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Tomasina R, González FC, Echeverría S, Cabrera A, Robello C. Insights into the Cell Division of Neospora caninum. Microorganisms 2023; 12:61. [PMID: 38257886 PMCID: PMC10818811 DOI: 10.3390/microorganisms12010061] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 12/14/2023] [Accepted: 12/20/2023] [Indexed: 01/24/2024] Open
Abstract
Neospora caninum is an apicomplexan protozoan parasite responsible for causing neosporosis in a range of animal species. It results in substantial economic losses in the livestock industry and poses significant health risks to companion and wild animals. Central to its survival and pathogenicity is the process of cell division, which remains poorly understood in this parasite. In this study, we explored the cell division of Neospora caninum using a combination of modern and classic imaging tools, emphasizing its pivotal role in perpetuating the parasite's life cycle and contributing to its ability to persist within host organisms. We described the intricacies of endodyogeny in Neospora caninum, detailing the dynamics of the cell assembly and the nuclear division by ultrastructure expansion microscopy and regular confocal microscopy. Furthermore, we explored the centrosome dynamics, the centrioles and the apicoplast through the advancement of the cell cycle. Our analysis described with unprecedented detail, the endodyogeny in this parasite. By advancing our understanding of these molecular mechanisms, we aimed to inspire innovative strategies for disease management and control, with the ultimate goal of mitigating the devastating impact of neosporosis on animal health and welfare.
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Affiliation(s)
- Ramiro Tomasina
- Laboratorio de Interacciones Hospedero Patógeno, Institut Pasteur de Montevideo, Montevideo 11400, Uruguay; (R.T.); (F.C.G.); (S.E.); (A.C.)
- Departamento de Parasitología y Micología, Facultad de Medicina, Universidad de la República, Montevideo 11800, Uruguay
| | - Fabiana C. González
- Laboratorio de Interacciones Hospedero Patógeno, Institut Pasteur de Montevideo, Montevideo 11400, Uruguay; (R.T.); (F.C.G.); (S.E.); (A.C.)
| | - Soledad Echeverría
- Laboratorio de Interacciones Hospedero Patógeno, Institut Pasteur de Montevideo, Montevideo 11400, Uruguay; (R.T.); (F.C.G.); (S.E.); (A.C.)
| | - Andrés Cabrera
- Laboratorio de Interacciones Hospedero Patógeno, Institut Pasteur de Montevideo, Montevideo 11400, Uruguay; (R.T.); (F.C.G.); (S.E.); (A.C.)
- Departamento de Parasitología y Micología, Facultad de Medicina, Universidad de la República, Montevideo 11800, Uruguay
| | - Carlos Robello
- Laboratorio de Interacciones Hospedero Patógeno, Institut Pasteur de Montevideo, Montevideo 11400, Uruguay; (R.T.); (F.C.G.); (S.E.); (A.C.)
- Departamento de Bioquímica, Facultad de Medicina, Universidad de la República, Montevideo 11800, Uruguay
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Li Z, Du W, Yang J, Lai DH, Lun ZR, Guo Q. Cryo-Electron Tomography of Toxoplasma gondii Indicates That the Conoid Fiber May Be Derived from Microtubules. Adv Sci (Weinh) 2023; 10:e2206595. [PMID: 36840635 DOI: 10.1002/advs.202206595] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 02/04/2023] [Indexed: 05/18/2023]
Abstract
Toxoplasma gondii (T. gondii) is the causative agent of toxoplasmosis and can infect numerous warm-blooded animals. An improved understanding of the fine structure of this parasite can help elucidate its replication mechanism. Previous studies have resolved the ultrastructure of the cytoskeleton using purified samples, which eliminates their cellular context. Here the application of cryo-electron tomography to visualize T. gondii tachyzoites in their native state is reported. The fine structure and cellular distribution of the cytoskeleton are resolved and analyzed at nanometer resolution. Additionally, the tachyzoite structural characteristics are annotated during its endodyogeny for the first time. By comparing the structural features in mature tachyzoites and their daughter buds, it is proposed that the conoid fiber of the Apicomplexa originates from microtubules. This work represents the detailed molecular anatomy of T. gondii, particularly during the budding replication stage of tachyzoite, and provides a reference for further studies of this fascinating organism.
