Redirecting N-acetylaspartate metabolism in the central nervous system normalizes myelination and rescues Canavan disease
Dominic J. Gessler, Danning Li, Hongxia Xu, Qin Su, Julio Sanmiguel, Serafettin Tuncer, Constance Moore, Jean King, Reuben Matalon, Guangping Gao
Dominic J. Gessler, Danning Li, Hongxia Xu, Qin Su, Julio Sanmiguel, Serafettin Tuncer, Constance Moore, Jean King, Reuben Matalon, Guangping Gao
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Research Article Metabolism Therapeutics

Redirecting N-acetylaspartate metabolism in the central nervous system normalizes myelination and rescues Canavan disease

Abstract

Canavan disease (CD) is a debilitating and lethal leukodystrophy caused by mutations in the aspartoacylase (ASPA) gene and the resulting defect in N-acetylaspartate (NAA) metabolism in the CNS and peripheral tissues. Recombinant adeno-associated virus (rAAV) has the ability to cross the blood-brain barrier and widely transduce the CNS. We developed a rAAV-based and optimized gene replacement therapy, which achieves early, complete, and sustained rescue of the lethal disease phenotype in CD mice. Our treatment results in a super-mouse phenotype, increasing motor performance of treated CD mice beyond that of WT control mice. We demonstrate that this rescue is oligodendrocyte independent, and that gene correction in astrocytes is sufficient, suggesting that the establishment of an astrocyte-based alternative metabolic sink for NAA is a key mechanism for efficacious disease rescue and the super-mouse phenotype. Importantly, the use of clinically translatable high-field imaging tools enables the noninvasive monitoring and prediction of therapeutic outcomes for CD and might enable further investigation of NAA-related cognitive function.

Authors

Dominic J. Gessler, Danning Li, Hongxia Xu, Qin Su, Julio Sanmiguel, Serafettin Tuncer, Constance Moore, Jean King, Reuben Matalon, Guangping Gao

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Figure 1

Optimized gene expression cassette rescues normal ASPA protein and NAA levels in Canavan disease knockout (CD KO) mice.

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Optimized gene expression cassette rescues normal ASPA protein and NAA l...
(A) Three expression cassettes were cloned carrying either half (HKz) or full Kozak (FKz) sequence and the WT human aspartoacylase (hASPA) cDNA or a codon-optimized (Opt) hASPA. ITR, inverted terminal repeat. (B) Mice were treated at P1 via facial vein with 4 × 1011 genome copies of recombinant adeno-associated virus 9 (rAAV9) carrying a 1st, 2nd, or 3rd generation expression cassette. Western blotting of the brains 42 days after treatment shows relative ASPA expression normalized to actin and WT; due to early lethality, untreated CD KO mice were used at P25 as control (n = 3 each). (C) Cerebral N-acetylaspartate (NAA) levels of treated CD KO mice were quantified using magnetic resonance spectroscopy in living mice at P42; untreated CD KO mice were used at P25 as control (n = 3–4). Displayed are total NAA (tNAA) over total creatine (tCr). Statistical analysis was performed using 1-way ANOVA with multiple comparison correction. Data are presented as the mean ± SD, n = 3. *P < 0.05, **P < 0.01, ****P < 0.0001. ns, not significant.