Alcohol-induced autophagy via upregulation of PIASy promotes HCV replication in human hepatoma cells

Abstract

Both alcohol and hepatitis C virus (HCV) infection could induce cellular autophagy in liver cells, which is considered to be essential for productive HCV replication. However, whether alcohol-induced autophagy is involved in the pathogenesis of HCV infection is still poorly understood. Alcohol treatment could induce autophagy in Huh7 cells (a hepatoma cell line that supports HCV JFH-1 replication), evidenced by the increase of LC3B-II levels, the conversion of LC3B-I to LC3B-II, and the formation of GFP-LC3 puncta as well as the decrease of p62 level in alcohol-treated cells compared with control cells. Alcohol treatment also significantly increased PIASy (a member of the PIAS family) expression, which can act as a SUMO (small ubiquitin-like modifier protein) E3 ligase to regulate a broader range of cellular processes including autophagy. Overexpression or the silencing expression of PIASy in alcohol-treated Huh7 cells could increase or decrease autophagic activation caused by alcohol treatment, respectively, and thus affect HCV replication correspondingly. In the absence of alcohol, overexpression or silencing expression of PIASy increase or decrease the level of cellular autophagy, judged by the changes of LC3B-II and p62 levels in the presence or absence of chloroquine (CQ), a lysosome inhibitor. More importantly, in the presence of 3-methyladenine (3-MA), an inhibitor in the early stage of autophagy, the effects of overexpression or silencing expression of PIASy on HCV replication were largely blocked. Furthermore, PIASy could selectively drive the accumulation of SUMO1-conjugated proteins, along with upregulation of the expression of several important autophagy factors, including ATG7 and ATG5–ATG12. In conclusion, alcohol promotes HCV replication through activation of autophagy in Huh7 cells, which partly attributes to its induction of PIASy expression. PIASy-enhanced accumulation of SUMO1-conjugated proteins may contribute to its inducing effect of autophagy. Our findings provide a novel mechanism for the action of alcohol-promoting HCV replication in the context of cellular autophagy.

Emerging Roles of Impaired Autophagy in Fatty Liver Disease and Hepatocellular Carcinoma

“…Acetylation of FoxO family members attenuated their transcriptional activity and reduced autophagy-related gene expression [ 82 , 83 ]. On the contrary, ethanol-induced autophagy increased the expression of PIAS family protein PIASy, which is involved in the accumulation of SUMO1-conjugated proteins, and enhanced HCV replication in hepatoma cell lines [ 84 ]. Indeed, these findings suggest that acute alcohol exposure increases autophagic flux in the liver and may prevent AFLD progression.…”

The Multifaceted Roles of Autophagy in Flavivirus-Host Interactions

“…On the other hand, Wang and colleagues showed that the STX17-mediated homotypic fusion of phagophores enhances HCV-induced autophagosome formation to benefit HCV viral RNA replication (Table 1) [441]. Very recently, alcohol was shown to enhance PIAS family protein (PIASy) expression to activate autophagy and thus promote HCV replication (Table 1) [426]. Recent studies implied that alternatively spliced forms of ATG10 can differentially modulate autophagic flux to regulate HCV replication (Table 1) [427,428].…”

Ubiquitin and Ubiquitin-Like Proteins in the Critical Equilibrium between Synapse Physiology and Intellectual Disability

“…Similarly, fetal cortices exposed to alcohol display an increased sumoylation of the Heat shock protein 1 (HSP1), a fundamental cellular sensor of environmental proteotoxic stress, resulting in prolonged activation of HSP1 ( El Fatimy et al, 2014 ). The E3 SUMO ligase PIASy is upregulated in alcohol-treated cultured cells and drives the induction of autophagy ( Ran et al, 2018 ), a well-known mechanism involved in synapse assembly and maturation ( Tomoda et al, 2020 ). Yet, whether alcohol-dependent PIASy upregulation could contribute to synaptic dysfunction in FASD is not known.…”