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Affiliation(s)
- Zhixun Li
- State Key Laboratory of Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, School of Life Sciences, Peking University, Beijing, 100871, P. R. China
| | - Wenjing Du
- State Key Laboratory of Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, School of Life Sciences, Peking University, Beijing, 100871, P. R. China
| | - Jiong Yang
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510275, P. R. China
| | - De-Hua Lai
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510275, P. R. China
| | - Zhao-Rong Lun
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510275, P. R. China
| | - Qiang Guo
- State Key Laboratory of Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, School of Life Sciences, Peking University, Beijing, 100871, P. R. China
- Changping Laboratory, Yard 28, Science Park Road, Beijing, 102206, P. R. China
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3
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Tomasina R, Gonzalez FC, Martins-Duarte ÉS, Bastin P, Gissot M, Francia ME. Separate To Operate: the Centriole-Free Inner Core of the Centrosome Regulates the Assembly of the Intranuclear Spindle in Toxoplasma gondii. mBio 2022;:e0185922. [PMID: 36069445 DOI: 10.1128/mbio.01859-22] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Centrosomes are the main microtubule-organizing center of the cell. They are normally formed by two centrioles, embedded in a cloud of proteins known as pericentriolar material (PCM). The PCM ascribes centrioles with their microtubule nucleation capacity. Toxoplasma gondii, the causative agent of toxoplasmosis, divides by endodyogeny. Successful cell division is critical for pathogenesis. The centrosome, one of the microtubule organizing centers of the cell, plays central roles in orchestrating the temporal and physical coordination of major organelle segregation and daughter cell formation during endodyogeny. The Toxoplasma centrosome is constituted by multiple domains: an outer core, distal from the nucleus; a middle core; and an inner core, proximal to the nucleus. This modular organization has been proposed to underlie T. gondii's cell division plasticity. However, the role of the inner core remains undeciphered. Here, we focus on understanding the function of the inner core by finely studying the localization and role of its only known molecular marker; TgCep250L1. We show that upon conditional degradation of TgCep250L1 parasites are unable to survive. Mutants exhibit severe nuclear segregation defects. In addition, the rest of the centrosome, defined by the position of the centrioles, disconnects from the nucleus. We explore the structural defects underlying these phenotypes by ultrastructure expansion microscopy. We show that TgCep250L1's location changes with respect to other markers, and these changes encompass the formation of the mitotic spindle. Moreover, we show that in the absence of TgCep250L1, the microtubule binding protein TgEB1, fails to localize at the mitotic spindle, while unsegregated nuclei accumulate at the residual body. Overall, our data support a model in which the inner core of the T. gondii centrosome critically participates in cell division by directly impacting the formation or stability of the mitotic spindle. IMPORTANCE Toxoplasma gondii parasites cause toxoplasmosis, arguably the most widespread and prevalent parasitosis of humans and animals. During the clinically relevant stage of its life cycle, the parasites divide by endodyogeny. In this mode of division, the nucleus, containing loosely packed chromatin and a virtually intact nuclear envelope, parcels into two daughter cells generated within a common mother cell cytoplasm. The centrosome is a microtubule-organizing center critical for orchestrating the multiple simultaneously occurring events of endodyogeny. It is organized in two distinct domains: the outer and inner cores. We demonstrate here that the inner core protein TgCEP250L1 is required for replication of T. gondii. Lack of TgCEP250L1 renders parasites able to form daughter cells, while unable to segregate their nuclei. We determine that, in the absence of TgCEP250L1, the mitotic spindle, which is responsible for karyokinesis, does not assemble. Our results support a role for the inner core in nucleation or stabilization of the mitotic spindle in T. gondii.
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Morano AA, Dvorin JD. The Ringleaders: Understanding the Apicomplexan Basal Complex Through Comparison to Established Contractile Ring Systems. Front Cell Infect Microbiol 2021; 11:656976. [PMID: 33954122 PMCID: PMC8089483 DOI: 10.3389/fcimb.2021.656976] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [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] [Received: 01/21/2021] [Accepted: 03/19/2021] [Indexed: 12/02/2022] Open
Abstract
The actomyosin contractile ring is a key feature of eukaryotic cytokinesis, conserved across many eukaryotic kingdoms. Recent research into the cell biology of the divergent eukaryotic clade Apicomplexa has revealed a contractile ring structure required for asexual division in the medically relevant genera Toxoplasma and Plasmodium; however, the structure of the contractile ring, known as the basal complex in these parasites, remains poorly characterized and in the absence of a myosin II homolog, it is unclear how the force required of a cytokinetic contractile ring is generated. Here, we review the literature on the basal complex in Apicomplexans, summarizing what is known about its formation and function, and attempt to provide possible answers to this question and suggest new avenues of study by comparing the Apicomplexan basal complex to well-studied, established cytokinetic contractile rings and their mechanisms in organisms such as S. cerevisiae and D. melanogaster. We also compare the basal complex to structures formed during mitochondrial and plastid division and cytokinetic mechanisms of organisms beyond the Opisthokonts, considering Apicomplexan diversity and divergence.
