g(m2)-ganglioside and Disease-Models--Animal

Paediatric neurodegenerative diseases are frequently caused by inborn errors in glycosphingolipid (GSL) catabolism and are collectively termed the glycosphingolipidoses. GSL catabolism occurs in the lysosome and a defect in an enzyme involved in GSL degradation leads to the lysosomal storage of its substrate(s). GSLs are abundantly expressed in the central nervous system (CNS) and the disorders frequently have a progressive neurodegenerative course. Our understanding of pathogenesis in these diseases is incomplete and currently few options exist for therapy. In this review we discuss how mouse models of these disorders are providing insights into pathogenesis and also leading to progress in evaluating experimental therapies.

Topics: 1-Deoxynojirimycin; Animals; Bone Marrow Transplantation; Chemotherapy, Adjuvant; Disease Models, Animal; G(M2) Ganglioside; Gangliosides; Glucosylceramides; Glucosyltransferases; Glycosphingolipids; Humans; Lysosomal Storage Diseases; Lysosomes; Mice; Models, Biological; Models, Chemical; Morpholines; Sandhoff Disease; Tay-Sachs Disease; Treatment Outcome

The hydrolysis of GM2-ganglioside is unusual in its requirements for the correct synthesis, processing, and ultimate combination of three gene products. Whereas two of these proteins are the alpha- (HEXA gene) and beta- (HEXB) subunits of beta-hexosaminidase A, the third is a small glycolipid transport protein, the GM2 activator protein (GM2A), which acts as a substrate specific co-factor for the enzyme. A deficiency of any one of these proteins leads to storage of the ganglioside, primarily in the lysosomes of neuronal cells, and one of the three forms of GM2-gangliosidosis, Tay-Sachs disease, Sandhoff disease or the AB-variant form. Studies of the biochemical impact of naturally occurring mutations associated with the GM2 gangliosidoses on mRNA splicing and stability, and on the intracellular transport and stability of the affected protein have provided some general insights into these complex cellular mechanisms. However, such studies have revealed little in the way of structure-function information on the proteins. It appears that the detrimental effect of most mutations is not specifically on functional elements of the protein, but rather on the proteins' overall folding and/or intracellular transport. The few exceptions to this generalization are missense mutations at two codons in HEXA, causing the unique biochemical phenotype known as the B1-variant, and one codon in both the HEXB and GM2A genes. Biochemical characterization of these mutations has led to the localization of functional residues and/or domains within each of the encoded proteins.

Topics: Amino Acid Sequence; Animals; Bacterial Proteins; beta-Hexosaminidase beta Chain; beta-N-Acetylhexosaminidases; Carbohydrate Sequence; Disease Models, Animal; DNA-Binding Proteins; G(M2) Activator Protein; G(M2) Ganglioside; Gene Deletion; Hexosaminidase A; Hexosaminidase B; Humans; Isoenzymes; Molecular Sequence Data; Mutation; Mutation, Missense; Phenotype; Proteins; RNA Splicing; Sandhoff Disease; Tay-Sachs Disease

The GM2 gangliosidoses are a group of heritable neurodegenerative disorders caused by excessive accumulation of the ganglioside GM2 owing to deficiency in beta-hexosaminidase activity. Tay-Sachs and Sandhoff diseases have similar clinical phenotypes resulting from a deficiency in human hexosaminidase alpha and beta subunits, respectively. The lack of treatment for GM2 gangliosidoses stimulated interest in developing animal models to understand the molecular mechanisms underlying the various forms of this disease and to test new potential therapies. In this review, we discuss the molecular biology of GM2 gangliosidoses and the different strategies that have been tested in animal models for the treatment of this genetic disorder, including gene transfer and cell engraftment of neural stem cells engineered to express the hexosaminidase isoenzymes.

Topics: 1-Deoxynojirimycin; Adolescent; Adult; Animals; beta-N-Acetylhexosaminidases; Bone Marrow Transplantation; Cats; Cell Transplantation; Child; Disease Models, Animal; Dogs; G(M2) Ganglioside; Genetic Therapy; Genetic Vectors; Glycolipids; HIV; Humans; Infant; Lysosomes; Mice; Mice, Knockout; Neurons; Phenotype; Point Mutation; Rats; Sandhoff Disease; Swine; Tay-Sachs Disease; Transplantation, Homologous

Tay-Sachs disease and Sandhoff disease are severe neurodegenerative disorders caused by a deficiency of beta-hexosaminidase A and resultant accumulation of its substrate, GM2 ganglioside, in neuronal lysosomes. The three clinical forms of the disorders (infantile, juvenile and adult) are of varying severity and onset, and have been correlated with the amount of residual GM2 ganglioside-degrading activity present in patients' cells. Through targeted disruption of the murine beta-hexosaminidase genes in embryonic stem cells, we have developed a set of mice that vary in their GM2 ganglioside-degrading capacity and exhibit many of the clinical features of the human diseases. These mice are valuable for the study of pathogenic mechanisms and for devising novel therapeutic strategies in these disorders.

Topics: Adult; Animals; beta-N-Acetylhexosaminidases; Child; Disease Models, Animal; G(M2) Ganglioside; Gangliosidoses; Gene Targeting; Humans; Infant; Lysosomes; Mice; Neurons; Sandhoff Disease; Stem Cells; Tay-Sachs Disease

Topics: Animals; Cats; Cattle; Disease Models, Animal; Dogs; G(M2) Ganglioside; Gangliosidoses; Gaucher Disease; Glycogen; Glycogen Storage Disease Type II; Glycopeptides; Humans; Leukodystrophy, Globoid Cell; Leukodystrophy, Metachromatic; Lipidoses; Lysosomes; Mannosidases; Metabolism, Inborn Errors; Mice; Niemann-Pick Diseases; Rabbits; Sphingolipids

Tay-Sachs disease is a lethal lysosomal storage disorder caused by mutations in the HexA gene encoding the α subunit of the lysosomal β-hexosaminidase enzyme (HEXA). Abnormal GM2 ganglioside accumulation causes progressive deterioration in the central nervous system in Tay-Sachs patients. Hexa-/- mouse model failed to display abnormal phenotype. Recently, our group generated Hexa-/-Neu3-/- mouse showed severe neuropathological indications similar to Tay-Sachs patients. Despite excessive GM2 ganglioside accumulation in the brain and visceral organs, the regulation of autophagy has not been clarified yet in the Tay-Sachs disease mouse model. Therefore, we investigated distinct steps of autophagic flux using markers including LC3 and p62 in four different brain regions from the Hexa-/-Neu3-/- mice model of Tay-Sachs disease. Our data revealed accumulated autophagosomes and autophagolysosomes indicating impairment in autophagic flux in the brain. We suggest that autophagy might be a new therapeutic target for the treatment of devastating Tay-Sachs disease.

Topics: Animals; Autophagy; beta-N-Acetylhexosaminidases; Brain; Disease Models, Animal; G(M2) Ganglioside; Hexosaminidase A; Mice; Tay-Sachs Disease

GM2 gangliosidosis disorders are a group of neurodegenerative diseases that result from a functional deficiency of the enzyme β-hexosaminidase A (HexA). HexA consists of an α- and β-subunit; a deficiency in either subunit results in Tay-Sachs Disease (TSD) or Sandhoff Disease (SD), respectively. Viral vector gene transfer is viewed as a potential method of treating these diseases. A recently constructed isoenzyme to HexA, called HexM, has the ability to effectively catabolize GM2 gangliosides in vivo. Previous gene transfer studies have revealed that the scAAV9-

Topics: Animals; beta-Hexosaminidase alpha Chain; Dependovirus; Disease Models, Animal; Female; G(M2) Ganglioside; Genetic Therapy; Genetic Vectors; Humans; Immunity; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Sandhoff Disease; Tay-Sachs Disease

Topics: Age of Onset; Animals; beta-Hexosaminidase alpha Chain; beta-Hexosaminidase beta Chain; Cerebellum; Disease Models, Animal; Enzyme Replacement Therapy; G(M2) Ganglioside; Gangliosidoses, GM2; Genetic Therapy; Glucosyltransferases; Glycoside Hydrolase Inhibitors; Gray Matter; Humans; Mutation; Retina; Spinal Cord; White Matter

The GM2 gangliosidoses, Tay-Sachs disease (TSD) and Sandhoff disease (SD), are fatal lysosomal storage disorders caused by mutations in the HEXA and HEXB genes, respectively. These mutations cause dysfunction of the lysosomal enzyme β-N-acetylhexosaminidase A (HexA) and accumulation of GM2 ganglioside (GM2) with ensuing neurodegeneration, and death by 5 years of age. Until recently, the most successful therapy was achieved by intracranial co-delivery of monocistronic adeno-associated viral (AAV) vectors encoding Hex alpha and beta-subunits in animal models of SD. The blood-brain barrier crossing properties of AAV9 enables systemic gene therapy; however, the requirement of co-delivery of two monocistronic AAV vectors to overexpress the heterodimeric HexA protein has prevented the use of this approach. To address this need, we developed multiple AAV constructs encoding simultaneously HEXA and HEXB using AAV9 and AAV-PHP.B and tested their therapeutic efficacy in 4- to 6-week-old SD mice after systemic administration. Survival and biochemical outcomes revealed superiority of the AAV vector design using a bidirectional CBA promoter with equivalent dose-dependent outcomes for both capsids. AAV-treated mice performed normally in tests of motor function, CNS GM2 ganglioside levels were significantly reduced, and survival increased by >4-fold with some animals surviving past 2 years of age.

