The hepatitis B x antigen anti-apoptotic effector URG7 is localized to the endoplasmic reticulum membrane

•The anti-apoptotic protein URG7 is targeted and localized to the ER.•URG7 is glycosylated in the N-terminal region.•URG7 is inserted into the ER membrane with a single transmembrane segment.•URG7 mainly adapts a topology with an Nlumen–Ccytosol orientation.•The results suggest that the C-tail of UR...

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Bibliographic Details
Published in:FEBS letters 2013-09, Vol.587 (18), p.3058-3062
Main Authors: Ostuni, A., Lara, P., Armentano, M.F., Miglionico, R., Salvia, A.M., Mönnich, M., Carmosino, M., Lasorsa, F.M., Monné, M., Nilsson, I., Bisaccia, F.
Format: Article
Language:English
Subjects:
Apoptosis
Cellular localization
Endoplasmic reticulum
Endoplasmic Reticulum - genetics
Endoplasmic Reticulum - metabolism
Endoplasmic Reticulum - virology
Fluorescent Antibody Technique
Gene Expression Regulation
Glycosylation
Hep G2 Cells
Hepatitis B Antigens - genetics
Hepatitis B Antigens - metabolism
Hepatitis B virus
Hepatitis B virus - chemistry
Hepatitis B virus - genetics
Hepatitis B virus - metabolism
Hepatitis B x antigen
Host-Pathogen Interactions
Humans
Intracellular Membranes - metabolism
Intracellular Membranes - virology
Multidrug Resistance-Associated Proteins - chemistry
Multidrug Resistance-Associated Proteins - genetics
Multidrug Resistance-Associated Proteins - metabolism
Protein Binding
Signal Transduction
Topology
URG7
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Summary:•The anti-apoptotic protein URG7 is targeted and localized to the ER.•URG7 is glycosylated in the N-terminal region.•URG7 is inserted into the ER membrane with a single transmembrane segment.•URG7 mainly adapts a topology with an Nlumen–Ccytosol orientation.•The results suggest that the C-tail of URG7 could sequester a pro-apoptotic signal. Hepatitis B x antigen up-regulates the liver expression of URG7 that contributes to sustain chronic virus infection and to increase the risk for hepatocellular carcinoma by its anti-apoptotic activity. We have investigated the subcellular localization of URG7 expressed in HepG2 cells and determined its membrane topology by glycosylation mapping in vitro. The results demonstrate that URG7 is N-glycosylated and located to the endoplasmic reticulum membrane with an Nlumen–Ccytosol orientation. The results imply that the anti-apoptotic effect of URG7 could arise from the C-terminal cytosolic tail binding a pro-apoptotic signaling factor and retaining it to the endoplasmic reticulum membrane.
ISSN:0014-5793
1873-3468
1873-3468
DOI:10.1016/j.febslet.2013.07.042