Chronic GM1 gangliosidosis presenting as dystonia: II. Biochemical studies

GM1 Gangliosidosis: Mechanisms and Management

The lysosomal storage disorder, GM1 gangliosidosis (GM1), is a neurodegenerative condition resulting from deficiency of the enzyme β-galactosidase (β-gal). Mutation of the GLB1 gene, which codes for β-gal, prevents cleavage of the terminal β-1,4-linked galactose residue from GM1 ganglioside. Subsequent accumulation of GM1 ganglioside and other substrates in the lysosome impairs cell physiology and precipitates dysfunction of the nervous system. Beyond palliative and supportive care, no FDA-approved treatments exist for GM1 patients. Researchers are critically evaluating the efficacy of substrate reduction therapy, pharmacological chaperones, enzyme replacement therapy, stem cell transplantation, and gene therapy for GM1. A Phase I/II clinical trial for GM1 children is ongoing to evaluate the safety and efficacy of adeno-associated virus-mediated GLB1 delivery by intravenous injection, providing patients and families with hope for the future.

Pathogenic role of ganglioside metabolism in neurodegenerative diseases

Ganglioside metabolism is altered in several neurodegenerative diseases, and this may participate in several events related to the pathogenesis of these diseases. Most changes occur in specific areas of the brain and their distinct membrane microdomains or lipid rafts. Antiganglioside antibodies may be involved in dysfunction of the blood-brain barrier and disease progression in these diseases. In lipid rafts, interactions of glycosphingolipids, including ganglioside, with proteins may be responsible for the misfolding events that cause the fibril and/or aggregate processing of disease-specific proteins, such as α-synuclein, in Parkinson's disease, huntingtin protein in Huntington's disease, and copper-zinc superoxide dismutase in amyotrophic lateral sclerosis. Targeting ganglioside metabolism may represent an underexploited opportunity to design novel therapeutic strategies for neurodegeneration in these diseases.

Primary dystonias and genetic disorders with dystonia as clinical feature of the disease

Dystonia is probably the most common form of movement disorder encountered in the clinical practice. It is characterized by sustained muscle contractions, usually producing twisting and repetitive movements or abnormal postures or positions. Dystonias can be classified in several ways, including primarily by the clinical phenomenology or by the underlining etiology, in particular to understand if the presentation is genetically determined. By advances of genetics, including contemporary genomic technologies, there is a growing understanding of the molecular underpinnings of genetically determined dystonias. The intricacy of information requires a user friendly, novel database that may efficiently serve clinicians to inform of advances of the field and to diagnose and manage these often complex cases. Here we present an up to date, comprehensive review - in tabulated formats - of genetically determined primary dystonias and complex Mendelian disorders with dystonia as central feature. The detailed search up to December 24, 2012, identified 24 hereditary primary dystonias (DYT1 to DYT 25) that are mostly monogenic disorders, and a larger group (>70) of genetic syndromes in which dystonia is one of the characteristic clinical features. We organized the findings not only by individual information (name of the conditions, pattern of inheritance, chromosome and gene abnormality, clinical features, relevant ancillary tests and key references), but also provide symptom-oriented organization of the clinical entities for efficient inquiries.

Lysosomal multienzyme complex: biochemistry, genetics, and molecular pathophysiology

Lysosomal enzymes sialidase (alpha-neuraminidase), beta-galactosidase, and N-acetylaminogalacto-6-sulfate sulfatase are involved in the catabolism of glycolipids, glycoproteins, and oligosaccharides. Their functional activity in the cell depends on their association in a multienzyme complex with lysosomal carboxypeptidase, cathepsin A. We review the data suggesting that the integrity of the complex plays a crucial role at different stages of biogenesis of lysosomal enzymes, including intracellular sorting and proteolytic processing of their precursors. The complex plays a protective role for all components, extending their half-life in the lysosome from several hours to several days; and for sialidase, the association with cathepsin A is also necessary for the expression of enzymatic activity. The disintegration of the complex due to genetic mutations in its components results in their functional deficiency and causes severe metabolic disorders: sialidosis (mutations in sialidase), GM1-gangliosidosis and Morquio disease type B (mutations in beta-galactosidase), galactosialidosis (mutations in cathepsin A), and Morquio disease type A (mutations in N-acetylaminogalacto-6-sulfate sulfatase). The genetic, biochemical, and direct structural studies described here clarify the molecular pathogenic mechanisms of these disorders and suggest new diagnostic tools.

