Takayoshi Shimohata

Expanded polyglutamine stretches interact with TAFII130, interfering with CREB-dependent transcription.

At least eight inherited neurodegenerative diseases are caused by expanded CAG repeats encoding polyglutamine (polyQ) stretches. Although cytotoxicities of expanded polyQ stretches are implicated, the molecular mechanisms of neurodegeneration remain unclear. We found that expanded polyQ stretches preferentially bind to TAFII130, a coactivator involved in cAMP-responsive element binding protein (CREB)-dependent transcriptional activation, and strongly suppress CREB-dependent transcriptional activation. The suppression of CREB-dependent transcription and the cell death induced by polyQ stretches were restored by the co-expression of TAFII130. Our results indicate that interference of transcription by the binding of TAFII130 with expanded polyQ stretches is involved in the pathogenetic mechanisms underlying neurodegeneration.

Suppression of aggregate formation and apoptosis by transglutaminase inhibitors in cells expressing truncated DRPLA protein with an expanded polyglutamine stretch

To elucidate the molecular mechanisms whereby expanded polyglutamine stretches elicit a gain of toxic function, we expressed full-length and truncated DRPLA (dentatorubral-pallidoluysian atrophy) cDNAs with or without expanded CAG repeats in COS-7 cells. We found that truncated DRPLA proteins containing an expanded polyglutamine stretch form filamentous peri- and intranuclear aggregates and undergo apoptosis. The apoptotic cell death was partially suppressed by the transglutaminase inhibitors cystamine and monodansyl cadaverine (but not putrescine), suggesting involvement of a transglutaminase reaction and providing a potential basis for the development of therapeutic measures for CAG-repeat expansion diseases.

Efficacy and safety of leuprorelin in patients with spinal and bulbar muscular atrophy (JASMITT study): a multicentre, randomised, double-blind, placebo-controlled trial

BACKGROUND Spinal and bulbar muscular atrophy is a hereditary motor neuron disease caused by the expansion of a polyglutamine tract in the androgen receptor. At present there are no treatments for spinal and bulbar muscular atrophy, although leuprorelin suppressed the accumulation of pathogenic androgen receptors in a phase 2 trial. We aimed to assess the efficacy and safety of leuprorelin for spinal and bulbar muscular atrophy. METHODS The Japan SBMA Interventional Trial for TAP-144-SR (JASMITT) was a 48-week, randomised, double-blind, placebo-controlled trial done at 14 hospitals between August, 2006, and March, 2008. Patients with spinal and bulbar muscular atrophy were randomly assigned (1:1) by minimisation to subcutaneous 11.25 mg leuprorelin or identical placebo every 12 weeks. Patients and investigators were masked to treatment allocation. The primary endpoint was pharyngeal barium residue, which indicates incomplete bolus clearance, measured at week 48 by videofluorography. All patients who were randomly assigned and who were assessed with videofluorography at least once were included in the analyses. This study is registered with the JMACCT clinical trials registry, number JMA-IIA00009, and the UMIN clinical trials registry, number UMIN000000465. FINDINGS 204 patients were randomly assigned and 199 started treatment: 100 with leuprorelin and 99 with placebo. At week 48, the pharyngeal barium residue after initial swallowing had changed by -5.1% (SD 21.0) in the leuprorelin group and by 0.2% (18.2) in the placebo group (difference between groups -5.3%; 95% CI -10.8 to 0.3; p=0.063). The mean difference in pharyngeal barium residue after piecemeal deglutition at week 48 was -3.2% (-6.4 to 0.0; p=0.049), but there was no significant difference between the groups after covariate adjustment for the baseline data (-4.1 to 1.6; p=0.392). In a predefined subgroup analysis, leuprorelin treatment was associated with a greater reduction in barium residue after initial swallowing than was placebo in patients with a disease duration less than 10 years (difference between groups -9.8, -17.1 to -2.5; p=0.009). There were no significant differences in the number of drug-related adverse events between groups (57 of 100 in the leuprorelin group and 54 of 99 in the placebo group; p=0.727). INTERPRETATION 48 weeks of treatment with leuprorelin did not show significant effects on swallowing function in patients with spinal and bulbar muscular atrophy, although it was well tolerated. Disease duration might influence the efficacy of leuprorelin and thus further clinical trials with sensitive outcome measures should be done in subpopulations of patients. FUNDING Large Scale Clinical Trial Network Project, Japan and Takeda Pharmaceuticals.

