Search PubMed⌕ Search

Biomedical subjects

H Sakuraba

Publications and source records attributed to H Sakuraba.

At least 109 records · Page 6Linked to original sources
PubMed1994

Evidence for direct binding of intracellularly distributed ganglioside GM2 to isolated vimentin intermediate filaments in normal and Tay-Sachs disease human fibroblasts.

Although some intracellularly distributed glycosphingolipids are reported to be associated with vimentin intermediate filaments or colchicine sensitive cytoskeleton, no direct evidence for such an association has yet been shown. In this report we demonstrated that the intracellularly distributed ganglioside GM2 directly binds to isolated vimentin intermediate filaments in normal and Tay-Sachs disease human fibroblasts. Indirect immunofluorescence microscopy using a GM2-specific monoclonal antibody demonstrated filamentously distributed GM2 in the cytoplasm. A double staining of Tay-Sachs fibroblasts with anti-GM2 and anti-vimentin monoclonal antibodies strongly suggested that the GM2 positive filaments are vimentin intermediate filaments. We then isolated vimentin, in the presence of a detergent and urea, from the normal human skin fibroblasts and murine mastocytoma cells. In a solid phase enzyme-linked immunosorbent assay, the isolated vimentin dose-dependently reacted with both anti-vimentin and anti-GM2 monoclonal antibodies but not with anti-GM3 or anti-GM1 monoclonal antibody. The molar ratio of GM2 to vimentin was approximately 20:1. The lipid fraction extracted from the purified vimentin preparation was immunostained with anti-GM2 on a thin-layer chromatography plate. Furthermore, only one band was detected at the molecular weight of 57 kDa, after electroblotting and simultaneous immunostaining with anti-GM2 and anti-vimentin monoclonal antibodies. These results clearly indicated that ganglioside GM2 directly binds to vimentin.

Animals↗
PubMed1994

[Molecular genetics of inherited metabolic diseases--its application to the investigation of pathogenesis and the diagnosis of Fabry disease].

Fabry disease is an X-linked inborn error of glycosphingolipid catabolism resulting from the deficient activity of the lysosomal hydrolase, alpha-galactosidase. Patients with classic Fabry disease of early onset show diverse clinical manifestations caused by generalized vasculopathy. Recent clinical and enzymatic examinations have revealed another form of this disease; progressive cardiomyopathy of late onset without other systemic signs or symptoms. Efforts were directed to identify the specific mutations in the alpha-galactosidase gene and to clarify the phenotype/genotype correlations. A variety of mutations, including deletions, nonsense mutations, splicing mutations and amino acid substitutions caused the classic form of Fabry manifestations, which resulted in the complete deficiency of alpha-galactosidase activity. Single base substitutions were detected in the upstream region of alpha-galactosidase gene exon 6, which resulted in residual enzyme activity. The degree of the expressed residual enzyme activity might determine the clinical phenotypes. Heterozygotes were successfully identified by gene analysis and immunofluorescence imaging diagnosis using confocal laser scanning microscopy.

DNA↗
PubMed1993

Characterization of a mutant alpha-galactosidase gene product for the late-onset cardiac form of Fabry disease.

The expression product of a mutant alpha-galactosidase gene, Q279E (279Gln-->Glu), found in an atypical variant (cardiac form) of Fabry disease, was purified and characterized. It had kinetic properties similar to those of normal alpha-galactosidase, but was markedly thermolabile at neutral pH. Galactose and melibiose at high concentrations stabilized the mutant enzyme in vitro. Its catalytic activity was 15% of that for the normal enzyme, when it was expressed in COS-1 cells at 37 degrees C. The activity increased at 30 degrees C or in the presence of galactose at 37 degrees C. An increase was also observed in lymphoblasts from a patient with this mutation in the presence of galactose or melibiose. We conclude that this mutant protein is posttranslationally inactivated under the neutral conditions in the cells. The possibility of a new therapeutic approach is suggested.

