Identification of human genes of iron homeostasis

哺乳动物细胞表达数十种含铁蛋白，但对金属配体结合的机制知之甚少。人多聚（rC）结合蛋白1 （PCBP1）是一种铁伴侣蛋白，结合铁并将其传递给铁蛋白，铁蛋白是一种细胞质铁储存蛋白。我们已经确定铁依赖性脯氨酸羟化酶（PHDs）和天冬酰胺羟化酶（FIH1）修饰缺氧诱导因子（HIFα）作为PCBP1的靶点。细胞中PCBP1或PCBP2的缺失导致PHD活性的丧失，表现为HIF1&#945的脯氨酰羟基化减少，通过VHL/蛋白酶体途径对HIF1&#945的降解受损，以及活性HIF1转录因子的积累。体外通过添加过量的Fe（II）或纯化的Fe-PCBP1恢复PHD活性，体内PCBP1与PHD2和FIH1结合。这些数据表明PCBP1是铁并入PHD所必需的，并表明PCBP1和2在将铁传递给胞质非血红素铁酶方面发挥着广泛的作用。

Mammalian cells express dozens of iron-containing proteins, yet little is known about the mechanism of metal ligand incorporation. Human poly (rC) binding protein 1 (PCBP1) is an iron chaperone that binds iron and delivers it to ferritin, a cytosolic iron storage protein. We have identified the iron-dependent prolyl hydroxylases (PHDs) and asparaginyl hydroxylase (FIH1) that modify hypoxia-inducible factor α (HIFα) as targets of PCBP1. Depletion of PCBP1 or PCBP2 in cells led to loss of PHD activity, manifested by reduced prolyl hydroxylation of HIF1α, impaired degradation of HIF1α through the VHL/proteasome pathway, and accumulation of active HIF1 transcription factor. PHD activity was restored in vitro by addition of excess Fe(II) or purified Fe-PCBP1, and PCBP1 bound to PHD2 and FIH1 in vivo. These data indicated that PCBP1 was required for iron incorporation into PHD and suggest a broad role for PCBP1 and 2 in delivering iron to cytosolic non-heme iron enzymes.