Ceramide Induces Human Hepcidin Gene Transcription through JAK/STAT3 Pathway.
Ceramide Induces Human Hepcidin Gene Transcription through JAK/STAT3 Pathway.
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DOI：
10.1371/journal.pone.0147474
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发表时间：
2016
期刊：
影响因子：
3.7
通讯作者：
Harrison-Findik DD
中科院分区：
文献类型：
--
作者：
Lu S;Natarajan SK;Mott JL;Kharbanda KK;Harrison-Findik DD
在脂肪肝患者的肝脏中观察到脂质代谢和铁含量的变化。铁调素（一种由肝脏合成的铁调节急性期蛋白）的表达也受到调节。脂质和铁代谢的潜在相互作用在很大程度上尚不清楚。我们研究了脂质中间体神经酰胺在人铁调素基因 HAMP 调节中的作用。用细胞可渗透的神经酰胺类似物处理人肝癌 HepG2 细胞。神经酰胺诱导 HepG2 细胞中 HAMP mRNA 表达显着上调。神经酰胺对 HAMP 表达的影响是通过转录机制介导的，因为它被放线菌素 D 处理完全阻断。报告基因检测还证实了神经酰胺对 0.6 kb HAMP 启动子的激活。用神经酰胺处理的 HepG2 细胞显示 STAT3、JNK 和 NF-κB 蛋白磷酸化增加。然而，如染色质免疫沉淀测定所示，神经酰胺诱导 STAT3（而非 NF-κB 或 c-Jun）与 HAMP 启动子结合。 0.6 kb HAMP启动子区域内STAT3响应元件的突变显着抑制了神经酰胺对HAMP启动子活性的刺激作用。类似地，用泛 JAK 激酶抑制剂和 STAT3 siRNA 池抑制 STAT3 也减少了神经酰胺对 HAMP 启动子活性和 mRNA 表达的诱导。总之，我们证明了神经酰胺通过 STAT3 在肝 HAMP 转录激活中的直接作用。我们的研究结果表明肝脏中脂质和铁代谢之间存在串扰，这可能导致肥胖相关脂肪肝疾病的发病机制。
Changes in lipid metabolism and iron content are observed in the livers of patients with fatty liver disease. The expression of hepcidin, an iron-regulatory and acute phase protein synthesized by the liver, is also modulated. The potential interaction of lipid and iron metabolism is largely unknown. We investigated the role of lipid intermediate, ceramide in the regulation of human hepcidin gene, HAMP. Human hepatoma HepG2 cells were treated with cell-permeable ceramide analogs. Ceramide induced significant up-regulation of HAMP mRNA expression in HepG2 cells. The effect of ceramide on HAMP expression was mediated through transcriptional mechanisms because it was completely blocked with actinomycin D treatment. Reporter assays also confirmed the activation of 0.6 kb HAMP promoter by ceramide. HepG2 cells treated with ceramide displayed increased phosphorylation of STAT3, JNK, and NF-κB proteins. However, ceramide induced the binding of STAT3, but not NF-κB or c-Jun, to HAMP promoter, as shown by the chromatin immunoprecipitation assays. The mutation of STAT3 response element within 0.6 kb HAMP promoter region significantly inhibited the stimulatory effect of ceramide on HAMP promoter activity. Similarly, the inhibition of STAT3 with a pan-JAK kinase inhibitor and STAT3 siRNA pool also diminished the induction of both HAMP promoter activity and mRNA expression by ceramide. In conclusion, we have shown a direct role for ceramide in the activation of hepatic HAMP transcription via STAT3. Our findings suggest a crosstalk between lipid and iron metabolism in the liver, which may contribute to the pathogenesis of obesity-related fatty liver disease.