K Sakoe

University of Yamanashi, Kōhu, Yamanashi, Japan

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Publications (29)198.63 Total impact

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    ABSTRACT: Autosomal recessive hereditary spastic paraplegias (AR-HSP) constitute a heterogeneous group of neurodegenerative diseases involving pyramidal tracts dysfunction. The genes responsible for many types of AR-HSPs remain unknown. We attempted to identify the gene responsible for AR-HSP with optic atrophy and neuropathy. The present study involved two patients in a consanguineous Japanese family. Neurologic examination and DNA analysis were performed for both patients, and a skin biopsy for one. We performed genome-wide linkage analysis involving single nucleotide polymorphism arrays, copy-number variation analysis, and exome sequencing. To clarify the mitochondrial functional alteration resulting from the identified mutation, we performed immunoblot analysis, mitochondrial protein synthesis assaying, blue native polyacrylamide gel electrophoresis (BN-PAGE) analysis, and respiratory enzyme activity assaying of cultured fibroblasts of the patient and a control. We identified a homozygous nonsense mutation (c.394C>T, p.R132X) in C12orf65 in the two patients in this family. This C12orf65 mutation was not found in 74 Japanese AR-HSP index patients without any mutations in previously known HSP genes. This mutation resulted in marked reduction of mitochondrial protein synthesis, followed by functional and structural defects in respiratory complexes I and IV. This novel nonsense mutation in C12orf65 could cause AR-HSP with optic atrophy and neuropathy, resulting in a premature stop codon. The truncated C12orf65 protein must lead to a defect in mitochondrial protein synthesis and a reduction in the respiratory complex enzyme activity. Thus, dysfunction of mitochondrial translation could be one of the pathogenic mechanisms underlying HSPs.
    Journal of Medical Genetics 12/2012; 49(12):777-84. · 5.70 Impact Factor
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    ABSTRACT: BACKGROUND AND PURPOSE: Magnetic resonance imaging (MRI) of autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) cases in Quebec and Europe was reported to show linear hypointensities in T2-weighted and Fluid Attenuated Inversion Recovery (FLAIR) images of the pons. We attempted to clarify the characteristics of the brain MRI findings in ARSACS cases. METHODS: Eight Japanese early-onset ataxia patients with ARSACS confirmed molecularly were investigated. We performed neurological examination, SACS gene analysis, and MRI in the patients. RESULTS: Hypointensity lesions in the middle cerebellar peduncles in addition to the pons were observed in T2-weighted and FLAIR images in all eight cases. Although superior cerebellar atrophy was seen in all cases, this MRI finding might not be specific for ARSACS. Upper cervical cord and medulla oblongata atrophy was not observed in 3 of the 7 patients examined. CONCLUSION: Not only pontine but also middle cerebellar peduncle hypointensity lesions observed in T2-weighted and FLAIR images could be specific findings for ARSACS even in cases with variable clinical phenotypes. J Neuroimaging 2012;XX:1-4.
    Journal of neuroimaging: official journal of the American Society of Neuroimaging 01/2012; · 3.36 Impact Factor
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    ABSTRACT: We present here a 25-year-old woman with genetically confirmed (p.R276L mutation in the GFAP gene) juvenile-onset AxD. Episodic vomiting appeared at age nine, causing anorexia and insufficient growth. Brain MRI at age 11 showed a small nodular lesion with contrast enhancement in the left dorsal portion of the cervicomedullary junction. Her episodic vomiting improved spontaneously at age 13, and she became neurologically asymptomatic. The enhancement of the lesion disappeared simultaneously, although the plaque remained. Longitudinal MRI observations, however, revealed insidiously progressive cervicomedullary atrophy without a signal change. This case broadens our knowledge of AxD: (1) molecular analysis of the GFAP gene is warranted in patients with MRI evidence of tumor-like lesions in the brainstem, particularly if they present with isolated episodic vomiting and/or anorexia; (2) the disease can be self-remitting for at least 12 years; (3) cervicomedullary atrophy, characteristic of the adult form, can be insidiously progressive without a signal change before the clinical symptoms appear.