Correction of acid beta-galactosidase deficiency in GM1 gangliosidosis human fibroblasts by retrovirus vector-mediated gene transfer: higher efficiency of release and cross-correction by the murine enzyme

Mutations in the lysosomal acid beta-galactosidase (EC 3.2.1.23) underlie two different disorders: GM1 gangliosidosis, which involves the nervous system and visceral organs to varying extents, and Morquio's syndrome type B (Morquio B disease), which is a skeletal-connective tissue disease without any CNS symptoms. This article shows that transduction of human GM1 gangliosidosis fibroblasts with retrovirus vectors encoding the human acid beta-galactosidase cDNA leads to complete correction of the enzymatic deficiency. The newly synthesized enzyme is correctly processed and targeted to the lysosomes in transduced cells. Cross-correction experiments using retrovirus-modified cells as enzyme donors showed, however, that the human enzyme is transferred at low efficiencies. Experiments using a different retrovirus vector carrying the human cDNA confirmed this observation. Transduction of human GM1 fibroblasts and mouse NIH 3T3 cells with a retrovirus vector encoding the mouse beta-galactosidase cDNA resulted in high levels of enzymatic activity. Furthermore, the mouse enzyme was found to be transferred to human cells at high efficiency. Enzyme activity measurements in medium conditioned by genetically modified cells suggest that the human beta-galactosidase enzyme is less efficiently released to the extracellular space than its mouse counterpart. This study suggests that lysosomal enzymes, contrary to the generalized perception in the field of gene therapy, may differ significantly in their properties and provides insights for design of future gene therapy interventions in acid beta-galactosidase deficiency.

GM1 gangliosidosis type 3 with severe jaw-closing impairment

The patient had adult GM1 gangliosidosis (type 3) with severe impairment of mastication caused by dystonia of anterior digastric muscles (jaw-opener) on clenching. This is the first report on jaw dystonia severe enough to cause the masticatory impairment in adult GM1 gangliosidosis. The discordance of closing and opening muscles during mastication might be caused by a basal ganglia lesion in this disease.

Type 3 GM1 gangliosidosis: characteristic MRI findings correlated with dystonia

We describe three brothers with type 3 GM1 gangliosidosis presenting as dystonia. The ages of the patients when examined were 28, 31, and 33. They had developed dysarthria with facial grimacing since early childhood. The common neurological sign was generalized dystonia. Both dystonic postures and dystonic movements resulting from varying degrees of fixed rigidity of each muscle involved did not disappear when the patients were lying or sitting relaxed. There was no correlation between the severity of dystonia and the residual activities of acid beta-galactosidase. Magnetic resonance imaging (MRI) showed bilaterally symmetric high intensity lesions only in the putamen on T2-weighted and proton density images. Selective putaminal changes on MRI may be the lesions most responsible for symptomatic dystonia in this disorder.

Accumulation of lysosphingolipids in tissues from patients with GM1 and GM2 gangliosidoses

By using a sensitive method, we assayed lysocompounds of gangliosides and asialogangliosides in tissues from four patients with GM2 gangliosidosis (one with Sandhoff disease and three with Tay-Sachs disease) and from three patients with GM1 gangliosidosis [one with infantile type (fetus), one with late-infantile, and one with adult type]. In the brain and spinal cord of all the patients except for an adult GM1 gangliosidosis patient, abnormal accumulation of the lipids was observed, though the concentration in the fetal tissue was low. In GM2 gangliosidosis, the amounts of lyso GM2 ganglioside accumulated in the brain were similar among the patient with Sandhoff disease and the patients with Tay-Sachs disease, whereas the concentration of asialo lyso GM2 ganglioside in the brain was higher in the former patient than in the latter patients. By comparing the sphingoid bases of neutral sphingolipids, gangliosides, and lysosphingolipids, it was suggested that lysosphingolipids in the diseased tissue are synthesized by sequential glycosylation from free sphingoid bases, but not by deacylation of the sphingolipids. Because lysosphingolipids are known to be cytotoxic, the abnormally accumulated lysophingolipids may well be the pathogenetic agent for the neuronal degeneration in gangliosidoses.