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Affiliation(s)
- Alexander A Morano
- Biological and Biomedical Sciences, Harvard Medical School, Boston, MA, United States.,Division of Infectious Diseases, Boston Children's Hospital, Boston, MA, United States
| | - Jeffrey D Dvorin
- Division of Infectious Diseases, Boston Children's Hospital, Boston, MA, United States.,Department of Pediatrics, Harvard Medical School, Boston, MA, United States
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Gubbels MJ, Coppens I, Zarringhalam K, Duraisingh MT, Engelberg K. The Modular Circuitry of Apicomplexan Cell Division Plasticity. Front Cell Infect Microbiol 2021; 11:670049. [PMID: 33912479 PMCID: PMC8072463 DOI: 10.3389/fcimb.2021.670049] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Accepted: 03/22/2021] [Indexed: 12/31/2022] Open
Abstract
The close-knit group of apicomplexan parasites displays a wide variety of cell division modes, which differ between parasites as well as between different life stages within a single parasite species. The beginning and endpoint of the asexual replication cycles is a 'zoite' harboring the defining apical organelles required for host cell invasion. However, the number of zoites produced per division round varies dramatically and can unfold in several different ways. This plasticity of the cell division cycle originates from a combination of hard-wired developmental programs modulated by environmental triggers. Although the environmental triggers and sensors differ between species and developmental stages, widely conserved secondary messengers mediate the signal transduction pathways. These environmental and genetic input integrate in division-mode specific chromosome organization and chromatin modifications that set the stage for each division mode. Cell cycle progression is conveyed by a smorgasbord of positively and negatively acting transcription factors, often acting in concert with epigenetic reader complexes, that can vary dramatically between species as well as division modes. A unique set of cell cycle regulators with spatially distinct localization patterns insert discrete check points which permit individual control and can uncouple general cell cycle progression from nuclear amplification. Clusters of expressed genes are grouped into four functional modules seen in all division modes: 1. mother cytoskeleton disassembly; 2. DNA replication and segregation (D&S); 3. karyokinesis; 4. zoite assembly. A plug-and-play strategy results in the variety of extant division modes. The timing of mother cytoskeleton disassembly is hard-wired at the species level for asexual division modes: it is either the first step, or it is the last step. In the former scenario zoite assembly occurs at the plasma membrane (external budding), and in the latter scenario zoites are assembled in the cytoplasm (internal budding). The number of times each other module is repeated can vary regardless of this first decision, and defines the modes of cell division: schizogony, binary fission, endodyogeny, endopolygeny.
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Affiliation(s)
- Marc-Jan Gubbels
- Department of Biology, Boston College, Chestnut Hill, MA, United States
| | - Isabelle Coppens
- Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, United States
| | - Kourosh Zarringhalam
- Department of Mathematics, University of Massachusetts Boston, Boston, MA, United States
| | - Manoj T. Duraisingh
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, MA, United States
| | - Klemens Engelberg
- Department of Biology, Boston College, Chestnut Hill, MA, United States
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Hawkins LM, Naumov AV, Batra M, Wang C, Chaput D, Suvorova ES. Novel CRK-Cyclin Complex Controls Spindle Assembly Checkpoint in Toxoplasma Endodyogeny. mBio 2021; 13:e0356121. [PMID: 35130726 DOI: 10.1128/mbio.03561-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Opportunistic parasites of the Apicomplexa phylum use a variety of division modes built on two types of cell cycles that incorporate two distinctive mechanisms of mitosis: uncoupled from and coupled to parasite budding. Parasites have evolved novel factors to regulate such unique replication mechanisms that are poorly understood. Here, we have combined genetics, quantitative fluorescence microscopy, and global proteomics approaches to examine endodyogeny in Toxoplasma gondii dividing by mitosis coupled to cytokinesis. In the current study, we focus on the steps controlled by the recently described atypical Cdk-related kinase T. gondii Crk6 (TgCrk6). While inspecting protein complexes, we found that this previously orphaned TgCrk6 kinase interacts with a parasite-specific atypical cyclin, TgCyc1. We built conditional expression models and examined primary cell cycle defects caused by the lack of TgCrk6 or TgCyc1. Quantitative microscopy assays revealed that tachyzoites deficient in either TgCrk6 or the cyclin partner TgCyc1 exhibit identical mitotic defects, suggesting cooperative action of the complex components. Further examination of the mitotic structures indicated that the TgCrk6/TgCyc1 complex regulates metaphase. This novel finding confirms a functional spindle assembly checkpoint (SAC) in T. gondii. Measuring global changes in protein expression and phosphorylation, we found evidence that canonical activities of the Toxoplasma SAC are intertwined with parasite-specific tasks. Analysis of phosphorylation motifs suggests that Toxoplasma metaphase is regulated by CDK, mitogen-activated kinase (MAPK), and Aurora kinases, while the TgCrk6/TgCyc1 complex specifically controls the centromere-associated network. IMPORTANCE The rate of Toxoplasma tachyzoite division directly correlates with the severity of the disease, toxoplasmosis, which affects humans and animals. Thus, a better understanding of the tachyzoite cell cycle would offer much-needed efficient tools to control the acute stage of infection. Although tachyzoites divide by binary division, the cell cycle architecture and regulation differ significantly from the conventional binary fission of their host cells. Unlike the unidirectional conventional cell cycle, the Toxoplasma budding cycle is braided and is regulated by multiple essential Cdk-related kinases (Crks) that emerged in the place of missing conventional cell cycle regulators. How these novel Crks control apicomplexan cell cycles is largely unknown. Here, we have discovered a novel parasite-specific complex, TgCrk6/TgCyc1, that orchestrates a major mitotic event, the spindle assembly checkpoint. We demonstrated that tachyzoites incorporated parasite-specific tasks in the canonical checkpoint functions.