Topics: Animals; beta-N-Acetylhexosaminidases; Dependovirus; Disease Management; Disease Models, Animal; G(M2) Ganglioside; Gene Expression; Genetic Predisposition to Disease; Genetic Therapy; Genetic Vectors; Mice; Mutation; Sandhoff Disease; Tay-Sachs Disease; Transgenes

Tay-Sachs disease (TSD), a type of GM2-gangliosidosis, is a progressive neurodegenerative lysosomal storage disorder caused by mutations in the α subunit of the lysosomal β-hexosaminidase enzyme. This disease is characterized by excessive accumulation of GM2 ganglioside, predominantly in the central nervous system. Although Tay-Sachs patients appear normal at birth, the progressive accumulation of undegraded GM2 gangliosides in neurons leads to death. Recently, an early onset Tay-Sachs disease mouse model, with genotype Hexa-/-Neu3-/-, was generated. Progressive accumulation of GM2 led to premature death of the double KO mice. Importantly, this double-deficient mouse model displays typical features of Tay-Sachs patients, such as cytoplasmic vacuolization of nerve cells, deterioration of Purkinje cells, neuronal death, deceleration in movement, ataxia, and tremors. GM2-gangliosidosis is characterized by acute neurodegeneration preceded by activated microglia expansion, macrophage, and astrocyte activation, along with the production of inflammatory mediators. However, the mechanism of disease progression in Hexa-/-Neu3-/- mice, relevant to neuroinflammation is poorly understood.. In this study, we investigated the onset and progression of neuroinflammatory changes in the cortex, cerebellum, and retina of Hexa-/-Neu3-/- mice and control littermates by using a combination of molecular genetics and immunochemical procedures.. We found elevated levels of pro-inflammatory cytokine and chemokine transcripts, such as Ccl2, Ccl3, Ccl4, and Cxcl10 and also extensive microglial and astrocyte activation and proliferation, accompanied by peripheral blood mononuclear cell infiltration in the vicinity of neurons and oligodendrocytes. Behavioral tests demonstrated a high level of anxiety, and age-dependent loss in both spatial learning and fear memory in Hexa-/-Neu3-/- mice compared with that in the controls.. Altogether, our data suggest that Hexa-/-Neu3-/- mice display a phenotype similar to Tay-Sachs patients suffering from chronic neuroinflammation triggered by GM2 accumulation. Furthermore, our work contributes to better understanding of the neuropathology in a mouse model of early onset Tay-Sachs disease.

Topics: Animals; Brain; Disease Models, Animal; G(M2) Ganglioside; Inflammation Mediators; Leukocytes, Mononuclear; Mice; Mice, 129 Strain; Mice, Inbred C57BL; Mice, Knockout; Neurons; Retina; Tay-Sachs Disease

Sandhoff disease (SD) is a rare inherited disorder caused by a deficiency of β-hexosaminidase activity which is fatal because no effective treatment is available. A mouse model of Hexb deficiency reproduces the key pathognomonic features of SD patients with severe ubiquitous lysosomal dysfunction, GM2 accumulation, neuroinflammation and neurodegeneration, culminating in death at 4 months. Here, we show that a single intravenous neonatal administration of a self-complementary adeno-associated virus 9 vector (scAAV9) expressing the Hexb cDNA in SD mice is safe and sufficient to prevent disease development. Importantly, we demonstrate for the first time that this treatment results in a normal lifespan (over 700 days) and normalizes motor function assessed by a battery of behavioral tests, with scAAV9-treated SD mice being indistinguishable from wild-type littermates. Biochemical analyses in multiple tissues showed a significant increase in hexosaminidase A activity, which reached 10-15% of normal levels. AAV9 treatment was sufficient to prevent GM2 and GA2 storage almost completely in the cerebrum (less so in the cerebellum), as well as thalamic reactive gliosis and thalamocortical neuron loss in treated Hexb-/- mice. In summary, this study demonstrated a widespread protective effect throughout the entire CNS after a single intravenous administration of the scAAV9-Hexb vector to neonatal SD mice.

Topics: Administration, Intravenous; Animals; Animals, Newborn; Brain; Disease Models, Animal; Female; G(M2) Ganglioside; Gangliosides; Hexosaminidase B; Male; Mice; Mice, Inbred C57BL; Sandhoff Disease

An efficient method was developed for the synthesis of a GM2 derivative suitable for the conjugation with various biomolecules. This GM2 derivative was covalently linked to keyhole limpet hemocyanin (KLH) and monophosphoryl lipid A (MPLA) to form novel therapeutic cancer vaccines. Immunological evaluations of the resultant conjugates in mice revealed that they elicited robust GM2-specific overall and IgG antibody responses. Moreover, the GM2-MPLA conjugate was disclosed to elicit strong immune responses without the use of an adjuvant, proving its self-adjuvant property. The antisera of both conjugates showed strong binding and mediated similarly effective complement-dependent cytotoxicity to GM2-expressing cancer cell line MCF-7. Based on these results, it was concluded that both GM2-MPLA and GM2-KLH are promising candidates as therapeutic cancer vaccines, whereas fully synthetic GM2-MPLA, which has homogeneous and well-defined structure and self-adjuvant property, deserves more attention and studies.

Topics: Adjuvants, Immunologic; Animals; Antibody-Dependent Cell Cytotoxicity; Cancer Vaccines; Complement System Proteins; Disease Models, Animal; Female; G(M2) Ganglioside; Lipid A; Mice; Molecular Structure; Neoplasms; Vaccines, Synthetic; Xenograft Model Antitumor Assays

Sandhoff disease (SD) is caused by the loss of β-hexosaminidase (Hex) enzymatic activity in lysosomes resulting from Hexb mutations. In SD patients, the Hex substrate GM2 ganglioside accumulates abnormally in neuronal cells, resulting in neuronal loss, microglial activation, and astrogliosis. Hexb

Topics: Animals; Astrocytes; beta-Hexosaminidase beta Chain; Cerebral Cortex; Disease Models, Animal; Fingolimod Hydrochloride; G(M2) Ganglioside; Gliosis; Heterozygote; Immunity; Immunosuppressive Agents; Mice, Inbred C57BL; Motor Activity; Phenotype; Receptors, Fc; Sandhoff Disease; Up-Regulation; Walking

Christianson syndrome (CS) is an X-linked neurodevelopmental and neurological disorder characterized in males by core symptoms that include non-verbal status, intellectual disability, epilepsy, truncal ataxia, postnatal microcephaly and hyperkinesis. CS is caused by mutations in the SLC9A6 gene, which encodes a multipass transmembrane sodium (potassium)-hydrogen exchanger 6 (NHE6) protein, functional in early recycling endosomes. The extent and variability of the CS phenotype in female heterozygotes, who presumably express the wild-type and mutant SLC9A6 alleles mosaically as a result of X-chromosome inactivation (XCI), have not yet been systematically characterized. Slc9a6 knockout mice (Slc9a6 KO) were generated by insertion of the bacterial lacZ/β-galactosidase (β-Gal) reporter into exon 6 of the X-linked gene. Mutant Slc9a6 KO male mice have been shown to develop late endosomal/lysosomal dysfunction associated with glycolipid accumulation in selected neuronal populations and patterned degeneration of Purkinje cells (PCs). In heterozygous female Slc9a6 KO mice, β-Gal serves as a transcriptional/XCI reporter and thus facilitates testing of effects of mosaic expression of the mutant allele on penetrance of the abnormal phenotype. Using β-Gal, we demonstrated mosaic expression of the mutant Slc9a6 allele and mosaically distributed lysosomal glycolipid accumulation and PC pathology in the brains of heterozygous Slc9a6 KO female mice. At the behavioral level, we showed that heterozygous female mice suffer from visuospatial memory and motor coordination deficits similar to but less severe than those observed in X-chromosome hemizygous mutant males. Our studies in heterozygous Slc9a6 KO female mice provide important clues for understanding the likely phenotypic range of Christianson syndrome among females heterozygous for SLC9A6 mutations and might improve diagnostic practice and genetic counseling by helping to characterize this presumably underappreciated patient/carrier group.

Topics: Alleles; Animals; Ataxia; Behavior, Animal; Cognition Disorders; Disease Models, Animal; Epilepsy; Female; G(M2) Ganglioside; Genetic Diseases, X-Linked; Genotype; Heterozygote; Intellectual Disability; Male; Mice; Mice, Knockout; Microcephaly; Mosaicism; Mutation; Ocular Motility Disorders; Phenotype; Purkinje Cells; Sodium-Hydrogen Exchangers

GM2 gangliosidosis is a family of three genetic neurodegenerative disorders caused by the accumulation of GM2 ganglioside (GM2) in neuronal tissue. Two of these are due to the deficiency of the heterodimeric (α-β), "A" isoenzyme of lysosomal β-hexosaminidase (HexA). Mutations in the α-subunit (encoded by HEXA) lead to Tay-Sachs disease (TSD), whereas mutations in the β-subunit (encoded by HEXB) lead to Sandhoff disease (SD). The third form results from a deficiency of the GM2 activator protein (GM2AP), a substrate-specific cofactor for HexA. In their infantile, acute forms, these diseases rapidly progress with mental and psychomotor deterioration resulting in death by approximately 4 years of age. After gene transfer that overexpresses one of the deficient subunits, the amount of HexA heterodimer formed would empirically be limited by the availability of the other endogenous Hex subunit. The present study used a new variant of the human HexA α-subunit, μ, incorporating critical sequences from the β-subunit that produce a stable homodimer (HexM) and promote functional interactions with the GM2AP- GM2 complex. We report the design of a compact adeno-associated viral (AAV) genome using a synthetic promoter-intron combination to allow self-complementary (sc) packaging of the HEXM gene. Also, a previously published capsid mutant, AAV9.47, was used to deliver the gene to brain and spinal cord while having restricted biodistribution to the liver. The novel capsid and cassette design combination was characterized in vivo in TSD mice for its ability to efficiently transduce cells in the central nervous system when delivered intravenously in both adult and neonatal mice. This study demonstrates that the modified HexM is capable of degrading long-standing GM2 storage in mice, and it further demonstrates the potential of this novel scAAV vector design to facilitate widespread distribution of the HEXM gene or potentially other similar-sized genes to the nervous system.

