Glycogen Synthase Kinase 3β Enhances Hepatitis C Virus Replication by Supporting miR-122

Abstract

Hepatitis C virus (HCV) infection is associated with alterations in host lipid and insulin signaling cascades, which are partially explained by a dependence of the HCV life cycle on key molecules in these metabolic pathways. Yet, little is known on the role in the HCV life cycle of glycogen synthase kinase 3 (GSK3), one of the most important kinases in cellular metabolism. Therefore, the impact of GSK3 on the HCV life cycle was assessed in human hepatoma cell lines harboring subgenomic genotype 1b and 2a replicons or producing cell culture-derived HCV genotype 2a by exposure to synthetic GSK3 inhibitors, GSK3 gene silencing, overexpression of GSK3 constructs and immunofluorescence analyses. In addition, the role of GSK3 in hepatitis E virus (HEV) replication was investigated to assess virus specificity of the observed findings. We found that both inhibition of GSK3 function by synthetic inhibitors as well as silencing of GSK3β gene expression resulted in a decrease of HCV replication and infectious particle production, whereas silencing of the GSK3α isoform had no relevant effect on the HCV life cycle. Conversely, overexpression of GSK3β resulted in enhanced HCV replication. In contrast, GSK3β had no effect on replication of subgenomic HEV replicon. The pro-viral effect of GSK3β on HCV replication was mediated by supporting expression of microRNA-122 (miR-122), a micro-RNA which is mandatory for wild-type HCV replication, as GSK3 inhibitors suppressed miR-122 levels and as inhibitors of GSK3 had no antiviral effect on a miR-122-independent HCV mutant. In conclusion, we have identified GSK3β is a novel host factor supporting HCV replication by maintaining high levels of hepatic miR-122 expression.

GSK3: A Kinase Balancing Promotion and Resolution of Inflammation

“…In hepatitis C virus (HCV)-treated human hepatocarcinoma Huh7.5 cells, GSK3 inhibitors prevented the release of HCV virions, while viral replication was not affected [174]. Another group found that GSK3β (but not GSK3α) inhibition reduced both replication and viral particle production of HCV but not hepatitis E virus in Huh7.5 cells [175]. Moreover, GSK3-mediated phosphorylation appears to be involved in the destabilization of PHD finger protein 13, a host factor that (amongst other functions) is involved in repressing HIV-1 [176] and human cytomegalovirus gene expression [177].…”

GSK3β Plays a Negative Role During White Spot Syndrome Virus (WSSV) Infection by Regulating NF-κB Activity in Shrimp Litopenaeus vannamei

“…GSK3b is known as an AKT substrate which plays a crucial role in influenza viral entry (13,14). GSK3b silence could decrease the hepatitis C virus (HCV) replication and the production of infectious particle while GSK3b overexpression enhanced HCV replication (15). Studies in vitro displayed that specific inhibitors (small molecules) of GSK3b significantly decreased Tat-dependent replication of human immunodeficiency virus 1 (HIV1) (16).…”

Kinases as Potential Therapeutic Targets for Anti-coronaviral Therapy

“… 254 , 255 The overexpression of GSK-3β has been associated with HCV entry. 256 In HIV-1 infected T cells and monocytic cell lines, the upregulation of GSK-3β has been identified. 257 Coxsackievirus B3 (CVB3) infection induced GSK-3 expression in HeLa cell lines and a mouse model, resulting in virus-driven cytopathic effects and apoptosis.…”

“… 260 , 257 In Huh 7.5 cells, inhibition of GSK-3β led to a reduction of both replication and viral particle production of HCV but for hepatitis E virus (HEV). 261 The increased GSK-3β-Ser9 phosphorylation has been linked to the replication of the HBV, 262 , 263 indicating a beneficial effect of GSK-3β inhibition for HBV replication. GSK-3 phosphorylation of assembly protein precursor, a protein involved in the organization and maturation of cytomegalovirus, is required.…”