Bauerly Kathryn A, Kelleher Shannon L, Lönnerdal Bo
Department of Nutrition, University of California, Davis, CA 95616, USA.
J Nutr Biochem. 2004 Mar;15(3):155-62. doi: 10.1016/j.jnutbio.2003.10.008.
Ctr1 and Atp7A are copper (Cu) transporters that may play a role in the regulation of intestinal Cu absorption; however, intestinal regulation of these transporters by Cu in vivo has not been well defined. In this study, we hypothesized that Cu supplementation would alter the expression of intestine Ctr1 and Atp7A in vivo and further documented effects of Cu exposure on Cu transport, Ctr1 and Atp7A levels and localization in enterocyte-like Caco-2 cells. Suckling rat pups were supplemented with Cu (0 and 25 microg Cu/day) for 10 days and small intestine Cu concentration, Ctr1, Atp7A and metallothionein (MT) gene expression were measured by Northern blot analysis. Caco-2 cells were treated with basal medium, or medium supplemented with 3 and 94 microM CuSO4 and 67Cu transport, Ctr1 and Atp7A levels and localization were determined. In rat pups, Cu supplementation increased intestinal Cu, Ctr1 and MT gene expression; however, Atp7A gene expression was not significantly affected. Caco-2 cells treated with 94 microM Cu had lower cellular Cu uptake and export compared to untreated cells. While Ctr1 and Atp7A gene and protein levels were unaffected, confocal microscopy indicated that Ctr1 was endocytosed and co-localized with transferrin in Cu treated cells. This study demonstrates the functional response of intestinal cells to Cu treatment and suggests that both Ctr1 and Atp7A may regulate Cu absorption.
Ctr1和Atp7A是铜（Cu）转运蛋白，可能在肠道铜吸收的调节中发挥作用；然而，体内铜对这些转运蛋白的肠道调节作用尚未明确界定。在本研究中，我们假设补充铜会改变体内肠道Ctr1和Atp7A的表达，并进一步记录铜暴露对类似肠上皮细胞的Caco-2细胞中铜转运、Ctr1和Atp7A水平及定位的影响。给乳鼠补充铜（0和25微克铜/天），持续10天，通过Northern印迹分析测定小肠铜浓度、Ctr1、Atp7A和金属硫蛋白（MT）基因表达。用基础培养基或补充有3和94微摩尔硫酸铜的培养基处理Caco-2细胞，并测定67铜转运、Ctr1和Atp7A水平及定位。在乳鼠中，补充铜增加了肠道铜、Ctr1和MT基因表达；然而，Atp7A基因表达未受到显著影响。与未处理的细胞相比，用94微摩尔铜处理的Caco-2细胞的细胞铜摄取和输出较低。虽然Ctr1和Atp7A基因及蛋白水平未受影响，但共聚焦显微镜显示，在铜处理的细胞中，Ctr1被内吞并与转铁蛋白共定位。本研究证明了肠道细胞对铜处理的功能反应，并表明Ctr1和Atp7A都可能调节铜吸收。