Age of Onset↗
PubMed1993

Cloning and sequence analysis of a full length cDNA encoding human mitochondrial 3-oxoacyl-CoA thiolase.

The cDNA sequence of human mitochondrial 3-oxoacyl-CoA thiolase was determined. The nucleotide sequence contains an open reading frame of 1191 base pairs and encodes an amino acid sequence of 397 residues which exhibits 86.6% homology with that of the rat enzyme. Northern blot analysis gave a single mRNA species of 1.6 kb in the human liver, fibroblasts and intercostal muscle.

Acetyl-CoA C-Acyltransferase↗
PubMed1993

Characterization of an anti-beta-galactosidase antibody recognizing a precursor but not a mature enzyme in solution.

A monospecific antibody was raised against a recombinant human 84-kDa beta-galactosidase precursor protein, which had been produced with a baculovirus gene expression system and affinity-purified. It bound to the 64-kDa mature enzyme protein extracted from human fibroblasts and the antigenic recombinant precursor on immunoblotting, but neither the fibroblast-derived mature enzyme nor the 64-kDa mature protein-like tryptic product of the recombinant precursor protein was immunoprecipitated. We conclude that it specifically recognized the precursor but not the mature protein in solution. Immunoprecipitation with this anti-precursor antibody revealed that the precursor protein mainly accounted for the residual enzyme activity in fibroblasts from an adult GM1-gangliosidosis patient, and the mature protein accounted for the activity in fibroblasts from a juvenile GM1-gangliosidosis patient.

Animals↗
PubMed1993

The major mutation among Japanese patients with infantile Tay-Sachs disease: a G-to-T transversion at the acceptor site of intron 5 of the beta-hexosaminidase alpha gene.

A G-to-T substitution at the 3'-splice site of intron 5 in the beta-hexosaminidase alpha-subunit gene has been identified among Japanese patients with infantile Tay-Sachs disease. Of the 24 patients from 24 unrelated families, 15 were homozygous and 8 were heterozygous for this mutation (38/48 mutant alleles). The mutation causes a splicing abnormality, and the resultant mRNA lacks the exon 6 sequence. Northern blot analysis showed a single band of mRNA, distinctly shorter in size and slightly smaller in quantity than normal. Since exon 6 consists of 102 nucleotides, the mRNA should generate a beta-hexosaminidase alpha-subunit missing 34 amino acids in the middle but otherwise normal in the primary structure. It must be catalytically inactive or unstable, or both. The high frequency of this mutation among the Japanese patients with the infantile form of Tay-Sachs disease and its apparent absence outside of Japan suggests that this mutation may have originated in Japan.

Base Sequence↗
PubMed1993

Purification and characterization of human lysosomal protective protein expressed in stably transformed Chinese hamster ovary cells.

Chinese hamster ovary cells were transfected with a recombinant DNA containing the entire coding sequence of human lysosomal protective protein cDNA under the control of mouse metallothionein I promoter. Neomycin and methotrexate-resistant stably transformed cell lines expressing this protein were isolated. Immunoprecipitation of the product with antiserum against human placental protective protein-beta-galactosidase complex revealed a 52-kDa protective protein precursor, which was then processed to mature form, a heterodimer of 32- and 20-kDa polypeptides. The precursor secreted in the culture medium was taken up by the mannose 6-phosphate receptor system and restored acid carboxypeptidase, beta-galactosidase, and neuraminidase activities in galactosialidosis fibroblasts. The expressed protein showed a granular pattern in intracellular distribution, was fractionated at the density of lysosomes, and had serine esterase activities; acid carboxypeptidase at pH 5.6, esterase at pH 7.0, and carboxyl-terminal deamidase at pH 7.0. They were inhibited simultaneously by phenylmethylsulfonyl fluoride, N-benzyloxycarbonyl-L-phenylalanine chloromethyl ketone, or iodoacetamide. The acid carboxypeptidase activity of the purified monomeric mature protective protein was labile in vitro under the acidic condition. Saposins (sphingolipid activator proteins) stabilized the activity at micromolar level concentrations.