Widespread occurrence of intranuclear atrophin-1 accumulation in the central nervous system neurons of patients with dentatorubral-pallidoluysian atrophy

Dentatorubral‐pallidoluysian atrophy (DRPLA) is an autosomal dominant neurodegenerative disorder caused by a CAG repeat expansion. In the present study of DRPLA, we have demonstrated immunohistochemically that diffuse accumulation of mutant atrophin‐1 in the neuronal nuclei, rather than the formation of neuronal intranuclear inclusions (NIIs), was the predominant pathologic condition and involved a wide range of central nervous system regions far beyond the systems previously reported to be affected. In the neuronal nuclei harboring NIIs, promyelocytic leukemia protein (PML) nuclear bodies were redistributed into a single NII, and the CREB (cAMP‐responsive element–binding protein)‐binding protein was also recruited into NIIs. The results suggest that the novel lesion distribution revealed by the diffuse nuclear labeling may be responsible for a variety of clinical features, such as dementia and epilepsy in DRPLA, and that certain transcriptional abnormalities may be induced secondarily in neuronal nuclei with the formation of NIIs. Ann Neurol 2001;49:14–23

Cerebellar involvement in progressive supranuclear palsy: A clinicopathological study†

The clinical heterogeneity of progressive supranuclear palsy (PSP), which is classified as classic Richardsons syndrome (RS) and PSP‐Parkinsonism (PSP‐P), has been previously discussed. We retrospectively analyzed 22 consecutive Japanese patients with pathologically proven PSP to investigate the clinicopathological heterogeneity. We investigated the clinical features both early in and at any time during the disease course. The pathological severities of neuronal loss with gliosis and tau pathology were also evaluated. On the basis of the clinical features, 10 patients were categorized as having RS, and 8 were categorized as having PSP‐P. Four patients presenting with cerebellar ataxia or cerebral cortical signs were categorized as having unclassifiable PSP. Among them, 3 developed cerebellar ataxia as the initial and principal symptom. Notably, tau‐positive inclusion bodies in Purkinje cells were significantly more frequently observed in the patients with cerebellar ataxia than in those without cerebellar ataxia. All the patients with cerebellar ataxia exhibited more neuronal loss with gliosis and higher densities of coiled bodies in the cerebellar dentate nucleus than those without cerebellar ataxia. This study confirms the wide spectrum of clinicopathological manifestations associated with PSP regardless of different ethnic origin, and demonstrates that PSP patients manifest cerebellar ataxia.

Huntington's disease–like 2 (HDL2) in North America and Japan

Huntingtons Disease–like 2 (HDL2) is a progressive, autosomal dominant, neurodegenerative disorder with marked clinical and pathological similarities to Huntingtons disease (HD). The causal mutation is a CTG/CAG expansion mutation on chromosome 16q24.3, in a variably spliced exon of junctophilin‐3. The frequency of HDL2 was determined in nine independent series of patients referred for HD testing or selected for the presence of an HD‐like phenotype in North America or Japan. The repeat length, ancestry, and age of onset of all North American HDL2 cases were determined. The results show that HDL2 is very rare, with a frequency of 0 to 15% among patients in the nine case series with an HD‐like presentation who do not have the HD mutation. HDL2 is predominantly, and perhaps exclusively, found in individuals of African ancestry. Repeat expansions ranged from 44 to 57 triplets, with length instability in maternal transmission detected in a repeat of 33 triplets. A younger age of onset is correlated with a longer repeat length (r2 = 0.29, p = 0.0098). The results further support the evidence that the repeat expansion at the chromosome 16q24.3 locus is the direct cause of HDL2 and provide preliminary guidelines for the genetic testing of patients with an HD‐like phenotype. Ann Neurol 2004

Atrophy of the cerebellum and brainstem in dentatorubral pallidoluysian atrophy. Influence of CAG repeat size on MRI findings.

