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Sun SY, Segev-Zarko LA, Pintilie GD, Kim CY, Staggers SR, Schmid MF, Egan ES, Chiu W, Boothroyd JC. Cryogenic electron tomography reveals novel structures in the apical complex of Plasmodium falciparum. mBio 2024; 15:e0286423. [PMID: 38456679 PMCID: PMC11005440 DOI: 10.1128/mbio.02864-23] [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: 11/01/2023] [Accepted: 02/07/2024] [Indexed: 03/09/2024] Open
Abstract
Intracellular infectious agents, like the malaria parasite, Plasmodium falciparum, face the daunting challenge of how to invade a host cell. This problem may be even harder when the host cell in question is the enucleated red blood cell, which lacks the host machinery co-opted by many pathogens for internalization. Evolution has provided P. falciparum and related single-celled parasites within the phylum Apicomplexa with a collection of organelles at their apical end that mediate invasion. This apical complex includes at least two sets of secretory organelles, micronemes and rhoptries, and several structural features like apical rings and a putative pore through which proteins may be introduced into the host cell during invasion. We perform cryogenic electron tomography (cryo-ET) equipped with Volta Phase Plate on isolated and vitrified merozoites to visualize the apical machinery. Through tomographic reconstruction of cellular compartments, we see new details of known structures like the rhoptry tip interacting directly with a rosette resembling the recently described rhoptry secretory apparatus (RSA), or with an apical vesicle docked beneath the RSA. Subtomogram averaging reveals that the apical rings have a fixed number of repeating units, each of which is similar in overall size and shape to the units in the apical rings of tachyzoites of Toxoplasma gondii. Comparison of these polar rings in Plasmodium and Toxoplasma parasites also reveals them to have a structurally conserved assembly pattern. These results provide new insight into the essential and structurally conserved features of this remarkable machinery used by apicomplexan parasites to invade their respective host cells. IMPORTANCE Malaria is an infectious disease caused by parasites of the genus Plasmodium and is a leading cause of morbidity and mortality globally. Upon infection, Plasmodium parasites invade and replicate in red blood cells, where they are largely protected from the immune system. To enter host cells, the parasites employ a specialized apparatus at their anterior end. In this study, advanced imaging techniques like cryogenic electron tomography (cryo-ET) and Volta Phase Plate enable unprecedented visualization of whole Plasmodium falciparum merozoites, revealing previously unknown structural details of their invasion machinery. Key findings include new insights into the structural conservation of apical rings shared between Plasmodium and its apicomplexan cousin, Toxoplasma. These discoveries shed light on the essential and conserved elements of the invasion machinery used by these pathogens. Moreover, the research provides a foundation for understanding the molecular mechanisms underlying parasite-host interactions, potentially informing strategies for combating diseases caused by apicomplexan parasites.
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Affiliation(s)
- Stella Y. Sun
- Department of Structural Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
- Department of Bioengineering, James H. Clark Center, Stanford University, Stanford, California, USA
| | - Li-av Segev-Zarko
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, USA
| | - Grigore D. Pintilie
- Department of Bioengineering, James H. Clark Center, Stanford University, Stanford, California, USA
| | - Chi Yong Kim
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, USA
- Department of Pediatrics, Stanford University School of Medicine, Stanford, California, USA
| | - Sophia R. Staggers
- Department of Structural Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Michael F. Schmid
- Division of Cryo-EM and Bioimaging, SSRL, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California, USA
| | - Elizabeth S. Egan
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, USA
- Department of Pediatrics, Stanford University School of Medicine, Stanford, California, USA
| | - Wah Chiu
- Department of Bioengineering, James H. Clark Center, Stanford University, Stanford, California, USA
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, USA
- Division of Cryo-EM and Bioimaging, SSRL, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California, USA
| | - John C. Boothroyd
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, USA
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Vladar EK, Kunimoto K, Rojas-Hernandez LS, Spano JM, Sellers ZM, Joo NS, Cooney RA, Axelrod JD, Milla CE. Notch signaling inactivation by small molecule gamma-secretase inhibitors restores the multiciliated cell population in the airway epithelium. Am J Physiol Lung Cell Mol Physiol 2023; 324:L771-L782. [PMID: 37039381 PMCID: PMC10202488 DOI: 10.1152/ajplung.00382.2022] [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] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2023] Open
Abstract
Multiciliated cell loss is a hallmark of airway epithelial remodeling in chronic inflammatory airway diseases including cystic fibrosis (CF), asthma, and chronic obstructive pulmonary disease. It disrupts mucociliary clearance, which fuels disease progression. Effective clearance requires an optimal proportion of multiciliated and secretory cells. This is controlled by Notch signaling such that between two adjacent cells the one that activates Notch becomes a secretory cell and the one that avoids Notch activation becomes a multiciliated cell. Consequently, blocking Notch by a small molecule inhibitor of the gamma-secretase enzyme that cleaves the Notch receptor for signal activation directs differentiation towards the multiciliated lineage. Thus, gamma-secretase inhibitor (GSI) treatment may alleviate multiciliated cell loss in lung disease. Here we demonstrate therapeutic restoration of multiciliated cells by the GSI LY450139 (semagacestat). LY450139 increased multiciliated cell numbers in a dose-dependent manner in healthy primary human nasal epithelial cells (HNECs) during differentiation and in mature cultures, but not when applied during early epithelialization of progenitors. LY450139 did not impact stem cell proliferation. Basal and apical administration were equally effective. In healthy adult mice, LY450139 increased multiciliated cell numbers without detectible toxicity. LY450139 also increased multiciliated cells and decreased excess mucus secretory cells in CF HNECs and IL-13 remodeled healthy HNECs. LY450139 normalized multiciliated cell numbers in CF HNECs without interfering with the activity of CFTR modulator compounds. In sum, we demonstrate that GSI administration is a promising therapeutic to restore multiciliated cells and potentially improve epithelial function in a wide range of chronic lung diseases.
