Han Okhee, Kim Eun-Young
Department of Nutritional Sciences, Pennsylvania State University, University Park, PA 16802, USA.
J Cell Biochem. 2007 Jul 1;101(4):1000-10. doi: 10.1002/jcb.21392.
An iron exporter ferroportin-1 (FPN-1) and a multi-copper oxidase hephaestin (Heph) are predicted to be expressed on the basolateral membrane of the enterocyte and involved in the processes of iron export across the basolateral membrane of the enterocyte. However, it is not clear where these proteins are exactly located in the intestinal absorptive cell. We examined cellular localization of FPN-1 and Heph in the intestinal absorptive cells using the fully differentiated Caco-2 cells. Confocal microscope study showed that FPN-1 and Heph are located on the basolateral membrane and they are associated with the transferrin receptor (TfR) in fully differentiated Caco-2 cells grown on microporous membrane inserts. However, Heph protein was not detected in the crypt cell-like proliferating Caco-2 cell. In stably transfected human intestinal absorptive cells expressing human FPN-1 modified by the addition of GFP at the C-terminus, we show that FPN-1-GFP is located on the basolateral membrane and it is associated with Heph suggesting the possibility that FPN-1 might associate and interact with Heph in the process of iron exit across the basolateral membrane of intestinal absorptive cell.
铁输出蛋白1（FPN-1）和多铜氧化酶血浆铜蓝蛋白（Heph）预计在肠细胞的基底外侧膜上表达，并参与铁穿过肠细胞基底外侧膜的输出过程。然而，尚不清楚这些蛋白质在肠吸收细胞中的具体位置。我们使用完全分化的Caco-2细胞研究了FPN-1和Heph在肠吸收细胞中的细胞定位。共聚焦显微镜研究表明，在微孔膜插入物上生长的完全分化的Caco-2细胞中，FPN-1和Heph位于基底外侧膜上，并且它们与转铁蛋白受体（TfR）相关联。然而，在隐窝样增殖的Caco-2细胞中未检测到Heph蛋白。在稳定转染的表达在C末端添加了GFP修饰的人FPN-1的人肠吸收细胞中，我们表明FPN-1-GFP位于基底外侧膜上，并且它与Heph相关联，这表明FPN-1在铁穿过肠吸收细胞基底外侧膜的输出过程中可能与Heph缔合并相互作用。
