Hepcidin is the master regulator of systemic iron homeostasis and its dysregulation is observed in several chronic liver diseases. Unlike the extracellular iron-sensing mechanisms, the intracellular iron-sensing mechanisms in the hepatocytes that lead to hepcidin induction and secretion are incompletely understood. Here, we aimed to understand the direct role of intracellular iron-loading on hepcidin mRNA and peptide secretion using our previously characterised recombinant HepG2 cells that over-express the cell-surface iron-importer protein transferrin receptor-1. Gene expression of hepcidin (HAMP) was determined by real-time PCR. Intracellular iron levels and secreted hepcidin peptide levels were measured by ferrozine assay and immunoassay, respectively. These measurements were compared in the recombinant and wild-type HepG2 cells under basal conditions at 30 min, 2 h, 4 h and 24 h. Data showed that in the recombinant cells, intracellular iron content was higher than wild-type cells at 30 min (3.1-fold, p < 0.01), 2 h (4.6-fold, p < 0.01), 4 h (4.6-fold, p < 0.01) and 24 h (1.9-fold, p < 0.01). Hepcidin (HAMP) mRNA expression was higher than wild-type cells at 30 min (5.9-fold; p = 0.05) and 24 h (6.1-fold; p < 0.03), but at 4 h, the expression was lower than that in wild-type cells (p < 0.05). However, hepcidin secretion levels in the recombinant cells were similar to those in wild-type cells at all time-points, except at 4 h, when the level was lower than wild-type cells (p < 0.01). High intracellular iron in recombinant HepG2 cells did not proportionally increase hepcidin peptide secretion. This suggests a limited role of elevated intracellular iron in hepcidin secretion.

中文翻译：

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Hepcidin的分泌与重组TfR1 HepG2细胞中的细胞内铁负荷不成正比：短时通讯。

铁调素是全身铁稳态的主要调节剂，在几种慢性肝病中观察到其失调。与细胞外铁感测机制不同，导致hepcidin诱导和分泌的肝细胞内细胞内铁感测机制尚不完全清楚。在这里，我们旨在使用我们先前表征的重组HepG2细胞来过度表达细胞表面铁导入蛋白转铁蛋白受体1，从而了解胞内铁负载对hepcidin mRNA和肽分泌的直接作用。hepcidin（HAMP）的基因表达通过实时PCR确定。细胞内铁水平和分泌的铁调素肽水平分别通过ferrozine测定和免疫测定来测量。在基础条件下30分钟，2小时，4小时和24小时，在重组和野生型HepG2细胞中比较了这些测量结果。数据显示，在重组细胞中，在30分钟（3.1倍，p <0.01），2小时（4.6倍，p <0.01），4小时（4.6倍，4.6倍）时，细胞内铁含量高于野生型细胞。 p <0.01）和24 h（1.9倍，p <0.01）。Hepcidin（HAMP）mRNA在30分钟（5.9倍； p = 0.05）和24 h（6.1倍； p <0.03）时高于野生型细胞，但在4 h时，其表达低于野生型细胞。野生型细胞（p <0.05）。但是，重组细胞中铁调素的分泌水平在所有时间点都与野生型细胞相似，除了在4 h时，其水平低于野生型细胞（p <0.01）。重组HepG2细胞中的高细胞内铁并没有成比例地增加铁调素肽的分泌。这表明升高的胞内铁在铁调素分泌中的作用有限。