Alteration of the Intracellular Copper Topography in Menkes and Atox1 Mutant Cells Visualized by X‐ray Fluorescence Microscopy

Copper is an essential element for the maintenance of human health. A number of diseases including Menkes’ and Wilson's disease are caused by impaired copper transport and regulation. Presently, the nature of cellular structures and organelles that may act as transient storage sites for copper and thus intimately participate in copper homeostasis remains elusive. Atox1p is a cytoplasmic copper chaperone known to interact with and deliver copper to the Menkes ATPase, which resides in the trans‐Golgi network and subsequently participates in copper export from the cell. To investigate how the intracellular copper distribution is altered in Menkes’ disease, we utilized an embryonic mouse fibrolast cell line (802‐1) that is defective for the gene encoding the Menkes protein (Mnkp). We used microprobe x‐ray fluorescence (micro‐XRF) to visualize the intracellular copper topography with submicron resolution, and thus to identify possible locations for copper storage. We have additionally utilized micro‐XRF to visualize the intracellular copper distribution in Atox1 deficient (Atox1−/−) cells and the corresponding wild‐type (Atox1 +/+) cells. Our results suggest that copper tends to accumulate largely in the nucleus of the Menkes deficient and Atox1 deficient cells under elevated copper conditions with respect to the corresponding wild‐type cells. Live‐cell imaging studies suggest both a rapid redistribution and copper‐dependent response for Atox1p and Mnkp.