Akihiro Kawata

Mutations of optineurin in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) has its onset in middle age and is a progressive disorder characterized by degeneration of motor neurons of the primary motor cortex, brainstem and spinal cord. Most cases of ALS are sporadic, but about 10% are familial. Genes known to cause classic familial ALS (FALS) are superoxide dismutase 1 (SOD1), ANG encoding angiogenin, TARDP encoding transactive response (TAR) DNA-binding protein TDP-43 (ref. 4) and fused in sarcoma/translated in liposarcoma (FUS, also known as TLS). However, these genetic defects occur in only about 20–30% of cases of FALS, and most genes causing FALS are unknown. Here we show that there are mutations in the gene encoding optineurin (OPTN), earlier reported to be a causative gene of primary open-angle glaucoma (POAG), in patients with ALS. We found three types of mutation of OPTN: a homozygous deletion of exon 5, a homozygous Q398X nonsense mutation and a heterozygous E478G missense mutation within its ubiquitin-binding domain. Analysis of cell transfection showed that the nonsense and missense mutations of OPTN abolished the inhibition of activation of nuclear factor kappa B (NF-κB), and the E478G mutation revealed a cytoplasmic distribution different from that of the wild type or a POAG mutation. A case with the E478G mutation showed OPTN-immunoreactive cytoplasmic inclusions. Furthermore, TDP-43- or SOD1-positive inclusions of sporadic and SOD1 cases of ALS were also noticeably immunolabelled by anti-OPTN antibodies. Our findings strongly suggest that OPTN is involved in the pathogenesis of ALS. They also indicate that NF-κB inhibitors could be used to treat ALS and that transgenic mice bearing various mutations of OPTN will be relevant in developing new drugs for this disorder.

Drug Screening for ALS Using Patient-Specific Induced Pluripotent Stem Cells

Anacardic acid attenuates mutant TDP-43–associated abnormalities in motor neurons derived from ALS patient–specific induced pluripotent stem cells. A Stepping Stone to ALS Drug Screening Amyotrophic lateral sclerosis (ALS) is an untreatable disorder in which the motor neurons degenerate, resulting in paralysis and death. Induced pluripotent stem cell (iPSC) technology makes it possible to analyze motor neurons from patients with ALS and to use them for screening new candidate drugs. In new work, Egawa et al. obtained motor neurons by inducing differentiation of iPSC lines derived from several patients with familial ALS. These patients carried disease-causing mutations in the gene encoding Tar DNA binding protein-43 (TDP-43). The ALS motor neurons in culture recapitulated cellular and molecular abnormalities associated with ALS. For example, the authors found that mutant TDP-43 in the ALS motor neurons perturbed RNA metabolism and that the motor neurons were more vulnerable to cellular stressors such as arsenite. The researchers then used the ALS motor neurons in a drug screening assay and identified a compound called anacardic acid, a histone acetyltransferase inhibitor, that could reverse some of the ALS phenotypes observed in the motor neurons. The new work provides an encouraging step toward using motor neurons generated from iPSCs derived from ALS patients to learn more about what triggers the death of motor neurons in this disease and to identify new candidate drugs that may be able to slow or reverse the devastating loss of motor neurons. Amyotrophic lateral sclerosis (ALS) is a late-onset, fatal disorder in which the motor neurons degenerate. The discovery of new drugs for treating ALS has been hampered by a lack of access to motor neurons from ALS patients and appropriate disease models. We generate motor neurons from induced pluripotent stem cells (iPSCs) from familial ALS patients, who carry mutations in Tar DNA binding protein-43 (TDP-43). ALS patient–specific iPSC–derived motor neurons formed cytosolic aggregates similar to those seen in postmortem tissue from ALS patients and exhibited shorter neurites as seen in a zebrafish model of ALS. The ALS motor neurons were characterized by increased mutant TDP-43 protein in a detergent-insoluble form bound to a spliceosomal factor SNRPB2. Expression array analyses detected small increases in the expression of genes involved in RNA metabolism and decreases in the expression of genes encoding cytoskeletal proteins. We examined four chemical compounds and found that a histone acetyltransferase inhibitor called anacardic acid rescued the abnormal ALS motor neuron phenotype. These findings suggest that motor neurons generated from ALS patient–derived iPSCs may provide a useful tool for elucidating ALS disease pathogenesis and for screening drug candidates.