GM1 gangliosidosis in adults: clinical and molecular analysis of 16 Japanese patients

Clinical findings were compared with the results of molecular analysis in 16 Japanese patients from 10 unrelated families with the adult/chronic form of GM1 gangliosidosis. Age of onset ranged from 3 to 30 years. Major clinical manifestations were gait and speech disturbances caused by persistent muscle hypertonia. Dystonic postures and movements, facial grimacing, and parkinsonian manifestations were commonly seen. Cerebellar signs, myoclonus, severe intellectual impairment, dysmorphism, or visceromegaly were not observed. A common single-base substitution, 51Ile(ATC)----Thr(ACC), reported in a previous study of ours, was confirmed in 14 patients by the Bsu36I restriction site analysis; one was a compound heterozygote with another mutation (457Arg[CGA]----Gln[CAA]) and the others were homozygotes of this mutation. Clinically, the compound-heterozygous patient showed more severe neurological manifestations and a more rapid clinical course than those of homozygotes. The homozygotes showed considerable variations in the age of onset and subsequent clinical course. The 51Ile----Thr mutant allele expressed a significant amount of beta-galactosidase activity, whereas the 457Arg----Gln mutant allele expressed extremely low activity in human GM1 gangliosidosis fibroblasts. We conclude that these gene mutations causing different residual enzyme activities are related to the severity of clinical manifestations, but some other genetic or environmental factors contribute to clinical heterogeneity. The Bsu36I restriction site analysis was performed in 7 families and provided clear results for the diagnosis of heterozygotes as well as homozygotes of this specific clinical form of GM1 gangliosidosis. The technique is applicable to prenatal diagnosis and genetic counseling.

Application of lectin histochemistry and carbohydrate analysis to the characterization of lysosomal storage diseases

In lysosomal storage diseases that involve a defect in the catabolism of glycoconjugates, lectin histochemistry adds a new dimension to the characterization of stored carbohydrates as it identifies sugar residues in situ in the affected cells and, thus, determines which cell types are affected by storage. It may be combined with chemical and biochemical analysis by h.p.l.c. The present review summarizes recent results for a variety of storage diseases and presents new data for GM1-gangliosidosis.

Uptake and metabolism of radiolabelled GM1-ganglioside in skin fibroblasts from controls and patients with GM1-gangliosidosis

The uptake and metabolism of [3-3H-sphingosine]GM1-ganglioside was measured in cultured skin fibroblasts from controls and patients with infantile, juvenile and adult GM1-gangliosidosis. When dissolved in medium with phosphatidylserine, GM1-ganglioside was efficiently taken up by cultured skin fibroblasts and transferred into lysosomes. A linear increase in GM1-ganglioside endocytosis was shown with phosphatidylserine concentrations of up to 40 micrograms/ml. A pulse-chase study revealed that [3H]GM1-ganglioside was metabolized to GM2-ganglioside, GM3-ganglioside, ceramide dihexoside, ceramide monohexoside, ceramide and sphingosine. Sphingosine was recycled to sphingomyelin. In a 20-h pulse study, cell lines from patients with GM1-gangliosidosis of infantile, juvenile and adult types hydrolysed 2-5%, 20-44% and 54-58% of the total endocytosed GM1-ganglioside respectively. These values were lower than in control cells (64.17 +/- 5.43% (n = 10]. The hydrolysis rates of exogenous [3H]GM1-ganglioside in cultured fibroblasts from patients with various types of GM1-gangliosidosis closely reflected the clinical severity.

