Search

Disrupted copper availability in the central nervous system (CNS) is implicated as a significant feature of the neurodegenerative disease amyotrophic lateral sclerosis (ALS). Solute carrier family 31 member 1 (Slc31a1; Ctr1) governs copper uptake in mammalian cells and mutations affecting Slc31a1 are associated with severe neurological abnormalities. Here, we examined the impact of decreased CNS copper caused by ubiquitous heterozygosity for functional Slc31a1 on spinal cord motor neurons in Slc31a1+/- mice. Congruent with the CNS being relatively susceptible to disrupted copper availability, brain and spinal cord tissue from Slc31a1+/- mice contained significantly less copper than wild-type littermates, even though copper levels in other tissues were unaffected. Slc31a1+/- mice had less spinal cord α-motor neurons compared to wild-type littermates, but they did not develop any overt physical signs of motor impairment. By contrast, ALS model SOD1G37R mice had fewer α-motor neurons than control mice and exhibited clear signs of motor function impairment. With the expression of Slc31a1 notwithstanding, spinal cord expression of genes related to copper handling revealed only minor differences between Slc31a1+/- and wild-type mice. This contrasted with SOD1G37R mice where changes in the expression of copper handling genes were pronounced. Similarly, the expression of genes related to toxic glial activation was unchanged in spinal cords from Slc31a1+/- mice but highly upregulated in SOD1G37R mice. Together, results from the Slc31a1+/- mice and SOD1G37R mice indicate that although depleted CNS copper has a significant impact on spinal cord motor neuron numbers, the manifestation of overt ALS-like motor impairment requires additional factors., (© The Author(s) 2024. Published by Oxford University Press.)

Demyelination within the central nervous system (CNS) is a significant feature of debilitating neurological diseases such as multiple sclerosis and administering the copper-selective chelatorcuprizone to mice is widely used to model demyelination in vivo. Conspicuous demyelination within the corpus callosum is generally attributed to cuprizone's ability to restrict copper availability in this vulnerable brain region. However, the small number of studies that have assessed copper in brain tissue from cuprizone-treated mice have produced seemingly conflicting outcomes, leaving the role of CNS copper availability in demyelination unresolved. Herein we describe our assessment of copper concentrations in brain samples from mice treated with cuprizone for 40 d. Importantly, we applied an inductively coupled plasma mass spectrometry methodology that enabled assessment of copper partitioned into soluble and insoluble fractions within distinct brain regions, including the corpus callosum. Our results show that cuprizone-induced demyelination in the corpus callosum was associated with decreased soluble copper in this brain region. Insoluble copper in the corpus callosum was unaffected, as were pools of soluble and insoluble copper in other brain regions. Treatment with the blood-brain barrier permeant copper compound CuII(atsm) increased brain copper levels and this was most pronounced in the soluble fraction of the corpus callosum. This effect was associated with significant mitigation of cuprizone-induced demyelination. These results provide support for the involvement of decreased CNS copper availability in demyelination in the cuprizone model. Relevance to human demyelinating disease is discussed., (© The Author(s) 2024. Published by Oxford University Press.)

Aberrant self-assembly and toxicity of wild-type and mutant superoxide dismutase 1 (SOD1) has been widely examined in silico, in vitro and in transgenic animal models of amyotrophic lateral sclerosis. Detailed examination of the protein in disease-affected tissues from amyotrophic lateral sclerosis patients, however, remains scarce. We used histological, biochemical and analytical techniques to profile alterations to SOD1 protein deposition, subcellular localization, maturation and post-translational modification in post-mortem spinal cord tissues from amyotrophic lateral sclerosis cases and controls. Tissues were dissected into ventral and dorsal spinal cord grey matter to assess the specificity of alterations within regions of motor neuron degeneration. We provide evidence of the mislocalization and accumulation of structurally disordered, immature SOD1 protein conformers in spinal cord motor neurons of SOD1-linked and non-SOD1-linked familial amyotrophic lateral sclerosis cases, and sporadic amyotrophic lateral sclerosis cases, compared with control motor neurons. These changes were collectively associated with instability and mismetallation of enzymatically active SOD1 dimers, as well as alterations to SOD1 post-translational modifications and molecular chaperones governing SOD1 maturation. Atypical changes to SOD1 protein were largely restricted to regions of neurodegeneration in amyotrophic lateral sclerosis cases, and clearly differentiated all forms of amyotrophic lateral sclerosis from controls. Substantial heterogeneity in the presence of these changes was also observed between amyotrophic lateral sclerosis cases. Our data demonstrate that varying forms of SOD1 proteinopathy are a common feature of all forms of amyotrophic lateral sclerosis, and support the presence of one or more convergent biochemical pathways leading to SOD1 proteinopathy in amyotrophic lateral sclerosis. Most of these alterations are specific to regions of neurodegeneration, and may therefore constitute valid targets for therapeutic development., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Guarantors of Brain.)