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Torres JA, Pasquarelli RR, Back PS, Moon AS, Bradley PJ. Identification and Molecular Dissection of IMC32, a Conserved Toxoplasma Inner Membrane Complex Protein That Is Essential for Parasite Replication. mBio 2021; 12:e03622-20. [PMID: 33593973 DOI: 10.1128/mBio.03622-20] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The inner membrane complex (IMC) is a unique organelle of apicomplexan parasites that plays critical roles in parasite motility, host cell invasion, and replication. Despite the common functions of the organelle, relatively few IMC proteins are conserved across the phylum and the precise roles of many IMC components remain to be characterized. Here, we identify a novel component of the Toxoplasma gondii IMC (IMC32) that localizes to the body portion of the IMC and is recruited to developing daughter buds early during endodyogeny. IMC32 is essential for parasite survival, as its conditional depletion results in a complete collapse of the IMC that is lethal to the parasite. We demonstrate that localization of IMC32 is dependent on both an N-terminal palmitoylation site and a series of C-terminal coiled-coil domains. Using deletion analyses and functional complementation, we show that two conserved regions within the C-terminal coiled-coil domains play critical roles in protein function during replication. Together, this work reveals an essential component of parasite replication that provides a novel target for therapeutic intervention of T. gondii and related apicomplexan parasites.IMPORTANCE The IMC is an important organelle that apicomplexan parasites use to maintain their intracellular lifestyle. While many IMC proteins have been identified, only a few central players that are essential for internal budding have been described and even fewer are conserved across the phylum. Here, we identify IMC32, a novel component of the Toxoplasma gondii IMC that localizes to very early daughter buds, indicating a role in the early stages of parasite replication. We then demonstrate that IMC32 is essential for parasite survival and pinpoint conserved regions within the protein that are important for membrane association and daughter cell formation. As IMC32 is unique to these parasites and not present in their mammalian hosts, it serves as a new target for the development of drugs that exclusively affect these important intracellular pathogens.
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Gubbels MJ, Keroack CD, Dangoudoubiyam S, Worliczek HL, Paul AS, Bauwens C, Elsworth B, Engelberg K, Howe DK, Coppens I, Duraisingh MT. Fussing About Fission: Defining Variety Among Mainstream and Exotic Apicomplexan Cell Division Modes. Front Cell Infect Microbiol 2020; 10:269. [PMID: 32582569 PMCID: PMC7289922 DOI: 10.3389/fcimb.2020.00269] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [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] [Received: 01/26/2020] [Accepted: 05/06/2020] [Indexed: 12/17/2022] Open
Abstract
Cellular reproduction defines life, yet our textbook-level understanding of cell division is limited to a small number of model organisms centered around humans. The horizon on cell division variants is expanded here by advancing insights on the fascinating cell division modes found in the Apicomplexa, a key group of protozoan parasites. The Apicomplexa display remarkable variation in offspring number, whether karyokinesis follows each S/M-phase or not, and whether daughter cells bud in the cytoplasm or bud from the cortex. We find that the terminology used to describe the various manifestations of asexual apicomplexan cell division emphasizes either the number of offspring or site of budding, which are not directly comparable features and has led to confusion in the literature. Division modes have been primarily studied in two human pathogenic Apicomplexa, malaria-causing Plasmodium spp. and Toxoplasma gondii, a major cause of opportunistic infections. Plasmodium spp. divide asexually by schizogony, producing multiple daughters per division round through a cortical budding process, though at several life-cycle nuclear amplifications stages, are not followed by karyokinesis. T. gondii divides by endodyogeny producing two internally budding daughters per division round. Here we add to this diversity in replication mechanisms by considering the cattle parasite Babesia bigemina and the pig parasite Cystoisospora suis. B. bigemina produces two daughters per division round by a “binary fission” mechanism whereas C. suis produces daughters through both endodyogeny and multiple internal budding known as endopolygeny. In addition, we provide new data from the causative agent of equine protozoal myeloencephalitis (EPM), Sarcocystis neurona, which also undergoes endopolygeny but differs from C. suis by maintaining a single multiploid nucleus. Overall, we operationally define two principally different division modes: internal budding found in cyst-forming Coccidia (comprising endodyogeny and two forms of endopolygeny) and external budding found in the other parasites studied (comprising the two forms of schizogony, binary fission and multiple fission). Progressive insights into the principles defining the molecular and cellular requirements for internal vs. external budding, as well as variations encountered in sexual stages are discussed. The evolutionary pressures and mechanisms underlying apicomplexan cell division diversification carries relevance across Eukaryota.