A case of chronic GM1 gangliosidosis presenting as dystonia: clinical and biochemical studies

Clinical and biochemical studies are reported on a 32-year-old man with GM1 gangliosidosis who presented with a slowly progressive dystonia that began when he was aged 7 years and eventually became almost totally incapacitating at the age of 35. There was only mild intellectual deterioration, but myoclonus, seizures and macular cherry-red spots were never observed. Proton-density and T2-weighted MRI scans showed symmetrical hyperintense lesions of both putamina. No increase of GM1 ganglioside was found in plasma or cerebrospinal fluid, and the metabolism of GM1 ganglioside in cultured skin fibroblasts from the patient was also almost normal, although the residual activity of GM1 ganglioside beta-galactosidase activity was only 10% of normal. These findings suggest that impaired GM1 ganglioside metabolism is not present systemically as it is in the infantile and juvenile types of the disorder, but is mainly confined to the central nervous system in chronic GM1 gangliosidosis.

Abnormal glycosphingolipid metabolism in the nervous system of galactosialidosis

In an autopsy case of galactosialidosis, GM3, GM2, GM1, and GD1a were accumulated in sympathetic and spinal ganglia and grey matter of the spinal cord. Especially, the accumulations of GM3 and GM2 amounted to 41- and 86-fold increases in sympathetic ganglia, respectively, as compared to normal controls. In addition LacCer, GA2 and GA1 were accumulated in sympathetic and spinal ganglia. The accumulations of GM3 and GD1a are considered to be the result of defective lysosomal sialidase activity and the accumulation of GM1, LacCer and GA1 is also considered to be due to decreased beta-galactosidase activity in this disorder. To better understand the possible mechanism of GM2 accumulation, we determined the activity of GM2 synthesizing enzyme (GM3:UDP-GalNAc transferase), as well as hexosaminidase activity, in sympathetic ganglia, but they did not change. Abnormal ganglioside and neutral glycosphingolipid metabolism, as well as sialyloligosaccharide and sialylglycoprotein metabolism, may be involved in the pathogenesis of this disorder.

Purification and characterization of human liver beta-galactosidase from a patient with the adult form of GM1 gangliosidosis and a normal control

beta-Galactosidases were purified to homogeneity from livers of a normal control and a patient with the adult form of GM1 gangliosidosis. The purification was achieved by chromatography on DEAE-Sepharose fast flow, Con A-Sepharose, p-aminophenyl-1-thio-beta-D-galactopyranoside-Sepharose, and QAE-Mono Q. The normal and mutant enzymes were purified about 5000-fold with a yield of 10% and 1800-fold with a yield of 34%, respectively, and could hydrolyze 4-methylumbelliferyl-beta-D-galactoside, GM1 ganglioside, and asialofetuin. The purified normal enzyme was eluted from a TSK gel G-4000SW column as three symmetrical peaks of protein which were coincident with the three peaks of enzyme activity. The enzyme in these three peaks had apparent molecular weights of 800,000 (polymer), 140,000 (dimer), and 65,000 (monomer), whereas the mutant enzyme was eluted as two symmetrical peaks of protein and enzyme activity. The apparent molecular weight of a major monomeric form of the enzyme (beta-galactosidase A) was 60,000, and no dimeric form of the enzyme existed. Normal and mutant purified enzyme preparations migrated as a single major protein band with apparent molecular weights of 65,000 or 60,000, respectively, by SDS-polyacrylamide gel electrophoresis after treatment with mercaptoethanol. On isoelectric focussing, the mutant enzyme migrated more anodally than the normal enzyme. The mutant enzyme also had altered enzyme properties, such as pH optimum, Km values, substrate specificity and heat-stability. These data on the characteristics of the purified enzyme preparations provide the first direct evidence that patients with the adult form of GM1 gangliosidosis have a structurally altered beta-galactosidase.

[Gangliosidosis GM1--type 1. Anatomo-clinical study of a case]

The observation of generalized GM1 gangliosidosis type 1 (Norman-Landing disease) is reported. The case is typical, featuring all the main clinical and biological signs of the disease. Diagnosis was established by the demonstration of a severe deficit in beta-galactosidase activity in leucocytes, by the demonstration of oligosaccharides in the urine, and by the histological examination after the fatal outcome before the age of two with severe respiratory distress.

