Hepatitis C virus impairs p53 via persistent overexpression of 3beta-hydroxysterol Delta24-reductase.
Persistent infection with hepatitis C virus (HCV) induces tumorigenicity in hepatocytes. To gain insight into the mechanisms underlying this process, we generated monoclonal antibodies on a genome-wide scale against an HCV-expressing human hepatoblastoma-derived cell line, RzM6-LC, showing augmented tumorigenicity. We identified 3beta-hydroxysterol Delta24-reductase (DHCR24) from this screen and showed that its expression reflected tumorigenicity. HCV induced the DHCR24 overexpression in human hepatocytes. Ectopic or HCV-induced DHCR24 overexpression resulted in resistance to oxidative stress-induced apoptosis and suppressed p53 activity. DHCR24 overexpression in these cells paralleled the increased interaction between p53 and MDM2 (also known as HDM2), a p53-specific E3 ubiquitin ligase, in the cytoplasm. Persistent DHCR24 overexpression did not alter the phosphorylation status of p53 but resulted in decreased acetylation of p53 at lysine residues 373 and 382 in the nucleus after treatment with hydrogen peroxide. Taken together, these results suggest that DHCR24 is elevated in response to HCV infection and inhibits the p53 stress response by stimulating the accumulation of the MDM2-p53 complex in the cytoplasm and by inhibiting the acetylation of p53 in the nucleus.
Department of Experimental Phylaxiology, Faculty of Medical and Pharmaceutical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto, Kumamoto 860-8556, Japan; Chemo-Sero-Therapeutic Research Institute, Kikuchi Research Center, Kyokushi, Kikuchi, Kumamoto 869-1298, Japan.
Tomohiro
T
Nishimura
Department of Microbiology and Cell Biology, Tokyo Metropolitan Institute of Medical Science, 1-6 Kamikitazawa 2-chome, Setagaya-ku, Tokyo 156-8506, Japan.
Michinori
M
Kohara
Laboratory Animal Research Center, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokane-dai, Minato-ku, Tokyo 108-8639, Japan.
Kosuke
K
Izumi
Department of Experimental Phylaxiology, Faculty of Medical and Pharmaceutical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto, Kumamoto 860-8556, Japan.
Yuri
Y
Kasama
Department of Microbiology and Cell Biology, Tokyo Metropolitan Institute of Medical Science, 1-6 Kamikitazawa 2-chome, Setagaya-ku, Tokyo 156-8506, Japan.
Yuichi
Y
Hirata
Laboratory Animal Research Center, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokane-dai, Minato-ku, Tokyo 108-8639, Japan.
Ying
Y
Huang
Department of Microbiology and Cell Biology, Tokyo Metropolitan Institute of Medical Science, 1-6 Kamikitazawa 2-chome, Setagaya-ku, Tokyo 156-8506, Japan.
Masahiro
M
Shuda
Study Service Department, PhoenixBio Company, Ltd., 3-4-1 Kagamiyama, Higashi-Hiroshima 739-0046, Japan.
Chise
C
Mukaidani
Department of Microbiology and Cell Biology, Tokyo Metropolitan Institute of Medical Science, 1-6 Kamikitazawa 2-chome, Setagaya-ku, Tokyo 156-8506, Japan.
Takashi
T
Takano
Department of Experimental Phylaxiology, Faculty of Medical and Pharmaceutical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto, Kumamoto 860-8556, Japan.
Yuko
Y
Tokunaga
Department of Microbiology and Cell Biology, Tokyo Metropolitan Institute of Medical Science, 1-6 Kamikitazawa 2-chome, Setagaya-ku, Tokyo 156-8506, Japan.
Hideko
H
Nuriya
Department of Experimental Phylaxiology, Faculty of Medical and Pharmaceutical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto, Kumamoto 860-8556, Japan.
Masaaki
M
Satoh
Department of Experimental Phylaxiology, Faculty of Medical and Pharmaceutical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto, Kumamoto 860-8556, Japan.
Makoto
M
Saito
Laboratory Animal Research Center, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokane-dai, Minato-ku, Tokyo 108-8639, Japan.
Chieko
C
Kai
Department of Experimental Phylaxiology, Faculty of Medical and Pharmaceutical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto, Kumamoto 860-8556, Japan. Electronic address: kkohara@kumamoto-u.ac.jp.
Kyoko
K
Tsukiyama-Kohara
D000107:Acetylation / Q000187:drug effects; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D002472:Cell Transformation, Viral; D003593:Cytoplasm / Q000235:genetics / Q000378:metabolism; D004790:Enzyme Induction / Q000235:genetics; D055106:Genome-Wide Association Study; D056945:Hep G2 Cells; D016174:Hepacivirus; D006526:Hepatitis C / Q000235:genetics / Q000378:metabolism*; D022781:Hepatocytes / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009419:Nerve Tissue Proteins / Q000096:biosynthesis* / Q000235:genetics; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects / Q000235:genetics; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000096:biosynthesis* / Q000235:genetics; D010766:Phosphorylation / Q000187:drug effects / Q000235:genetics; D051736:Proto-Oncogene Proteins c-mdm2 / Q000235:genetics / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*
D009419:Nerve Tissue Proteins; D016877:Oxidants; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D006861:Hydrogen Peroxide; D044925:Oxidoreductases Acting on CH-CH Group Donors; C499055:DHCR24 protein, human; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2