Effect of medium copper concentration on the growth, uptake and intracellular balance of copper and zinc in Menkes' and normal control cells

Abstract

The precise nature of the variation in cellular copper load against medium copper concentration is defined using a comprehensive logarithmically incremented series of medium copper concentrations ranging from low levels (4.8 p.p.b.) through 'normal' to toxic levels (40 p.p.m.) in which fibroblasts were grown followed by determination of intracellular content. Menkes' fibroblasts showed an unexpected plateau region of stable intracellular copper content against a change in medium concentration of over 100-fold, albeit only when sufficient copper was present in the medium (0.08-8.0 p.p.m.). Thus, Menkes' cells are clearly capable of balancing uptake/efflux providing copper availability allows. Simultaneous analysis of cellular copper and zinc load at various medium copper concentrations shows an indistinguishable intracellular copper:zinc ratio between the two cell lines. The nature of non-labeled copper uptake by fibroblasts over a 40 min and 7 day period is reported. During the 40 min period copper uptake (20 p.p.m.) was essentially the same in both cell lines. However, copper absorbed was superimposed upon large pre-existing copper pools in the case of Menkes' cells only. Advantages of techniques determining non-labeled copper in copper uptake/efflux experiments are discussed in the light of these results. Fibroblast growth studies showed that, compared with normal cells, Menkes' cells are significantly (P < 0.01) more growth sensitive to extended exposure to low copper concentrations. Thus, Menkes' disease appears to be not only a result of copper maldistribution but also a direct result of an inability of Menkes' cells to function normally in low copper environments.

Copper Concentration in Body Tissues and Fluids in Normal Subjects of Southern Poland

“…Copper accumulation manifests itself in severe pathologies, including neurodegeneration, liver lesions, and behavioral abnormalities [3,7]. Other disturbance of copper metabolism occurs in Menkes disease in which copper deficiency is associated with symptoms from the CNS, vascular tissues, and bones [6,8,9].…”

ATP‐dependent copper transport by the Menkes protein in membrane vesicles isolated from cultured Chinese hamster ovary cells

“…Neurological symptoms observed in Menkes patients are believed to be due to deficiencies in the activity of copper‐dependent cytochrome c oxidase, Cu‐Zn superoxide dismutase and dopamine β‐hydroxylase [3, 4], while lysyl oxidase deficiency is responsible for the abnormalities of connective tissue [3, 4, 6]. The accumulation of copper in cell lines derived from Menkes patients compared to normal cells [7–11]concomitant with decreased activity of copper‐containing lysyl oxidase [6, 12, 13]suggests that the delivery of copper to various cellular compartments is a significant aspect of Menkes disease. Taken together, all these findings support the concept that the primary cause of Menkes disease is impaired copper homeostasis.…”

Metal X‐ray microanalysis in the olfactory system of rainbow trout exposed to low level of copper

“…The reason of such interaction is unclear although it has been suggested that the increase of zinc uptake may be related to induction of copper-metallothioneins [lo]. It has been shown that both metallothionein and increased zinc are indicators of copper overload [43]. In a previous study [28], we have demonstrated that fish seem to acclimate to a chronic low-level copper exposure.…”

“…Related zinc and copper sequestrations in early appearing lysosomes have been identified by X-ray microanalysis in hepatocytes of copperloaded rats [17]. Dependence of zinc concentration on copper content has also been shown in fibroblast cultures incubated with various copper concentrations [43]. The reason of such interaction is unclear although it has been suggested that the increase of zinc uptake may be related to induction of copper-metallothioneins [lo].…”