To elucidate how the size of the expanded CAG repeat of the gene for dentatorubral pallidoluysian atrophy (DRPLA) and other factors affect the atrophy of the brainstem and cerebellum, and the appearance of high-intensity signals on T2-weighted MRI of the cerebral white matter of patients with DRPLA, we quantitatively analyzed the MRI findings of 26 patients with DRPLA, the diagnosis of which was confirmed by molecular analysis of the DRPLA gene. When we classified the patients into two groups based on the size of the expanded CAG repeat of the DRPLA gene (group 1, number of CAG repeat units≥66; group 2, number of CAG repeat units ≤65), we found strong inverse correlations between the age at MRI and the areas of midsagittal structures of the cerebellum and brainstem in group 1 but not in group 2. Multiple regression analysis, however, revealed that both the patients age at MRI and the size of the expanded CAG repeat correlated with the areas of midsagittal structures. Involvement of the cerebral white matter as detected on T2-weighted images was observed more frequently in patients belonging to group 2 than in group 1 patients. Furthermore it was demonstrated that high-intensity signals can be detected on T2-weighted images of the cerebral white matter of patients with a largely expanded CAG repeat (group 1) in their thirties. These results suggest that patient age as well as the size of the expanded CAG repeat are related to the degree of atrophy of the brainstem and cerebellum, and the white matter changes in patients with DRPLA.

Interaction between Neuronal Intranuclear Inclusions and Promyelocytic Leukemia Protein Nuclear and Coiled Bodies in CAG Repeat Diseases

Neuronal intranuclear inclusions (NIIs) are a pathological hallmark of CAG repeat diseases. To elucidate the influence of NII formation on intranuclear substructures, we investigated the relationship of NIIs with nuclear bodies in brains of dentatorubral-pallidoluysian atrophy and Machado-Joseph disease. In both diseases, promyelocytic leukemia protein, a major component of the promyelocytic leukemia protein nuclear bodies, altered the normal distribution and was rearranged around NII, forming a single capsular structure. We further demonstrated that NIIs were present in close contact with coiled bodies, a highly dynamic domain that may be involved in the biogenesis of small nuclear ribonucleoproteins. The preferential association of intranuclear polyglutamine aggregates with coiled bodies was also confirmed in the dentatorubral-pallidoluysian atrophy transgenic mouse brain and culture cells expressing mutant atrophin-1. The results suggest that the interaction between NIIs and nuclear bodies may play a role in the pathogenesis of CAG repeat diseases.

Symptomatic Narcolepsy in Patients With Neuromyelitis Optica and Multiple Sclerosis New Neurochemical and Immunological Implications

OBJECTIVE To characterize factors that contribute to symptomatic narcolepsy and excessive daytime sleepiness in neuromyelitis optica and multiple sclerosis. SETTING Japanese university hospitals. DESIGN Case study. PATIENTS Seven Japanese patients whose initial diagnoses were multiple sclerosis and who were exhibiting excessive daytime sleepiness. MAIN OUTCOME MEASURES Lesions on magnetic resonance imaging, cerebrospinal fluid hypocretin-1 levels, and serum anti-aquaporin 4 (AQP4) antibody titer. RESULTS Bilateral and symmetrical hypothalamic lesions associated with marked or moderate hypocretin deficiency were found in all 7 cases. Four of these patients met the International Classification of Sleep Disorders 2 narcolepsy criteria. Three patients, including 2 patients with narcolepsy, were seropositive for anti-AQP4 antibody and diagnosed as having neuromyelitis optica-related disorder. CONCLUSION Since AQP4 is highly expressed in the hypothalamic periventricular regions, an immune attack on AQP4 may be partially responsible for the bilateral and hypothalamic lesions and hypocretin deficiency in narcolepsy/excessive daytime sleepiness associated with autoimmune demyelinating diseases.

No mutation in the entire coding region of the α-synuclein gene in pathologically confirmed cases of multiple system atrophy

To determine whether mutations in the coding region of the alpha-synuclein gene are relevant in cases of multiple system atrophy (MSA), detailed nucleotide sequence analysis of the alpha-synuclein gene was performed using total RNA obtained from autopsied brain specimens of 11 pathologically confirmed cases of MSA. The brain specimens used in this study contained both gray and white matter, which were dissected from the frontal, temporal or occipital lobe. No nucleotide alterations were found in the entire coding region of the alpha-synuclein gene in any of the cases. While mutations in the regulatory or intronic regions of the gene were not ruled out, our results suggest that mutations in the coding region of the alpha-synuclein gene are unlikely to contribute to the pathogenesis of MSA.