Copper Trafficking in Sheep: A Pilot Proteomic Analysis of Enterocytes and Hepatocytes Under Dietary Copper Supplementation

Seven Rambouillet-crossbred wethers were utilized to examine the impact of copper (Cu) supplementation on plasma, bile, liver, duodenum, jejunum, and ileum tissue Cu concentrations and Cu trafficking proteins abundance in the duodenum and liver. Wethers were assigned to one of two treatments: (1) control: no supplemental Cu and (2) +Cu: 12 mg of supplemental Cu/kg DM. After receiving treatments for 29 days, all wethers were harvested, and blood, bile, liver, duodenum, jejunum, and ileum samples were collected for Cu concentration analysis. Additional duodenum and liver samples were collected for proteomic analysis. Animals in the +Cu group had a greater (p < 0.02) Cu concentration in plasma, liver, and jejunum, but a lesser (p < 0.01) ileum Cu Concentration compared to controls. Duodenum and bile Cu concentrations and protein abundance for Cu trafficking proteins in the duodenum and liver were similar (p > 0.10) across treatments. In the +Cu group, 23 and 5 proteins were unique to the duodenum and liver, respectively, while the control group had 20 and 28 unique proteins in those tissues. These data indicate that known proteins responsible for Cu trafficking were not changed by the dose of Cu supplementation, ultimately allowing Cu to accumulate in the liver.