Study Objectives: Evaluate serum and brain noniron metals in the pathology and genetics of restless legs syndrome (RLS)., Methods: In two independent studies (cohorts 1 and 2), in which subjects either remained on medications or tapered off medications, we analyzed serum levels of iron, calcium, magnesium, manganese, copper, and zinc both in RLS patients and controls, and assessed the prevalence of the MEIS1 and BTBD9 risk alleles previously established through genome-wide association studies. Human brain sections and a nematode genetic model were also quantified for metal levels using mass spectrometry., Results: We found a significant enrichment for the BTBD9 risk genotype in the RLS affected group compared to control (p = 0.0252), consistent with previous literature. Serum (p = 0.0458 and p = 0.0139 for study cohorts 1 and 2, respectively) and brain (p = 0.0413) zinc levels were significantly elevated in the RLS patients versus control subjects., Conclusion: We show for the first time that serum and brain levels of zinc are elevated in RLS. Further, we confirm the BTBD9 genetic risk factor in a new population, although the zinc changes were not significantly associated with risk genotypes. Zinc and iron homeostasis are interrelated, and zinc biology impacts neurotransmitter systems previously linked to RLS. Given the modest albeit statistically significant increase in serum zinc of ~20%, and the lack of association with two known genetic risk factors, zinc may not represent a primary etiology for the syndrome. Further investigation into the pathogenetic role that zinc may play in restless legs syndrome is needed., (© Sleep Research Society 2020. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.)

Mutations in the copper (Cu)- and zinc (Zn)-binding metalloenzyme Cu/Zn-superoxide dismutase (SOD1) cause familial forms of amyotrophic lateral sclerosis (ALS), a fatal adult-onset neurodegenerative disorder of the central nervous system (CNS). Transgenic over-expression of mutant SOD1 produces a robust ALS-like phenotype in mice. Despite being ubiquitously expressed from the moment of conception, the mechanisms underlying the CNS-selective phenotype of mutant SOD1 expression remain poorly understood. We have previously shown that the physiological requirement for copper in SOD1 is unsatiated in the CNS of adult mice overexpressing mutant SOD1 and that suboptimal delivery of Cu to SOD1 in these mice progressively worsens with age. An age-related impediment to Cu availability may therefore contribute to the adult onset of disease in cases of ALS caused by mutant SOD1. Here, we have extended the age-related investigation of Cu in SOD1 overexpressing transgenic mice to the embryonic stage of development. We used the quantitative in situ elemental imaging method, laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), to assess the endogenous distribution of Cu, Zn and other endogenous elements (carbon, phosphorus, sulphur, magnesium, manganese and iron) in the embryonic day 14 (E14) embryos of transgenic mice overexpressing wild-type human SOD1 (hSOD1Wt) or mutant human SOD1 (hSOD1G37R). We show that in contrast to adult mice, SOD1 overexpression (both wild-type and mutant) is associated with an overt redistribution of Cu from the liver to the CNS during embryonic development. Also in contrast to adult mice, Zn redistribution to the CNS in response to SOD1 over-expression is relatively modest in embryonic mice, being limited to the brainstem. No other elemental changes between genotypes were observed. Our application of quantitative LA-ICP-MS in situ imaging details the first anatomical mapping of endogenous elements in embryonic mice. The observed redistribution of Cu from the liver to the CNS in response to SOD1 overexpression during embryogenesis indicates that the impediment of Cu delivery to SOD1, which is evident in adult mutant SOD1 overexpressing mice, only occurs at a later stage in life.