Regulation of type I interferon response of macrophages to virus infections

Wang, Yan (2023) Regulation of type I interferon response of macrophages to virus infections. PhD thesis, University of Liverpool.

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Abstract

Macrophage, a versatile sentinel immune cell in host defence, not only is the major type I interferons (IFNs-I) producer upon virus infections, but also acts as an important target cell for many RNA viruses. However, the regulatory mechanism for the IFNs-I response of macrophages to respond to a viral challenge is not fully understood. Adhesion and degranulation-protein adaptor protein (ADAP), originally identified in T-cells as a key regulatory adaptor protein in TCR signalling and T-cell adhesion, has emerged as a critical regulator of innate immune cells including macrophages, mast cells and dendritic cells. Despite this, the link of ADAP to the polarization and IFNs-I responses of macrophages to RNA virus infection remains elusive. In this project, I show that ADAP, an immune adaptor protein, is indispensable for the induction and sustaining of IFNs-I signalling in macrophages response to virus infection via inhibition of the conjugation of ubiquitin-like interferon-stimulated gene 15 (ISG15) to RIG-I. Firstly, ADAP deficiency exhibits increased susceptibility to RNA-virus infection in vivo accompanied by higher viral load in macrophages. Subsequently, ADAP selectively interacts with RIG-I but not MDA5, and the C-terminal domain (CTD) of RIG-I is responsible for ADAP binding. The interaction of ADAP with RIG-I occurs mainly on mitochondria but not lipid rafts in macrophages, which is induced by RNA virus infections or LPS stimulation. Moreover, I show ADAP deficiency leads to an enhancement of ISGylation of RIG-I, whereas overexpression of ADAP exhibits the opposite effect in vitro, indicating ADAP inhibits RIG-I ISGylation during viral infections. Finally, the RIG-I – MAVS association is slightly decreased in ADAP deficiency, which reduces the RNA virus-induced phosphorylation of IRF3 and TBK1, and the production of type I IFNs in macrophages. Taken together, my data demonstrates that ADAP exerts an antagonistic activity in the cell-intrinsic control of RIG-I ISGylation for RIG-I – IFNs-I signalling in response to RNA virus infections in macrophages.

Item Type:	Thesis (PhD)
Uncontrolled Keywords:	macrophages; ADAP; type I IFNs; RIG-I; ISGylation; anti-viral immunity
Divisions:	Faculty of Health and Life Sciences
Depositing User:	Symplectic Admin
Date Deposited:	31 Jan 2024 08:34
Last Modified:	31 Jan 2024 08:34
DOI:	10.17638/03172957
Supervisors:	Han, Guoxia Liu, Hebin Hiscox, Julian
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3172957