Topics: Animals; Animals, Newborn; Dependovirus; Disease Models, Animal; Female; G(M2) Ganglioside; Genetic Therapy; Genetic Vectors; Hexosaminidases; Liver; Mice; Mice, Inbred C57BL; Mutation; Tay-Sachs Disease

Fucosidosis is a rare lysosomal storage disorder caused by the inherited deficiency of the lysosomal hydrolase α-L-fucosidase, which leads to an impaired degradation of fucosylated glycoconjugates. Here, we report the generation of a fucosidosis mouse model, in which the gene for lysosomal α-L-fucosidase (Fuca1) was disrupted by gene targeting. Homozygous knockout mice completely lack α-L-fucosidase activity in all tested organs leading to highly elevated amounts of the core-fucosylated glycoasparagine Fuc(α1,6)-GlcNAc(β1-N)-Asn and, to a lesser extent, other fucosylated glycoasparagines, which all were also partially excreted in urine. Lysosomal storage pathology was observed in many visceral organs, such as in the liver, kidney, spleen and bladder, as well as in the central nervous system (CNS). On the cellular level, storage was characterized by membrane-limited cytoplasmic vacuoles primarily containing water-soluble storage material. In the CNS, cellular alterations included enlargement of the lysosomal compartment in various cell types, accumulation of secondary storage material and neuroinflammation, as well as a progressive loss of Purkinje cells combined with astrogliosis leading to psychomotor and memory deficits. Our results demonstrate that this new fucosidosis mouse model resembles the human disease and thus will help to unravel underlying pathological processes. Moreover, this model could be utilized to establish diagnostic and therapeutic strategies for fucosidosis.

Topics: alpha-L-Fucosidase; Animals; Behavior, Animal; Brain; Disease Models, Animal; Enzyme Activation; Fucose; Fucosidosis; G(M2) Ganglioside; Glycoconjugates; Glycoproteins; Humans; Inflammation; Lysosomes; Mice, Inbred C57BL; Organ Specificity; Proteolysis; Purkinje Cells; Viscera

G(M2) gangliosidoses are severe neurodegenerative disorders resulting from a deficiency in β-hexosaminidase A activity and lacking effective therapies. Using a Sandhoff disease (SD) mouse model (Hexb(-/-)) of the G(M2) gangliosidoses, we tested the potential of systemically delivered adeno-associated virus 9 (AAV9) expressing Hexb cDNA to correct the neurological phenotype. Neonatal or adult SD and normal mice were intravenously injected with AAV9-HexB or -LacZ and monitored for serum β-hexosaminidase activity, motor function, and survival. Brain G(M2) ganglioside, β-hexosaminidase activity, and inflammation were assessed at experimental week 43, or an earlier humane end point. SD mice injected with AAV9-LacZ died by 17 weeks of age, whereas all neonatal AAV9-HexB-treated SD mice survived until 43 weeks (P < 0.0001) with only three exhibiting neurological dysfunction. SD mice treated as adults with AAV9-HexB died between 17 and 35 weeks. Neonatal SD-HexB-treated mice had a significant increase in brain β-hexosaminidase activity, and a reduction in G(M2) ganglioside storage and neuroinflammation compared to adult SD-HexB- and SD-LacZ-treated groups. However, at 43 weeks, 8 of 10 neonatal-HexB injected control and SD mice exhibited liver or lung tumors. This study demonstrates the potential for long-term correction of SD and other G(M2) gangliosidoses through early rAAV9 based systemic gene therapy.

Topics: Age Factors; Animals; Animals, Newborn; beta-Hexosaminidase beta Chain; Brain; Dependovirus; Disease Models, Animal; Female; G(M2) Ganglioside; Gene Expression; Genetic Therapy; Genetic Vectors; Inflammation; Injections, Intravenous; Lac Operon; Liver Neoplasms; Lung Neoplasms; Lysosomes; Male; Mice; Mice, Knockout; Motor Activity; Sandhoff Disease; Survival Analysis

Receptors expressed on the host cell surface adhere viruses to target cells and serve as determinants of viral tropism. Several viruses bind cell surface glycans to facilitate entry, but the contribution of specific glycan moieties to viral disease is incompletely understood. Reovirus provides a tractable experimental model for studies of viral neuropathogenesis. In newborn mice, serotype 1 (T1) reovirus causes hydrocephalus, whereas serotype 3 (T3) reovirus causes encephalitis. T1 and T3 reoviruses engage distinct glycans, suggesting that glycan-binding capacity contributes to these differences in pathogenesis. Using structure-guided mutagenesis, we engineered a mutant T1 reovirus incapable of binding the T1 reovirus-specific glycan receptor, GM2. The mutant virus induced substantially less hydrocephalus than wild-type virus, an effect phenocopied by wild-type virus infection of GM2-deficient mice. In comparison to wild-type virus, yields of mutant virus were diminished in cultured ependymal cells, the cell type that lines the brain ventricles. These findings suggest that GM2 engagement targets reovirus to ependymal cells in mice and illuminate the function of glycan engagement in reovirus serotype-dependent disease.. Receptor utilization strongly influences viral disease, often dictating host range and target cell selection. Different reovirus serotypes bind to different glycans, but a precise function for these molecules in pathogenesis is unknown. We used type 1 (T1) reovirus deficient in binding the GM2 glycan and mice lacking GM2 to pinpoint a role for glycan engagement in hydrocephalus caused by T1 reovirus. This work indicates that engagement of a specific glycan can lead to infection of specific cells in the host and consequent disease at that site. Since reovirus is being developed as a vaccine vector and oncolytic agent, understanding reovirus-glycan interactions may allow manipulation of reovirus glycan-binding properties for therapeutic applications.

Topics: Animals; Animals, Newborn; Cells, Cultured; Disease Models, Animal; G(M2) Ganglioside; Hydrocephalus; Mice; Receptors, Virus; Reoviridae; Reoviridae Infections; Serogroup; Virus Attachment

The GM2 gangliosidoses are progressive neurodegenerative disorders due to defects in the lysosomal β-N-acetylhexosaminidase system. Accumulation of β-hexosaminidases A and B substrates is presumed to cause this fatal condition. An authentic mouse model of Sandhoff disease (SD) with pathological characteristics resembling those noted in infantile GM2 gangliosidosis has been described. We have shown that expression of β-hexosaminidase by intracranial delivery of recombinant adeno-associated viral vectors to young adult SD mice can prevent many features of the disease and extends lifespan. To investigate the nature of the neurological injury in GM2 gangliosidosis and the extent of its reversibility, we have examined the evolution of disease in the SD mouse; we have moreover explored the effects of gene transfer delivered at key times during the course of the illness. Here we report greatly increased survival only when the therapeutic genes are expressed either before the disease is apparent or during its early manifestations. However, irrespective of when treatment was administered, widespread and abundant expression of β-hexosaminidase with consequent clearance of glycoconjugates, α-synuclein and ubiquitinated proteins, and abrogation of inflammatory responses and neuronal loss was observed. We also show that defects in myelination occur in early life and cannot be easily resolved when treatment is given to the adult brain. These results indicate that there is a limited temporal opportunity in which function and survival can be improved-but regardless of resolution of the cardinal pathological features of GM2 gangliosidosis, a point is reached when functional deterioration and death cannot be prevented.

Topics: alpha-Synuclein; Animals; beta-N-Acetylhexosaminidases; Brain; Dependovirus; Disease Models, Animal; G(M2) Ganglioside; Genetic Therapy; Genetic Vectors; Humans; Injections, Intralesional; Mice; Mice, Knockout; Mice, Transgenic; Sandhoff Disease; Tay-Sachs Disease; Ubiquitin

Explosive detonations generate atmospheric pressure changes that produce nonpenetrating blast induced "mild" traumatic brain injury (bTBI). The structural basis for mild bTBI has been extremely controversial. The present study applies matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging to track the distribution of gangliosides in mouse brain tissue that were exposed to very low level of explosive detonations (2.5-5.5 psi peak overpressure). We observed major increases of the ganglioside GM2 in the hippocampus, thalamus, and hypothalamus after a single blast exposure. Moreover, these changes were accompanied by depletion of ceramides. No neurological or brain structural signs of injury could be inferred using standard light microscopic techniques. The first source of variability is generated by the Latency between blast and tissue sampling (peak intensity of the blast wave). These findings suggest that subtle molecular changes in intracellular membranes and plasmalemma compartments may be biomarkers for biological responses to mild bTBI. This is also the first report of a GM2 increase in the brains of mature mice from a nongenetic etiology.

