The accumulation of enzymatically inactive cuproenzymes is a CNS-specific phenomenon of the SOD1G37R mouse model of ALS and can be restored by overexpressing the human copper transporter hCTR1

James B Hilton; Kai Kysenius; Anthony R White; Peter J Crouch

doi:10.1016/j.expneurol.2018.06.006

The accumulation of enzymatically inactive cuproenzymes is a CNS-specific phenomenon of the SOD1^G37R mouse model of ALS and can be restored by overexpressing the human copper transporter hCTR1

Exp Neurol. 2018 Sep:307:118-128. doi: 10.1016/j.expneurol.2018.06.006. Epub 2018 Jun 12.

Authors

James B Hilton¹, Kai Kysenius², Anthony R White³, Peter J Crouch²

Affiliations

¹ Department of Pharmacology and Therapeutics, the University of Melbourne, Victoria 3010, Australia. Electronic address: james.hilton@unimelb.edu.au.
² Department of Pharmacology and Therapeutics, the University of Melbourne, Victoria 3010, Australia; Florey Institute of Neuroscience and Mental Health, the University of Melbourne, Victoria 3010, Australia.
³ Cell and Molecular Biology, QIMR Berghofer Medical Research Institute, Queensland 4006, Australia.

PMID: 29906423
DOI: 10.1016/j.expneurol.2018.06.006

Abstract

Mutations to the copper-dependent enzyme Cu/Zn-superoxide dismutase (SOD1) cause amyotrophic lateral sclerosis (ALS) in humans, and transgenic overexpression of mutant SOD1 represents a robust murine model of the disease. We have previously shown that the copper-containing compound Cu^II(atsm) phenotypically improves mutant SOD1 mice and delivers copper to copper-deficient SOD1 in the CNS to restore its physiological function. Cu^II(atsm) is now in clinical trials for the treatment of ALS. In this study, we demonstrate that cuproenzyme dysfunction extends beyond SOD1 in SOD1^G37R mice to also affect the endogenous copper-dependent ferroxidase ceruloplasmin. We show that SOD1 and ceruloplasmin both accumulate progressively in the SOD1^G37R mouse spinal cord as the animals' ALS-like symptoms progress, yet the biochemical activity of the two cuproenzymes does not increase commensurately, indicating that, as per mutant SOD1, ceruloplasmin accumulates in a copper-deficient form. Consistent with this finding, we show that expression of the human copper transporter 1 (hCTR1) in SOD1^G37R mice increases copper levels in the spinal cord and concurrently restores SOD1 and ceruloplasmin activity. Soluble misfolded SOD1, a proposed driver of pathology in this model, is readily detectable in the SOD1^G37R mouse spinal cord. However, misfolded SOD1^G37R levels do not change in abundance with disease progression and are less abundant than misfolded SOD1 in the spinal cords of age-matched transgenic SOD1^WT mice which do not exhibit an evident ALS-like phenotype. Collectively, these outcomes support a copper malfunction phenomenon in mutant SOD1 mouse models of ALS and a copper-related mechanism of action for the therapeutic agent Cu^II(atsm).

Keywords: Amyotrophic lateral sclerosis (ALS); Ceruloplasmin; Copper; Copper transporter 1 (CTR1); Cytochrome c oxidase (CCO); Diacetyl-bis(4-methylthiosemicarbazonato)copper(II) [Cu(II)(atsm)]; Motor neurone disease; Mouse model; Neurodegeneration; Superoxide dismutase 1 (SOD1).

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Amyotrophic Lateral Sclerosis / genetics
Amyotrophic Lateral Sclerosis / metabolism*
Amyotrophic Lateral Sclerosis / pathology
Animals
Cation Transport Proteins / biosynthesis*
Cation Transport Proteins / genetics
Central Nervous System / metabolism
Central Nervous System / pathology
Copper Transporter 1
Disease Models, Animal*
Gene Expression
Humans
Mice
Mice, Inbred C57BL
Mice, Transgenic
Spinal Cord / metabolism
Spinal Cord / pathology
Superoxide Dismutase / biosynthesis*
Superoxide Dismutase / genetics

Substances

Cation Transport Proteins
Copper Transporter 1
SLC31A1 protein, human
SOD1 G37R protein, mouse
Superoxide Dismutase