Association of Ferroportin‐1 with Hephaestin in human intestinal cells

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The recent accumulating information suggests that iron transport step across the basolateral membrane of small intestinal enterocyte is the major site in regulating intestinal iron absorption during various patho-physiological conditions. Based on the recent findings, it was proposed that ferroportin-1 and hephaestin play an important key role in the transfer of iron across the basolateral membrane of enterocytes. While ferroportin-1 is expected to function as an iron exporter across the enterocyte, hephaestin is proposed to have an important role in iron transport across the basolateral membrane of the enterocyte by oxidizing ferrous to ferric ion before release into the circulation. Molecular genetic studies in yeast cells as well as in mouse astrocytes suggest a possibility that ferroportin-1 and hephaestin are required for the exit of iron across the intestinal basolateral membrane as associated. Thus, we investigated whether ferroportin-1 is associated with hephaestin in intestinal absorptive cells utilizing human intestinal Caco-2 cells. Our study demonstrates that both ferroportin-1 and hephaestin proteins are primarily localized on the basolateral membrane as associated in human intestinal cells. The confocal microscope study shows that ferroportin-1 protein is colocalized with hephaestin protein on the basolateral membrane in human intestinal enterocytes. Our immuno-coprecipitation study revealed that hephaestin is coprecipitated with ferroportin-1, which suggests that ferroportin-1 might interact with hephaestin in the process of iron exit across the basolateral membrane of intestinal absorptive cell.