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Affiliation(s)
- Marc-Jan Gubbels
- Department of Biology, Boston College, Chestnut Hill, MA, United States
| | - Caroline D Keroack
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Harvard University, Boston, MA, United States
| | - Sriveny Dangoudoubiyam
- Department of Veterinary Science, Gluck Equine Research Center, University of Kentucky, Lexington, KY, United States
| | - Hanna L Worliczek
- Department of Biology, Boston College, Chestnut Hill, MA, United States.,Institute of Parasitology, University of Veterinary Medicine, Vienna, Austria
| | - Aditya S Paul
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Harvard University, Boston, MA, United States
| | - Ciara Bauwens
- Department of Biology, Boston College, Chestnut Hill, MA, United States
| | - Brendan Elsworth
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Harvard University, Boston, MA, United States.,School of Biosciences, University of Melbourne, Melbourne, VIC, Australia
| | - Klemens Engelberg
- Department of Biology, Boston College, Chestnut Hill, MA, United States
| | - Daniel K Howe
- Department of Veterinary Science, Gluck Equine Research Center, University of Kentucky, Lexington, KY, United States
| | - Isabelle Coppens
- Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, United States
| | - Manoj T Duraisingh
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Harvard University, Boston, MA, United States
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9
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Affiliation(s)
- David S Lindsay
- Zoonotic Protozoal Diseases Laboratory, Department of Biomedical Sciences and Pathobiology, Center for One Health Research, Virginia Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, United States
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Dubey R, Harrison B, Dangoudoubiyam S, Bandini G, Cheng K, Kosber A, Agop-Nersesian C, Howe DK, Samuelson J, Ferguson DJP, Gubbels MJ. Differential Roles for Inner Membrane Complex Proteins across Toxoplasma gondii and Sarcocystis neurona Development. mSphere 2017; 2:e00409-17. [PMID: 29062899 DOI: 10.1128/mSphere.00409-17] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 09/29/2017] [Indexed: 12/30/2022] Open
Abstract
The inner membrane complex (IMC) is a defining feature of apicomplexan parasites key to both their motility and unique cell division. To provide further insights into the IMC, we analyzed the dynamics and functions of representative alveolin domain-containing IMC proteins across developmental stages. Our work shows universal but distinct roles for IMC1, -3, and -7 during Toxoplasma asexual division but more specialized functions for these proteins during gametogenesis. In addition, we find that IMC15 is involved in daughter formation in both Toxoplasma and Sarcocystis tachyzoites, bradyzoites, and sporozoites. IMC14 and IMC15 function in limiting the number of Toxoplasma offspring per division. Furthermore, IMC7, -12, and -14, which are recruited in the G1 cell cycle stage, are required for stress resistance of extracellular tachyzoites. Thus, although the roles of the different IMC proteins appear to overlap, stage- and development-specific behaviors indicate that their functions are uniquely tailored to each life stage requirement. The inner membrane complex (IMC) of apicomplexan parasites contains a network of intermediate filament-like proteins. The 14 alveolin domain-containing IMC proteins in Toxoplasma gondii fall into different groups defined by their distinct spatiotemporal dynamics during the internal budding process of tachyzoites. Here, we analyzed representatives of different IMC protein groups across all stages of the Toxoplasma life cycle and during Sarcocystis neurona asexual development. We found that across asexually dividing Toxoplasma stages, IMC7 is present exclusively in the mother’s cytoskeleton, whereas IMC1 and IMC3 are both present in mother and daughter cytoskeletons (IMC3 is strongly enriched in daughter buds). In developing macro- and microgametocytes, IMC1 and -3 are absent, whereas IMC7 is lost in early microgametocytes but retained in macrogametocytes until late in their development. We found no roles for IMC proteins during meiosis and sporoblast formation. However, we observed that IMC1 and IMC3, but not IMC7, are present in sporozoites. Although the spatiotemporal pattern of IMC15 and IMC3 suggests orthologous functions in Sarcocystis, IMC7 may have functionally diverged in Sarcocystis merozoites. To functionally characterize IMC proteins, we knocked out IMC7, -12, -14, and -15 in Toxoplasma. IMC14 and -15 appear to be involved in switching between endodyogeny and endopolygeny. In addition, IMC7, -12, and -14, which are all recruited to the cytoskeleton outside cytokinesis, are critical for the structural integrity of extracellular tachyzoites. Altogether, stage- and development-specific roles for IMC proteins can be discerned, suggesting different niches for each IMC protein across the entire life cycle. IMPORTANCE The inner membrane complex (IMC) is a defining feature of apicomplexan parasites key to both their motility and unique cell division. To provide further insights into the IMC, we analyzed the dynamics and functions of representative alveolin domain-containing IMC proteins across developmental stages. Our work shows universal but distinct roles for IMC1, -3, and -7 during Toxoplasma asexual division but more specialized functions for these proteins during gametogenesis. In addition, we find that IMC15 is involved in daughter formation in both Toxoplasma and Sarcocystis. IMC14 and IMC15 function in limiting the number of Toxoplasma offspring per division. Furthermore, IMC7, -12, and -14, which are recruited in the G1 cell cycle stage, are required for stress resistance of extracellular tachyzoites. Thus, although the roles of the different IMC proteins appear to overlap, stage- and development-specific behaviors indicate that their functions are uniquely tailored to each life stage requirement.
