New insights on the functional role of URG7 in the cellular response to ER stress

Hepatitis B virus (HBV) induces stress in the host cell endoplasmic reticulum and through HBx, a transactivating viral protein, activates the Unfolded Protein Response (UPR) pathways, favouring virus replication and cell survival1. Among others, HBx protein activates the expression of the Up- regulated Gene clone 7 (URG7), a protein localized into the ER2, with an anti-apoptotic activity, due to the PI3K/AKT signalling activation3. In order to shed light on the molecular mechanisms underlying URG7 activity, we studied its putative role in the ER stress response. Our main results demonstrate that URG7 is able to modulate the expression of UPR markers toward survival outcomes. The analysis of its interactome suggests that URG7 is able to interact with proteins involved in the synthesis, folding and protein degradation, in concert with an increase of total protein ubiquitination. All together, these data suggest that URG7 plays a pivotal role as a reliever of ER stress-induced apoptosis.