Topics: Animals; Blast Injuries; Brain Injuries; Ceramides; Disease Models, Animal; G(M2) Ganglioside; Gangliosides; Male; Mice; Mice, Inbred ICR; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization

Mucopolysaccharide diseases (MPS) are caused by deficiency of glycosaminoglycan (GAG) degrading enzymes, leading to GAG accumulation. Neurodegenerative MPS diseases exhibit cognitive decline, behavioural problems and shortened lifespan. We have characterised neuropathological changes in mouse models of MPSI, IIIA and IIIB to provide a better understanding of these events.Wild-type (WT), MPSI, IIIA and IIIB mouse brains were analysed at 4 and 9 months of age. Quantitative immunohistochemistry showed significantly increased lysosomal compartment, GM2 ganglioside storage, neuroinflammation, decreased and mislocalised synaptic vesicle associated membrane protein, (VAMP2), and decreased post-synaptic protein, Homer-1, in layers II/III-VI of the primary motor, somatosensory and parietal cortex. Total heparan sulphate (HS), was significantly elevated, and abnormally N-, 6-O and 2-O sulphated compared to WT, potentially altering HS-dependent cellular functions. Neuroinflammation was confirmed by significantly increased MCP-1, MIP-1α, IL-1α, using cytometric bead arrays. An overall genotype effect was seen in all parameters tested except for synaptophysin staining, neuronal cell number and cortical thickness which were not significantly different from WT. MPSIIIA and IIIB showed significantly more pronounced pathology than MPSI in lysosomal storage, astrocytosis, microgliosis and the percentage of 2-O sulphation of HS. We also observed significant time progression of all genotypes from 4-9 months in lysosomal storage, astrocytosis, microgliosis and synaptic disorganisation but not GM2 gangliosidosis. Individual genotype*time differences were disparate, with significant progression from 4 to 9 months only seen for MPSIIIB with lysosomal storage, MPSI with astrocytocis and MPSIIIA with microgliosis as well as neuronal loss. Transmission electron microscopy of MPS brains revealed dystrophic axons, axonal storage, and extensive lipid and lysosomal storage. These data lend novel insight to MPS neuropathology, suggesting that MPSIIIA and IIIB have more pronounced neuropathology than MPSI, yet all are still progressive, at least in some aspects of neuropathology, from 4-9 months.

Topics: Animals; Carrier Proteins; Cytokines; Disease Models, Animal; Disease Progression; Female; G(M2) Ganglioside; Glycosaminoglycans; Heparitin Sulfate; Homer Scaffolding Proteins; Immunohistochemistry; Lysosomes; Male; Mice; Mucopolysaccharidosis I; Mucopolysaccharidosis III; Neurons; Parietal Lobe; Somatosensory Cortex; Vesicle-Associated Membrane Protein 2

Tay-Sachs and Sandhoff diseases are lethal inborn errors of acid β-N-acetylhexosaminidase activity, characterized by lysosomal storage of GM2 ganglioside and related glycoconjugates in the nervous system. The molecular events that lead to irreversible neuronal injury accompanied by gliosis are unknown; but gene transfer, when undertaken before neurological signs are manifest, effectively rescues the acute neurodegenerative illness in Hexb-/- (Sandhoff) mice that lack β-hexosaminidases A and B. To define determinants of therapeutic efficacy and establish a dynamic experimental platform to systematically investigate cellular pathogenesis of GM2 gangliosidosis, we generated two inducible experimental models. Reversible transgenic expression of β-hexosaminidase directed by two promoters, mouse Hexb and human Synapsin 1 promoters, permitted progression of GM2 gangliosidosis in Sandhoff mice to be modified at pre-defined ages. A single auto-regulatory tetracycline-sensitive expression cassette controlled expression of transgenic Hexb in the brain of Hexb-/- mice and provided long-term rescue from the acute neuronopathic disorder, as well as the accompanying pathological storage of glycoconjugates and gliosis in most parts of the brain. Ultimately, late-onset brainstem and ventral spinal cord pathology occurred and was associated with increased tone in the limbs. Silencing transgenic Hexb expression in five-week-old mice induced stereotypic signs and progression of Sandhoff disease, including tremor, bradykinesia, and hind-limb paralysis. As in germline Hexb-/- mice, these neurodegenerative manifestations advanced rapidly, indicating that the pathogenesis and progression of GM2 gangliosidosis is not influenced by developmental events in the maturing nervous system.

Topics: Animals; beta-N-Acetylhexosaminidases; Brain; Disease Models, Animal; Doxycycline; G(M2) Ganglioside; Gene Expression Regulation; HEK293 Cells; Humans; Lysosomes; Mice; Mice, Transgenic; Neurons; Promoter Regions, Genetic; Sandhoff Disease; Spinal Cord; Tay-Sachs Disease

Niemann-Pick disease type C1 (NPC1) is a genetic neurovisceral disorder characterized by abnormalities in intracellular sterol trafficking. A knockout mouse model (NPC1) is an important tool for the study of pathogenesis and treatment strategies. In the present study, NPC1 mice were examined for pathological changes in the cornea.. Fifteen inbred homozygous NPC1 knockout mice (NPC1, 5-10 weeks old), 5 age-matched heterozygous mice (NPC1), and 14 wild-type control mice (NPC1) were examined. In vivo confocal laser scanning microscopy (CLSM) was performed on both eyes of each animal; afterward, the eyes were processed for histology, electron microscopy, and lipid analysis.. In vivo CLSM disclosed hyperreflective intracellular deposits in the intermediate and basal cell layers of corneal epithelium in all NPC1 mice. At the electron microscopy level, however, vacuolated cytoplasmic structures, 200-500 nm in diameter, with electron-dense material appeared in all structures investigated, including all epithelial layers and stromal keratocytes. These deposits were negative for filipin, a marker for unesterified cholesterol. Lipid analysis showed a marked increase in disialotetrahexosylganglioside 2 (GM2) level in NPC1 mice corneas, whereas no changes were detected in free cholesterol and disialotetrahexosylganglioside 3 (GM3) levels when compared with controls.. Morphological changes characteristic for the NPC1 mouse cornea were visualized in all epithelial layers and keratocytes. In vivo CLSM findings were confirmed by other techniques. In vivo detection of ocular manifestations and analysis of ocular tissue have the potential to aid the diagnosis of NPC1 disease and to monitor the efficacy of treatment.

Topics: Animals; Cholesterol; Chromatography, High Pressure Liquid; Corneal Diseases; Disease Models, Animal; G(M2) Ganglioside; G(M3) Ganglioside; Intracellular Signaling Peptides and Proteins; Lipids; Mass Spectrometry; Mice; Mice, Inbred BALB C; Mice, Knockout; Microscopy, Confocal; Niemann-Pick C1 Protein; Niemann-Pick Disease, Type C; Proteins

Sandhoff disease (SD) is a lysosomal disease caused by a mutation of the HEXB gene associated with excessive accumulation of GM2 ganglioside (GM2) in lysosomes and neurological manifestations. Production of autoantibodies against the accumulated gangliosides has been reported to be involved in the progressive pathogenesis of GM2 gangliosidosis, although the underlying mechanism has not been fully elucidated. The thymus is the key organ in the acquired immune system including the development of autoantibodies. We showed here that thymic involution and an increase in cell death in the organ occur in SD model mice at a late stage of the pathogenesis. Dramatic increases in the populations of Annexin-V(+) cells and terminal deoxynucletidyl transferase dUTP nick end labeling (TUNEL) (+) cells were observed throughout the thymuses of 15-week old SD mice. Enhanced caspase-3/7 activation, but not that of caspase-1/4, -6 ,-8, or -9, was also demonstrated. Furthermore, the serum level of corticosterone, a potent inducer of apoptosis of thymocytes, was elevated during the same period of apoptosis. Our studies suggested that an increase in endocrine corticosterone may be one of the causes that accelerate the apoptosis of thymocytes leading to thymic involution in GM2 gangliosidosis, and thus can be used as a disease marker for evaluation of the thymic condition and disease progression.

Topics: Age Factors; Animals; Apoptosis; Atrophy; beta-Hexosaminidase alpha Chain; Caspases; Corticosterone; Disease Models, Animal; Disease Progression; G(M2) Ganglioside; Mice; Mice, Inbred C57BL; Mice, Knockout; Phenotype; Sandhoff Disease; Thymus Gland

Autopsy studies of four Jacob sheep dying within their first 6-8 months of a progressive neurodegenerative disorder suggested the presence of a neuronal storage disease. Lysosomal enzyme studies of brain and liver from an affected animal revealed diminished activity of hexosaminidase A (Hex A) measured with an artificial substrate specific for this component of β-hexosaminidase. Absence of Hex A activity was confirmed by cellulose acetate electrophoresis. Brain lipid analyses demonstrated the presence of increased concentrations of G(M2)-ganglioside and asialo-G(M2)-ganglioside. The hexa cDNA of Jacob sheep was cloned and sequenced revealing an identical number of nucleotides and exons as in human HexA and 86% homology in nucleotide sequence. A missense mutation was found in the hexa cDNA of the affected sheep caused by a single nucleotide change at the end of exon 11 resulting in skipping of exon 11. Transfection of normal sheep hexa cDNA into COS1 cells and human Hex A-deficient cells led to expression of Hex S but no increase in Hex A indicating absence of cross-species dimerization of sheep Hex α-subunit with human Hex β-subunits. Using restriction site analysis, the heterozygote frequency of this mutation in Jacob sheep was determined in three geographically separate flocks to average 14%. This large naturally occurring animal model of Tay-Sachs disease is the first to offer promise as a means for trials of gene therapy applicable to human infants.

Topics: Animals; Base Sequence; beta-N-Acetylhexosaminidases; Brain Chemistry; Chlorocebus aethiops; Cloning, Molecular; COS Cells; Disease Models, Animal; DNA, Complementary; Female; G(M2) Ganglioside; Heterozygote; Hexosaminidase A; Humans; Lipid Metabolism; Male; Molecular Sequence Data; N-Acetylneuraminic Acid; Point Mutation; Sequence Homology, Nucleic Acid; Sheep; Sheep Diseases; Tay-Sachs Disease; Transfection

The trigeminal sensory system was evaluated for the retrograde transfer of gene therapy vectors into the CNS. The feline immunodeficiency viral vector, FIV(HEXB), encoding for the human HEXB gene, was injected intra-articularly in the temporomandibular joint of 12 week-old HexB(-/-) mice displaying clinical and histopathological signs of Sandhoff disease. This treatment regiment reduced GM(2) storage and ameliorated neuroinflammation in the brain of HexB(-/-) mice, as well as attenuated behavioral deficits. In conclusion, retrograde transfer along trigeminal sensory nerves may prove to be a valuable route of gene therapy administration for the treatment of lysosomal storage disorders and other neurodegenerative diseases.

