The role of microbial-mediated genotoxicity during pathogenesis

Crowder, Molly Katherine

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https://hdl.handle.net/2142/129713 Copy

Description

Title

The role of microbial-mediated genotoxicity during pathogenesis

Author(s)

Crowder, Molly Katherine

Issue Date

2025-04-23

Director of Research (if dissertation) or Advisor (if thesis)

Blanke, Steven R

Doctoral Committee Chair(s)

Blanke, Steven R

Committee Member(s)

• Wilson, Brenda A
• Brooke, Christopher B
• Gaskins, H Rex

Department of Study

Microbiology

Discipline

Microbiology

Degree Granting Institution

University of Illinois Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• DNA damage
• pathogenesis
• bacterial toxin
• p53
• autophagy
• differentiation
• epithelial tissues
• epithelial regeneration

Abstract

Pathogenic bacteria modulate host cell physiology to generate infection microenvironments suitable for colonization. Several mucosal-associated members of the Proteobacteria phylum produce a genotoxin, cytolethal distending toxin (CDT), which generates double-strand breaks in host cell DNA. Exogenous DNA damage results in changes to host cell functionality as cells attempt to repair DNA and restore homeostasis. Deviance from normal cellular function during DNA damage repair (DDR) can have vast implications on tissue function and renewal. This is especially true for dynamic tissues like the intestinal epithelium, which experiences rapid cellular turnover driven by highly proliferative cells within intestinal crypts, which replace aged cells that routinely shed into the lumen. DDR-mediated alterations to proliferative cell function impact epithelial cell function and the organization of the intestinal epithelial barrier, though the molecular mechanisms involved remain unclear. Our studies reveal that host cell autophagy, an ancient and conserved eukaryotic stress response pathway, is suppressed in cell exposed to Campylobacter jejuni CDT (Cj-CDT) through a previously undescribed p53-proteasome-LC3 axis. Suppression of autophagy in the face of DNA damage alters intestinal epithelial cell function, proteostasis, and response to stresses such as starvation. Moreover, we adopted a 3D organoid model that recapitulates the rapid cellular turnover, morphological organization, and heterogenous cell population of the physiological intestine to facilitate the study of microbial genotoxicity on epithelial barriers. Here, we show that Cj-CDT is associated with altered lineage specification in intestinal organoids, with an increased bias towards secretory lineage differentiation. Our data support the model that CDT-dependent lineage mis-specification occurs by reduction of the transcription factor SNAI1 and results in increased secretion of secretory cell factors. Together, these results suggest a role for CDT in the pathogenesis of CDT-producing bacteria: remodeling of the infection microenvironment at mucosal barriers such that CDT-producing pathogens are better able to colonize harsh epithelial environments.

Graduation Semester

2025-05

Type of Resource

Thesis

Handle URL

https://hdl.handle.net/2142/129713

Copyright and License Information

Copyright 2025 Molly Crowder

Owning Collections