Ceruloplasmin Oxidation, a Feature of Parkinson's Disease CSF, Inhibits Ferroxidase Activity and Promotes Cellular Iron Retention

Abstract

Parkinson's disease is a neurodegenerative disorder characterized by oxidative stress and CNS iron deposition. Ceruloplasmin is an extracellular ferroxidase that regulates cellular iron loading and export, and hence protects tissues from oxidative damage. Using two-dimensional electrophoresis, we investigated ceruloplasmin patterns in the CSF of human Parkinson's disease patients. Parkinson's disease ceruloplasmin profiles proved more acidic than those found in healthy controls and in other human neurological diseases (peripheral neuropathies, amyotrophic lateral sclerosis, and Alzheimer's disease); degrees of acidity correlated with patients' pathological grading. Applying an unsupervised pattern recognition procedure to the two-dimensional electrophoresis images, we identified representative pathological clusters. In vitro oxidation of CSF in two-dimensional electrophoresis generated a ceruloplasmin shift resembling that observed in Parkinson's disease and co-occurred with an increase in protein carbonylation. Likewise, increased protein carbonylation was observed in Parkinson's disease CSF, and the same modification was directly identified in these samples on ceruloplasmin. These results indicate that ceruloplasmin oxidation contributes to pattern modification in Parkinson's disease. From the functional point of view, ceruloplasmin oxidation caused a decrease in ferroxidase activity, which in turn promotes intracellular iron retention in neuronal cell lines as well as in primary neurons, which are more sensitive to iron accumulation. Accordingly, the presence of oxidized ceruloplasmin in Parkinson's disease CSF might be used as a marker for oxidative damage and might provide new insights into the underlying pathological mechanisms.

Oxidation-induced Structural Changes of Ceruloplasmin Foster NGR Motif Deamidation That Promotes Integrin Binding and Signaling

“…In contrast, deamidation of the 962 NGR site, which is buried inside two ␤-strands of the protein structure and is blocked in a stable conformation by polar interactions with neighboring amino acids, can occur only after structural changes induced by an oxidative microenvironment. Protein oxidation and conformational changes similar to those reported here have been shown to cause copper ions to release from Cp (17,26,28). Noticeable, copper ions are necessary for the Cp ferroxidase activity (17,26,28).…”

“…Protein oxidation and conformational changes similar to those reported here have been shown to cause copper ions to release from Cp (17,26,28). Noticeable, copper ions are necessary for the Cp ferroxidase activity (17,26,28). Because protein aging under oxidative stress is a condition that may occur in some neurodegenerative diseases (19,(31)(32)(33), we hypothesize that Cp aging under pathological conditions promotes modifications that favor structural changes that in turn foster both copper ion release and NGR deamidation.…”

“…We previously reported that Cp undergoes oxidative modifications in the CSF of Parkinson disease and AD patients (17), as a consequence of changes in the environmental redox status of pathological CSF (18,19). Cp oxidation causes a decrease in its ferroxidase activity that may have pathological implications (17).…”

“…We previously reported that Cp undergoes oxidative modifications in the CSF of Parkinson disease and AD patients (17), as a consequence of changes in the environmental redox status of pathological CSF (18,19). Cp oxidation causes a decrease in its ferroxidase activity that may have pathological implications (17). Because oxidative conditions might cause structural changes that accelerate Asn deamidation, we investigated whether the Cp NGR motifs can deamidate during aging under oxidative conditions and whether, as a consequence, Cp acquires integrin binding properties mediated by isoDGR.…”

Free Radicals: Properties, Sources, Targets, and Their Implication in Various Diseases

“…Ceruloplasmin (an extracellular ferroxidase required for regulating cellular iron load and transport) oxidation results in the decreased ferroxidase activity followed by the accumulation of intracellular iron in neurons in PD. The increased levels of Fe ?3 mediate the production of hydroxyl radicals, results in the damage of dopaminergic neurons in PD [117].…”