Hideji Hashida

High-density cDNA filter analysis: a novel approach for large-scale, quantitative analysis of gene expression

In order to analyze the expression profiles of a large number of genes in the tissues (or cells) of interest, and to identify the genes preferentially expressed in the tissues, we have developed a large-scale gene expression analysis system. It is based on the hybridization of the mRNAs from the tissues with a high-density cDNA filter followed by the quantitative measurement of the amount of the hybridized mRNA on each cDNA spot. By employing a high-performance bioimaging analyzer, the system allowed us to compare the expression profiles of thousands of genes (cDNAs) simultaneously with a sensitivity comparable to conventional Northern blotting analysis. By this system (called high-density cDNA filter analysis or HDCFA), the expression profiles of 2505 cloned human brain cDNAs (genes) were monitored. Through the comparison of the expression profiles of these cDNAs in the adult brain, fetal brain and adult liver, about one half of these brain cDNAs (1239 clones) were identified as the candidates which were expressed preferentially in the brain. Among these, 408 and 288 clones were found to be preferentially expressed in the adult and fetal brain, respectively. The results have shown that the system may be widely applicable for analysis of the gene expression profiles of various tissues on a large scale.

IFNβ-1b may severely exacerbate Japanese optic-spinal MS in neuromyelitis optica spectrum

Background: Interferon-β-1b (IFNβ-1b) has been used to prevent exacerbation of relapsing-remitting multiple sclerosis (RRMS) including optic-spinal multiple sclerosis (OSMS) in Japan. We encountered 2 patients with OSMS with unexpectedly severe exacerbation soon after the initiation of IFNβ-1b therapy. The experience urged us to retrospectively review the patients with RRMS who had been treated with IFNβ-1b to identify similar cases. Methods: At neurologic departments of 9 hospitals, the medical records of 56 patients with RRMS were reviewed to identify those who showed severe exacerbation soon after the initiation of IFNβ-1b therapy. Results: Of 56 patients with RRMS, we identified 7 who experienced severe exacerbation (exacerbation with increased scores of Expanded Disability Status Scale ≧7.0) within 90 days of the initiation of IFNβ-1b therapy. In all 7 patients, the exacerbations after the initiation of IFNβ-1b therapy were more severe than those experienced by the individual patients before the use of IFNβ-1b, and seemed to have occurred unexpectedly in a short time after the initiation of INFβ-1b therapy. A retrospective analysis revealed that all 7 patients had antibodies toward aquaporin 4, and the clinical features of all 7 patients after the exacerbation were consistent with those of neuromyelitis optica (NMO) spectrum. Conclusions: Our study suggests that IFNβ-1b may trigger severe exacerbation in patients with the NMO spectrum. In INFβ-1b therapy, cases in NMO spectrum should be carefully excluded.

Human spinal motoneurons express low relative abundance of GluR2 mRNA: an implication for excitotoxicity in ALS

AMPA receptor‐mediated neurotoxicity is currently the most plausible hypothesis for the etiology of amyotrophic lateral sclerosis (ALS). The mechanism initiating this type of neuronal death is believed to be exaggerated Ca2+‐influx through AMPA receptors, which is critically determined by the presence or absence of the glutamate receptor subunit 2 (GluR2) in the assembly. We have provided the first quantitative measurements of the expression profile of AMPA receptor subunits mRNAs in human single neurons by means of quantitative RT–PCR with a laser microdissector. Among the AMPA subunits, GluR2 shared the vast majority throughout the neuronal subsets and tissues examined. Furthermore, both the expression level and the proportion of GluR2 mRNA in motoneurons were the lowest among all neuronal subsets examined, whereas those in motoneurons of ALS did not differ from the control group, implying that selective reduction of the GluR2 subunit cannot be a mechanism of AMPA receptor‐mediated neurotoxicity in ALS. However, the low relative abundance of GluR2 might provide spinal motoneurons with conditions that are easily affected by changes of AMPA receptor properties including deficient GluR2 mRNA editing in ALS.

Enhanced SUMOylation in polyglutamine diseases

Small ubiquitin-like modifiers (SUMOs) are proteins homologous to ubiquitin that possibly regulate intranuclear protein localization, nuclear transport, and ubiquitination. We examined patients of DRPLA, SCA1, MJD, and Huntingtons disease and found that neurons in affected regions of the brain react strongly to SUMO-1, a family member of SUMOs. Western blot with a transgenic mouse expressing mutant ataxin-1 showed the increase of SUMOylated proteins in the cerebellar cortex, which we named ESCA1 and ESCA2. These results indicated activation of SUMO-1 system in polyglutamine diseases and predicted its involvement in the pathology.

Age-dependent and tissue-specific CAG repeat instability occurs in mouse knock-in for a mutant Huntington's disease gene

Huntingtons disease (HD) is a neurodegenerative disorder characterized by the expansion of CAG repeats in exon 1 of the HD gene. To clarify the instability of expanded CAG repeats in HD patients, an HD model mouse has been generated by gene replacement with human exon 1 of the HD gene with expansion to 77 CAG repeats. Chimeric proteins composed of human mutated exon 1 and mouse huntingtin are expressed ubiquitously in brain and peripheral tissues. One or two CAG repeat expansion was found in litters from paternal transmission, whereas contraction of CAG repeat in litters was observed through maternal transmission. Elderly mice show greater CAG repeat instability than younger mice, and a unique case was observed of an expanded 97 CAG repeat mouse. Somatic CAG repeat instability is particularly pronounced in the liver, kidney, stomach, and brain but not in the cerebellum of 100‐week‐old mice. The same results of expanded CAG repeat instability as observed in this HD model mouse were confirmed in the human brain of HD patients. Glial fibrillary acidic protein (GFAP)‐positive cells have been found to be increased in the substantia nigra (SN), globus pallidus (GP), and striatum (St) in the brains of 40‐week‐old affected mice, although without neuronal cell death. The CAG repeat instability and increase in GFAP‐positive cells in this mouse model appear to mirror the abnormalities in HD patients. The HD model mouse may therefore have advantages for investigations of molecular mechanisms underlying instability of CAG repeats. J. Neurosci. Res. 65:289–297, 2001.