    Neurological Sciences 12/2011; · 1.41 Impact Factor
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    ABSTRACT: The goal of this study was to explore the molecular mechanisms of aberrant hypoxia inducible factor-1 (HIF-1) activation in lymphoma cells. We analyzed the expression of the α subunit of HIF-1 in three lymphoma cell lines and in normal CD19-positive B cells by Western blotting. To investigate the role of nuclear factor (NF)-κB in abnormal HIF-1α expression in lymphoma cells, we performed a reporter assay using HIF-1α promoter constructs that contained or lacked an NF-κB binding site. We also used a chromatin immunoprecipitation assay to assess whether NF-κB binds the HIF-1α promoter. In addition, we took advantage of NF-κB inhibitors. To analyze the function of HIF-1 in lymphoma cells, we established stable HIF-1α knockdown cells using short-hairpin RNA. Malignant lymphoma cells, but not normal B cells, demonstrated constitutive expression of HIF-1α. Inhibitors of NF-κB, however, drastically suppressed this HIF-1α expression at both the messenger RNA and protein levels. Furthermore, we found that exposure of lymphoma cells to ionizing radiation clearly induced NF-κB activation and increased HIF-1α expression. Suppressing HIF-1α expression by short-hairpin RNA increased the sensitivity of lymphoma cells to ionizing radiation-induced cell death. In searching for downstream targets of the NF-κB/HIF-1 axis, we identified survivin, a member of the IAP family of anti-apoptotic proteins. We found that aberrant activation of HIF-1 in malignant lymphoma cells was mediated, at least in part, by NF-κB activity. Our observations suggest that HIF-1 inhibition may be an effective strategy to improve the outcomes of lymphoma patients treated with radiation.
    Experimental hematology 12/2010; 38(12):1199-208. · 3.11 Impact Factor
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    ABSTRACT: Alexander disease (ALX) is a rare neurological disorder characterized by white matter degeneration and cytoplasmic inclusions in astrocytes called Rosenthal fibers, labeled by antibodies against glial fibrillary acidic protein (GFAP). Three subtypes are distinguished according to age at onset: infantile (under age 2), juvenile (age 2 to 12) and adult (over age 12). Following the identification of heterozygous mutations in GFAP that cause this disease, cases of adult-onset ALX have been increasingly reported. We present a 60-year-old Japanese man with an unremarkable past and no family history of ALX. After head trauma in a traffic accident at the age of 46, his character changed, and dementia and dysarthria developed, but he remained independent. Spastic paresis and dysphagia were observed at age 57 and 59, respectively, and worsened progressively. Neurological examination at the age of 60 revealed dementia, pseudobulbar palsy, left-side predominant spastic tetraparesis, axial rigidity, bradykinesia and gaze-evoked nystagmus. Brain MRI showed tadpole-like atrophy of the brainstem, caused by marked atrophy of the medulla oblongata, cervical spinal cord and midbrain tegmentum, with an intact pontine base. Analysis of the GFAP gene revealed a heterozygous missense mutation, c.827G>T, p.R276L, which was already shown to be pathogenic in a case of pathologically proven hereditary adult-onset ALX. The typical tadpole-like appearance of the brainstem is strongly suggestive of adult-onset ALX, and should lead to a genetic investigation of the GFAP gene. The unusual feature of this patient is the symmetrical involvement of the basal ganglia, which is rarely observed in the adult form of the disease. More patients must be examined to confirm, clinically and neuroradiologically, extrapyramidal involvement of the basal ganglia in adult-onset ALX.
    BMC Neurology 04/2010; 10:21. · 2.56 Impact Factor
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    ABSTRACT: All-trans retinoic acid (ATRA) induces granulocytic differentiation and apoptosis in acute promyelocytic leukemia (APL) cells, although the detailed mechanisms are not fully understood. We investigated ATRA-induced cellular responses mediated by the transcription factor FOXO3A in APL cells. FOXO3A was constitutively phosphorylated and localized in the cytoplasm in both APL-derived NB4 cells and primary APL cells. Upon treating the cells with ATRA, FOXO3A phosphorylation was reduced and FOXO3A translocated into the nucleus. In addition, the expression of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), a target molecule for FOXO3A, was increased at the transcriptional and protein levels. As expected, transfection of a short hairpin RNA (shRNA) oligonucleotide specific for FOXO3A significantly inhibited ATRA-induced granulocytic differentiation and apoptosis in NB4 cells. In NB4-derived ATRA-resistant NB4/RA cells, neither FOXO3A nuclear localization nor subsequent TRAIL induction was observed after ATRA treatment. Furthermore, forced expression of active FOXO3A in the nucleus induced TRAIL production and apoptosis in NB4/RA cells. We conclude that activation of FOXO3A is an essential event for ATRA-induced cellular responses in NB4 cells. FOXO3A is a promising target for therapeutic approaches to overcome ATRA resistance in APL.