Topics: Animals; Axonal Transport; Behavior, Animal; beta-Hexosaminidase beta Chain; Disease Models, Animal; Encephalitis; G(M2) Ganglioside; Genetic Therapy; Genetic Vectors; Humans; Immunodeficiency Virus, Feline; Lysosomal Storage Diseases, Nervous System; Mice; Mice, Knockout; Neurodegenerative Diseases; Sandhoff Disease; Treatment Outcome; Trigeminal Nerve

Myeloid-derived immune cells, including microglia, macrophages and monocytes, have been previously implicated in neurodegeneration. We investigated the role of infiltrating peripheral blood mononuclear cells (PBMC) in neuroinflammation and neurodegeneration in the HexB-/- mouse model of Sandhoff disease. Ablation of the chemokine receptor CCR2 in the HexB-/- mouse resulted in significant inhibition of PBMC infiltration into the brain, decrease in TNFalpha and MHC-II mRNA abundance and retardation in clinical disease development. There was no change in the level of GM2 storage and pro-apoptotic activity or astrocyte activation in HexB-/-; Ccr2-/- double knockout mice, which eventually succumbed secondary to GM2 gangliosidosis.

Topics: Animals; Apoptosis; Disease Models, Animal; Encephalitis; Female; G(M2) Ganglioside; Hexosaminidase B; Leukocytes, Mononuclear; Male; Mice; Mice, Knockout; Microglia; Nerve Degeneration; Receptors, CCR2; Sandhoff Disease

The biological effects of lead are well defined; however, neither the risk exposure level nor the subcellular mechanism of its action is completely clear. The present work was undertaken to investigate the effects of low level and long term lead exposure on the composition and expression of rat renal gangliosides. In order to identify ganglioside expression, frozen sections of kidneys were stained with monoclonal antibodies GMB16 (GM1 specific), GM28 (GM2 specific), AMR-10 (GM4 specific) and CDW 60 (9-O-Ac-GD3 specific). Strong reactivity was observed for GMB28, AMR-10 and CDW 60, while GMB16 developed only weak labelling in treated kidney compared with the control. The alterations in the expression of renal gangliosides observed by immunohistochemistry were accompanied by quantitative and qualitative changes in the thin layer chromatography of total gangliosides isolated from kidney tissues. Lead treatment produced a significant increase in 9-O-Ac GD3, a ganglioside involved in apoptotic processes. In agreement with this result, a significant decrease in the number of apoptotic glomerular cells was observed with the TUNEL assay. These findings lead us to suggest that alterations in renal gangliosides produced by low level lead exposure are associated with the apoptotic processes that take place in the kidney. These findings provide evidence that low level and long term lead exposure produces renal ganglioside alterations with urinary microalbumin excretion. The results suggest that lead levels within the limits of biological tolerance already cause molecular renal damage without clinical signs of toxicity.

Topics: Albuminuria; Animals; Apoptosis; Body Weight; Chromatography, Thin Layer; Disease Models, Animal; Eating; G(M1) Ganglioside; G(M2) Ganglioside; Gangliosides; Immunohistochemistry; In Situ Nick-End Labeling; Kidney; Kidney Diseases; Lead Poisoning; Male; Organometallic Compounds; Rats; Rats, Wistar; Time Factors

Sandhoff disease involves the CNS accumulation of ganglioside GM2 and asialo-GM2 (GA2) due to inherited defects in the beta-subunit gene of beta-hexosaminidase A and B (Hexb gene). Accumulation of these glycosphingolipids (GSLs) produces progressive neurodegeneration, ultimately leading to death. Substrate reduction therapy (SRT) aims to decrease the rate of glycosphingolipid (GSL) biosynthesis to compensate for the impaired rate of catabolism. The imino sugar, N-butyldeoxygalactonojirimycin (NB-DGJ) inhibits the first committed step in GSL biosynthesis. NB-DGJ treatment, administered from postnatal day 2 (p-2) to p-5 (600 mg/kg/day)), significantly reduced total brain ganglioside and GM2 content in the Sandhoff disease (Hexb(-/-)) mice, but did not reduce the content of GA2. We also found that NB-DGJ treatment caused a slight, but significant elevation in brain sialidase activity. The drug had no adverse effects on viability, body weight, brain weight, or brain water content in the mice. No significant alterations in neutral lipids or acidic phospholipids were observed in the NB-DGJ-treated Hexb(-/-) mice. Our results show that NB-DGJ is effective in reducing total brain ganglioside and GM2 content at early neonatal ages.

Topics: 1-Deoxynojirimycin; Animals; Animals, Newborn; beta-Hexosaminidase alpha Chain; Brain; Brain Chemistry; Disease Models, Animal; Down-Regulation; G(M2) Ganglioside; Gangliosides; Glycosphingolipids; Mice; Mice, Knockout; Nerve Degeneration; Neuraminidase; Sandhoff Disease; Treatment Outcome

The quality of tissue imaging by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) depends on the effectiveness of the matrix deposition, especially for lipids that may dissolve in the solvent used for the matrix application. This article describes the use of an oscillating capillary nebulizer (OCN) to spray small droplets of matrix aerosol onto the sample surface for improved matrix homogeneity, reduced crystal size, and controlled solvent effects. This system was then applied to the analysis of histological slices of brains from mice with homozygous disruption of the hexb gene (hexb-/-), a model of Tay-Sachs and Sandhoff disease, versus the functionally normal heterozygote (hexb+/-) by imaging MALDI-MS. This allowed profiling and localization of many different lipid species, and of particular interest, ganglioside GM2, asialo-GM2 (GA2), and sulfatides (ST). The presence of these compounds was confirmed by analysis of brain extracts using electrospray ionization in conjunction with tandem mass spectrometry (MS/MS). The major fatty acid of the ceramide backbone of both GM2 and GA2 was identified as stearic acid (18:0) versus nervonic acid (24:1) for ST by both tissue-imaging MS and ESI-MS/MS. GM2 and GA2 were highly elevated in hexb-/- and were both localized in the granular cell region of the cerebellum. ST, however, was localized mainly in myelinated fiber (white matter) region of the cerebellum as well as in the brain stem with a relatively uniform distribution and had similar relative signal intensity for both hexb+/- and hexb-/- brain. It was also observed that there were distinct localizations for numerous other lipid subclasses; hence, imaging MALDI-MS could be used for "lipidomic" studies. These results illustrate the usefulness of tissue-imaging MALDI-MS with matrix deposition by OCN for histologic comparison of lipids in tissues such as brains from this mouse model of Tay-Sachs and Sandhoff disease.

Topics: Animals; Brain; Brain Chemistry; Disease Models, Animal; G(M2) Ganglioside; Gangliosides; Lipid Metabolism; Lipids; Mice; Nebulizers and Vaporizers; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Sphingolipids; Sulfoglycosphingolipids; Tay-Sachs Disease

To investigate the effects of deficient degradation of glycolipids on the morphological appearance of all retinal cells in a murine model of G(M2) gangliosidosis (Sandhoff disease).. The morphological appearance of the retina in Sandhoff mice at symptomatic stages (3 and 4 months of age) was examined by immunohistochemistry, lectin histochemistry and electron microscopy.. Under a light microscope, intense immunoreactivity for G(M2) ganglioside was observed in the ganglion cell, inner plexiform, and inner nuclear layers in the Sandhoff mice. The ganglion cell layers and retinal pigment epithelium in the Sandhoff mice were stained intensely with concanavalin A agglutinin and succinylated wheat germ agglutinin. Ultrastructural studies revealed numerous inclusions in the cytoplasm of retinal ganglion cells and other neuronal cells (particularly amacrine cells), whereas we failed to detect apparent involvement of photoreceptor cells. In addition to the cytoplasmic inclusions in the retinal neurons, vacuolation was evident in the retinal pigment epithelium.. These findings suggest that neuronal cells and pigment epithelial cells are more vulnerable to the deficient ganglioside degradation than other retinal cells in Sandhoff mice.

Topics: Animals; Disease Models, Animal; G(M2) Ganglioside; Immunoenzyme Techniques; Mice; Microscopy, Immunoelectron; Neurons, Afferent; Pigment Epithelium of Eye; Retina; Retinal Ganglion Cells; Sandhoff Disease

Sandhoff disease, a neurodegenerative disorder characterized by the intracellular accumulation of GM2 ganglioside, is caused by mutations in the hexosaminidase beta-chain gene resulting in a hexosaminidase A (alphabeta) and B (betabeta) deficiency. A bicistronic lentiviral vector encoding both the hexosaminidase alpha and beta chains (SIV.ASB) has previously been shown to correct the beta-hexosaminidase deficiency and to reduce GM2 levels both in transduced and cross-corrected human Sandhoff fibroblasts. Recent advances in determining the neuropathophysiological mechanisms in Sandhoff disease have shown a mechanistic link between GM2 accumulation, neuronal cell death, reduction of sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase (SERCA) activity, and axonal outgrowth. To examine the ability of the SIV.ASB vector to reverse these pathophysiological events, hippocampal neurons from embryonic Sandhoff mice were transduced with the lentivector. Normal axonal growth rates were restored, as was the rate of Ca(2+) uptake via the SERCA and the sensitivity of the neurons to thapsigargin-induced cell death, concomitant with a decrease in GM2 and GA2 levels. Thus, we have demonstrated that the bicistronic vector can reverse the biochemical defects and down-stream consequences in Sandhoff neurons, reinforcing its potential for Sandhoff disease in vivo gene therapy.

