[Mechanism of hepatocarcinogenesis by hepatitis B virus].
The X gene product of hepatitis B virus (HBV) has a trans-activation function. The AP-1, AP-2, kappa B-like, and C/EBP-like sequences, and the 26-bp element in HBV enhancer were identified as X-responsive elements. Although the X protein possesses a transcriptional activation domain, it doesn't bind to the X-responsive elements. However, CREB/ATF-2 becomes able to bind to a CRE-related sequence in the 26-bp element once it complexes with X protein. In addition, X protein was shown to have amino acid sequences homologous to the essential domain of Kunitz-type serine protease inhibitors and directly interacted with the protease, tryptase TL2. Results suggest that X protein modulates the tryptase TL2 activity, which may be involved in the proteolytic cleavage of cellular transcription factors.
Takada
S
S
Department of Gene Research, Cancer Institute.
Koike
K
K
D000595:Amino Acid Sequence; D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000382:microbiology*; D053818:Chymases; D005814:Genes, Viral; D006515:Hepatitis B virus / Q000235:genetics*; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics / Q000382:microbiology*; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000378:metabolism; D015842:Serine Proteinase Inhibitors; D015533:Transcriptional Activation; D053802:Tryptases; D014764:Viral Proteins
D015842:Serine Proteinase Inhibitors; D014764:Viral Proteins; D012697:Serine Endopeptidases; C083294:chymase 2; D053818:Chymases; D053802:Tryptases