The role of microbial-mediated genotoxicity during pathogenesis

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.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Microbiology

Grantor

University of Illinois Urbana-Champaign

Year dc:date

2025

Author dc:creator

• Crowder, Molly Katherine

Contributors dc:contributor

• Blanke, Steven R
• Wilson, Brenda A
• Brooke, Christopher B
• Gaskins, H Rex

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

Statement dc:rights

• Copyright 2025 Molly Crowder

Language dc:language

en, eng

Handle dc:identifier

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

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F129713