The crucial role of caspase-9 in the disease progression of a transgenic ALS mouse model

Mutant copper/zinc superoxide dismutase (SOD1)‐overexpressing transgenic mice, a mouse model for familial amyotrophic lateral sclerosis (ALS), provides an excellent resource for developing novel therapies for ALS. Several observations suggest that mitochondria‐dependent apoptotic signaling, including caspase‐9 activation, may play an important role in mutant SOD1‐related neurodegeneration. To elucidate the role of caspase‐9 in ALS, we examined the effects of an inhibitor of X chromosome‐linked inhibitor of apoptosis (XIAP), a mammalian inhibitor of caspase‐3, ‐7 and ‐9, and p35, a baculoviral broad caspase inhibitor that does not inhibit caspase‐9. When expressed in spinal motor neurons of mutant SOD1 mice using transgenic techniques, XIAP attenuated disease progression without delaying onset. In contrast, p35 delayed onset without slowing disease progression. Moreover, caspase‐9 was activated in spinal motor neurons of human ALS subjects. These data strongly suggest that caspase‐9 plays a crucial role in disease progression of ALS and constitutes a promising therapeutic target.

Participation of the limbic system and its associated areas in the dementia of amyotrophic lateral sclerosis

The topographic distribution of degenerative changes in large brain sections from five sporadic amyotrophic lateral sclerosis (ALS) patients with dementia and three without dementia was examined. The dementia characteristics were impaired shifting from one line of thinking to another, perseveration, and emotional disinhibition as well as impairment of cognition, and judgment. Neuropathological examinations showed definite ALS changes in all the patients studied. In addition, the five patients with dementia showed neuronal loss, gliosis, and sponginess of the superficial layers throughout the cerebral cortices, predominantly in the dorsomedial cortex of the temporal tip and the parahippocampal, ambiens, anterior cingulate, rectal, orbital, and insular gyri as well as neuronal loss in the basolateral nucleus of the amygdala, nucleus accumbens, and subiculum of the hippocampus. Ubiquitin-immunoreactive inclusions were present in some neurons in the granular cell layers of the hippocampus. Fibrous gliosis was extensive in the subcortical and deep white matter of the frontotemporal lobes. The affected regions take in the limbic system and its associated areas which are the sources of the psychological problems, including emotional disturbance, experienced by these ALS patients. The psychological problems of ALS need to be investigated in relation to the involvement of the limbic system.

Autonomic failure in ALS with a novel SOD1 gene mutation

Article abstract The authors report a patient with ALS and a novel SOD1 gene mutation who was in the totally locked-in state and developed autonomic failure followed by sudden cardiac arrest. A neuropathologic study showed widespread multisystem degeneration, including involvement of the autonomic nuclei in the medulla and spinal cord. SOD1 gene analysis detected a missense mutation of V118L in exon 4. These findings show notable phenotypic heterogeneity for SOD1-associated ALS.

Optineurin is co-localized with FUS in basophilic inclusions of ALS with FUS mutation and in basophilic inclusion body disease

We recently reported that mutations in the gene encoding optineurin (OPTN) cause amyotrophic lateral sclerosis (ALS) [2]. In that report, we demonstrated the co-localization of OPTN with TAR DNA-binding protein of 43 kDa (TDP-43) or Cu/Zn superoxide dismutase (SOD1) in the pathognomonic inclusions of sporadic (SALS) or familial ALS (FALS) with mutated SOD1, respectively [2]. Fused in sarcoma (FUS) is another causative gene of ALS [1, 7]. FUS-immunoreactivity is identifiable in basophilic inclusions (BIs) from patients with sporadic basophilic inclusion body disease (BIBD) [4] and in those from ‘FALS with FUS mutation’ patients. The fact that both FUS and OPTN cause ALS when mutated prompted us to investigate the correlation between these proteins. We analyzed postmortem material from three patients with sporadic BIBD and from three with FALS with FUS mutation. All the patients manifested upper and lower motor neuron signs, but no cognitive impairment was noted. Their demographic and clinical features are given in Online Resource 1. The ‘FALS with FUS mutation’ patients had missense mutations R514S, R521C, and P525L in their respective FUS gene. Genetic analysis of the sporadic BIBD patients for FUS and OPTN was unsuccessful, probably because of deterioration of the genomic DNA in the formalin-fixed material. No frozen tissue was available. Electronic supplementary material The online version of this article (doi:10.1007/s00401-011-0809-z) contains supplementary material, which is available to authorized users.

