Non-Canonical functions of ATG16L1 in immunity and infection

Bone, Benjamin (2021) Non-Canonical functions of ATG16L1 in immunity and infection. Doctoral thesis, University of East Anglia.

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ATG16L1 has many non-canonical roles outside its classical role in autophagy. It plays a vital role in the innate immune response LC3-associated phagocytosis (LAP). Furthermore, it has been recently shown to be involved in lysosomal fusion to the plasma membrane (PM), which is necessary for cholesterol transport to the PM. Our group developed a mouse model (ΔWD) that expresses an ATG16L1 protein truncated at position E230, lacking the WD domain. This mouse has increased susceptibility to the influenza A virus (IAV), with increased viral replication in the mouse, in addition to a lethal cytokine storm. The aim of this thesis was to investigate the mechanism by which the WD domain protects mice from lethal IAV infection.

Initially, I investigated differences in tissues and mouse embryonic fibroblast (MEF) cell lines isolated from wild type (WT) and ΔWD mice. I found that cholesterol was reduced in the PM of ΔWD brain and lung tissue as well as ΔWD MEFs.

I then investigated whether modulation of the membrane cholesterol would affect IAV fusion. IAV fused more efficiently to the PM of ΔWD MEFs, when infected by acid bypass, that allows the virus to fuse directly with the PM.

IAV endocytosis and fusion in ΔWD MEFs were measured using a differential immunostaining assay and FACs respectively. Increased endocytosis and fusion were seen in ΔWD MEFs. I showed that IAV replicated to higher levels in ΔWD MEFs and in precision cut lung slices. Additionally, interferon and ISG expression were higher in infected ΔWD MEFs and lung slices, mimicking the cytokine storm seen in the mutant mice. Overall, this thesis demonstrates that the WD domain of ATG16L1 has a role in cholesterol transport to the PM, a WD deficiency resulting in IAV entering cells more efficiently and replicating to higher levels and causing elevated cytokine expression.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Medicine and Health Sciences > Norwich Medical School
Depositing User: Chris White
Date Deposited: 08 Feb 2022 13:14
Last Modified: 08 Feb 2022 13:14

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