Cleavage of Grb2-Associated Binding Protein 2 by Viral Proteinase 2A during Coxsackievirus Infection

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.

Isolation of a natural DNA virus of Drosophila melanogaster, and characterisation of host resistance and immune responses

“…We tested whether these candidate polymorphisms were enriched in any molecular, biological, or cellular processes using a GO enrichment analysis, and found the top hit to be the torso signalling pathway with 2 genes of 34 in the category (p = 0.0004), tailless and daughter of sevenless ( dos ). Torso signalling is upstream of extracellular-signal-regulated kinase (ERK) pathway activation in some tissues, and human orthologues of dos (GAB1/GAB2/GAB4) are cleaved by an enterovirus-encoded protease, thereby activating ERK signalling and promoting viral replication [ 69 , 70 ]. ERK signalling is also an important regulator of virus replication in the fly midgut, where it couples nutrient availability with antiviral activity [ 71 , 72 ].…”

Enhanced Autophagy in GAB1-Deficient Vascular Endothelial Cells Is Responsible for Atherosclerosis Progression

“…Cells were harvested using modified oncogene science lysis buffer (250 mM NaCl, 50 mM Tris–HCl, 0.1% Non-idet P-40, 2 mM EDTA, and 10% glycerol) supplemented with protease inhibitors and phosphatase inhibitors. Western blot analysis was performed as previously described ( Deng et al, 2017 ). In brief, equal amounts of proteins were resolved by SDS-PAGE and then transferred to 0.45-μm PVDF membranes.…”

Isolation of a natural DNA virus ofDrosophila melanogaster, and characterisation of host resistance and immune responses

“…We tested whether these candidate polymorphisms were enriched in any molecular, biological, or cellular processes using a GO enrichment analysis, and found the top hit to be the torso signalling pathway with 2 genes of 34 in the category (p = 0.0004), tailless and daughter of sevenless (dos). Torso signalling is upstream of extracellular-signal-regulated kinase (ERK) pathway activation in some tissues, and human orthologues of dos (GAB1/GAB2/GAB4) are cleaved by an enterovirus-encoded protease, thereby activating ERK signalling and promoting viral replication (Deng et al 2015;Deng et al, 2017). ERK signalling is also an important regulator of virus replication in the fly midgut, where it couples nutrient availability with antiviral activity (Xu et al, 2013;Liu et al, 2017).…”