Hardman B, Manuelpillai U, Wallace E M, Monty J-F, Kramer D R, Kuo Y M, Mercer J F B, Ackland M L
Deakin University, Centre for Cellular and Molecular Biology, School of Biological and Chemical Sciences, Burwood Campus, Burwood, Victoria 3125, Australia.
Placenta. 2006 Sep-Oct;27(9-10):968-77. doi: 10.1016/j.placenta.2005.10.011. Epub 2005 Dec 13.
Copper is an essential trace element necessary for normal growth and development. During pregnancy, copper is transported from the maternal circulation to the fetus by mechanisms which have not been clearly elucidated. The copper uptake protein, hCTR1 is predicted to play a role in copper transport in human placental cells. This study has examined the expression and localisation of hCTR1 in human placental tissue and Jeg-3 cells. In term placental tissue the hCTR1 protein was detected as a 105 kDa protein, consistent with the size of a trimer which may represent the functional protein. A 95 kDa band, possibly representing the glycosylated protein, was also detected. hCTR1 was localised within the syncytiotrophoblast layer and the fetal vascular endothelial cells in the placental villi and interestingly was found to be localised toward the basal plasma membrane. It did not co-localise with either the Menkes or the Wilson copper transporting ATPases. Using the placental cell line Jeg-3, it was shown that the 35 kDa monomer was absent in the extracts of cells exposed to insulin, estrogen or progesterone and in cells treated with estrogen an additional 65 kDa band was detected which may correspond to a dimeric form of the protein. The 95 kDa band was not detected in the cultured cells. These results provide novel insights indicating that hormones have a role in the formation of the active hCTR1 protein. Furthermore, insulin altered the intracellular localisation of hCTR1, suggesting a previously undescribed role of this hormone in regulating copper uptake through the endocytic pathway.
铜是正常生长发育所必需的一种微量元素。在孕期，铜通过尚未完全阐明的机制从母体循环转运至胎儿体内。铜摄取蛋白hCTR1预计在人胎盘细胞的铜转运中发挥作用。本研究检测了hCTR1在人胎盘组织和Jeg-3细胞中的表达及定位。在足月胎盘组织中，hCTR1蛋白被检测为一种105 kDa的蛋白，与可能代表功能蛋白的三聚体大小一致。还检测到一条95 kDa的条带，可能代表糖基化蛋白。hCTR1定位于胎盘绒毛的合体滋养层和胎儿血管内皮细胞内，有趣的是，它定位于基底质膜附近。它与门克斯或威尔逊铜转运ATP酶均无共定位。利用胎盘细胞系Jeg-3研究发现，在暴露于胰岛素、雌激素或孕酮的细胞提取物中不存在35 kDa的单体，在用雌激素处理的细胞中检测到一条额外的65 kDa条带，可能对应于该蛋白的二聚体形式。在培养细胞中未检测到95 kDa的条带。这些结果提供了新的见解，表明激素在活性hCTR1蛋白的形成中起作用。此外，胰岛素改变了hCTR1的细胞内定位，提示该激素在通过内吞途径调节铜摄取方面有一个以前未描述的作用。
