Decreased activity of cytochromec oxidase in the macular mottled mouse: an immuno-electron microscopic study

Abstract

The macular mottled mouse is a murine model of the kinky hair syndrome, characterized by a deficiency in copper transport. Cytochrome c oxidase (CCO), a respiratory enzyme, is located in the inner mitochondrial membrane and consists of seven subunits, along with copper and iron. Biochemical and histochemical findings indicated that CCO activity was decreased in the cerebellum of the macular mottled mice but not in that of the controls. Immunocytochemical analysis, using anti-CCO and anti-complex III rabbit sera, revealed that CCO in the macular mottled mice was stained more weakly than that in the controls. Immuno-electron microscopic examination of CCO and complex III, using a method of gold labeling, was also performed. In the control mice, a high concentration of gold particles present over CCO and complex III could be seen in the inner mitochondrial membrane. The number of CCO-labeled gold particles was remarkably less, however, in the macular mottled mice, while no significant difference was found in the labeling of complex III between the two groups. It may be concluded that the very low CCO enzyme content in the macular mottled mouse results not only from a copper transport disorder but also from a CCO protein synthesis disorder which impairs the localization of CCO protein in the cerebellum.

Perinatal Copper Deficiency Alters Rat Cerebellar Purkinje Cell Size and Distribution

“…Recent biochemical findings in cerebella of CuD rats on CCO function and expression confirm that cerebellum is a sensitive target of dietary copper limitation [19,20]. Both macular and brindled mice mutants also show reduced CCO activity [21,22]. These results provide a biochemical rationale for the cerebellar dysfunction and ataxia seen in dietary copper deficiency and Menkes disease.…”

Molecular basis of neurodegeneration and neurodevelopmental defects in Menkes disease

“…We have found that there is no appreciable difference in the levels of nearly 80 mitochondrial proteins including complex IV subunits in the Menkes mitochondrial proteome (unpublished data). The most consistent finding concerning complex IV is a reduction in the cytochrome oxidase C enzymatic activity (Hunt, 1977; Kodama et al, 1989; Kunz et al, 1999; Kuznetsov et al, 1996; Maehara et al, 1983; Meguro et al, 1991; Seki et al, 1989). Despite this decreased activity, the metabolism of high-energy phosphate compounds, such as ATP, does not seem to be affected in mouse cells lacking Atp7a (Kunz et al, 1999; Kuznetsov et al, 1996).…”

“…Cytochrome oxidase C is a 13-subunit copper-dependent complex necessary for oxidative phosphorylation (Saraste, 1999). Decreased content of cytochrome oxidase C subunits have been frequently reported in human cells in culture and mouse tissues affected by Menkes (Hunt, 1977; Kodama et al, 1989; Kumode et al, 1994; Kunz et al, 1999; Kuznetsov et al, 1996; Maehara et al, 1983; Meguro et al, 1991; Rezek and Moore, 1986; Rossi et al, 2001; Seki et al, 1989; Sparaco et al, 1993; Yoshimura et al, 1990). This is in contrast with our quantitative mass spectrometry studies performed in cultured Menkes fibroblasts.…”