CALCOCO2, a positively selected gene in bats has differential effects on host susceptibility to bacterial infection
Abstract/Contents
- Abstract
- Bats are the likely reservoirs for many zoonotic pathogens, including Nipah, Marburg, SARS, and Ebola viruses, that can be lethal to humans but cause little disease in bats. Meta-analysis of several genes under positive selection in 18 bat species identified CALCOCO2, an intracellular autophagy receptor that targets invading microbes for destruction. An antimicrobial function of CALCOCO2 during Salmonella Typhimurium infection has been characterized in human epithelial cell lines, leading to our investigation of its effect on infections in bat cells. The objective of this work is to characterize signatures of positive selection in Chiropteran CALCOCO2 sequences, determine its function in bat cell lines, and investigate molecular mechanisms by which it impacts microbial replication. Phylogenetic analyses predict an evolutionary history of CALCOCO2 that implies long-term selective pressure on this gene. In Chapter 2, I analyze the evolution of CALCOCO2 in bats, and determine which regions display signatures of interesting evolution. Our investigation of sequence conservation and divergence highlights hotspots of polymorphism localizing to CALCOCO2 domains and motifs that regulate xenophagy initiation and completion. Chapter 3 investigates the role of CALCOCO2 in the context of Salmonella infection in bats. Depletion of CALCOCO2 via si-RNA and CRISPR-generated CALCOCO2 knockouts cells reveal a surprising pro-bacterial role of CALCOCO2 in cells from two evolutionarily distant bat species. This pro-bacterial role is not due to a differential ability of bat CALCOCO2 to detect Salmonella, and is downstream of bacterial entry. In Chapter 4, I explore the molecular mechanism underlying this pro-bacterial effect by infecting WT and KO cell lines with Salmonella inducing different levels of membrane damage, and monitoring the kinetics of autophagic membrane recruitment to bacteria. Remarkably, CALCOCO2 contributes to early SCV integrity in both human and bat cell lines, and facilitates long-term association of autophagic membranes to Salmonella only in Egyptian fruit bat cell. Collectively, this work provides evidence for microbially-driven positive selection on regulation of selective autophagy in bats, and sheds light on a genetic signature that might enable bats to tolerate dangerous pathogens without succumbing to infection.
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 | 2022; ©2022 |
| Publication date | 2022; 2022 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Tovar, Dorothy |
|---|---|
| Degree supervisor | Hadly, Elizabeth Anne, 1958- |
| Degree supervisor | Kirkegaard, Karla |
| Thesis advisor | Hadly, Elizabeth Anne, 1958- |
| Thesis advisor | Kirkegaard, Karla |
| Thesis advisor | Carette, Jan, 1971- |
| Thesis advisor | Sawyer, Sara |
| Degree committee member | Carette, Jan, 1971- |
| Degree committee member | Sawyer, Sara |
| Associated with | Stanford University, Department of Microbiology and Immunology |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Dorothy Tovar. |
|---|---|
| Note | Submitted to the Department of Microbiology and Immunology. |
| Thesis | Thesis Ph.D. Stanford University 2022. |
| Location | https://purl.stanford.edu/rw401jy1866 |
Access conditions
- Copyright
- © 2022 by Dorothy Tovar
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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