Inactivation of Atp7b Copper Transporter in Intestinal Epithelial Cells Is Associated with Altered Lipid Processing and Cell Growth Machinery Independent from Hepatic Copper Accumulation and Severity of Liver Histology.

Abstract

The clinical manifestations of Wilson disease (WD) are related to copper accumulation in the liver and brain, but little is known about the role of other organs expressing the ATP7B copper transporter on metabolic and ultrastructural changes characterizing WD. To examine the consequences of intestinal Atp7b inactivation in the absence of hepatic copper accumulation, a new mouse model (Atp7b) characterized by enterocyte-specific Atp7b inactivation was generated. Atp7bmice were compared with wild-type mice with the same genetic background (iWT). The Atp7b global knockout (Atp7b) model of WD on a C57Bl/6 background was previously generated and compared with its respective wild type (WT). Hepatic copper, lipid metabolism, liver and intestine histology, and electron microscopy were assessed over time up to 30 weeks of age. Although there was no evidence of intestine copper accumulation in Atp7bmice, transcriptome analysis in Atp7bmice revealed changes in genes involved in AMP-activated protein kinase signaling, fatty acid metabolism, and cell cycle both with partial overlap between the intestinal epithelial cells and the liver. Mitochondrial and other ultrastructural changes were observed in the intestinal epithelial cells of both Atp7band Atp7bmice. Intestine-specific Atp7b deficit affects systemic metabolic pathways and intestine morphology, and hepatic metabolic perturbations are associated with intestinal dysfunction, independently from hepatic copper accumulation, providing evidence that the WD phenotype is at least partially influenced by organ-specific ATP7B variants.