Date of Award
2023
Document Type
Thesis - ECU Access Only
Publisher
Edith Cowan University
Degree Name
Doctor of Philosophy
School
School of Medical and Health Sciences
First Supervisor
Wei Wang
Second Supervisor
Zhaohua Zhong
Third Supervisor
Lois Balmer
Abstract
Background and significance:
Coxsackievirus B (CVB), a member of the family Picornaviridae, is the leading pathogen of viral myocarditis (VMC) and dilated cardiomyopathy (DCM). Presently there is no specific treatment and prevention measurement available. CVB induces autophagy upon infection. However, the mechanism of CVB-induced autophagy remains a subject of debate. Lysosome is an important membrane organelle responsible for various cell processes including autophagy, where its production and function are regulated by the transcription factor EB (TFEB). This project revealed a novel mechanism of CVB type 3 (CVB3) disrupting lysosomal function by targeting TFEB resulting in human cellular injuries. This PhD project could provide new targets for the prevention and medication of CVB infection, such as, human viral myocarditis and acute pancreatitis.
Objectives:
This project aims to reveal novel mechanism of CVB 3A protein targeting on host cellular lysosomes as a common pathogenesis of Enteroviruses, providing novel targets for anti-CVB or anti-Enterovirus medicine development.
Results:
1) CVB3 3A protein and lysosome marker LAMP1 co-located on the lysosome membrane;
2) CVB3 3A expression was observed on lysosomal membrane;
3) CVB3 3A and late endosome marker Rag7 were co-localized;
4) CVB3 AO detection showed that the size and number of lysosomes were increased after CVB3 3A over-expression;
5) Lysosensor detection revealed that the acidification and membrane permeability of lysosome is not significantly changed after CVB3 3A over-expression;
6) CVB3 3A motif which induce autophagy and TFEB nucleus translocation were located at the 51-89th amino acid sites of 3A protein;
7) CVB3 3A protein was able to inactivate the mTOR signaling pathway, leading to a decrease of RagC subunit expression in the LYNUS complex;
8) CVB3 3A was able to bind with Annexin A2 (ANXA2) protein, which can hinder the binding of ANXA2 with RagC and further resulted in instability of LYNUS complex and dephosphorylation of TFEB;
9) Upregulation of autophagy-related genes and activation of autophagy are induced by TFEB nucleus translocation;
10) Myocardial injury was caused by CVB3 infection in vivo, and TFEB showed nucleus localization after CVB3 infection
Conclusion:
1. CVB3 and CVB3 3A proteins can induce up-regulation of autophagy.
2. The functional motif of 3A protein is located at amino acids 51-89, and CVB3 3A protein is located on lysosomal membrane, causing lysosomal storage.
3. CVB3 3A affects the instability of lysosomal membrane lynus complex by binding to annexin A2, which induces TFEB nuclear translocation related autophagy and promotes virus replication.
DOI
10.25958/2ynd-f068
Access Note
Access to this thesis is embargoed until 10th November 2024.
Recommended Citation
Wang, X. (2023). How coxsackievirus B3 infection impairing host cells by inducing aberrant autophagy. Edith Cowan University. https://doi.org/10.25958/2ynd-f068