Human hepatitis B virus X protein induces apoptosis in HepG2 cells: role of BH3 domain.
The smallest protein of hepatitis B virus, HBX, has been implicated in the development of liver diseases by interfering with normal cellular processes. Its role in cell proliferation has been unclear as both pro-apoptotic and anti-apoptotic activities have been reported. We showed molecular evidence that HBX induced apoptosis in HepG2 cells. A Bcl-2 Homology Domain 3 was identified in HBX, which interacted with anti-apoptotic but not pro-apoptotic members of the Bcl-2 family of proteins. HBX induced apoptosis when transfected into HepG2 cells, as demonstrated by both flow cytometry and caspase-3 activity. However, HBX protein may not be stable in apoptotic cells triggered by its own expression as only its mRNA or the fusion protein with the glutathione-S-transferase was detected in transfected cells. Our results suggested that HBX behaved as a pro-apoptotic protein and was able to induce apoptosis.
Lu
Yi Wei
YW
School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive 05N-10, Singapore 637551, Singapore.
Chen
Wei Ning
WN
D000595:Amino Acid Sequence; D017209:Apoptosis; D045744:Cell Line, Tumor; D006515:Hepatitis B virus / Q000235:genetics; D006801:Humans; D008969:Molecular Sequence Data; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D054334:Viral Regulatory and Accessory Proteins; D051028:bcl-2-Associated X Protein / Q000235:genetics / Q000378:metabolism
D012333:RNA, Messenger; D015534:Trans-Activators; D054334:Viral Regulatory and Accessory Proteins; D051028:bcl-2-Associated X Protein; C057628:hepatitis B virus X protein