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11
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Morlon-Guyot J, Francia ME, Dubremetz JF, Daher W. Towards a molecular architecture of the centrosome in Toxoplasma gondii. Cytoskeleton (Hoboken) 2017; 74:55-71. [PMID: 28026138 DOI: 10.1002/cm.21353] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Revised: 12/14/2016] [Accepted: 12/15/2016] [Indexed: 12/21/2022]
Abstract
Toxoplasma gondii is the causative agent of toxoplasmosis. The pathogenicity of this unicellular parasite is tightly linked to its ability to efficiently proliferate within its host. Tachyzoites, the fast dividing form of the parasite, divide by endodyogeny. This process involves a single round of DNA replication, closed nuclear mitosis, and assembly of two daughter cells within a mother. The successful completion of endodyogeny relies on the temporal and spatial coordination of a plethora of simultaneous events. It has been shown that the Toxoplasma centrosome serves as signaling hub which nucleates spindle microtubules during mitosis and organizes the scaffolding of daughter cells components during cytokinesis. In addition, the centrosome is essential for inheriting both the apicoplast (a chloroplast-like organelle) and the Golgi apparatus. A growing body of evidence supports the notion that the T. gondii centrosome diverges in protein composition, structure and organization from its counterparts in higher eukaryotes making it an attractive source of potentially druggable targets. Here, we summarize the current knowledge on T. gondii centrosomal proteins and extend the putative centrosomal protein repertoire by in silico identification of mammalian centrosomal protein orthologs. We propose a working model for the organization and architecture of the centrosome in Toxoplasma parasites. Experimental validation of our proposed model will uncover how each predicted protein translates into the biology of centrosome, cytokinesis, karyokinesis, and organelle inheritance in Toxoplasma parasites.
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Affiliation(s)
- Juliette Morlon-Guyot
- Dynamique des Interactions Membranaires Normales et Pathologiques, UMR5235 CNRS, Université Montpellier, Montpellier, France
| | - Maria E Francia
- Molecular Biology Unit, Institut Pasteur de Montevideo, Mataojo 2020, Montevideo, 11400, Uruguay
| | - Jean-François Dubremetz
- Dynamique des Interactions Membranaires Normales et Pathologiques, UMR5235 CNRS, Université Montpellier, Montpellier, France
| | - Wassim Daher
- Dynamique des Interactions Membranaires Normales et Pathologiques, UMR5235 CNRS, Université Montpellier, Montpellier, France
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12
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Berry L, Chen CT, Reininger L, Carvalho TG, El Hajj H, Morlon-Guyot J, Bordat Y, Lebrun M, Gubbels MJ, Doerig C, Daher W. The conserved apicomplexan Aurora kinase TgArk3 is involved in endodyogeny, duplication rate and parasite virulence. Cell Microbiol 2016; 18:1106-1120. [PMID: 26833682 DOI: 10.1111/cmi.12571] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 01/19/2016] [Accepted: 01/20/2016] [Indexed: 12/25/2022]
Abstract
Aurora kinases are eukaryotic serine/threonine protein kinases that regulate key events associated with chromatin condensation, centrosome and spindle function and cytokinesis. Elucidating the roles of Aurora kinases in apicomplexan parasites is crucial to understand the cell cycle control during Plasmodium schizogony or Toxoplasma endodyogeny. Here, we report on the localization of two previously uncharacterized Toxoplasma Aurora-related kinases (Ark2 and Ark3) in tachyzoites and of the uncharacterized Ark3 orthologue in Plasmodium falciparum erythrocytic stages. In Toxoplasma gondii, we show that TgArk2 and TgArk3 concentrate at specific sub-cellular structures linked to parasite division: the mitotic spindle and intranuclear mitotic structures (TgArk2), and the outer core of the centrosome and the budding daughter cells cytoskeleton (TgArk3). By tagging the endogenous PfArk3 gene with the green fluorescent protein in live parasites, we show that PfArk3 protein expression peaks late in schizogony and localizes at the periphery of budding schizonts. Disruption of the TgArk2 gene reveals no essential function for tachyzoite propagation in vitro, which is surprising giving that the P. falciparum and P. berghei orthologues are essential for erythrocyte schizogony. In contrast, knock-down of TgArk3 protein results in pronounced defects in parasite division and a major growth deficiency. TgArk3-depleted parasites display several defects, such as reduced parasite growth rate, delayed egress and parasite duplication, defect in rosette formation, reduced parasite size and invasion efficiency and lack of virulence in mice. Our study provides new insights into cell cycle control in Toxoplasma and malaria parasites and highlights Aurora kinase 3 as potential drug target.
