Liver mitochondrial membrane crosslinking and destruction in a rat model of Wilson disease
Hans Zischka, Josef Lichtmannegger, Sabine Schmitt, Nora Jägemann, Sabine Schulz, Daniela Wartini, Luise Jennen, Christian Rust, Nathanael Larochette, Lorenzo Galluzzi, Veronique Chajes, Nathan Bandow, Valérie S. Gilles, Alan A. DiSpirito, Irene Esposito, Martin Goettlicher, Karl H. Summer, Guido Kroemer
Hans Zischka, Josef Lichtmannegger, Sabine Schmitt, Nora Jägemann, Sabine Schulz, Daniela Wartini, Luise Jennen, Christian Rust, Nathanael Larochette, Lorenzo Galluzzi, Veronique Chajes, Nathan Bandow, Valérie S. Gilles, Alan A. DiSpirito, Irene Esposito, Martin Goettlicher, Karl H. Summer, Guido Kroemer
View: Text | PDF
Research Article Hepatology

Liver mitochondrial membrane crosslinking and destruction in a rat model of Wilson disease

Abstract

Wilson disease (WD) is a rare hereditary condition that is caused by a genetic defect in the copper-transporting ATPase ATP7B that results in hepatic copper accumulation and lethal liver failure. The present study focuses on the structural mitochondrial alterations that precede clinical symptoms in the livers of rats lacking Atp7b, an animal model for WD. Liver mitochondria from these Atp7b–/– rats contained enlarged cristae and widened intermembrane spaces, which coincided with a massive mitochondrial accumulation of copper. These changes, however, preceded detectable deficits in oxidative phosphorylation and biochemical signs of oxidative damage, suggesting that the ultrastructural modifications were not the result of oxidative stress imposed by copper-dependent Fenton chemistry. In a cell-free system containing a reducing dithiol agent, isolated mitochondria exposed to copper underwent modifications that were closely related to those observed in vivo. In this cell-free system, copper induced thiol modifications of three abundant mitochondrial membrane proteins, and this correlated with reversible intramitochondrial membrane crosslinking, which was also observed in liver mitochondria from Atp7b–/– rats. In vivo, copper-chelating agents reversed mitochondrial accumulation of copper, as well as signs of intra-mitochondrial membrane crosslinking, thereby preserving the functional and structural integrity of mitochondria. Together, these findings suggest that the mitochondrion constitutes a pivotal target of copper in WD.

Authors

Hans Zischka, Josef Lichtmannegger, Sabine Schmitt, Nora Jägemann, Sabine Schulz, Daniela Wartini, Luise Jennen, Christian Rust, Nathanael Larochette, Lorenzo Galluzzi, Veronique Chajes, Nathan Bandow, Valérie S. Gilles, Alan A. DiSpirito, Irene Esposito, Martin Goettlicher, Karl H. Summer, Guido Kroemer

×

Figure 4

Oxidative damage in Atp7b–/– mitochondria occurs at a late disease stage.

Options: View larger image (or click on image) Download as PowerPoint
Oxidative damage in Atp7b–/– mitochondria occurs at a late disease stage...
(A) No early mitochondrial oxidative damage occurs at the level of the redox-sensitive mitochondrial aconitase in Atp7b–/– animals in comparison to control animals (the higher activity in the age group 60–61 days may be due to the younger animal age). Mitochondria from clinically apparent Atp7b–/– animals showed markedly lower activities. Mitochondria were isolated from controls (86–114 days, 4 measurements) and Atp7b–/– rats (60–61 days, 3 measurements; 81–89 days, 5 measurements; clinically apparent, 106–113 days, 2 measurements; D-PA–treated, 121–122 days, 4 measurements). (B) Unsaturated mitochondrial fatty acids are depleted only at a late stage of WD progression in Atp7b–/– rats. The major abundant fatty acids, accounting for 94% of the typical mitochondrial fatty acid composition (values from control mitochondria given in parentheses) are displayed. Fatty acids were isolated from mitochondria from Atp7b–/– animals at the ages of 60–61 days (n = 3), 72–73 days (n = 3), and 85–86 days (n = 3) and from clinically apparent Atp7b–/– animals at age 86–100 days (n = 8). Fatty acid amounts are given relative to values obtained from control mitochondria (n = 3) set to 100%. (C) Enzymatic activities in mitochondria isolated from controls (85–86 days, n = 6) were highly similar to activities in mitochondria from Atp7b–/– animals (88–89 days, n = 5) and only slightly altered in mitochondria from clinically apparent animals (92–99 days, n = 5). A significant decrease in activities occurs in mitochondria from the pellet fraction of clinically apparent animals (88–103 days, n = 3).*P < 0.05, **P < 0.01, ***P < 0.001.