    Blood 03/2010; 115(18):3787-95. · 9.78 Impact Factor
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    ABSTRACT: Abnormal activation of hypoxia-inducible factor-1 (HIF-1), one of the most important transcription factors for the adaptation of cells to hypoxia, is frequently observed in numerous types of solid tumors. Dysregulation of HIF-1 induces tumor angiogenesis and enhances the expression of anti-apoptotic proteins and glycolysis-associated enzymes in cancer cells, which in turn leads to the promotion of tumor growth. In the present study, we examined the pathophysiologic role of HIF-1 in multiple myeloma. Furthermore, we explored the possibility that HIF-1 may be a molecular target for myeloma therapy. We identified constitutive expression of the hypoxia-inducible factor-1 alpha (HIF-1alpha)-subunit in established myeloma cell lines and in primary myeloma cells. Treatment with insulin-like growth factor-1 (IGF-1) significantly increased HIF-1alpha expression through activation of the AKT and mitogen-activated protein kinase signaling pathways. Inhibition of HIF-1 function either by echinomycin, a specific HIF-1 inhibitor, or a siRNA against HIF-1alpha resulted in enhanced sensitivity to melphalan in myeloma cells. This inhibition of HIF-1 also reversed the protective effect of IGF-1 on melphalan-induced apoptosis. Inhibition of HIF-1 drastically reduced both basal and IGF-1-induced expression of survivin, one of the most important anti-apoptotic proteins in myeloma cells. We conclude that HIF-1 inhibition may be an attractive therapeutic strategy for multiple myeloma.
    Molecular Cancer Therapeutics 09/2009; 8(8):2329-38. · 5.60 Impact Factor
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    ABSTRACT: We describe a Japanese family with familial platelet disorder with propensity to develop myeloid malignancies (FPD/MM). Among the three affected individuals, two members developed myeloid malignancies. Sequence studies demonstrate that all affected individuals of the pedigree display a heterozygous single nucleotide deletion in exon 8 of the RUNX1 gene.
    Haematologica 02/2008; 93(1):155-6. · 5.94 Impact Factor
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    ABSTRACT: The authors describe the four patients in the first known Belgian family with autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS). A novel homozygous missense mutation, NM_014363.3: c.3491T>A in exon 9, of the SACS gene was identified in the present family, which results in an original amino acid of methionine to lysine substitution at amino acid residue 1164 (p.M1164K). Although the cardinal clinical features, i.e., spastic ataxia with peripheral neuropathy, in our patients were similar to those in Quebec patients, our patients exhibited some atypical clinical features, e.g., teenage-onset and absence of retinal hypermyelination. The present family is from Wallonia, and there could be shared ethnicity with the families of Charlevoix-Saguenay.
    Journal of the Neurological Sciences 01/2008; 264(1-2):73-6. · 2.24 Impact Factor
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    ABSTRACT: The authors describe an unusual case of autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) without leg spasticity, which is a core clinical feature of ARSACS. This is the second family with a spasticity-lacking phenotype in ARSACS. A peripheral nerve conduction study disclosed decreases in motor and sensory nerve conduction velocities with the disease progression. Although the leg spasticity is reported to become progressively worse during the disease and is prevalent in older patients, we first observed that the symptom had disappeared, probably due to the progressive peripheral nerve degeneration in the disease course. Thus, we should analyze the SACS gene even in cases of early-onset cerebellar ataxia without spasticity. The patient had a novel homozygous 2-base pair deletion mutation (c.5988-9 del CT) of the SACS gene, but the genotype was different from that in our first family of this phenotype. A further genotype-phenotype correlation study is required to clarify the molecular mechanism underlying 'sacsinopathies'.
    Journal of the Neurological Sciences 05/2007; 255(1-2):87-9. · 2.24 Impact Factor
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    ABSTRACT: The autosomal dominant cerebellar ataxias (ADCAs) comprise a genetically and clinically heterogenous group of neurodegenerative disorders. Very recently, a C-to-T single nucleotide substitution in the puratrophin-1 gene was found to be strongly associated with a form of ADCA linked to chromosome 16q22.1 (16q-linked ADCA; OMIM 600223). We found the C-to-T substitution in the puratrophin-1 gene in 20 patients with ataxia (16 heterozygotes and four homozygotes) and four asymptomatic carriers in 9 of 24 families with an unknown type of ADCA. We also found two cases with 16q-linked ADCA among 43 sporadic patients with late-onset cortical cerebellar atrophy (LCCA). The mean age at onset in the 22 patients was 61.8 years, and that of homozygous patients was lower than that of heterozygous ones in one family. Neurological examination revealed that the majority of our patients showed exaggerated deep tendon reflexes in addition to the cardinal symptom of cerebellar ataxia (100%), and 37.5% of them had sensorineural hearing impairment, whereas sensory axonal neuropathy was absent. The frequency of 16q-linked ADCA was about 1/10 of our series of 110 ADCA families, making it the third most frequent ADCA in Japan.
