Anderson G J, Powell L W, Halliday J W
Liver Unit, Queensland Institute of Medical Research, Brisbane, Australia.
Gastroenterology. 1994 Feb;106(2):414-22. doi: 10.1016/0016-5085(94)90600-9.
BACKGROUND/AIMS: The transferrin receptor is a prominent protein on the basal and lateral membranes of intestinal epithelial cells, yet little is known of the function of the receptor in the intestine. The aim of the present study was to determine whether intestinal transferrin receptors were capable of facilitating transferrin internalization.
Using the rat as an experimental model, the uptake of radiolabeled transferrin by cells isolated from different regions along the crypt-villus axis of the proximal small intestine was studied.
An intestinal epithelial cell fraction highly enriched in crypt cells bound most radiolabeled transferrin. Cells in this fraction were able to internalize transferrin and recycle it back to the cell surface. A high affinity, saturable pathway of transferrin uptake by these cells predominated at transferrin concentrations below 0.3 mumol/L, whereas at higher concentrations, most uptake was via a nonsaturable process. Intravenously injected radiolabeled transferrin could be detected within intestinal crypt cells, indicating that these cells are able to internalize transferrin in vivo.
These data suggest that intestinal crypt cells have an active transferrin/transferrin receptor system. Transferrin may play an important role in iron delivery to and/or as a growth factor for the rapidly proliferating intestinal epithelium.
背景/目的：转铁蛋白受体是肠上皮细胞基底膜和侧膜上的一种重要蛋白质，但对该受体在肠道中的功能了解甚少。本研究的目的是确定肠道转铁蛋白受体是否能够促进转铁蛋白的内化。
以大鼠为实验模型，研究了从近端小肠隐窝 - 绒毛轴不同区域分离的细胞对放射性标记转铁蛋白的摄取。
高度富集隐窝细胞的肠上皮细胞组分结合了大部分放射性标记的转铁蛋白。该组分中的细胞能够内化转铁蛋白并将其循环回到细胞表面。在转铁蛋白浓度低于0.3μmol/L时，这些细胞摄取转铁蛋白的高亲和力、可饱和途径占主导，而在较高浓度下，大多数摄取是通过非饱和过程。静脉注射的放射性标记转铁蛋白可在肠道隐窝细胞内检测到，表明这些细胞能够在体内内化转铁蛋白。
这些数据表明肠道隐窝细胞具有活跃的转铁蛋白/转铁蛋白受体系统。转铁蛋白可能在向快速增殖的肠上皮细胞输送铁和/或作为生长因子方面发挥重要作用。
