Single cell transcriptomic profiling of the impact of effector proteins from the parasite toxoplasma gondii on host cell gene expression
Abstract/Contents
- Abstract
- The Apicomplexan protist Toxoplasma gondii is an obligate intracellular parasite that can infect and replicate within virtually every nucleated cell type in a vast range of homeothermic organisms. This dissertation employs single cell RNA sequencing (scRNA-seq) to explore: 1) Toxoplasma's asexual development, and 2) Toxoplasma's ability to co-opt host cells using an armamentarium of effector proteins. Toxoplasma's asexual development involves a transition between its rapidly expanding tachyzoite stage and its quiescent bradyzoite chronic stage. To reveal the transcriptional dynamics of asynchronous Toxoplasma parasites during asexual development, we applied scRNA-seq to over 5,000 Toxoplasma parasites of three widely used strains (i.e., RH, Pru, and ME49) subjected to in vitro alkaline induction of the tachyzoite to bradyzoite transition. As a result, we constructed a comprehensive atlas of Toxoplasma's asexual development and its intimate relationships with the parasite cell cycle. Analysis of this atlas uncovered previously invisible subpopulations within asexually developing parasites, as well as a subset of parasite-specific genes (including genes encoding surface antigens) that varies independently of measurement noise, cell cycle, and asexual development. In addition, to co-opt host cell biology during tachyzoite infection, Toxoplasma secretes rhoptry effectors (ROPs), which are injected into the host cytosol prior to parasite invasion, and dense granule effectors (GRAs), which are thought to be released after the ROPs. To examine the individual impacts of ROP and GRA proteins on host gene expression, we enriched for an ultrapure population of rare but naturally arising host cells called uninfected-injected (U-I) cells, which Toxoplasma injects with ROPs but subsequently fails to invade. We performed scRNA-seq within 3 hours post-infection of host monolayers on the monolayers' U-I cells, as well as on uninfected and infected controls, to identify the host's earliest response to ROPs, GRAs, and infection overall. Our analyses reveal that the host's earliest response to infection appears to be driven primarily by the injected ROPs, which appear to induce immune and cellular stress pathways. These ROP-dependent inflammatory signatures are counteracted by a subset of GRAs that require the presence of the parasite protein MYR1 to penetrate host cells. We also uncover evidence for the introduction of at least some MYR1-independent GRAs prior to full invasion of the host cell. This work captures the earliest stage of Toxoplasma gondii's interaction with host cells and dissects the effects of individual parasite effector classes on host biology
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2020; ©2020 |
| Publication date | 2020; 2020 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Rastogi, Suchita |
|---|---|
| Degree supervisor | Boothroyd, John C |
| Thesis advisor | Boothroyd, John C |
| Thesis advisor | Amieva, Manuel |
| Thesis advisor | Jardetzky, Theodore |
| Thesis advisor | Monack, Denise M |
| Thesis advisor | Yeh, Ellen |
| Degree committee member | Amieva, Manuel |
| Degree committee member | Jardetzky, Theodore |
| Degree committee member | Monack, Denise M |
| Degree committee member | Yeh, Ellen |
| Associated with | Stanford University, Department of Microbiology and Immunology. |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Suchita Rastogi |
|---|---|
| Note | Submitted to the Department of Microbiology and Immunology |
| Thesis | Thesis Ph.D. Stanford University 2020 |
| Location | electronic resource |
Access conditions
- Copyright
- © 2020 by Suchita Rastogi
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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