    Journal of the Neurological Sciences 10/2006; 247(2):180-6. · 2.24 Impact Factor
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    ABSTRACT: The authors describe a Japanese autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) patient with a compound heterozygous mutation (32627-32636delACACTGTTAC and 31760delT) in a new exon of the SACS gene. The new exons upstream of the gigantic one should be analyzed when a case is clinically compatible with ARSACS, even without any mutation in the gigantic exon.
    Neurology 05/2006; 66(7):1103-4. · 8.30 Impact Factor
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    ABSTRACT: The authors describe two Japanese siblings with autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) without spasticity, usually a core feature of this disorder. They had a novel homozygous missense mutation (T987C) of the SACS gene, which resulted in a phenylalanine-to-serine substitution at amino acid residue 304.
    Neurology 07/2005; 64(12):2129-31. · 8.30 Impact Factor
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    ABSTRACT: The authors describe two patients in a Japanese family with autosomal recessive spastic ataxia of Charlevoix-Saguenay. They presented early onset spastic ataxia, sensorimotor neuropathy, nystagmus, slurred speech, and hypermyelinated retinal nerve fibers. The authors identified a homozygous missense mutation (T7492C) in the SACS gene, which resulted in the substitution of arginine for tryptophan at amino acid residue 2498 (W2498R).
    Neurology 02/2004; 62(1):107-9. · 8.30 Impact Factor
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    ABSTRACT: Alexander's disease, a leukodystrophy characterized by Rosenthal fibers (RFs) in the brain, is categorized into three subtypes: infantile, juvenile, and adult. Although most are sporadic, occasional familial Alexander's disease cases have been reported for each subtype. Hereditary adult-onset Alexander's disease shows progressive spastic paresis, bulbar or pseudobulbar palsy, palatal myoclonus symptomatologically, and prominent atrophy of the medulla oblongata and upper spinal cord on magnetic resonance imaging. Recent identification of GFAP gene mutations in the sporadic infantile- and juvenile-onset Alexander's disease prompted us to examine the GFAP gene in two Japanese hereditary adult-onset Alexander's disease brothers with autopsy in one case. Both had spastic paresis without palatal myoclonus, and magnetic resonance imaging showed marked atrophy of the medulla oblongata and cervicothoracic cord. The autopsy showed severely involved shrunken pyramids, but scarce Rosenthal fibers (RFs). Moderate numbers of Rosenthal fibers (RFs) were observed in the stratum subcallosum and hippocampal fimbria. In both cases, we found a novel missense mutation of a G-to-T transition at nucleotide 841 in the GFAP gene that results in the substitution of arginine for leucine at amino acid residue 276 (R276L). This is the first report of identification of the causative mutation of the GFAP gene for neuropathologically proven hereditary adult-onset Alexander's disease, suggesting a common molecular mechanism underlies the three Alexander's disease subtypes.
    Annals of Neurology 01/2003; 52(6):779-85. · 11.19 Impact Factor
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    ABSTRACT: We report the results of clinical and genetic studies on a Japanese SPG4 family. Family N included eight patients in four generations with autosomal dominant transmission. We performed neurological and molecular analyses on the SPG4 gene in the family members comprising three patients, 12 at-risk individuals, and three normal spouses. The three patients showed pure spastic paraplegia, two of them exhibiting a decrease in vibration sense. There was marked intrafamilial variability in age at onset and clinical severity in the present family. On molecular analysis, a novel missense mutation (nt1579 C-->T) in exon 12 of the SPG4 gene was found in the three patients, three probably affected, and an asymptomatic carrier. The present SPG4 family, which was shown to have a novel SPG4 mutation, exhibited marked variability in the clinical features, indicating the participation of additional factors in the phenotypic appearance of this family.