Animals↗
PubMed1993

Quantitative analysis of dystrophin gene amplification products using a PC-based image analysis system.

A PC-based image analysis system for gel photographs of DNA gel patterns was developed. It was originally designed as a general-purpose, low-cost, yet high-performance system for wide applications in the biomedical area. In this study, we performed analysis of gel images obtained by polymerase chain reaction (PCR) amplification. The system employs a high-resolution CCD camera that can accurately measure grayness of the gel photographs for quantitative analysis of PCR products. The target DNA (exon 52 of the dystrophin gene), which had been found to be deleted in some patients with Duchenne/Becker muscular dystrophy (DMD/BMD), was amplified for the female family members together with the control DNA (exon 60) as a reference. The ratio of the target DNA to the control DNA was determined from PCR products to identify the carrier status of this disease by means of gene dosage. We conclude that 'the PC-based image analysis system' was useful for quantitative deletion analysis of DMD/BMD heterozygotes.

Adult↗
PubMed1993

Immunofluorescence imaging diagnosis of Fabry heterozygotes using confocal laser scanning microscopy.

An immunofluorometric method was developed for the semiquantitative determination of trihexosylceramide in cultured fibroblasts from Fabry disease patients, using a laser scanning confocal imaging system. The accumulated glycolipid was detected as granular inclusions in the cells. Heterozygote identification was achieved both by counting of immunoreactive cells and by measuring the relative fluorescence intensity with a digital imaging system.

Adult↗
PubMed1993

Protective protein gene mutations in galactosialidosis.

Four different protective protein cDNA mutations, 146A-->G (Q49R), 193T-->C (W65R), 268-269TC-->CT (S90L), and 1184A-->G (Y395C), were identified in six Japanese galactosialidosis patients with various phenotypic manifestations, and another mutation, 746T-->A (Y249N), in a patient of French-German origin with an atypical clinical course. Y395C was a common mutation in four Japanese patients in infancy and childhood; two juvenile patients were compound heterozygotes of Y395C and another common mutation, SpDEx7, and the other two infants were compound heterozygotes of Y395C and mutant alleles other than SpDEx7. We confirmed these mutations in genomic DNA by direct-sequence analysis or restriction-site analysis. The mutant cDNA clones, transiently expressed in a transformed galactosialidosis cell line, did not restore the secondarily deficient beta-galactosidase or alpha-neuraminidase activity except for the Y249N mutation that expressed some carboxypeptidase activity and restored the two lysosomal enzyme activities. Pulse-chase analysis detected a small amount of the mature form, as well as the precursor, in the cells transfected with the Y249N cDNA. Only precursor proteins were detected, mature proteins not appearing for the other mutant cDNAs.

Adolescent↗
PubMed1992

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.

Adult↗
PubMed1992

Point mutations in the upstream region of the alpha-galactosidase A gene exon 6 in an atypical variant of Fabry disease.

Single point mutations in the upstream region of exon 6 of the alpha-galactosidase A gene were found in two Japanese cases of the cardiac form of Fabry disease; 301Arg----Gln (902G----A) in a case that has already been published and 279Gln----Glu (835C----G) in a new case. They both expressed markedly low, but significant, amounts of residual activity in COS-1 cells. In contrast, two unrelated cases with classic Fabry disease were found to have different point mutations, which showed a complete loss of enzyme activity in a transient expression assay; 328Gly----Arg (982G----A) in the downstream region of exon 6 in one case and two combined mutations, 66Glu----Gln (196G----C)/112Arg----Cys (334C----T), in exon 2 in the other. We conclude, on the basis of the results recorded in this study and those in previous reports, that the pathogenesis of atypical Fabry disease is closely associated with point mutations in the upstream region of exon 6 of the alpha-galactosidase A gene.

Adolescent↗
PubMed1992

Invariant exon skipping in the human alpha-galactosidase A pre-mRNA: Ag+1 to t substitution in a 5'-splice site causing Fabry disease.

