Apoptosis induced by Fas signaling does not alter hepatic hepcidin expression

• 作者: Duygu Dee Harrison-Findik Emily Zmijewski John Gollan Sizhao Lu
• 来源期刊: 世界生物化学杂志：英文版（电子版）
• 学科: 医学
• 关键词: Iron METABOLISM Jo2 CH11 EXTRINSIC APOPTOSIS Stat3
• 年，卷（期）: 2014,（3）
• 页码范围: 387-397
• 页数: 11页
• 分类号: R575

摘要

AIM: To determine the regulation of human hepcidin(HAMP) and mouse hepcidin(hepcidin-1 and hepcidin-2) gene expression in the liver by apoptosis using in vivo and in vitro experimental models. METHODS: For the induction of the extrinsic apoptotic pathway, HepG2 cells were treated with various concentrations of CH11, an activating antibody for human Fas receptor, for 12 h. Male C57BL/6NCR and C57BL/6J strains of mice were injected intraperitoneally with sublethal doses of an activating antibody for mouse Fas receptor, Jo2. The mice were anesthetized and sacrificed 1 or 6 h after the injection. The level of apoptosis was quantified by caspase-3 activity assay. Liver injury was assessed by measuring the levels of ALT/AST enzymes in the serum. The acute phase reaction in the liver was examined by determining the expression levels of IL-6 and SAA3 genes by SYBR green quantitative real-time PCR(qPCR). The phosphorylation of transcription factors, Stat3, Smad4 and NF-κB was determined by western blotting. Hepcidin gene expression was determined by Taqman qPCR. The binding of transcription factors to hepcidin-1 promoter was studied using chromatin immunoprecipitation(ChIP) assays.RESULTS: The treatment of HepG2 cells with CH11 induced apoptosis, as shown by the significant activation of caspase-3(P 【 0.001), but did not cause any significant changes in HAMP expression. Short-term(1 h) Jo2 treatment(0.2 μg/g b.w.) neither induced apoptosis and acute phase reaction nor altered mRNA expression of mouse hepcidin-1 in the livers of C57BL/6NCR mice. In contrast, 6 h after Jo2 injection, the livers of C57BL/6NCR mice exhibited a significant level of apoptosis(P 【 0.001) and an increase in SAA3(P 【 0.023) and IL-6(P 【 0.005) expression in the liver. However, mRNA expression of hepcidin-1 in the liver was not significantly altered. Despite the Jo2-induced phosphorylation of Stat3, no occupancy of hepcidin-1 promoter by Stat3 was observed, as shown by ChIP assays. Compared to C57BL/6NCR mice, Jo2 treatment(0.2 μg/g