Functional and molecular responses of suckling rat pups and human intestinal Caco-2 cells to copper treatment

Ctrl 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 Ctrl and Atp7A in vivo and further documented effects of Cu exposure on Cu transport, CtrI and Atp7A levels and localization in enterocyte-like Caco-2 cells. Suckling rat pups were supplemented with Cu (0 and 25 mug Cu/day) for 10 days and small intestine Cu concentration, Ctrl, 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 muM CuSO4 and Cu-67 transport, Ctrl and Atp7A levels and localization were determined. In rat pups, Cu supplementation increased intestinal Cu, Ctrl and MT gene expression; however, Atp7A gene expression was not significantly affected. Caco-2 cells treated with 94 muM Cu had lower cellular Cu uptake and export compared to untreated cells. While Ctrl and Atp7A gene and protein levels were unaffected, confocal microscopy indicated that Ctrl 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 Ctrl and Atp7A may regulate Cu absorption. (C) 2004 Elsevier Inc. All fights reserved. Published by Elsevier Inc. All rights reserved.