The genomic structure and expression of MJD, the Machado-Joseph disease gene

AbstractMachado-Joseph disease (MJD) is an autosomal dominant neurodegenerative disorder that is clinically characterized by cerebellar ataxia and various associated symptoms. The disease is caused by an unstable expansion of the CAG repeat in the MJD gene. This gene is mapped to chromosome 14q32.1. To determine its genomic structure, we constructed a contig composed of six cosmid clones and eight bacterial artificial chromosome (BAC) clones. It spans approximately 300kb and includes MJD. We also determined the complete sequence (175,330bp) of B445M7, a human BAC clone that contains MJD. The MJD gene was found to span 48,240bp and to contain 11 exons. Northern blot analysis showed that MJD mRNA is ubiquitously expressed in human tissues, and in at least four different sizes; namely, 1.4, 1.8, 4.5, and 7.5kb. These different mRNA species probably result from differential splicing and polyadenylation, as shown by sequences of the 21 independent cDNA clones isolated after the screening of four human cDNA libraries prepared from whole brain, caudate, retina, and testis. The sequences of these latter clones relative to the MJD gene in B445M7 indicate that there are three alternative splicing sites and eight polyadenylation signals in MJD that are used to generate the differently sized transcripts.

A novel ferritin light chain gene mutation in a Japanese family with neuroferritinopathy: Description of clinical features and implications for genotype–phenotype correlations

Neuroferritinopathy is a hereditary neurodegenerative disorder caused by mutations in the ferritin light chain gene (FTL1). The cardinal features are progressive movement disturbance, hypoferritinemia, and iron deposition in the brain. To date, five mutations have been described in Caucasian and Japanese families, but the genotype–phenotype correlations remain to be established. We identified a novel FTL1 mutation (exon 4, c.641/642, 4‐nucletotide duplication) in a Japanese family and compared the clinical traits with those previously reported. All mutations but one are insertions in exon 4, resulting in frameshifts. Clinical features are similar among patients with the same mutations. Middle‐age onset chorea is common in patients with insertions in the 5′ portion of exon 4 including our cases, whereas patients with insertions in the 3′ portion of exon 4 develop early‐onset tremor, suggesting genotype–phenotype correlations. In this family, male predominance and normal serum ferritin levels are characteristic.

A Clinical Profile of Corticobasal Degeneration Presenting as Primary Progressive Aphasia

We report a patient with primary progressive aphasia who first presented with amnesic aphasia that developed over the course of 3 years into nonfluent aphasia with buccofacial apraxia, followed in the next year by cognitive impairment and parkinsonism. Pathological findings were typical for corticobasal degeneration except for the distribution of cortical atrophy. This case suggests that corticobasal degeneration should be included in the differential diagnosis of primary progressive aphasia, especially in association with parkinsonism.

Single cell analysis of CAG repeat in brains of dentatorubral-pallidoluysian atrophy (DRPLA)

Somatic mosaicism of an expanded repeat is present in tissues of patients with triplet repeat diseases. Of the spinocerebellar ataxias associated with triplet repeat expansion, the most prominent heterogeneity of the expanded repeat is seen in dentatorubral-pallidoluysian atrophy (DRPLA). The common feature of this somatic mosaicism is the difference in the repeat numbers found in the cerebellum as compared to other tissues. The expanded allele in the cerebellum shows a smaller degree of expansion. We previously showed by microdissection analysis that the expanded allele in the granular layer in DRPLA cerebellum has less expansion than expanded alleles in the molecular layer and white matter. Whether this feature of lesser expansion in granule cells is common to other types of neurons is yet to be clarified. We used a newly developed excimer laser microdissection system to analyze somatic mosaicism in the brains of two patients, one with early- and another with late-onset DRPLA, and used single cell PCR to observe the cell-to-cell differences in repeat numbers. In the late onset patient, repeat expansion was more prominent in Purkinje cells than in granule cells, but less than that in the glial cells. In the early onset patient, repeat expansion in Purkinje cells was greater than in granule cells but did not differ from that in glial cells. These findings suggest that there is a difference in repeat expansion among neuronal subgroups and that the number of cell division cycles is not the only determinant of somatic mosaicism.

High-density cDNA filter analysis of the expression profiles of the genes preferentially expressed in human brain.

We previously established a method, called high-density cDNA filter analysis (HDCFA), for analyzing the expression profiles of a large number of genes in a systematic manner. In the present study, we constructed a cDNA filter of about 8300 cDNAs from a human cerebral cortex cDNA library and quantitatively analyzed their expression in human adult brain, fetal brain, kidney and liver using HDCFA. Using a comparison of the relative amount of expression of each clone in different tissues and following (partial) sequence analysis, about 200 clones were selected as those preferentially expressed in adult or fetal brain, one half of which may be unknown. Their expression was further analyzed in human neuroblastoma cell lines, a human glioma cell line, human cerebral cortex, cerebellum and kidney. Finally, eight clones were selected and sequenced as characteristically expressed genes (cDNAs). A homology search revealed that three clones were human homologues of the rat genes preferentially expressed in brain and five clones were unknown. The full-length cDNA sequence of one of the unknown clones was determined.