Type III (chronic) GM1-gangliosidosis. Histochemical and ultrastructural studies of rectal biopsy

Type III GM1-gangliosidosis is a rare hereditary storage disease caused by lack of lysosomal beta-galactosidase and characterized by a slowly progressive course, and extrapyramidal signs, but without prominent skeletal changes or visceromegaly. The storage substance was reported to be located only in the basal ganglia. There has been no detailed report on visceral lesions in type III GM1-gangliosidosis. In this report we describe a case of type III GM1-gangliosidosis, and the histochemical and ultrastructural findings from biopsied rectum. The patient was a 22-year-old female who exhibited dysarthria, gait disturbance, and generalized dystonia with rigidity. Beta-galactosidase activity in leukocytes was absent and sialidase activity in cultured fibroblasts was normal. Many histiocytes were found in biopsied rectal mucosa. Histochemical studies showed that the granules of histiocytes contained acidic glycoconjugates, beta-galactose, beta-N-acetylgalactosamine and sialic acid. Ultrastructural investigations revealed that ganglion cells of Meissner's plexus had many osmiophilic lamellar inclusions, similar to "membranous cytoplasmic bodies". These findings are crucial for the clinical diagnosis of type III GM1-gangliosidosis.

Hemidystonia: a report of 22 patients and a review of the literature

Hemidystonia defined as involuntary, sustained posturing of the unilateral arm, leg, and face was studied in 12 male and 10 female patients. Hemidystonia was caused by cerebrovascular disease in eight patients, perinatal trauma or childhood injury in four, head trauma and its sequelae in three, neuronal storage disorders in two, neurodegenerative disease in two, lesions after thalamotomy in two, and presumed encephalitis in one. Sixteen patients (73%) had CT evidence of contralateral basal ganglia damage, history of hemiparesis, or both. Brain damage before 7 years of age produced contralateral hemidystonia with a mean delay of 9-7 years. In older patients hemidystonia appeared within 6 months after injury. Hemidystonia may result from a disconnection between the striatum and the thalamus with relative preservation of the corticospinal pathways.

Cerebral and visceral organ gangliosides and related glycolipids in gm1-gangliosidosis type 1, type 2 and chronic type

Biochemical analyses of the samples of GM1-gangliosidosis Type 1, Type 2, and Chronic type at autopsy showed that GM1 and asialo-GM1 are markedly increased in the whole cerebral tissues of patients with Type 1 and Type 2, but mainly in the basal ganglia including caudate nucleus and putamen in the Chronic Type as already reported by Kobayashi and Suzuki in 1981. On the other hand, the finding that the Type 1 visceral organs contained unusual glycolipids rather than gangliosides was contrasted to those of Type 2 which seemed less abnormal. The unusual glycolipids included particularly fucolipid I and II consisting of glucose:galactose:N-acetylglucosamine:fucose (1:2:1:1) and (1:3:2:2), respectively. The chemical structure of oligosaccharide moiety of fucolipid I may be identical with Lacto-N-fucopentaose II or Lacto-N-fucopentaose III. The fucolipid II may be proposed to be Lacto-N-difucooctanose.

Chronic GM1 gangliosidosis presenting as dystonia: I. Clinical and pathological features

Clinical and pathological studies are reported from investigation of a 27-year-old man with GM1 gangliosidosis who experienced a slowly progressive dystonia that began about age 4, primarily affected the face and limbs, and eventually became almost totally incapacitating. There was only mild intellectual deterioration; myoclonus, seizures, and macular cherry-red spots were never observed. Postmortem examination revealed intraneuronal storage, localized predominantly to the basal ganglia, in which neurons contained round, multilamellated inclusions. Golgi studies revealed meganeurites arising from medium spiny neurons. Other areas of the central nervous system appeared relatively unaffected, although small basilar dilatations were observed in scattered cortical pyramidal neurons and Purkinje cell dendrites showed focal swellings. Vacuolated cells of the reticuloendothelial system were observed, including Kupffer cells and histiocytes in the spleen, marrow, and intestinal tract. Biochemical analysis revealed a generalized beta-galactosidase deficiency with specific accumulation of GM1 ganglioside in the basal ganglia.