Development and polarization of cationic amino acid transporters and regulators in the human placenta
Development and polarization of cationic amino acid transporters and regulators in the human placenta
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DOI：
10.1152/ajpcell.2000.278.6.c1162
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发表时间：
2000-06-01
影响因子：
5.5
通讯作者：
Glazier, JD
中科院分区：
文献类型：
--
作者：
Ayuk, PTY;Sibley, CP;Glazier, JD
我们已经调查了L-精氨酸运输系统在整个妊娠人类胎盘合体滋养层使用纯化的微绒毛（MVM）和基底（BM）质膜囊泡。在孕早期和足月胎盘MVM中，L-精氨酸转运主要通过y（+）和y（+）L系统。然而，在BM（足月胎盘）中，仅存在系统y（+）L的证据。Y（+）L系统米氏常数在孕早期显著低于足月MVM（P < 0.05），足月MVM显著低于BM（P < 0.05）。没有系统B（0+）在术语MVM或BM中的功能证据。用RT-PCR方法检测妊娠期胎盘组织中阳离子氨基酸转运蛋白（CAT）1、CAT 4和4F 2 hc的表达。足月胎盘中未检测到rBAT。在还原和非还原条件下，MVM中分别检测到类似于85-kDa和类似于135-kDa的蛋白，与4F 2 hc单体和4F 2 hc-轻链二聚体一致，并且与早期MVM相比，它们的表达在足月时显著升高（P < 0.05）。尽管有系统y（+）L的功能证据，但在BM中未检测到这些蛋白质。这些数据表明，不同的角色4F 2 hc在合胞体滋养层的阳离子氨基酸转运蛋白的发展和极化。
We have investigated L-arginine transport systems in the human placental syncytiotrophoblast across gestation using purified microvillous (MVM) and basal (BM) plasma membrane vesicles. In MVM from first-trimester and term placentas, L-arginine transport was by systems y(+) and y(+) L. In BM (term placentas), however, there was evidence for system y(+) L only. The Michaelis constant of system y(+) L was significantly lower (P < 0.05) in first-trimester compared with term MVM and lower in term MVM compared with BM (P < 0.05). There was no functional evidence for system b(0+) in term MVM or BM. Cationic amino acid transporter (CAT) 1, CAT 4, and 4F2hc were detected using RT-PCR in placentas throughout gestation. rBAT was not detected in term placentas. An similar to 85-kDa and an similar to 135-kDa protein was detected by Western blotting in MVM under reducing and nonreducing conditions, respectively, consistent with the 4F2hc monomer and the 4F2hc-light chain dimer, and their expression was significantly higher (P < 0.05) in term compared with first-trimester MVM. These proteins were not detected in BM despite functional evidence for system y(+) L. These data suggest different roles for 4F2hc in the development and polarization of cationic amino acid transporters in the syncytiotrophoblast.