Dataset Information

AAV-mediated gene delivery in adult GM1-gangliosidosis mice corrects lysosomal storage in CNS and improves survival.

ABSTRACT:

Background

GM1-gangliosidosis is a glycosphingolipid (GSL) lysosomal storage disease caused by a genetic deficiency of acid ?-galactosidase (?gal), which results in the accumulation of GM1-ganglioside and its asialo-form (GA1) primarily in the CNS. Age of onset ranges from infancy to adulthood, and excessive ganglioside accumulation produces progressive neurodegeneration and psychomotor retardation in humans. Currently, there are no effective therapies for the treatment of GM1-gangliosidosis.

Methodology/principal findings

In this study we examined the effect of thalamic infusion of AAV2/1-?gal vector in adult GM1 mice on enzyme distribution, activity, and GSL content in the CNS, motor behavior, and survival. Six to eight week-old GM1 mice received bilateral injections of AAV vector in the thalamus, or thalamus and deep cerebellar nuclei (DCN) with pre-determined endpoints at 1 and 4 months post-injection, and the humane endpoint, or 52 weeks of age. Enzyme activity was elevated throughout the CNS of AAV-treated GM1 mice and GSL storage nearly normalized in most structures analyzed, except in the spinal cord which showed ?50% reduction compared to age-matched untreated GM1 mice spinal cord. Survival was significantly longer in AAV-treated GM1 mice (52 wks) than in untreated mice. However the motor performance of AAV-treated GM1 mice declined over time at a rate similar to that observed in untreated GM1 mice.

Conclusions/significance

Our studies show that the AAV-modified thalamus can be used as a 'built-in' central node network for widespread distribution of lysosomal enzymes in the mouse cerebrum. In addition, this study indicates that thalamic delivery of AAV vectors should be combined with additional targets to supply the cerebellum and spinal cord with therapeutic levels of enzyme necessary to achieve complete correction of the neurological phenotype in GM1 mice.

SUBMITTER: Baek RC

PROVIDER: S-EPMC2956705 | biostudies-literature | 2010 Oct

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

AAV-mediated gene delivery in adult GM1-gangliosidosis mice corrects lysosomal storage in CNS and improves survival.

Baek Rena C RC Broekman Marike L D ML Leroy Stanley G SG Tierney Laryssa A LA Sandberg Michael A MA d'Azzo Alessandra A Seyfried Thomas N TN Sena-Esteves Miguel M

PloS one 20101018 10

<h4>Background</h4>GM1-gangliosidosis is a glycosphingolipid (GSL) lysosomal storage disease caused by a genetic deficiency of acid β-galactosidase (βgal), which results in the accumulation of GM1-ganglioside and its asialo-form (GA1) primarily in the CNS. Age of onset ranges from infancy to adulthood, and excessive ganglioside accumulation produces progressive neurodegeneration and psychomotor retardation in humans. Currently, there are no effective therapies for the treatment of GM1-gangliosid ...[more]

PMID: 20976108

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Project description:Introduction:GM1 gangliosidosis is a rare autosomal recessive genetic disorder caused by the disruption of the GLB1 gene that encodes ?-galactosidase, a lysosomal hydrolase that removes ?-linked galactose from the non-reducing end of glycans. Deficiency of this catabolic enzyme leads to the lysosomal accumulation of GM1 and its asialo derivative GA1 in ?-galactosidase deficient patients and animal models. In addition to GM1 and GA1, there are other glycoconjugates that contain ?-linked galactose whose metabolites are substrates for ?-galactosidase. For example, a number of N-linked glycan structures that have galactose at their non-reducing end have been shown to accumulate in GM1 gangliosidosis patient tissues and biological fluids. Objective:In this study, we attempt to fully characterize the broad array of GLB1 substrates that require GLB1 for their lysosomal turnover. Results:Using tandem mass spectrometry and glycan reductive isotope labeling with data-dependent mass spectrometry, we have confirmed the accumulation of glycolipids (GM1 and GA1) and N-linked glycans with terminal beta-linked galactose. We have also discovered a novel set of core 1 and 2 O-linked glycan metabolites, many of which are part of structurally-related isobaric series that accumulate in disease. In the brain of GLB1 null mice, the levels of these glycan metabolites increased along with those of both GM1 and GA1 as a function of age. In addition to brain tissue, we found elevated levels of both N-linked and O-linked glycan metabolites in a number of peripheral tissues and in urine. Both brain and urine samples from human GM1 gangliosidosis patients exhibited large increases in steady state levels for the same glycan metabolites, demonstrating their correlation with this disease in humans as well. Conclusions:Our studies illustrate that GLB1 deficiency is not purely a ganglioside accumulation disorder, but instead a broad oligosaccharidosis that include representatives of many ?-linked galactose containing glycans and glycoconjugates including glycolipids, N-linked glycans, and various O-linked glycans. Accounting for all ?-galactosidase substrates that accumulate when this enzyme is deficient increases our understanding of this severe disorder by identifying metabolites that may drive certain aspects of the disease and may also serve as informative disease biomarkers to fully evaluate the efficacy of future therapies.

Project description:Central nervous system (CNS) deficiencies of the monoamine neurotransmitters dopamine and serotonin have been implicated in the pathophysiology of neuropsychiatric dysfunction in human phenylketonuria (PKU). In this study, we confirmed the occurrence of brain dopamine and serotonin deficiencies in association with severe behavioral alterations and cognitive impairments in hyperphenylalaninemic C57BL/6-Pahenu2/enu2 mice, a model of human PKU. Phenylalanine-reducing treatments, including either dietary phenylalanine restriction or liver-directed gene therapy, initiated during adulthood were associated with increased brain monoamine content along with improvements in nesting behavior but without a change in the severe cognitive deficits exhibited by these mice. At euthanasia, there was in Pahenu2/enu2 brain a significant reduction in the protein abundance and maximally stimulated activities of tyrosine hydroxylase (TH) and tryptophan hydroxylase 2 (TPH2), the rate limiting enzymes catalyzing neuronal dopamine and serotonin synthesis respectively, in comparison to levels seen in wild type brain. Phenylalanine-reducing treatments initiated during adulthood did not affect brain TH or TPH2 content or maximal activity. Despite this apparent fixed deficit in striatal TH and TPH2 activities, initiation of phenylalanine-reducing treatments yielded substantial correction of brain monoamine neurotransmitter content, suggesting that phenylalanine-mediated competitive inhibition of already constitutively reduced TH and TPH2 activities is the primary cause of brain monoamine deficiency in Pahenu2 mouse brain. We propose that CNS monoamine deficiency may be the cause of the partially reversible adverse behavioral effects associated with chronic HPA in Pahenu2 mice, but that phenylalanine-reducing treatments initiated during adulthood are unable to correct the neuropathology and attendant cognitive deficits that develop during juvenile life in late-treated Pahenu2/enu2 mice.

Dataset Information

AAV-mediated gene delivery in adult GM1-gangliosidosis mice corrects lysosomal storage in CNS and improves survival.

Background

Methodology/principal findings

Conclusions/significance

Publications

AAV-mediated gene delivery in adult GM1-gangliosidosis mice corrects lysosomal storage in CNS and improves survival.

Similar Datasets

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