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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: UNLABELLED. Meshes: Animals, Apoptosis, Glycochenodeoxycholic Acid, Microtubule-Associated Proteins, NF-kappa B, Rats, Rats, Sprague-Dawley, Signal Transduction, Survivin.
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Is survivin signaling regulated through nuclear factor-kappa B pathway during glycochenodeoxycholate-induced hepatocyte apoptosis? Context: Hepatocytes in primary culture undergo apoptosis upon exposure to glycochenodeoxycholate (GCDC). The signaling mechanisms of GCDC-induced apoptosis remain unclear. To investigate the role of antiapoptotic genes, we compared apoptotic response in primary hepatocytes following GCDC treatment. The hepatocytes from adult Sprague-Dawley rats were cultured in collagen-coated dishes and treated with GCDC in varying concentrations, or the same concentration at different time intervals. Apoptosis was detected by the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay, DNA fragmentation assay, and caspase assays. Expression of apoptosis-related genes and proteins was evaluated by RT-PCR, quantitative real-time PCR (qRT-PCR), and Western blotting, respectively. The DNA-binding property of a nuclear protein was assessed by electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP) assay. An interesting result was that GCDC caused hepatocyte apoptosis to display a biphasic phenomenon at a dosage of 50μM, whereas it was not found at higher dosages such as 200μM. GCDC stimulated the expression of antiapoptotic Survivin, which also presented a biphasic response. The activation of nuclear factor-kappaB (NF-κB) corresponded with the up-regulation of Survivin. The inhibitor of NF-κB, BAY 11-7082, suppressed the expression of Survivin and simultaneously eliminated the biphasic response. The expression of Survivin was transcriptionally mediated by the activation of NF-κB, as shown by EMSA and ChIP assay.
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These results demonstrated that a low dosage of GCDC induced the hepatocyte apoptosis to exhibit the biphasic response, which was regulated by the expression of Survivin through NF-κB signaling pathway. Final Decision: yes