Topics: Animals; beta-N-Acetylhexosaminidases; Calcium; Calcium-Transporting ATPases; Cell Death; Cells, Cultured; Disease Models, Animal; Down-Regulation; Female; G(M2) Ganglioside; Genes; Genetic Therapy; Genetic Vectors; Growth Cones; Hexosaminidase A; Hippocampus; Lentivirus; Male; Mice; Mice, Knockout; Sandhoff Disease; Sarcoplasmic Reticulum Calcium-Transporting ATPases; Transduction, Genetic

The original mucopolysaccharidosis type IIIA (MPS IIIA) mice were identified in a mixed background with contributions from four different strains. To ensure long-term stability and genetic homogeneity of this lysosomal storage disease (LSD) model, the aim of this study was to develop and characterize a C57BL/6 congenic strain. The B6.Cg-Sgsh(mps3a) strain compares favorably with the original mixed donor strain, exhibiting low liver sulfamidase activity and significant brain heparan sulfate-derived disaccharide elevation from birth. A rapid increase in brain disaccharide levels occurred after birth, with a plateau reached by 13 weeks of age at 110x the levels observed in brains of age-matched unaffected mice. Typical lysosomal inclusions were observed in cerebral cortical and cerebellar neurons and in liver hepatocytes and Kupffer cells. Ubiquitin-positive spheroids and GM(2)-ganglioside were also detected in brain. Using the Morris water maze in male mice, impaired memory and spatial learning was evident at 20 weeks of age in B6.Cg-Sgsh(mps3a) MPS IIIA mice. Other behavioral changes include motor, cognitive and sensory deficits, and aggression. Male B6.Cg-Sgsh(mps3a) MPS IIIA mice exhibited more behavioral abnormalities than B6.Cg-Sgsh(mps3a) MPS IIIA females, as observed previously in the original mixed background strain. Affected mice generally survive to 9 to 12 months of age, before death or euthanasia for humane reasons. Overall, minor differences were apparent between the new congenic and previously described mixed MPS IIIA strains. Availability of an in-bred strain will ensure more reproducible experimental outcomes thereby assisting in our goal of developing effective therapies for LSD with central nervous system disease.

Topics: Age Factors; Animals; Behavior, Animal; Body Weight; Brain; Breeding; Disease Models, Animal; Exploratory Behavior; Female; G(M2) Ganglioside; Gas Chromatography-Mass Spectrometry; Hydrolases; Immunohistochemistry; Male; Maze Learning; Mice; Mice, Congenic; Mice, Inbred C57BL; Microscopy, Electron, Transmission; Mucopolysaccharidosis III; Sex Factors; Ubiquitin

Sandhoff disease is a lysosomal storage disease caused by simultaneous deficiencies of beta-hexosaminidase A (HexA; alphabeta) and B (HexB; betabeta), due to a primary defect of the beta-subunit gene (HEXB) associated with excessive accumulation of GM2 ganglioside (GM2) and oligosaccharides with N-acetylhexosamine residues at their non-reducing termini, and with neurosomatic manifestations. To elucidate the neuroinflammatory mechanisms involved in its pathogenesis, we analyzed the expression of chemokines in Sandhoff disease model mice (SD mice) produced by disruption of the murine Hex beta-subunit gene allele (Hexb-/-). We demonstrated that chemokine macrophage inflammatory protein-1 alpha (MIP-1alpha) was induced in brain regions, including the cerebral cortex, brain stem and cerebellum, of SD mice from an early stage of the pathogenesis but not in other systemic organs. On the other hand, little changes in other chemokine mRNAs, including those of RANTES (regulated upon activation, normal T expressed and secreted), MCP-1 (monocyte chemotactic protein-1), SLC (secondary lymphoid-tissue chemokine), fractalkine and SDF-1 (stromal derived factor-1), were detected. Significant up-regulation of MIP-1alpha mRNA and protein in the above-mentioned brain regions was observed in parallel with the accumulation of natural substrates of HexA and HexB. Immunohistochemical analysis revealed that MIP-1alpha-immunoreactivity (IR) in the above-mentioned brain regions of SD mice was co-localized in Iba1-IR-positive microglial cells and partly in glial fibrillary acidic protein (GFAP)-IR-positive astrocytes, in which marked accumulation of N-acetylglucosaminyl (GlcNAc)-oligosaccharides was observed from the presymptomatic stage of the disease. In contrast, little MIP-1alpha-IR was observed in neurons in which GM2 accumulated predominantly. These results suggest that specific induction of MIP-1alpha might coincide with the accumulation of GlcNAc-oligosaccharides due to a HexB deficiency in resident microglia and astrocytes in the brains of SD mice causing their activation and acceleration of the progressive neurodegeneration in SD mice.

Topics: Acetylglucosamine; Animals; Astrocytes; beta-N-Acetylhexosaminidases; Brain; Calcium-Binding Proteins; Chemokine CCL3; Chemokine CCL4; Chemokines; Disease Models, Animal; Disease Progression; G(M2) Ganglioside; Gene Expression Regulation; Glial Fibrillary Acidic Protein; Glycoconjugates; Hexosaminidase A; Hexosaminidase B; Macrophage Inflammatory Proteins; Mice; Mice, Inbred C57BL; Mice, Knockout; Microfilament Proteins; Microglia; Neuroglia; Protein Subunits; RNA, Messenger; Sandhoff Disease; Up-Regulation

Sandhoff disease is an autosomal recessive lysosomal storage disease caused by a defect of the beta-subunit gene (HEXB) associated with simultaneous deficiencies of beta-hexosaminidase A (HexA; alphabeta) and B (HexB; betabeta), and excessive accumulation of GM2 ganglioside (GM2) and oligosaccharides with N-acetylglucosamine (GlcNAc) residues at their non-reducing termini. Recent studies have shown the involvement of microglial activation in neuroinflammation and neurodegeneration of this disease. We isolated primary microglial cells from the neonatal brains of Sandhoff disease model mice (SD mice) produced by disruption of the murine Hex beta-subunit gene allele (Hexb-/-). The cells expressed microglial cell-specific ionized calcium binding adaptor molecule 1 (Iba1)-immunoreactivity (IR) and antigen recognized by Ricinus communis agglutinin lectin-120 (RCA120), but not glial fibrillary acidic protein (GFAP)-IR specific for astrocytes. They also demonstrated significant intracellular accumulation of GM2 and GlcNAc-oligosaccharides. We produced a lentiviral vector encoding for the murine Hex beta-subunit and transduced it into the microglia from SD mice with the recombinant lentivirus, causing elimination of the intracellularly accumulated GM2 and GlcNAc-oligosaccharides and secretion of Hex isozyme activities from the transduced SD microglial cells. Recomibinant HexA isozyme isolated from the conditioned medium of a Chinese hamster ovary (CHO) cell line simultaneously expressing the human HEXA (alpha-subunit) and HEXB genes was also found to be incorporated into the SD microglia via cell surface cation-independent mannose 6-phosphate receptor and mannose receptor to degrade the intracellularly accumulated GM2 and GlcNAc-oligosaccharides. These results suggest the therapeutic potential of recombinant lentivirus encoding the murine Hex beta-subunit and the human HexA isozyme (alphabeta heterodimer) for metabolic cross-correction in microglial cells involved in progressive neurodegeneration in SD mice.

Topics: Animals; beta-N-Acetylhexosaminidases; Brain; Calcium-Binding Proteins; Dimerization; Disease Models, Animal; Encephalitis; Female; G(M2) Ganglioside; Genetic Therapy; Genetic Vectors; Gliosis; Hexosaminidase A; Hexosaminidase B; Humans; Isoenzymes; Lentivirus; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Microfilament Proteins; Microglia; Protein Subunits; Receptor, IGF Type 2; Sandhoff Disease

To investigate the effects of lysosomal storage on the morphologic appearance and the neurite outgrowth capability of the retina in a mouse model of G(M2) gangliosidosis (Sandhoff disease).. Histopathologic appearances of retinas in Sandhoff (SD) mice at 3 and 4 months of age were examined by light and electron microscopy. Retinas of SD mice and wild-type (WT) mice at 1, 2, and 4 months of age were cultured in collagen gel in the presence or absence of brain-derived neurotrophic factor (BDNF), and neurite outgrowth was examined.. Morphologic studies revealed accumulation of G(M2) ganglioside in the retinal ganglion cells of SD mice in a time-dependent manner. The number of neurites from the retinal explants after 7 and 10 days in culture were significantly lower in 2- and 4-month-old SD mice than in the age-matched WT mice. The application of BDNF significantly improved neurite outgrowth from the retina in both SD and WT mice at 2 months of age. At 4 months of age, BDNF was much less effective at stimulating neurite outgrowth in the retina of SD mice than in retina of WT mice.. These results indicate that lysosomal storage of G(M2) ganglioside impairs the capability of neurite outgrowth in retinal ganglion cells in culture and that BDNF is effective at diminishing this impairment during the early stage of the disease.

Topics: Animals; beta-N-Acetylhexosaminidases; Brain-Derived Neurotrophic Factor; Disease Models, Animal; G(M2) Ganglioside; Mice; Mice, Knockout; Nerve Degeneration; Neurites; Organ Culture Techniques; Retinal Diseases; Retinal Ganglion Cells; Sandhoff Disease; Time Factors

The G(M2) activator protein is required for successful degradation of G(M2) ganglioside by the A isozyme of lysosomal beta-N-acetylhexosaminidase (EC 3.2.1.52). Deficiency of the G(M2) activator protein leads to a relentlessly progressive accumulation of G(M2) ganglioside in neuronal lysosomes and subsequent fatal deterioration of central nervous system function. G(M2) activator deficiency has been described in humans, dogs and mice. This manuscript reports the discovery and characterization of a feline model of G(M2) activator deficiency that exhibits many disease traits typical of the disorder in other species. Cats deficient in the G(M2) activator protein develop clinical signs at approximately 14 months of age, including motor incoordination and exaggerated startle response to sharp sounds. Affected cats exhibit central nervous system abnormalities such as swollen neurons, membranous cytoplasmic bodies, increased sialic acid content and elevated levels of G(M2) ganglioside. As is typical of G(M2) activator deficiency, hexosaminidase A activity in tissue homogenates appears normal when assayed with a commonly used synthetic substrate. When the G(M2) activator cDNA was sequenced from normal and affected cats, a deletion of 4 base pairs was identified as the causative mutation, resulting in alteration of 21 amino acids at the C terminus of the G(M2) activator protein.

