胎盘铁转运的分子机制研究进展

Progress in research on molecular mechanism of placental iron transfer

铁从母体向胎儿的转运过程至今并不完全清楚。铁经过胎盘向胎儿的转运首先由位于胎盘滋养细胞母体面转铁蛋白受体1的吸收，然后来自母体的转铁蛋白再返回到母体血循环中。遗传性血色素沉着病缺陷蛋白可能参与了转铁蛋白受体1对转铁蛋白铁吸收的调节。滋养细胞顶端的铁蛋白受体也可能参与了胎盘的部分铁吸收。吸收入内吞小体里的铁很可能通过二价金属离子转运蛋白1转入胞浆。进入胞浆后，铁或以铁蛋白的形式贮存、或参与生物合成、或被转出滋养细胞，具体机制尚不清楚。铁转出滋养细胞很可能是通过位于其基底膜的膜铁转运蛋白1，但似乎还存在其它的转出路径。另外，参与胎盘输出铁氧化的铜氧化酶可能与膜铁转运辅助蛋白和血浆铜蓝蛋白都不同，且目前研究定位也不清楚。至于在滋养细胞基底面发现的转铁蛋白受体1、金属离子转运蛋白1、铁蛋白和遗传性血色素沉着病缺陷蛋白等是否参与胎盘铁的输出目前尚无支持的证据。因此。对于胎盘铁转运过程的理解还有许多工作要做。

The certain process of iron transport from mother to the fetus is unclear yet now. It has been proved that iron is absorbed by transferrin receptor 1 （ TfR1 ） located on maternal side of placental syncytiotrophoblast （ STB）, and then the tranferrin （Tf） returns to maternal blood. Hereditary haemochromatosis protein （HFE） may be involved in regulation of iron uptake through TfR1-Tf route. Also, the ferritin receptor （FnR） located on apex of STB may absorb part of iron into STB. The iron absorbed in the endosome is probably exported into the cytoplasm by divalent metal transporter 1 （ DMT1 ）. After entering the plasma of STB, the iron can be stored in ferritin or participate in biosynthesis or be exported out of the STB, but the certain molecular mechanisms are unclear now. Iron is exported out of STB probably by ferroprotinl （ FP1 ） located on basement membrane of STB. In addition, copper oxidase involved in placental iron export may be different from hephaestin （Hp） and caernloplasm （Cp）, and localization of copper oxidase is also unknown. There have not been enough evidences to prove that whether TfR1, DMT1, Ferritin and HFE located on the basal surface of STB are all involved in placental iron exportation or not. Therefore, much work needs to be done to understand the process of placental iron transfer.