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Cleavage of Grb2-Associated Binding Protein 2 by Viral Proteinase 2A during Coxsackievirus Infection
Haoyu Deng1, Gabriel Fung2, Ye Qiu2
1Centre for Heart Lung Innovation, St. Paul's Hospital and Department of Pathology and Laboratory Medicine, University of British ColumbiaVancouver, BC, Canada; Department of Vascular Surgery, RenJi Hospital, Shanghai Jiaotong University School of MedicineShanghai, China.
Abstract:
Coxsackievirus type B3 (CV-B3), an enterovirus associated with the pathogenesis of several human diseases, subverts, or employs the host intracellular signaling pathways to support effective viral infection. We have previously demonstrated that Grb2-associated binding protein 1 (GAB1), a signaling adaptor protein that serves as a platform for intracellular signaling assembly and transduction, is cleaved upon CV-B3 infection, resulting in a gain-of-pro-viral-function via the modification of GAB1-mediated ERK1/2 pathway. GAB2 is a mammalian homolog of GAB1. In this study, we aim to address whether GAB2 plays a synergistic role with GAB1 in the regulation of CV-B3 replication. Here, we reported that GAB2 is also a target of CV-B3-encoded viral proteinase. We showed that GAB2 is cleaved at G238 during CV-B3 infection by viral proteinase 2A, generating two cleaved fragments of GAB2-N1-237 and GAB2-C238-676. Moreover, knockdown of GAB2 significantly inhibits the synthesis of viral protein and subsequent viral progeny production, accompanied by reduced levels of phosphorylated p38, suggesting a pro-viral function for GAB2 linked to p38 activation. Finally, we examined whether the cleavage of GAB2 can promote viral replication as observed for GAB1 cleavage. We showed that expression of neither GAB2-N1-237 nor GAB2-C238-676 results in enhanced viral infectivity, indicating a loss-of-function, rather than a gain-of-function of GAB2 cleavage in mediating virus replication. Taken together, our findings in this study suggest a novel host defense machinery through which CV-B3 infection is limited by the cleavage of a pro-viral protein.
Insights
Coxsackievirus B3 (CV-B3) cleaves the host protein GAB2, inhibiting viral replication. This cleavage acts as a host defense mechanism, limiting CV-B3 infection by reducing viral protein synthesis and progeny production.
Area of Science:
- Virology
- Molecular Biology
- Immunology
Background:
- Coxsackievirus type B3 (CV-B3) infection involves host intracellular signaling pathways.
- Grb2-associated binding protein 1 (GAB1) cleavage upon CV-B3 infection enhances viral replication via the ERK1/2 pathway.
- GAB2 is a mammalian homolog of GAB1, suggesting a potential role in CV-B3 pathogenesis.
Purpose of the Study:
- To investigate the role of GAB2 in CV-B3 replication.
- To determine if GAB2 functions synergistically with GAB1 during CV-B3 infection.
- To elucidate the mechanism by which GAB2 interacts with CV-B3.
Main Methods:
- Investigated GAB2 cleavage by CV-B3 viral proteinase 2A.
- Utilized gene knockdown to assess GAB2's effect on viral protein synthesis and progeny production.
- Analyzed the impact of GAB2 cleavage fragments on viral infectivity.
- Measured levels of phosphorylated p38 signaling pathway.
Main Results:
- GAB2 is cleaved by CV-B3 viral proteinase 2A at G238, producing GAB2-N1-237 and GAB2-C238-676 fragments.
- Knockdown of GAB2 significantly inhibits viral protein synthesis and progeny production.
- GAB2 knockdown is associated with reduced phosphorylated p38 levels, indicating a pro-viral function linked to p38 activation.
- Expression of GAB2 cleavage fragments does not enhance viral infectivity, suggesting a loss-of-function.
Conclusions:
- GAB2 is a target of CV-B3 proteinase 2A.
- GAB2 plays a pro-viral role in CV-B3 replication, potentially through p38 activation.
- Cleavage of GAB2 by CV-B3 results in loss-of-function, acting as a host defense mechanism to limit viral replication.