Mechanism of hepatocytes apoptosis induced by the proapoptosis protein Bid.
OBJECTIVE
To investigate the mechanism of hepatocyte apoptosis induced by the proapoptosis protein Bid.


METHODS
Mouse primary hepatocytes were isolated from wild-type and Bid-deficient mice and treated with tumor necrosis factor-alpha (TNF-alpha) or anti-Fas antibody to induce cell apoptosis. Immunofluorescence staining of Bax was performed to recognize Bax translocation and its conformational change. The wild-type mice or wild-type mice transfected with the adenovirus carried DN-FADD (Dominant Negative-Fas Associated Death Domain) and the Bid-deficient mice were injected with anti-Fas antibody 2 h before being killed. Caspase 3 and 8 activities were measured. Bands of Bid cleavage and Bax conformational change were detected by Western blot.


RESULTS
Death receptors, including TNF-alpha and anti-Fas antibody, induced hepatocytes apoptosis, Bax translocation and conformational change through activation of Bid, which caused Bax to be inserted into the mitochondrial membrane of hepatocytes. The translocation and insertion of Bax were blocked when Bid was knocked out or blocked, and hepatocyte apoptosis was delayed or inhibited.


CONCLUSIONS
Hepatocyte apoptosis induced by death receptors is regulated by Bid and the translocation and insertion of Bax are also dependent on Bid.
Bai
Li
L
Department of Digestive diseases, General Air Force Hospital, Beijing, China. bai_li@hotmail.com
Cao
Chuan Ping
CP
Mao
Gao Ping
GP
D000818:Animals; D017209:Apoptosis; D051023:BH3 Interacting Domain Death Agonist Protein; D002352:Carrier Proteins / Q000494:pharmacology*; D019254:Genes, bcl-2; D022781:Hepatocytes / Q000187:drug effects* / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010446:Peptide Fragments; D019253:Proto-Oncogene Proteins c-bcl-2; D014178:Translocation, Genetic; D051028:bcl-2-Associated X Protein; D019014:fas Receptor
D051023:BH3 Interacting Domain Death Agonist Protein; C494827:Bax protein, mouse; C494815:Bid protein, mouse; D002352:Carrier Proteins; D010446:Peptide Fragments; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D019014:fas Receptor