    Acta Neurologica Scandinavica 12/2002; 106(6):387-91. · 2.47 Impact Factor
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    ABSTRACT: Early-onset ataxia with hypoalbuminemia is regarded as a variant form of Friedreich ataxia in Japan. Early-onset ataxia with hypoalbuminemia and ataxia with ocular motor apraxia have been considered as the same clinical entity because of the recent identification of a common mutation in the aprataxin gene. A new clinical entity named early-onset ataxia with ocular motor apraxia and hypoalbuminemia (EAOH) has been proposed to explain these two diseases. To disclose the clinical features of EAOH and to identify the mutations in the aprataxin gene in six patients in four Japanese families with EAOH. The clinical features, laboratory findings, sural nerve biopsy results, and brain MRI or CT findings for these patients were evaluated, and molecular analysis was performed, which involved sequencing of the aprataxin gene directly or use of the subcloning method. Cerebellar ataxia and peripheral neuropathy were noted in all six patients. Ocular motor apraxia was observed in five patients; two of these patients had obvious head thrust. Choreiform movements of the limbs and mental deterioration were observed in five patients. Although foot deformity was noted in five patients, kyphoscoliosis was noted only in one patient. In all patients, hypoalbuminemia and hypercholesterolemia were evident, and brain MRI or CT showed marked cerebellar atrophy. Nerve biopsy revealed depletion of large myelinated fibers in three of the five patients examined. Molecular analysis of the aprataxin gene revealed an insertion mutation (insT at nt167) and two missense mutations (A-to-G transition at nt80 and C-to-T transition at nt95, the former being novel). We found clinical heterogeneity in the patients with EAOH in this study. With the disease course, the choreiform movements tended to reduce in degree, and hypoalbuminemia became evident. Molecular analysis identified one insertion and two missense mutations including a novel missense one, which was located at a highly conserved amino acid residue in the aprataxin gene product.
    Neurology 09/2002; 59(4):590-5. · 8.30 Impact Factor
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    ABSTRACT: We describe the unusual case of a 51-year-old woman with spinocerebellar ataxia type 1 (SCA1) who showed choreiform movements in addition to cerebellar ataxia. To date, extrapyramidal signs including involuntary movements have been rarely reported in SCA1. Surface electromyogram in our patient revealed grouped discharges whose duration was longer than that of chorea observed in HD, indicating that the involuntary movements represented choreoathetosis rather than pure chorea. These choreiform movements have not been seen in non-hereditary spinocerebellar ataxia. Therefore, if "sporadic" cases of cerebellar ataxia show such movements, the possibility of genetic origin of the ataxia is high and a surveillance of various forms of hereditary spinocerebellar ataxia including SCA1 is required.
    Journal of the Neurological Sciences 07/2001; 187(1-2):103-6. · 2.24 Impact Factor
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    ABSTRACT: Intergenerational stability of the CAG repeat number has been considered to be a specific molecular feature of SCA6 compared with other CAG repeat diseases. Nevertheless, we showed meiotic instability of the CAG repeats in the SCA6/CACNL1A gene in two Japanese SCA6 families, including de novo expansion. In one family, the CAG20 allele expanded to the CAG26 one during paternal transmission, and in the other family, the CAG19 allele expanded to the CAG20 one during maternal transmission. Although it is controversial as to whether the CAG20 allele is pathological or not, this is the first case of haplotype analysis-proven de novo expansion in SCA6, confirming the derivation of an expanded allele from one normal allele. We should carefully follow up the individuals carrying the CAG20 allele in our family who show normal neurological and radiological findings at present.
    Journal of the Neurological Sciences 05/2001; 185(2):101-7. · 2.24 Impact Factor
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    ABSTRACT: We studied a large Japanese family with autosomal dominant pure hereditary spastic paraplegia (ADPHSP) clinically and genetically. To date, seven loci causing ADPHSP have been mapped to chromosomes 14q, 2p, 15q, 8q, 12q, 2q, and 19q. Among these loci, the SPG4 locus on chromosome 2p21--p22 has been shown to account for approximately 40% of all autosomal dominant hereditary spastic paraplegia (ADHSP) families. Very recently, Hazan et al. identified the SPG4 gene encoding a new member of the AAA (ATPases associated with diverse cellular activities) protein family, named spastin. We found a novel insertion mutation (nt1272--1273insA) in exon 8 of the SPG4 gene in the present family. Our study is the first to confirm the causative mutation of the SPG4 gene in Japanese. Clinically, it is noteworthy that the disease progression in the patients of this family was slow in spite of the late onset, and more than half of the patients showed severe constipation in addition to pure spastic paraplegia.
    Journal of the Neurological Sciences 04/2001; 185(1):63-8. · 2.24 Impact Factor

Publication Stats

646 Citations
198.63 Total Impact Points

Institutions

  • 2009–2012
    • University of Yamanashi
      • • Department of Neurology
      • • Department of Hematology and Oncology
      Kōhu, Yamanashi, Japan
  • 1997–2012
    • Jichi Medical University
      • Division of Neurology
      Totigi, Tochigi, Japan
  • 2010
    • Juntendo University
      • Division of Hematology
      Edo, Tōkyō, Japan
  • 1999
    • New York Blood Center
      New York City, New York, United States