Role played by the WD domain of ATG16L1 in defense against Salmonella infection in vivo

Zhang, Weijiao (2021) Role played by the WD domain of ATG16L1 in defense against Salmonella infection in vivo. Doctoral thesis, University of East Anglia.

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Non-canonical autophagy, or LC3-associated phagocytosis (LAP), conjugates
autophagy protein LC3 to endo-lysosome compartments to facilitate delivery of
extracellular materials to lysosomes. The WD domain of autophagy protein ATG16L1
is required for conjugation of LC3 to endo-lysosomes during LAP, but is not required
for LC3 conjugation during autophagy. Mice lacking the WD domain of ATG16L1
(WD mice) are therefore defective in LAP, but can activate autophagy to maintain
tissue homeostasis. This study has used WD mice to determine the role played by the
WD domain of ATG16L1 during S. Typhimurium infection "in vivo".
S. Typhimurium showed increased replication and virulence in δWD mice
characterized by high mortality rate, severe weight loss, and enhanced dissemination
of bacteria and lymphocytes to liver and spleen. Crosses with LysMcre and villincre
mice showed that expression of the WD domain of ATG16L1 in intestinal epithelial
cells, rather than myeloid cells, protected against S. Typhimurium.
SopF is an S. Typhimurium SPI-1 T3SS effector thought to increase virulence by
blocking the binding of the WD domain of ATG16L1 to the endo-lysosome v-ATPase
to prevent recruitment of LC3 to Salmonella containing vacuoles. A SopF knockout S.
Typhimurium strain (JH3009δSOPF), generated by lambda recombination, showed
reduced virulence in control mice, but both wild type S. Typhimurium and
JH3009δSOPF showed increased virulence in mice lacking the WD domain. This
suggested that the WD domain restricted S. Typhimurium replication by additional
pathways that are independent of the WD-v-ATPase axis blocked by Sop-F.
Fluorescent probes and biosensors showed that cells and tissues of WD mice had
raised intracellular cholesterol that accumulated at sites of replication. Replication
was reduced by cholesterol-lowering drugs. Taken together the results suggest that
WD domain of ATG16L1 restricts S. Typhimurium replication in intestinal epithelial
cells partly by reducing intracellular cellular cholesterol levels.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Jackie Webb
Date Deposited: 29 Apr 2022 13:46
Last Modified: 31 Mar 2024 01:38


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