Ryoichi Nakano

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.

Familial amyotrophic lateral sclerosis with a mutation in the Cu/Zn superoxide dismutase gene

Several missense mutations within exons 1, 2, 4 and 5 of the gene for Cu/Zn-binding superoxide dismutase (SOD1) have been discovered to be involved in the development of chromosome 21q-linked familial amyotrophic lateral sclerosis (FALS). We describe here an autopsied patient with FALS, in whom we have recently identified a novel missense mutation in exon 1 of the SOD1 gene. The neuropathological findings were compatible with those described previously in patients with FALS with posterior column involvement. This suggests that mutations of the SOD1 gene may be responsible for this form of FALS.

Cytotoxic T lymphocyte-mediated cell death in paraneoplastic sensory neuronopathy with anti-Hu antibody

Abstract Paraneoplastic sensory neuronopathy (PSN) has been shown to harbor characteristic anti-neuronal autoantibody ‘anti-Hu’ in their sera and cerebrospinal fluid. Creation of animal models exhibiting clinical or pathological features seen in PSN by means of passive transfer of anti-Hu positive IgG has not been achieved. Although, anti-Hu antibody was shown to induce neuronal cell lysis in vitro, this result has not been reproduced so far. Since prominent T cell infiltration are seen in the central nervous system and posterior spinal ganglion of the patients with anti-Hu syndrome, we studied cytotoxic T cell (CTL) activity in peripheral mononuclear cells from a patient with PSN harboring anti-Hu antibody. The activated CD8+ T cells from the patient’s venous blood were shown to lyse her own fibroblasts which were incubated with interferon-γ to induce HLA class I molecules on their surface and the recombinant HuD protein was injected into the cells by microinjector. This is the first report showing the existence of CTL in a patient with PSN.

Expression of the large myelin-associated glycoprotein isoform during the development in the mouse peripheral nervous system

The developmental maximum expression of the large myelin-associated glycoprotein isoform (L-MAG) protein prior to that of the small myelin-associated glycoprotein isoform (S-MAG) in both the central and peripheral nervous systems (CNS, PNS) in mice was shown by immunoblotting techniques using specific antibodies to the L-MAG protein and the S-MAG protein. Both the L-MAG protein and the S-MAG protein were expressed earlier in the PNS than in the CNS, which reflects earlier myelination in the PNS. The peak of the L-MAG protein concentration was 8 days in the sciatic nerve and 15 days in the brainstem. The concentration of the S-MAG protein in the sciatic nerve reached a peak at 15 days, whereas in the brainstem it increased rapidly between 15 and 20 days and gradually thereafter. Thus, the preceding maximum expression of the L-MAG during active myelination in the PNS demonstrated here as well as in the CNS strongly suggests an important role for L-MAG in myelin formation.

Instability of mutant Cu/Zn superoxide dismutase (Ala4Thr) associated with familial amyotrophic lateral sclerosis☆

In about 20-25% of cases of familial amyotrophic lateral sclerosis (FALS) patients have mutations in the Cu/Zn superoxide dismutase (SOD1) gene. The mechanism through which the mutations in the SOD1 gene cause ALS still remain unknown. We performed pulse-chase experiments using a system for the transient expression of human SOD1 in COS7 cells to examine whether the Ala4Thr mutation, which we previously reported, decreases the stability of SOD1. The expression vector (pEF-BOS) carrying the wild-type or mutant (Ala4Thr) human SOD1 cDNA was transfected into COS7 cells, and transiently expressed human SOD1 was then metabolically radiolabeled. Half-lives of the wild-type and the Ala4Thr mutant SOD1 were determined to be 78 h and 18 h, respectively. These results suggest that the Ala4Thr mutation in SOD1 decreases the stability of SOD1 and that this instability may play an important role in the pathogenesis of the degeneration of motor neurons in FALS.

Administration of prosaposin ameliorates spatial learning disturbance and reduces cavity formation following stab wounds in rat brain

The effectiveness of prosaposin as a neurotrophic factor was investigated using rats with bilateral stab wounds, injecting 240 ng per day of prosaposin for 3 days. In Morris water maze task, after 3 weeks postoperation, the stab-wounds rats show significant impairment in acquisition compared with the sham-operated rats. In the transfer test the mean number of crossings of the platform place in stab-wounds was significantly lower than that in sham-operated rats (P < 0.01). The stab-wounds rats treated with prosaposin showed significant improvement (P < 0.05). The cavities following stab wounds in the rats treated with prosaposin were significantly smaller than those in the rats treated with (P < 0.05). Our data support that prosaposin is likely to be a new agent for brain injury.