Topics: Aging; Amino Acid Sequence; Animals; Base Sequence; Brain Chemistry; Cats; Central Nervous System; Disease Models, Animal; DNA, Complementary; Female; G(M2) Activator Protein; G(M2) Ganglioside; Gangliosidoses, GM2; Gene Deletion; Hexosaminidases; Liver; Male; Molecular Sequence Data; Mutation; N-Acetylneuraminic Acid; Neurons; Pedigree; Thymus Gland

Sandhoff disease is a severe neurodegenerative disorder with visceral involvement caused by mutations in the HEXB gene coding for the beta subunit of the lysosomal hexosaminidases A and B. HEXB mutations result in the accumulation of undegraded substrates such as GM2 and GA2 in lysosomes. We evaluated the efficacy of cationic liposome-mediated plasmid gene therapy using the Sandhoff disease mouse, an animal model of a human lysosomal storage disease. The mice received a single intravenous injection of two plasmids, encoding the human alpha and beta subunits of hexosaminidase cDNAs. As a result, 10-35% of normal levels of hexosaminidase expression, theoretically therapeutic levels, were achieved in most visceral organs, but not in the brain, 3 days after injection with decreased levels by day 7. Histochemical staining confirmed widespread enzyme activity in visceral organs. Both GA2 and GM2 were reduced by almost 10% and 50%, respectively, on day 3, and by 60% and 70% on day 7 compared with untreated age-matched Sandhoff disease mice. Consistent with the biochemical results, a reduction in GM2 was observed in liver cells histologically as well. These initial findings support further development of the plasmid gene therapy against lysosomal diseases with visceral pathology.

Topics: Animals; beta-N-Acetylhexosaminidases; Cell Line; Disease Models, Animal; G(M2) Ganglioside; Gene Transfer Techniques; Genetic Therapy; Hexosaminidase B; Humans; Liver; Mice; Mice, Knockout; Plasmids; Sandhoff Disease; Tissue Distribution

Gangliosides are found at high levels in neuronal tissues where they play a variety of important functions. In the gangliosidoses, gangliosides accumulate because of defective activity of the lysosomal proteins responsible for their degradation, usually resulting in a rapidly progressive neurodegenerative disease. However, the molecular mechanism(s) leading from ganglioside accumulation to neurodegeneration is not known. We now examine the effect of ganglioside GM2 accumulation in a mouse model of Sandhoff disease (one of the GM2 gangliosidoses), the Hexb-/- mouse. Microsomes from Hexb-/- mouse brain showed a significant reduction in the rate of Ca2+-uptake via the sarco/endoplasmic reticulum Ca2+-ATPase (SERCA), which was prevented by feeding Hexb-/- mice with N-butyldeoxynojirimycin (NB-DNJ), an inhibitor of glycolipid synthesis that reduces GM2 storage. Changes in SERCA activity were not due to transcriptional regulation but rather because of a decrease in Vmax. Moreover, exogenously added GM2 had a similar effect on SERCA activity. The functional significance of these findings was established by the enhanced sensitivity of neurons cultured from embryonic Hexb-/- mice to cell death induced by thapsigargin, a specific SERCA inhibitor, and by the enhanced sensitivity of Hexb-/- microsomes to calcium-induced calcium release. This study suggests a mechanistic link among GM2 accumulation, reduced SERCA activity, and neuronal cell death, which may be of significance for delineating the neuropathophysiology of Sandhoff disease.

Topics: 1-Deoxynojirimycin; Adenosine Triphosphate; Animals; Blotting, Western; Brain; Calcium; Calcium-Transporting ATPases; Cell Death; Disease Models, Animal; Dose-Response Relationship, Drug; Electrophoresis, Polyacrylamide Gel; Endoplasmic Reticulum; Enzyme Inhibitors; G(M2) Ganglioside; Gangliosides; Genotype; Glycolipids; Hippocampus; Kinetics; Lipid Metabolism; Mice; Mice, Transgenic; Microsomes; Neurons; Reverse Transcriptase Polymerase Chain Reaction; Sandhoff Disease; Sarcoplasmic Reticulum; Sarcoplasmic Reticulum Calcium-Transporting ATPases; Spectrophotometry; Thapsigargin; Time Factors

Mouse models of the G(M2) gangliosidoses, Tay-Sachs and Sandhoff disease, are null for the hexosaminidase alpha and beta subunits respectively. The Sandhoff (Hexb-/-) mouse has severe neurological disease and mimics the human infantile onset variant. However, the Tay-Sachs (Hexa-/-) mouse model lacks an overt phenotype as mice can partially bypass the blocked catabolic pathway and escape disease. We have investigated whether a subset of Tay-Sachs mice develop late onset disease. We have found that approximately 65% of the mice develop one or more clinical signs of the disease within their natural life span (n = 52, P < 0.0001). However, 100% of female mice with repeat breeding histories developed late onset disease at an earlier age (n = 21, P < 0.0001) and displayed all clinical features. Repeat breeding of a large cohort of female Tay-Sachs mice confirmed that pregnancy induces late onset Tay-Sachs disease. Onset of symptoms correlated with reduced up-regulation of hexosaminidase B, a component of the bypass pathway.

Topics: Age of Onset; Animals; Brain; Disease Models, Animal; Female; G(M2) Ganglioside; Male; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Muscle, Skeletal; Phenotype; Pregnancy; Tay-Sachs Disease

Sandhoff disease is a heritable lysosomal storage disease resulting from impaired degradation of GM2 ganglioside and related substrates. A mouse model of Sandhoff disease created by gene targeting displays progressive neurological manifestations, similar to patients with the disease. In the present in vivo and in vitro studies, we examined morphological and functional abnormalities of dorsal root ganglion (DRG) neurones in Sandhoff disease mice at an asymptomatic stage (approximately 1 month of age). Light microscopic studies with Nissl staining and immunocytochemistry suggested extensive intracytoplasmic storage of GM2 ganglioside in the Sandhoff mouse DRG neurones. These findings were consistent with the results of electron microscopy, in which a huge number of pleomorphic inclusion bodies immunoreactive for GM2 ganglioside were present in the cytoplasm of the neurones. The inclusion bodies were also identified in satellite cells and Schwann cells in the Sandhoff mouse DRG. The survival ratios of DRG neurones after 1, 2, 4 and 6 days in culture were significantly lower in the Sandhoff mice than in the age-matched heterozygous mice. The ratio of neurite-bearing cells on poly-l-lysine-coated dishes after 2 days in culture was also lower by approximately 10% in the Sandhoff mice compared to the heterozygotes, but additional coating of laminin onto poly-l-lysine dramatically enhanced the neurite extension from the neurones in both groups of mice. These results indicate that accumulation of GM2 ganglioside in DRG neurones impairs the capability of the neurones to survive in vitro, although viable neurones from the Sandhoff mice in culture can regenerate neurites nearly as well as unaffected neurones.

Topics: Animals; Bacterial Proteins; Cell Survival; Cells, Cultured; Disease Models, Animal; DNA-Binding Proteins; G(M2) Ganglioside; Ganglia, Spinal; Genotype; In Vitro Techniques; Inclusion Bodies; Lysosomes; Mice; Mice, Knockout; Microscopy, Electron; Neurites; Sandhoff Disease

Topics: Animals; beta-N-Acetylhexosaminidases; Blood Cells; Brain; Cell Death; Disease Models, Animal; G(M2) Ganglioside; Gene Expression; Humans; Lysosomal Storage Diseases; Mice; Microglia; Sandhoff Disease

Topics: Animals; beta-N-Acetylhexosaminidases; Disease Models, Animal; Female; G(M2) Ganglioside; History, 20th Century; Humans; Isoenzymes; Male; Mutation; Pedigree; Tay-Sachs Disease

Lipopolysaccharides (LPS) from Campylobacter jejuni strains isolated from patients with Guillain-Barré syndrome (GBS) display molecular mimicry with GM1. We immunized rabbits with C. jejuni LPS from GBS-associated strains containing a GM1-like epitope. All animals produced high titre anti-LPS antibodies that were cross-reactive with GM1. We conclude that C. jejuni strains from GBS patients are able to induce antibodies that cross-react with gangliosides and LPS. This study further confirms the role of molecular mimicry in the induction of anti-ganglioside antibodies in GBS patients.

Topics: Animals; Antibodies; Antibody Formation; Campylobacter jejuni; Disease Models, Animal; Epitopes; G(M1) Ganglioside; G(M2) Ganglioside; Guillain-Barre Syndrome; Humans; Immunization; Immunoglobulin G; Immunoglobulin M; Lipopolysaccharides; Rabbits; Time Factors

Although gangliosides are abundant molecular determinants on all vertebrate nerve cells (comprising approximately 1.5% of brain dry weight) their functions have remained obscure. We report that mice engineered to lack a key enzyme in complex ganglioside biosynthesis (GM2/GD2 synthase), and which express only the simple ganglioside molecular species GM3 and GD3, develop significant and progressive behavioral neuropathies, including deficits in reflexes, strength, coordination, and balance. Quantitative indices of motor abilities, applied at 8 and 12 months of age, also revealed progressive gait disorders in complex ganglioside knockout mice compared to controls, including reduced stride length, stride width, and increased hindpaw print length as well as a marked reduction in rearing. Compared to controls, null mutant mice tended to walk in small labored movements. Twelve-month-old complex ganglioside knockout mice also displayed significant incidence of tremor and catalepsy. These comprehensive neurobehavioral studies establish an essential role for complex gangliosides in the maintenance of normal neural physiology in mice, consistent with a role in maintaining axons and myelin (Sheikh, K. A. , J. Sun, Y. Liu, H. Kawai, T. O. Crawford, R. L. Proia, J. W. Griffin, and R. L. Schnaar. 1999. Mice lacking complex gangliosides develop Wallerian degeneration and myelination defects. Proc. Natl. Acad. Sci. USA 96: 7532-7537), and may provide insights into the mechanisms underlying certain neural degenerative diseases.

