Dual effect of APOBEC3G on Hepatitis B virus.
G to A hypermutation of Hepatitis B virus (HBV) and retroviruses appears as a result of deamination activities of host APOBEC proteins and is thought to play a role in innate antiviral immunity. Alpha and gamma interferons (IFN-alpha and -gamma) have been reported to upregulate the transcription of APOBEC3G, which is known to reduce the replication of HBV. We investigated the number of hypermutated genomes under various conditions by developing a quantitative measurement. The level of hypermutated HBV in a HepG2 cell line, which is semi-permissive for retrovirus, was 2.3 in 10(4) HBV genomes, but only 0.5 in 10(4) in permissive Huh7 cells. The level of APOBEC3G mRNA was about ten times greater in HepG2 cells than in Huh7 cells. Treatment of HepG2 cells with either IFN-alpha or -gamma increased the transcription of APOBEC3G and hypermutation of HBV. These mRNAs and hypermutation of HBV genomes were induced more prominently by IFN-gamma than by IFN-alpha. Both IFNs decreased the number of replicative intermediate of HBV. Overexpression of APOBEC3G reduced the number of replicative intermediate of HBV and increased hypermutated genomes 334 times, reaching 968 in 10(4) genomes. Deamination-inactive APOBEC3G did not induce hypermutation, but reduced the virus equally. Our results suggest that APOBEC3G, upregulated by IFNs, has a dual effect on HBV: induction of hypermutation and reduction of virus synthesis. The effect of hypermutation on infectivity should be investigated further.
Noguchi
Chiemi
C
Liver Research Project Center, Hiroshima University, Hiroshima, Japan.|Department of Medicine and Molecular Science, Division of Frontier Medical Science, Programs for Biomedical Research, Graduate School of Biomedical Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima-shi 734-8551, Japan.
Hiraga
Nobuhiko
N
Liver Research Project Center, Hiroshima University, Hiroshima, Japan.|Department of Medicine and Molecular Science, Division of Frontier Medical Science, Programs for Biomedical Research, Graduate School of Biomedical Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima-shi 734-8551, Japan.
Mori
Nami
N
Liver Research Project Center, Hiroshima University, Hiroshima, Japan.|Department of Medicine and Molecular Science, Division of Frontier Medical Science, Programs for Biomedical Research, Graduate School of Biomedical Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima-shi 734-8551, Japan.
Tsuge
Masataka
M
Liver Research Project Center, Hiroshima University, Hiroshima, Japan.|Department of Medicine and Molecular Science, Division of Frontier Medical Science, Programs for Biomedical Research, Graduate School of Biomedical Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima-shi 734-8551, Japan.
Imamura
Michio
M
Liver Research Project Center, Hiroshima University, Hiroshima, Japan.|Department of Medicine and Molecular Science, Division of Frontier Medical Science, Programs for Biomedical Research, Graduate School of Biomedical Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima-shi 734-8551, Japan.
Takahashi
Shoichi
S
Liver Research Project Center, Hiroshima University, Hiroshima, Japan.|Department of Medicine and Molecular Science, Division of Frontier Medical Science, Programs for Biomedical Research, Graduate School of Biomedical Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima-shi 734-8551, Japan.
Fujimoto
Yoshifumi
Y
Laboratory for Liver Diseases, SNP Research Center, The Institute of Physical and Chemical Research (RIKEN), Yokohama 230-0045, Japan.|Liver Research Project Center, Hiroshima University, Hiroshima, Japan.
Ochi
Hidenori
H
Laboratory for Liver Diseases, SNP Research Center, The Institute of Physical and Chemical Research (RIKEN), Yokohama 230-0045, Japan.|Liver Research Project Center, Hiroshima University, Hiroshima, Japan.
Abe
Hiromi
H
Laboratory for Liver Diseases, SNP Research Center, The Institute of Physical and Chemical Research (RIKEN), Yokohama 230-0045, Japan.|Department of Medicine and Molecular Science, Division of Frontier Medical Science, Programs for Biomedical Research, Graduate School of Biomedical Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima-shi 734-8551, Japan.
Maekawa
Toshiro
T
Laboratory for Liver Diseases, SNP Research Center, The Institute of Physical and Chemical Research (RIKEN), Yokohama 230-0045, Japan.
Yatsuji
Hiromi
H
Department of Gastroenterology, Toranomon Hospital, Tokyo, Japan.|Department of Medicine and Molecular Science, Division of Frontier Medical Science, Programs for Biomedical Research, Graduate School of Biomedical Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima-shi 734-8551, Japan.
Shirakawa
Kotaro
K
Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan.
Takaori-Kondo
Akifumi
A
Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan.
Chayama
Kazuaki
K
Laboratory for Liver Diseases, SNP Research Center, The Institute of Physical and Chemical Research (RIKEN), Yokohama 230-0045, Japan.|Liver Research Project Center, Hiroshima University, Hiroshima, Japan.|Department of Medicine and Molecular Science, Division of Frontier Medical Science, Programs for Biomedical Research, Graduate School of Biomedical Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima-shi 734-8551, Japan.
D000071480:APOBEC-3G Deaminase; D002460:Cell Line; D003564:Cytidine Deaminase; D004279:DNA, Viral / Q000737:chemistry / Q000235:genetics; D016679:Genome, Viral; D006515:Hepatitis B virus / Q000187:drug effects* / Q000235:genetics; D016898:Interferon-alpha / Q000494:pharmacology; D007371:Interferon-gamma / Q000494:pharmacology; D009154:Mutation; D009700:Nucleoside Deaminases / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D015854:Up-Regulation; D014779:Virus Replication
D004279:DNA, Viral; D016898:Interferon-alpha; D012333:RNA, Messenger; D012097:Repressor Proteins; D007371:Interferon-gamma; D009700:Nucleoside Deaminases; D000071480:APOBEC-3G Deaminase; C464924:APOBEC3G protein, human; D003564:Cytidine Deaminase