Yong Kwang Park1, Eun-Sook Park1, Doo Hyun Kim2, Sung Hyun Ahn2, Seung Hwa Park3, Ah Ram Lee2, Soree Park2, Hong Seok Kang2, Ji-Hyun Lee4, Jong Man Kim5, Suk-Koo Lee5, Keo-Heun Lim2, Nathalie Isorce6, Shuping Tong7, Fabien Zoulim6, Kyun-Hwan Kim8. 1. Department of Pharmacology, Center for Cancer Research and Diagnostic Medicine, IBST, School of Medicine, Konkuk University, Seoul, Republic of Korea; KU Open Innovation Center, Konkuk University, Seoul, Republic of Korea. 2. Department of Pharmacology, Center for Cancer Research and Diagnostic Medicine, IBST, School of Medicine, Konkuk University, Seoul, Republic of Korea. 3. Department of Anatomy, School of Medicine, Konkuk University, Seoul, Republic of Korea. 4. Samsung Biomedical Research Institute, Seoul, Republic of Korea. 5. Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea. 6. INSERM Unité 1052, Cancer Research Center of Lyon, Hospices Civils de Lyon, Lyon University, Lyon, France. 7. Liver Research Center, Rhode Island Hospital, Brown University, Providence, RI, USA. 8. Department of Pharmacology, Center for Cancer Research and Diagnostic Medicine, IBST, School of Medicine, Konkuk University, Seoul, Republic of Korea; KU Open Innovation Center, Konkuk University, Seoul, Republic of Korea; Research Institute of Medical Sciences, Konkuk University, Seoul, Republic of Korea. Electronic address: khkim10@kku.ac.kr.
Abstract
BACKGROUND & AIMS: Cytokines are key molecules implicated in the defense against virus infection. Tumor necrosis factor-alpha (TNF-α) is well known to block the replication of hepatitis B virus (HBV). However, the molecular mechanism and the downstream effector molecules remain largely unknown. METHODS: In this study, we investigated the antiviral effect and mechanism of p22-FLIP (FLICE-inhibitory protein) by ectopic expression in vitro and in vivo. In addition, to provide the biological relevance of our study, we examined that the p22-FLIP is involved in TNF-α-mediated suppression of HBV in primary human hepatocytes. RESULTS: We found that p22-FLIP, a newly discovered c-FLIP cleavage product, inhibited HBV replication at the transcriptional level in both hepatoma cells and primary human hepatocytes, and that c-FLIP conversion to p22-FLIP was stimulated by the TNF-α/NF-κB pathway. p22-FLIP inhibited HBV replication through the upregulation of HNF3β but downregulation of HNF4α, thus inhibiting both HBV enhancer elements. Finally, p22-FLIP potently inhibited HBV DNA replication in a mouse model of HBV replication. CONCLUSIONS: Taken together, these findings suggest that the anti-apoptotic p22-FLIP serves a novel function of inhibiting HBV transcription, and mediates the antiviral effect of TNF-α against HBV replication.
BACKGROUND & AIMS: Cytokines are key molecules implicated in the defense against virus infection. Tumor necrosis factor-alpha (TNF-α) is well known to block the replication of hepatitis B virus (HBV). However, the molecular mechanism and the downstream effector molecules remain largely unknown. METHODS: In this study, we investigated the antiviral effect and mechanism of p22-FLIP (FLICE-inhibitory protein) by ectopic expression in vitro and in vivo. In addition, to provide the biological relevance of our study, we examined that the p22-FLIP is involved in TNF-α-mediated suppression of HBV in primary human hepatocytes. RESULTS: We found that p22-FLIP, a newly discovered c-FLIP cleavage product, inhibited HBV replication at the transcriptional level in both hepatoma cells and primary human hepatocytes, and that c-FLIP conversion to p22-FLIP was stimulated by the TNF-α/NF-κB pathway. p22-FLIP inhibited HBV replication through the upregulation of HNF3β but downregulation of HNF4α, thus inhibiting both HBV enhancer elements. Finally, p22-FLIP potently inhibited HBV DNA replication in a mouse model of HBV replication. CONCLUSIONS: Taken together, these findings suggest that the anti-apoptotic p22-FLIP serves a novel function of inhibiting HBV transcription, and mediates the antiviral effect of TNF-α against HBV replication.