The role of subcutaneous adipose tissue in supporting the copper balance in rats with a chronic deficiency in holo-ceruloplasmin

Abstract

We have previously shown that (1) an acute deficiency in blood serum holo-ceruloplasmin (Cp) developed in rats that were fed fodder containing silver ions (Ag-fodder) for one month and (2) the deficiency in holo-Cp was compensated by non-hepatic holo-Cp synthesis in rats that were chronically fed Ag-fodder for 6 months (Ag-rats). The purpose of the present study is to identify the organ(s) that compensate for the hepatic holo-Cp deficiency in the circulation. This study was performed on rats that were fed Ag-fodder (40 mg Ag·kg-1 body mass daily) for 6 months. The relative expression levels of the genes responsible for copper status were measured by RT-PCR. The in vitro synthesis and secretion of [14C]Cp were analyzed using a metabolic labeling approach. Oxidase activity was determined using a gel assay with o-dianisidine. Copper status and some hematological indexes were measured. Differential centrifugation, immunoblotting, immunoelectrophoresis, and atomic absorption spectrometry were included in the investigation. In the Ag-rats, silver accumulation was tissue-specific. Skeletal muscles and internal (IAT) and subcutaneous (SAT) adipose tissues did not accumulate silver significantly. In SAT, the mRNAs for the soluble and glycosylphosphatidylinositol-anchored ceruloplasmin isoforms were expressed, and their relative levels were increased two-fold in the Ag-rats. In parallel, the levels of the genes responsible for Cp metallation (Ctr1 and Atp7a/b) increased correspondingly. In the SAT of the Ag-rats, Cp oxidase activity was observed in the Golgi complex and plasma membrane. Moreover, full-length [14C]Cp polypeptides were released into the medium by slices of SAT. The possibilities that SAT is part of a system that controls the copper balance in mammals, and it plays a significant role in supporting copper homeostasis throughout the body are discussed.

Influence of Silver Nanoparticles on the Growth of Ascitic and Solid Ehrlich Adenocarcinoma: Focus on Copper Metabolism

“…The system that ensures the copper turnover in the body comprises an intracellular system that provides the synthesis of cuproenzymes, including secretory ones (Figure 1), and an extracellular system that controls the copper balance in the whole organism [66]. A key player of extracellular copper metabolism is Cp, which indicates the current state of copper homeostasis and corresponds to the physiological requirements of various organs with copper [63,[67][68][69][70]. Cp, a representative example of a "moonlighting" protein, is the major extracellular copper-containing protein in vertebrates [71,72].…”

Silver Ions as a Tool for Understanding Different Aspects of Copper Metabolism

“…In vivo pulse-chase experiments revealed that de novo synthesis of [ 14 C]Cp in Ag-fed animals occurred even when the liver was isolated from the bloodstream [65]. It turned out that this Cp was synthesized and excreted by the cells of subcutaneous adipose tissue, to which silver was not delivered [160]. Thus, the silver helped to uncover the interorgan control mechanism that supports copper balance in the blood and compensates for the deficit of oxidase Cp.…”

Shape-dependent biological activity of spherical and quasi-spherical silver nanoparticles in E. coli, A549 cells and mice

“…In liver cells, Ag( i ) ions are erroneously inserted in the active sites of the forming Cp of the blood serum, which contain cysteine residues and can coordinate Cu( i )/Ag( i ) ions. 38,63,91 The resulting Cp variant is enzymatically inactive, so the serum copper concentration and Cp oxidase activity decrease, while the Cp protein concentration remains the same (Fig. 8B, C and D).…”