64Cu metabolism in menkes and normal cultured skin fibroblasts

Nicholas G. Beratis, Peter Price, Gundula Labadie, Kurt Hirschhorn

Research output: Contribution to journalArticlepeer-review

54 Scopus citations


The amount of radioactivity accumulated in normal skin fibroblasts cultured in the presence of 64Cu increased during the first few hours of incubation, and reached a plateau after 18 hr. Fibroblasts from patients with Menkes syndrome continued to accumulate64Cu and after 48 hr, the mutant cells contained over 3 times more radioactivity than the normal cells. Normal skin fibroblasts grown in the presence of64Cu for 24 hr and chased for 6 and 24 hr with64Cu-free medium released 78% and 91% of the radioactivity, respectively, whereas Menkes fibroblasts grown under similar conditions released only 22% and 51%, respectively. The amount of radioactivity incorporated by fibroblasts increased with increasing concentrations of64Cu in the culture medium, but the Menkes fibroblasts incorporated more64Cu than normal fibroblasts. A slight reduction in the incorporation and efflux of64Cu was seen with several metabolic inhibitors, but there was no difference between normal and mutant cells. Treatment of labeled cells with trypsin did not affect the amount of64Cu picked up by the cells. Most of the radioactive copper incorporated by the cells was not precipitated by trichloroacetic acid or phosphotungstic acid, although the percentage of precipitated64Cu as consistently higher in normal than in Menkes fibroblasts. Most of the 64Cu was bound to a molecule with a molecular weight of about 10,000, whereas a small fraction, proportionally higher in normal cells, was bound to a large molecular weight component(s). The amount of64Cu bound to the small molecular weight species was significantly greater in Menkes fibroblasts than in normal cells. Menkes fibroblasts were more sensitive to high nonphysiologic levels of nonradioactive copper than were normal cells. These findings demonstrate pronounced metabolic differences between normal and Menkes fibroblasts and indicate the need for further studies before proper treatment of this disease can be instituted. Speculation: Copper picked up by cultured skin fibroblasts is preferentially bound to a molecule with a molecular weight of about 10,000. The increased copper accumulation in Menkes fibroblasts may be caused by the deficiency of an enzyme that catalyzes the cleavage of this bond, by the presence of an increased amount of this small molecular weight molecule in the mutant cells, or by an increased binding capacity of this molecule for copper.

Original languageEnglish
Pages (from-to)699-702
Number of pages4
JournalPediatric Research
Issue number6
StatePublished - Jun 1978


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