Fabry disease, an inborn error of glycosphingolipid catabolism, results from lesions in the X-linked gene encoding the human lysosomal hydrolase, alpha-galactosidase A (alpha-D-galactoside galactohydrolase; EC 3.2.1.22). To detect alpha-galactosidase A RNA processing or stability defects causing Fabry disease, Northern hybridization analyses were performed with poly(A)+ RNA isolated from cultured lymphoblasts from unrelated Fabry hemizygotes. Using a riboprobe complimentary to the normal 1.45-kb alpha-galactosidase A mRNA, a single 1.25-kb transcript was identified in three classically affected brothers from a Japanese Fabry family. Densitometric analysis revealed that the 1.25-kb transcripts were present at 50 to 60% of normal amounts. RNase A analysis identified a deletion of about 200 bp that appeared to include the entire 198 bp of exon 6. Amplification and direct sequencing of a genomic region containing exon 6 from an affected hemizygote revealed a g+1 to t transversion in the invariant gt consensus 5'-splice site of intron 6, which resulted in the deletion of the entire exon 6 sequence. This novel splicing lesion causing Fabry disease is the first g+1 to t transversion of a mammalian 5'-splice site that consistently eliminates the preceding exon.

Base Sequence↗
PubMed1992

Carrier detection of Duchenne/Becker muscular dystrophy: computer-assisted direct quantitation of gene amplification products.

An improved method by quantitative dystrophin gene deletion analysis was developed for the detection of Duchenne/Becker muscular dystrophy (DMD/BMD) carriers. Exon 52, which had been found to be deleted in DMD probands, was amplified for female family members, together with exon 60 as a reference, at the exponential phase of polymerase chain reaction. The products were separated by electrophoresis, the band intensities on gel photographs were quantitated, and the target/control ratios were calculated. The values for three heterozygous mothers were approximately half those for normal individuals and two definite non-heterozygous mothers. This procedure is easy, rapid and useful for the carrier diagnosis of DMD/BMD.

Base Sequence↗
PubMed1992

Two cases of Fabry's disease: a hemizygote with a point mutation in the alpha-galactosidase A gene and his relative.

A 34-year-old Japanese male had leg pain, edema of the legs, hypohidrosis, whorl-like opacities of the bilateral cornea, bilateral subcapsular cataracts, and chest discomfort on exercise. He had no characteristic angiokeratomas but did have telangiectases. The electrocardiogram revealed high voltage. The echocardiogram revealed mild mitral regurgitation. The alpha-galactosidase A activity in cultured lymphoblasts was deficient (0.5 nmol/h/mg protein). Electron microscopic examination of the skin revealed lamellar cytoplasmic inclusions in the endothelial cells, pericytes, and fibroblasts. He had a G--> A transition at nucleotide 982 in the coding sequence of the alpha-galactosidase A gene which resulted in a glycine to arginine amino acid substitution at residue 328. His uncle also had leg pain, edema of the legs, hypohidrosis, and chest pain on exercise. He had no characteristic angiokeratomas but did have telangiectases. Cardiovascular examination revealed hypertrophic cardiomyopathy and stenoses of coronary arteries. Electron microscopic examination of the skin revealed lamellar cytoplasmic inclusions in the endothelial cells, pericytes, and fibroblasts.

Adult↗
PubMed1992

GM1-gangliosidosis: tandem duplication within exon 3 of beta-galactosidase gene in an infantile patient.

A 23-nucleotide tandem duplication (GGACCTTGAAAGTACTC-GGGACC) was found within exon 3 of the beta-galactosidase gene in a patient with infantile-form GM1-gangliosidosis, which generated a premature stop codon after translation of 36 amino acids. Homologous sequences at the area of duplication suggested that the mutation resulted from an unequal crossover. A single base substitution 316Trp----Cys was found in the other allele. Family study showed that the duplication was transmitted from his father and the base substitution from his mother.

Base Sequence↗