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To clarify the neuroprotective property of ceruloplasmin and the pathogenesis of aceruloplasminemia, we generated ceruloplasmin-deficient (CP⁻/⁻) mice on the C57BL/10 genetic background and further treated them with a mitochondrial complex I inhibitor, rotenone. There was no iron accumulation in the brains of CP⁻/⁻ mice at least up to 60 weeks of age. Without rotenone treatment, CP⁻/⁻ mice showed slight motor dysfunction compared with CP⁺/⁺ mice, but there were no detectable differences in the levels of oxidative stress markers between these two groups. A low dose of rotenone did not affect the mitochondrial complex I activity in our mice, however, it caused a significant change in motor behavior, neuropathology, or the levels of oxidative stress markers in CP⁻/⁻ mice, but not in CP⁺/⁺ mice. Our data support that ceruloplasmin protects against rotenone-induced oxidative stress and neurotoxicity, probably through its antioxidant properties independently of its function of iron metabolism.

Aceruloplasminemia is an autosomal recessive disorder of iron metabolism caused by mutations in the ceruloplasmin (Cp) gene. The neuropathological hallmark of this disease is intracellular iron overload, which is thought to lead to neuronal cell death through increased oxidative stress. We evaluated and characterized protein oxidation in the brain of a patient with this disease. The protein carbonyl content in the cerebral cortex of the patient was elevated compared to controls. Furthermore, peptide mass fingerprinting and partial amino acid sequencing identified glial fibrillary acidic protein (GFAP) as the major carbonylated protein in the cerebral cortex of the patient. In conjunction with the facts that Cp mainly localizes to astrocytes in the central nervous system and that astrocytes are loaded with much more iron than neurons in the cerebral cortex, our findings indicate that Cp deficiency may primarily damage astrocytes. We speculate that the dysfunction of astrocytes may be causatively related to neuronal cell loss in aceruloplasminemia.

Abstract: Ceruloplasmin (Cp) is the strongest ferroxidase in human plasma. Hereditary deficiency of this protein, named aceruloplasminemia, is an interesting model to elucidate the pathogenesis and pathophysiology of neurodegeneration induced by oxidative stress. Enhanced oxidative stress due to excessive iron accumulation is observed in the brains of aceruloplasminemia patients. Rotenone, a selective mitochondrial complex I inhibitor, induces neurodegeneration mimicking Parkinson’s disease. We investigated the influence of Cp deficiency upon neurodegeneration using rotenone-treated, Cp-deficient mouse brains. Immunohistochemical examination showed that acrolein, one of the products of lipid peroxides, and ubiquitin were more markedly immunoreacted in the brains of rotenone-treated, Cp-deficient mice than in rotenone-untreated, Cp-deficient or rotenone-treated, wild-type mice. These molecules were localized in neuronal cells. These results suggested that rotenone-induced lipid peroxidation and accumulation of ubiquitin immunoreactivity were enhanced in the absence of Cp. Therefore, Cp may protect neuronal cells from oxidative stress-induced neurodegeneration. [Copyright &y& Elsevier]

Numerous studies have demonstrated that adiponectin plays a crucial role in the protection from diabetes and atherosclerosis. Recently, we have identified AdipoR1 and AdipoR2 as the major receptors for adiponectin, although the precise mechanism whereby adiponectin improves insulin sensitivity through these receptors has not been fully elucidated. In the present study, we have extensively analyzed the changes in the levels of proteins in liver, the major site of adiponeetin effects, by overexpressing each receptor. B6 male mice were treated with the adenovirus encoding LacZ, AdipoR1 or AdipoR2 (n=4, each group). The mice overexpressing AdipoR1 or AdipoR2 in the liver showed significantly lower insulin concentrations with comparable glucose levels compared to the control mice, indicating that these mice are more sensitive to insulin. The livers were removed 7 days after the adenovirus injection and were extracted followed by a proteomics analysis. Spots whose intensity was altered (either increased or decreased more than 1.5 fold) by AdipoR1 or AdipoR2 overexpression compared to LacZ control were applied to mass spectrometry. Total 84 proteins were altered in expression by overexpressing AdipoR1, while 146 proteins were modulated by overexpressing AdipoR2. Interestingly, most of the enzymes in the glycolytic pathway and the TCA cycle were up-regulated by AdipoR1 overexpression, whereas these trends were not observed by AdipoR2 overexpression. Moreover, AdipoR1 overexpression prominently increased catalase expression and decreased SOD1 and SOD2 expression, suggesting that the increased catalase suppresses oxidative stress, leading to reductions in SOD1 and SOD2. This up-regulation of catalase by AdipoR1 was also confirmed in the primary hepatocytes overespressing AdipoR1, suggesting that AdipoR1-mediated signal directly modulates catalase expression. The enhanced glucose catabolism increases NADH production necessarily accompanied by the increased electron leak, leading to oxidative stress. These data suggest the fine mechanism of the effects by adiponectin that adiponectin coordinately enhances glucose catabolism by up-regulating the regulatory enzymes expression and the protection machinery for the oxidative stress against the increased NADH production through AdipoR1. Thus, the subjects with hyperadiponectinemia have better glucose utilization without increasing oxidative stress, leading to protection of diabetes and atherosclerosis. [ABSTRACT FROM AUTHOR]