [Indexed: 11/30/2022]
Abstract
Trypanosoma brucei is a unicellular parasite that causes sleeping sickness in humans. Most of its transcription is constitutive and driven by RNA polymerase II. RNA polymerase I (Pol I) transcribes not only ribosomal RNA genes, but also protein-encoding genes, including variant surface glycoproteins (VSGs) and procyclins. In T. brucei, histone H1 (H1) is required for VSG silencing and chromatin condensation. However, whether H1 has a genome-wide role in transcription is unknown. Here, using RNA sequencing we show that H1 depletion changes the expression of a specific cohort of genes. Interestingly, the predominant effect is partial loss of silencing of Pol I loci, such as VSG and procyclin genes. Labelling of nascent transcripts with 4-thiouridine showed that H1 depletion does not alter the level of labelled Pol II transcripts. In contrast, the levels of 4sU-labelled Pol I transcripts were increased by two- to sixfold, suggesting that H1 preferentially blocks transcription at Pol I loci. Finally, we observed that parasites depleted of H1 grow almost normally in culture but they have a reduced fitness in mice, suggesting that H1 is important for host-pathogen interactions.
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Affiliation(s)
- Ana C Pena
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, Edifício Egas Moniz, 1649-028, Lisboa, Portugal
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