Hepcidin-2 in mouse urine as a candidate radiation-responsive molecule

We used high-performance liquid chromatography to separate urine obtained from whole-body gamma-irradiated mice (4 gy) before analyzing each fraction with matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry to identify radiation-responsive molecules. we identified two candidates: hepcidin antimicrobial peptide 2 (hepcidin-2) and peptide fragments of kidney androgen-regulated protein (kap). we observed that peak increases of hepcidin-2 in urine were delayed in a dose-dependent manner (1 gy and above); however,the amount of kap peptide fragments showed no correlation with radiation dose. in addition,an increase in hepcidin-2 after exposure to relatively low radiation doses (0.25 and 0.5 gy,respectively) was biphasic (at 8-48 h and 120-168 h,respectively,after irradiation). the increase in hepcidin-2 paralleled an increase in hepcidin-2 gene (hamp2) mrna levels in the liver. these results suggest that radiation exposure directly or indirectly induces urinary excretion of hepcidin-2 at least in part by the upregulation of hamp2 mrna in the liver. © 2016 the author 2016. published by oxford university press on behalf of the japan radiation research society and japanese society for radiation oncology.