Topics: Animals; Ataxia; Axons; Behavior, Animal; Catalepsy; Demyelinating Diseases; Disease Models, Animal; Exploratory Behavior; G(M2) Ganglioside; G(M3) Ganglioside; Gait; Male; Mice; Mice, Knockout; Mice, Neurologic Mutants; Muscle Contraction; N-Acetylgalactosaminyltransferases; Polypeptide N-acetylgalactosaminyltransferase; Postural Balance; Reflex, Abnormal; Tremor; Walking; Wallerian Degeneration

The glycosphingolipid (GSL) lysosomal storage diseases result from the inheritance of defects in the genes encoding the enzymes required for catabolism of GSLs within lysosomes. A strategy for the treatment of these diseases, based on an inhibitor of GSL biosynthesis N-butyldeoxynojirimycin, was evaluated in a mouse model of Tay-Sachs disease. When Tay-Sachs mice were treated with N-butyldeoxynojirimycin, the accumulation of GM2 in the brain was prevented, with the number of storage neurons and the quantity of ganglioside stored per cell markedly reduced. Thus, limiting the biosynthesis of the substrate (GM2) for the defective enzyme (beta-hexosaminidase A) prevents GSL accumulation and the neuropathology associated with its lysosomal storage.

Topics: 1-Deoxynojirimycin; Animals; Blood-Brain Barrier; Brain; Disease Models, Animal; Enzyme Inhibitors; G(M2) Ganglioside; Lysosomes; Mice; Microscopy, Electron; Neurons; Tay-Sachs Disease

Tay-Sachs and Sandhoff diseases are autosomal recessive neurodegenerative diseases resulting from the inability to catabolize GM2 ganglioside by beta-hexosaminidase A (Hex A) due to mutations of the alpha subunit (Tay-Sachs disease) or beta subunit (Sandhoff disease) of Hex A. Hex B (beta beta homodimer) is also defective in Sandhoff disease. We previously developed mouse models of both diseases and showed that Hexa-/- (Tay-Sachs) mice remain asymptomatic to at least 1 year of age while Hexb-/- (Sandhoff) mice succumb to a profound neurodegenerative disease by 4-6 months of age. Here we find that neuron death in Hexb-/- mice is associated with apoptosis occurring throughout the CNS, while Hexa-/- mice were minimally involved at the same age. Studies of autopsy samples of brain and spinal cord from human Tay-Sachs and Sandhoff diseases revealed apoptosis in both instances, in keeping with the severe expression of both diseases. We suggest that neuron death is caused by unscheduled apoptosis, implicating accumulated GM2 ganglioside or a derivative in triggering of the apoptotic cascade.

Topics: Animals; Apoptosis; beta-N-Acetylhexosaminidases; Child, Preschool; Disease Models, Animal; G(M2) Ganglioside; Gangliosidoses; Gene Deletion; Hexosaminidase A; Hexosaminidase B; Humans; Infant; Mice; Neurons; Sandhoff Disease; Tay-Sachs Disease

Glycosphingolipids (GSLs) form cell-type-specific patterns on the surface of eukaryotic cells. Degradation of GSLs requires endocytotic membrane flow of plasma membrane-derived GSLs into the lysosomes as the digesting organelles. Recent research focused on the mechanisms leading to selective membrane degradation in the lysosomes and on the mechanism and physiological function of sphingolipid activator proteins, which are needed for degradation of GSLs with short oligosaccharide chains in addition to hydrolysing enzymes. Both, the inherited deficiency of lysosomal hydrolases and of sphingolipid activator proteins give rise to sphingolipid storage diseases. In some cases it was possible to correlate residual enzyme activities with the onset and the course of the disease.

Topics: Animals; Disease Models, Animal; Endocytosis; G(M2) Activator Protein; G(M2) Ganglioside; Glycosphingolipids; Humans; Hydrolysis; Lysosomes; Proteins; Tay-Sachs Disease

We have generated mouse models of human Tay-Sachs and Sandhoff diseases by targeted disruption of the Hexa (alpha subunit) or Hexb (beta subunit) genes, respectively, encoding lysosomal beta-hexosaminidase A (structure, alpha) and B (structure, beta beta). Both mutant mice accumulate GM2 ganglioside in brain, much more so in Hexb -/- mice, and the latter also accumulate glycolipid GA2. Hexa -/- mice suffer no obvious behavioral or neurological deficit, while Hexb -/- mice develop a fatal neurodegenerative disease, with spasticity, muscle weakness, rigidity, tremor and ataxia. The Hexb -/- but not the Hexa -/- mice have massive depletion of spinal cord axons as an apparent consequence of neuronal storage of GM2. We propose that Hexa -/- mice escape disease through partial catabolism of accumulated GM2 via GA2 (asialo-GM2) through the combined action of sialidase and beta-hexosaminidase B.

Topics: Animals; Base Sequence; beta-N-Acetylhexosaminidases; Brain Chemistry; Brain Injuries; Disease Models, Animal; Female; G(M2) Ganglioside; Gene Targeting; Glycosphingolipids; Hexosaminidase A; Hexosaminidase B; Humans; Liver; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Molecular Sequence Data; Organ Specificity; Phenotype; RNA, Messenger; Sandhoff Disease; Spinal Cord; Tay-Sachs Disease

4-Methylumbelliferyl-N-acetylglucosamine-6-sulfate (4MUGLc6S) which is known to be a specific substrate for human hexosaminidase A was used to determine enzymatic features of canine GM2-gangliosidosis. The enzyme activity using 4MUGlc6S in affected dog brain and liver was less than 20 to 30% of control tissues, whereas total 4-methylumbelliferyl beta-glucosaminidase activity in canine GM2-gangliosidosis was normal or elevated. However, when beta-hexosaminidase was fractionated by DEAE-Sepharose column chromatography, beta-hexosaminidase A like fraction in affected dog tissues was reduced to 20 to 30% of control. These data suggest that canine GM2-gangliosidosis is analogous to human juvenile.

Topics: Animals; beta-N-Acetylhexosaminidases; Chromatography, DEAE-Cellulose; Disease Models, Animal; Dog Diseases; Dogs; G(M2) Ganglioside; Gangliosidoses; Hexosaminidase A; Hymecromone; Isoenzymes

Topics: Animals; beta-N-Acetylhexosaminidases; Brain; Cat Diseases; Cats; Disease Models, Animal; G(M2) Ganglioside; Gangliosidoses; Hexosaminidases; Humans

The rapid plasma clearance of human placental beta-hexosaminidase in the cat is due mainly to a receptor-mediated mechanism recognizing terminal N-acetyl glucosaminyl and mannosyl residues on glycoproteins. Using a sensitive single radial immunodiffusion assay, specific for human beta-hexosaminidase, we have shown that, in normal cats, the liver is responsible for most of the clearance of human beta-hexosaminidase. Two hours after injection of approximately 6 X 10(6) U beta-hexosaminidase/kg bw, 70-90% of the enzyme was recovered in the liver. Spleen, kidney, lung, bone, bone, pancreas, adrenals, testes and ovaries, cardiac and skeletal muscle, lymph nodes, and placenta, however, also participated in the clearance, although specific uptake in most organs was < 5% of that of liver. Exogenous beta-hexosaminidase was also present in bile, indicating that the hepatocytes are involved in clearance. Injection of terminal mannose-rich S. cerevisiae mannans (50-150 mg/kg bw), prolonged the plasma half-life of the enzyme (t 1/2 up to 290 min). In these animals, beta-hexosaminidase uptake by liver was reduced to < 10% of controls but uptake by other organs was not proportionally or uniformly reduced, suggesting the existence of different uptake mechanisms in different tissues. Permeability of the blood-brain barrier was induced by exposing cats to 100% O2 at 2.5 ATA for 90 min. Injection of 6 X 10(6) U beta-hexosaminidase/kg bw during or immediately after exposure resulted in apparent uptake of enzyme by nervous tissue, qualitatively detectable by immunologic methods, but below the limits of sensitivity of the radial immunoassay(ie < 150 U/gr). When enzyme uptake by liver was inhibited by injection of ovomucoid or mannans, however, the hyperbaric oxygen-induced apparent uptake of beta-hexosaminidase by brain, cerebellum, and spinal cord was 200-500 U/gr of blood-free tissue, suggesting that the transport mechanism involved (presumably at the level of the nervous system vascular endothelium) is different from the carbohydrate-dependent hepatic uptake. The mechanism by which hyperbaric oxygenation induces permeability of the blood-brain barrier is not clear. The combination of this procedure (routinely used in human therapy) with specific inhibition of hepatic uptake, however, appears to be a promising approach for lysosomal enzyme targeting to the central nervous system.

Topics: Animals; Brain; Cats; Disease Models, Animal; G(M2) Ganglioside; Hexosaminidases; Humans; Immunodiffusion; Kinetics; Oxygen; Spinal Cord; Tay-Sachs Disease; Tissue Distribution

Topics: Animals; Cytoplasmic Granules; Disease Models, Animal; G(M2) Ganglioside; Gangliosidoses; Hexosaminidases; Humans; Swine; Swine Diseases

Topics: Animals; Arylsulfatases; Brain; Disease Models, Animal; G(M2) Ganglioside; Gangliosides; Hexosaminidases; Isoenzymes; Leukodystrophy, Metachromatic; Lipidoses; Rats; Sulfatases; Vitamin E Deficiency