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Affiliation(s)
- Eszter K Vladar
- Department of Medicine, Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
- Department of Pathology, Stanford University, Stanford, CA, United States
| | - Koshi Kunimoto
- Department of Pathology, Stanford University, Stanford, CA, United States
| | - Laura S Rojas-Hernandez
- Center for Excellence in Pulmonary Biology, Stanford University, Palo Alto, CA, United States
| | - Jacquelyn M Spano
- Center for Excellence in Pulmonary Biology, Stanford University, Palo Alto, CA, United States
| | - Zachary M Sellers
- Division of Pediatric Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, Stanford University, Stanford, CA, United States
| | - Nam Soo Joo
- Center for Excellence in Pulmonary Biology, Stanford University, Palo Alto, CA, United States
| | - Riley A Cooney
- Department of Medicine, Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Jeffrey D Axelrod
- Department of Pathology, Stanford University, Stanford, CA, United States
| | - Carlos E Milla
- Center for Excellence in Pulmonary Biology, Stanford University, Palo Alto, CA, United States
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Kawagishi T, Sánchez-Tacuba L, Feng N, Costantini VP, Tan M, Jiang X, Green KY, Vinjé J, Ding S, Greenberg HB. Mucosal and systemic neutralizing antibodies to norovirus induced in infant mice orally inoculated with recombinant rotaviruses. Proc Natl Acad Sci U S A 2023; 120:e2214421120. [PMID: 36821582 PMCID: PMC9992845 DOI: 10.1073/pnas.2214421120] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [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: 09/10/2022] [Accepted: 01/26/2023] [Indexed: 02/24/2023] Open
Abstract
Rotaviruses (RVs) preferentially replicate in the small intestine and frequently cause severe diarrheal disease, and the following enteric infection generally induces variable levels of protective systemic and mucosal immune responses in humans and other animals. Rhesus rotavirus (RRV) is a simian RV that was previously used as a human RV vaccine and has been extensively studied in mice. Although RRV replicates poorly in the suckling mouse intestine, infection induces a robust and protective antibody response. The recent availability of plasmid only-based RV reverse genetics systems has enabled the generation of recombinant RVs expressing foreign proteins. However, recombinant RVs have not yet been experimentally tested as potential vaccine vectors to immunize against other gastrointestinal pathogens in vivo. This is a newly available opportunity because several live-attenuated RV vaccines are already widely administered to infants and young children worldwide. To explore the feasibility of using RV as a dual vaccine vector, we rescued replication-competent recombinant RRVs harboring bicistronic gene segment 7 that encodes the native RV nonstructural protein 3 (NSP3) protein and a human norovirus (HuNoV) VP1 protein or P domain from the predominant genotype GII.4. The rescued viruses expressed HuNoV VP1 or P protein in infected cells in vitro and elicited systemic and local antibody responses to HuNoV and RRV following oral infection of suckling mice. Serum IgG and fecal IgA from infected suckling mice bound to and neutralized both RRV and HuNoV. These findings have encouraging practical implications for the design of RV-based next-generation multivalent enteric vaccines to target HuNoV and other human enteric pathogens.
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Affiliation(s)
- Takahiro Kawagishi
- Division of Gastroenterology and Hepatology, Department of Medicine, Stanford University School of Medicine, Stanford, CA94305
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA94305
- Department of Veterans Affairs, VA Palo Alto Health Care System, Palo Alto, CA94304
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO63110
| | - Liliana Sánchez-Tacuba
- Division of Gastroenterology and Hepatology, Department of Medicine, Stanford University School of Medicine, Stanford, CA94305
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA94305
- Department of Veterans Affairs, VA Palo Alto Health Care System, Palo Alto, CA94304
| | - Ningguo Feng
- Division of Gastroenterology and Hepatology, Department of Medicine, Stanford University School of Medicine, Stanford, CA94305
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA94305
- Department of Veterans Affairs, VA Palo Alto Health Care System, Palo Alto, CA94304
| | - Veronica P. Costantini
- National Calicivirus Laboratory, Centers for Disease Control and Prevention, Atlanta, GA30333
| | - Ming Tan
- Divison of Infectious Diseases, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH45229
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH45229
| | - Xi Jiang
- Divison of Infectious Diseases, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH45229
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH45229
| | - Kim Y. Green
- Laboratory of Infectious Disease, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD20892
| | - Jan Vinjé
- National Calicivirus Laboratory, Centers for Disease Control and Prevention, Atlanta, GA30333
| | - Siyuan Ding
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO63110
| | - Harry B. Greenberg
- Division of Gastroenterology and Hepatology, Department of Medicine, Stanford University School of Medicine, Stanford, CA94305
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA94305
- Department of Veterans Affairs, VA Palo Alto Health Care System, Palo Alto, CA94304
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