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Affiliation(s)
- Laurence Berry
- Dynamique des Interactions Membranaires Normales et Pathologiques, UMR5235 CNRS, Université Montpellier, Montpellier, France
| | - Chun-Ti Chen
- Department of Biology, Boston College, Chestnut Hill, MA 02467, USA
| | - Luc Reininger
- Laboratoire de Biologie Cellulaire Comparative des Apicomplexes, INSERM U1016, Institut Cochin, Paris, France
| | - Teresa G Carvalho
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Victoria, Australia, 3800
| | - Hiba El Hajj
- Department of Internal Medicine and Experimental Pathology, Immunology and Microbiology, American University of Beirut, Beirut 1107 2020, Lebanon
| | - Juliette Morlon-Guyot
- Dynamique des Interactions Membranaires Normales et Pathologiques, UMR5235 CNRS, Université Montpellier, Montpellier, France
| | - Yann Bordat
- Dynamique des Interactions Membranaires Normales et Pathologiques, UMR5235 CNRS, Université Montpellier, Montpellier, France
| | - Maryse Lebrun
- Dynamique des Interactions Membranaires Normales et Pathologiques, UMR5235 CNRS, Université Montpellier, Montpellier, France
| | - Marc-Jan Gubbels
- Department of Biology, Boston College, Chestnut Hill, MA 02467, USA
| | - Christian Doerig
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Victoria, Australia, 3800
| | - Wassim Daher
- Dynamique des Interactions Membranaires Normales et Pathologiques, UMR5235 CNRS, Université Montpellier, Montpellier, France
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Varberg JM, Padgett LR, Arrizabalaga G, Sullivan WJ Jr. TgATAT-Mediated α-Tubulin Acetylation Is Required for Division of the Protozoan Parasite Toxoplasma gondii. mSphere 2016; 1:e00088-15. [PMID: 27303695 DOI: 10.1128/mSphere.00088-15] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 01/05/2016] [Indexed: 01/05/2023] Open
Abstract
Toxoplasma gondii is an opportunistic parasite that infects at least one-third of the world population. New treatments for the disease (toxoplasmosis) are needed since current drugs are toxic to patients. Microtubules are essential cellular structures built from tubulin that show promise as antimicrobial drug targets. Microtubules can be regulated by chemical modification, such as acetylation on lysine 40 (K40). To determine the role of K40 acetylation in Toxoplasma and whether it is a liability to the parasite, we performed mutational analyses of the α-tubulin gene. Our results indicate that parasites cannot survive without K40 acetylation unless microtubules are stabilized with a secondary mutation. Additionally, we identified the parasite enzyme that acetylates α-tubulin (TgATAT). Genetic disruption of TgATAT caused severe defects in parasite replication, further highlighting the importance of α-tubulin K40 acetylation in Toxoplasma and its promise as a potential new drug target. Toxoplasma gondii is a widespread protozoan parasite that causes potentially life-threatening opportunistic disease. New inhibitors of parasite replication are urgently needed, as the current antifolate treatment is also toxic to patients. Microtubules are essential cytoskeletal components that have been selectively targeted in microbial pathogens; further study of tubulin in Toxoplasma may reveal novel therapeutic opportunities. It has been noted that α-tubulin acetylation at lysine 40 (K40) is enriched during daughter parasite formation, but the impact of this modification on Toxoplasma division and the enzyme mediating its delivery have not been identified. We performed mutational analyses to provide evidence that K40 acetylation stabilizes Toxoplasma microtubules and is required for parasite replication. We also show that an unusual Toxoplasma homologue of α-tubulin acetyltransferase (TgATAT) is expressed in a cell cycle-regulated manner and that its expression peaks during division. Disruption of TgATAT with CRISPR/Cas9 ablates K40 acetylation and induces replication defects; parasites appear to initiate mitosis yet exhibit incomplete or improper nuclear division. Together, these findings establish the importance of tubulin acetylation, exposing a new vulnerability in Toxoplasma that could be pharmacologically targeted. IMPORTANCEToxoplasma gondii is an opportunistic parasite that infects at least one-third of the world population. New treatments for the disease (toxoplasmosis) are needed since current drugs are toxic to patients. Microtubules are essential cellular structures built from tubulin that show promise as antimicrobial drug targets. Microtubules can be regulated by chemical modification, such as acetylation on lysine 40 (K40). To determine the role of K40 acetylation in Toxoplasma and whether it is a liability to the parasite, we performed mutational analyses of the α-tubulin gene. Our results indicate that parasites cannot survive without K40 acetylation unless microtubules are stabilized with a secondary mutation. Additionally, we identified the parasite enzyme that acetylates α-tubulin (TgATAT). Genetic disruption of TgATAT caused severe defects in parasite replication, further highlighting the importance of α-tubulin K40 acetylation in Toxoplasma and its promise as a potential new drug target.