Immunohistochemical localization of myelin-associated glycoprotein isoforms during the development in the mouse brain ☆

The developmental changes in localization of myelin-associated glycoprotein (MAG) isoforms in the mouse brain were demonstrated by an immunohistochemical method using antisera specific to two MAG isoforms. The antiserum to the large isoform of MAG (L-MAG) stained the myelin sheaths and the cytoplasm of oligodendroglia in the active myelinating stage in the mouse central nervous system. However, the antiserum to the small isoform of MAG (S-MAG) stained only myelin sheaths in the adult stage. These findings suggest that L-MAG plays an important role in active myelination.

Familial amyotrophic lateral sclerosis with bulbar onset and a novel Asp101Tyr Cu/Zn superoxide dismutase gene mutation

We describe a patient with familial amyotrophic lateral sclerosis (FALS) in whom we identified a novel missense mutation in exon 4 (Asp101Tyr) of the Cu/Zn superoxide dismutase (SOD1) gene. The disease started with a bulbar symptom (rapidly progressive hoarseness) and at autopsy showed degenerative changes restricted to the upper and lower motor neuron systems (more strictly, with lower motor predominance, showing the most severe degeneration in the nucleus ambiguus). Occasional intracytoplasmic Lewy-body-like hyaline inclusions that were immunoreactive for ubiquitin and SOD1, but immunonegative for neurofilament protein, were found in the lower motor neurons. This is the first report of hoarseness as the initial manifestation of FALS. This SOD1 gene mutation may be associated with a particular clinicopathological phenotype.

Familial amyotrophic lateral sclerosis with widespread vacuolation and hyaline inclusions

This report presents a familial amyotrophic lateral sclerosis (FALS) patient with widespread vacuoles and hyaline inclusions strongly immunostained with the anti-superoxide dismutase (SOD1) antibody. The overall pathologic similarity between our non-SOD1-linked FALS patient and transgenic mice expressing a mutated human SOD1 gene suggests that common pathogenetic mechanisms other than an SOD1 mutation exist in the development of these disease.

Protein-bound crotonaldehyde accumulates in the spinal cord of superoxide dismutase-1 mutation-associated familial amyotrophic lateral sclerosis and its transgenic mouse model

Growing evidence documents oxidative stress involvement in ALS. We previously demonstrated accumulation of a protein‐bound form of the highly toxic lipid peroxidation product crotonaldehyde (CRA) in the spinal cord of sporadic ALS patients. In the present study, to the determine the role for CRA in the disease processes of superoxide dismutase‐1 (SOD1) mutation‐associated familial ALS (FALS), we performed immunohistochemical and semiquantitative cell count analyses of protein‐bound CRA (P‐CRA) in the spinal cord of SOD1‐mutated FALS and its transgenic mouse model. Immunohistochemical analysis revealed increased P‐CRA immunoreactivity in the spinal cord of the FALS patients and the transgenic mice compared to their respective controls. In the FALS patients, P‐CRA immunoreactivity was localized in almost all of the chromatolytic motor neurons, neurofilamentous conglomerates, spheroids, cordlike swollen axons, reactive astrocytes and microglia, and the surrounding neuropil in the affected areas represented by the anterior horns. In the transgenic mice, P‐CRA immunoreactivity was localized in only a few ventral horn glia in the presymptomatic stage, in almost all of the vacuolated motor neurons and cordlike swollen axons and some of the ventral horn reactive astrocytes and microglia in the onset stage, and in many of the ventral horn reactive astrocytes and microglia in the advanced stage. Cell count analysis on mouse spinal cord sections disclosed a statistically significant increase in the density of P‐CRA‐immunoreactive glia in the ventral horns of the young to old G93A mice compared to the age‐matched control mice. The present results indicate that enhanced CRA formation occurs in motor neurons and reactive glia in the spinal cord of SOD1‐mutated FALS and its transgenic mouse model as well as sporadic ALS, suggesting implications for CRA in the pathomechanism common to these forms of ALS.