ATP7A Gene Addition to the Choroid Plexus Results in Long-term Rescue of the Lethal Copper Transport Defect in a Menkes Disease Mouse Model

Abstract

Menkes disease is a lethal infantile neurodegenerative disorder of copper metabolism caused by mutations in a P-type ATPase, ATP7A. Currently available treatment (daily subcutaneous copper injections) is not entirely effective in the majority of affected individuals. The mottled-brindled (mo-br) mouse recapitulates the Menkes phenotype, including abnormal copper transport to the brain owing to mutation in the murine homolog, Atp7a, and dies by 14 days of age. We documented that mo-br mice on C57BL/6 background were not rescued by peripheral copper administration, and used this model to evaluate brain-directed therapies. Neonatal mo-br mice received lateral ventricle injections of either adeno-associated virus serotype 5 (AAV5) harboring a reduced-size human ATP7A (rsATP7A) complementary DNA (cDNA), copper chloride, or both. AAV5-rsATP7A showed selective transduction of choroid plexus epithelia and AAV5-rsATP7A plus copper combination treatment rescued mo-br mice; 86% survived to weaning (21 days), median survival increased to 43 days, 37% lived beyond 100 days, and 22% survived to the study end point (300 days). This synergistic treatment effect correlated with increased brain copper levels, enhanced activity of dopamine-β-hydroxylase, a copper-dependent enzyme, and correction of brain pathology. Our findings provide the first definitive evidence that gene therapy may have clinical utility in the treatment of Menkes disease.

Maternofetal and neonatal copper requirements revealed by enterocyte-specific deletion of the Menkes disease protein

“…This hierarchy of copper distribution preferential to the brain is also observed in Menkes disease patients with residual ATP7A activity who have minimal central nervous system pathology despite systemic copper deficiency (10). Although the precise mechanisms underlying this hierarchy remain unknown, observations in the developing zebrafish embryo suggest that as copper becomes limiting, tissues expressing higher levels of Atp7a are advantaged (22), a finding supported by recent studies demonstrating a critical role for expression of Atp7a in the choroid plexus in the preservation of neurological function in Menkes disease (4,5). Other studies have indicated that the copper-deficient brain is resistant to copper repletion in postweanling rats, arguing that the mechanisms of hierarchical copper allocation to the brain are functionally restricted to early neonatal development (26), a suggestion that is consistent with our observation that copper deficiency persisted in the …”

Varicella-zoster virus ORF7 interacts with ORF53 and plays a role in its trans-Golgi network localization

“…Firstly, we found that both ORF7 and ORF53 co-localized well with the TGN46 protein ( Figure 3A and 3B), which is widely used as a TGN marker in numerous studies (Barr et al, 2010;Donsante et al, 2011;Zhao et al, 2012;Charles et al, 2014;Nonnenmacher et al, 2015;Pillay et al, 2016). The Pearson's coefficients were 0.70 ± 0.09 and 0.68 ± 0.08 in the co-localized volume of TGN46 with ORF7 and ORF53, respectively (n = 10 in each group).…”

Inborn errors of copper metabolism

“…We recently rescued a mouse model of severe Menkes disease using combination brain-directed therapies: recombinant adeno-associated virus serotype 5 (AAV5) vector expressing a reduced size human ATP7A, plus copper chloride (Donsante et al, 2011). Neither treatment alone was effective, but combination therapy significantly enhanced survival.…”