Hepatitis B virus X protein impairs a-interferon signaling via up-regulation of suppressor of cytokine signaling 3 and protein phosphatase 2A.

Journal of medical virology

PubMedID: 27459003

Tsunematsu S, Suda G, Yamasaki K, Kimura M, Izumi T, Umemura M, Ito J, Sato F, Nakai M, Sho T, Morikawa K, Ogawa K, Tanaka Y, Watashi K, Wakita T, Sakamoto N. Hepatitis B virus X protein impairs a-interferon signaling via up-regulation of suppressor of cytokine signaling 3 and protein phosphatase 2A. J Med Virol. 2016;.
Hepatitis B Virus (HBV) causes liver cirrhosis and hepatocellular carcinoma. Standard therapy includes treatment with interferon (IFN); however, its efficacy is limited. HBV has been reported to impair IFN signaling; however, the mechanism is unclear. Here, the relationship between HBV X protein (HBx) and IFN signaling was investigated by establishing HepG2 cells, stably expressing HBx (HepG2/HBx) via retrovirus-mediated gene transfer. Subsequently, IFN negative-regulator expression and its mechanism were studied. HepG2/HBx cells showed reduced expression of IFN-stimulated genes and expressed higher levels of suppressor of cytokine signaling 3 (SOCS3) and protein phosphatase 2A (PP2A) suppressor compared with control cells. Knockdown of SOCS3 and PP2A restored IFN sensitivity. Moreover, HepG2/HBx cells showed higher phosphorylation levels of signal transducers and activators of transcription 3 and endoplasmic reticulum stress, which are inducers of SOCS3 and PP2A, respectively. Additionally, HBx-knockdown restored IFN sensitivity in HepG2. 2. 15. 7 cells. It was also confirmed that SOCS3 and PP2A expression levels were up-regulated in the liver of patients with HBV infection. THE RESULTS
of this study demonstrated that HBx impairs IFN signaling via increased expression of SOCS3 and PP2A, a novel mechanistic insight, providing a potential therapeutic target to enhance the efficiency of IFN therapy.J. Med. Virol. © 2016 Wiley Periodicals, Inc.