Identification and functional characterisation of epidermal regulators of the oomycete recognition response in C. elegans
File(s)
Author(s)
Drury, Florence
Type
Thesis
Abstract
Oomycetes are eukaryotic pathogens of plants and animals that were recently discovered to
naturally infect Caenorhabditis elegans. Animal-oomycete infections can be deadly but are
critically understudied, partly due to the lack of a suitable model to study host-pathogen
interactions. In C. elegans, pathogen recognition alone is sufficient to trigger transcriptional
upregulation of the oomycete recognition response; this includes multiple chitinase-like genes and
provides a protective effect against infection. In this thesis, I utilised forward genetic screens to
identify suppressors of the oomycete recognition response and have identified two novel, key
regulators old-1 and T01G5.1, which are both members of the KIN-16 family of receptor tyrosine
kinases. Both old-1 and T01G5.1 are required for protection against infection and overexpression
of old-1 results in constitutive activation of oomycete recognition response genes. I provide
evidence that OLD-1 is an active kinase whereas T01G5.1 is likely a pseudokinase and suggest a
model wherein they pair at the epidermal membrane to facilitate downstream signalling and that
pseudokinase T01G5.1 is both required to facilitate signalling and regulate OLD-1 expression. This
kinase-pseudokinase interaction adds to the expanding role for pseudokinases in immune
signalling. I also demonstrate that old-1 is part of a genomic cluster with chil genes and other KIN-
16 family members and identify oomycete-resistance immunity islands across the genome. I
identify PAX6 transcription factor VAB-3 to regulate old-1 expression which provides the first
involvement of a PAX-6 transcription factor in immune signalling. Finally, I use proteomics and
phosphoproteomics to identify oomycete recognition-dependent and old-1-dependent
phosphorylation events. Overall, these findings expand our understanding of host-pathogen
interactions in response to oomycete infection in animals and provide new immune functions for
both conserved and C. elegans-specific genes.
naturally infect Caenorhabditis elegans. Animal-oomycete infections can be deadly but are
critically understudied, partly due to the lack of a suitable model to study host-pathogen
interactions. In C. elegans, pathogen recognition alone is sufficient to trigger transcriptional
upregulation of the oomycete recognition response; this includes multiple chitinase-like genes and
provides a protective effect against infection. In this thesis, I utilised forward genetic screens to
identify suppressors of the oomycete recognition response and have identified two novel, key
regulators old-1 and T01G5.1, which are both members of the KIN-16 family of receptor tyrosine
kinases. Both old-1 and T01G5.1 are required for protection against infection and overexpression
of old-1 results in constitutive activation of oomycete recognition response genes. I provide
evidence that OLD-1 is an active kinase whereas T01G5.1 is likely a pseudokinase and suggest a
model wherein they pair at the epidermal membrane to facilitate downstream signalling and that
pseudokinase T01G5.1 is both required to facilitate signalling and regulate OLD-1 expression. This
kinase-pseudokinase interaction adds to the expanding role for pseudokinases in immune
signalling. I also demonstrate that old-1 is part of a genomic cluster with chil genes and other KIN-
16 family members and identify oomycete-resistance immunity islands across the genome. I
identify PAX6 transcription factor VAB-3 to regulate old-1 expression which provides the first
involvement of a PAX-6 transcription factor in immune signalling. Finally, I use proteomics and
phosphoproteomics to identify oomycete recognition-dependent and old-1-dependent
phosphorylation events. Overall, these findings expand our understanding of host-pathogen
interactions in response to oomycete infection in animals and provide new immune functions for
both conserved and C. elegans-specific genes.
Version
Open Access
Date Issued
2022-06
Date Awarded
2022-12
Copyright Statement
Creative Commons Attribution NonCommercial Licence
License URL
Advisor
Barkoulas, Michalis
Sponsor
Imperial College London
Publisher Department
Life Sciences
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)