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Abstract
Toxoplasmosis is the clinical and pathological consequence of acute infection with the obligate intracellular apicomplexan parasite Toxoplasma gondii. Symptoms result from tissue destruction that accompanies lytic parasite growth. This review updates current understanding of the host cell invasion, parasite replication, and eventual egress that constitute the lytic cycle, as well as the ways T. gondii manipulates host cells to ensure its survival. Since the publication of a previous iteration of this review 15 years ago, important advances have been made in our molecular understanding of parasite growth and mechanisms of host cell egress, and knowledge of the parasite's manipulation of the host has rapidly progressed. Here we cover molecular advances and current conceptual frameworks that include each of these topics, with an eye to what may be known 15 years from now.
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Affiliation(s)
- Ira J Blader
- Department of Microbiology and Immunology, University at Buffalo, Buffalo, New York 14127;
| | - Bradley I Coleman
- Department of Biology, Boston College, Chestnut Hill, Massachusetts 02467; , ,
| | - Chun-Ti Chen
- Department of Biology, Boston College, Chestnut Hill, Massachusetts 02467; , ,
| | - Marc-Jan Gubbels
- Department of Biology, Boston College, Chestnut Hill, Massachusetts 02467; , ,
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15
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Abstract
The centrosome serves as a central hub coordinating multiple cellular events in eukaryotes. A recent study in Toxoplasma gondii revealed a unique bipartite structure of the centrosome, which coordinates the nuclear cycle (S-phase and mitosis) and budding cycle (cytokinesis) of the parasite, and deciphers the principle behind flexible apicomplexan cell division modes.
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Affiliation(s)
- Chun-Ti Chen
- Department of Biology, Boston College, Chestnut Hill, MA 02467, USA
| | - Marc-Jan Gubbels
- Department of Biology, Boston College, Chestnut Hill, MA 02467, USA.
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Resende DV, Assis DC, Ribeiro MFB, Cabrine-Santos M, Frenkel JK, Correia D, Oliveira-Silva MB. Ultrastructural aspects of Cystoisospora belli (syn. Isospora belli) in continuous cell lines. Microsc Res Tech 2014; 77:472-8. [PMID: 24771702 DOI: 10.1002/jemt.22372] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 03/21/2014] [Accepted: 04/13/2014] [Indexed: 11/11/2022]
Abstract
Cystoisospora belli is an opportunistic protozoan that causes human cystoisosporiasis, an infection characterized by diarrhea, steatorrhea, abdominal pain, fever, and weight loss. The lack of animal models susceptible to C. belli, and the difficulty in obtaining clinical samples with fair amounts of oocysts have limited the research pertaining to the basic biology of this parasite. This study aimed to describe the ultrastructure of endogenous stages of C. belli in Monkey Rhesus Kidney Cells (MK2) and Human Ileocecal Adenocarcinoma cells (HCT-8). Zoites of C. belli exhibited typical morphological features of coccidia, which included a trilaminar pellicle, an apical complex formed by a conoid, polar rings, rhoptries, and micronemes, in addition to dense granules and the endoplasmic reticulum. No crystalloid body was observed but various lipid and amylopectin granules were usually present in the cytoplasm of zoites. We observed a tendency of the endoplasmic reticulum of the host cell to be located near the parasitophorous vacuole membrane. Merozoites were formed by endodyogeny and during replication, the apical complex of the mother cell remained intact. The formation of gametes or oocysts was not observed. The ultrastructural findings of C. belli are further evidence of its proximity to Sarcocystidae family members and corroborate their reclassification as Cystoisospora spp.
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Affiliation(s)
- Deisy V Resende
- Technics School of Health, Federal University of the Uberlândia, Umuarama, CEP 38400-902, Uberlândia, Minas Gerais, Brazil
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Gjerde B. Ultrastructure of the cysts of Sarcocystis tarandivulpes from skeletal muscle of reindeer (Rangifer tarandus tarandus). Acta Vet Scand 1985; 26:91-104. [PMID: 2931009 PMCID: PMC8202606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The cysts of S. tarandivulpes were found to be limited by a unit membrane which has been called the cyst membrane. The surface of the cysts was covered by closely packed and hexagonally arranged knob-like protrusions. The protrusions were 0.6–1.2 μm long and had an elliptical cross section. At the base of and between the bases of the protrusions the cyst mem brane was raised into low anastomosing folds which delineated shallow compartments. Between the folds the cyst membrane formed small vesicle-like invaginations into the cyst. On the apical part of the protrusions the cyst membrane had a smooth contour and was underlined by 2 layers of electron-dense material. Cyst ground substance divided the interior of the cyst into compartments containing either metrocytes or cystozoites. Cystozoites undergoing endodyogeny were present among the nondividing cystozoites. Some new terms were introduced to denote structures at the border of the cyst. The old terms are reviewed and the structural resemblance between S. tarandivulpes and S. odocoileocanis from Odocoileus virginianus is discussed.
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