Reduction rate of body mass index predicts prognosis for survival in amyotrophic lateral sclerosis: A multicenter study in Japan

Malnutrition in the early stage has been reported as an independent predictor of survival in amyotrophic lateral sclerosis (ALS). We analyzed retrospectively the effect of variation of body mass index (BMI) on survival in ALS patients. In total, 77 consecutive ALS patients were enrolled from nine hospitals in Japan. Reduction rate of BMI was calculated from BMI before the disease onset and at the time of the first visit to each hospital. We analyzed the correlation between BMI reduction rate and total disease duration. Results showed that the median BMI reduction rate was 2.5 per year (interquartile range 1.3–3.8). The BMI reduction rate was significantly correlated with survival length (p <0.0001). There was also a significant difference in survival between ALS patients with a BMI reduction rate ≥ and < 2.5 (Kaplan-Meier survival analysis and the log-rank test, p < 0.0001; hazard ratio by the Cox model, 2.9816). In conclusion, faster reduction of BMI at the initial stage before the first visit to hospital predicts shorter survival length also in Japanese ALS patients.

Prominent sensory and autonomic disturbances in familial amyotrophic lateral sclerosis with a Gly93Ser mutation in the SOD1 gene

A missense mutation (Gly93-->Ser) was identified in exon 4 of the Cu/Zn superoxide dismutase (SOD1) gene of a 48-year-old Japanese man with familial amyotrophic lateral sclerosis (FALS). The SOD1 activities in the fibroblasts and in a lysate of erythrocytes of the patient did not differ from those of healthy controls. The clinical characteristics of the patient were fairly slow progression of the illness, prominent sensory impairment, urinary disturbance and blood pressure fluctuation due to sympathetic hyperactivity. The severe sensory and autonomic disturbances, association of which with FALS has not been previously reported, may represent specific clinical features associated with the Gly93Ser mutation or may indicate the variability of clinical findings even in patients with the same mutation.

Decrease of medullary catecholaminergic neurons in multiple system atrophy and Parkinson's disease and their preservation in amyotrophic lateral sclerosis

We investigated the number of tyrosine hydroxylase (TH)-immunoreactive neurons in the C1 and A2 regions of the medulla, the sites of the baroreflex arc, in 7 patients with multiple system atrophy (MSA), 8 with Parkinsons disease (PD), 9 with amyotrophic lateral sclerosis (ALS), and 12 age-matched normal subjects to analyze the relationship between cardiovascular dysfunction and medullary catecholaminergic neurons. Orthostatic hypotension (OH) was marked in all the MSA patients and moderate in three PD patients. Three of the five ALS patients who had been on respirators showed lability of blood pressure; paroxysmal hypertension and nocturnal hypotension without compensatory tachycardia. All the MSA patients showed extremely marked decrease of TH-immunoreactive neurons in both the C1 and A2 regions. In the patients with Parkinsons disease, numerous TH-immunoreactive neurons contained Lewy bodies that were immunostained by antibody to TH. TH-immunoreactive neurons were decreased very markedly in the A2 regions of two patients with OH, and three patients without OH showed fairly marked decreases in the C1 or A2 region. In contrast, the number of TH-immunoreactive neurons in ALS was the same as in normal subjects. In MSA and some PD patients, orthostatic hypotension may partly be due to the involvement of the medullary catecholaminergic neurons. The lability of blood pressure in ALS probably is not related to the medullary catecholaminergic neurons.

Proportional neuronal loss between the primary motor and sensory cortex in amyotrophic lateral sclerosis.

The number of neurons in the primary motor cortex (MI) and the primary somatosensory cortex (SI) were estimated in the same locations of brains from sporadic amyotrophic lateral sclerosis (ALS) cases and controls. The number of MI and SI neurons and Betz cells were significantly decreased in the ALS cases as compared to the controls. The number of neurons in MI and SI was independent of age at death or duration of disease. Moreover, the number of neurons in MI and SI was significantly correlated, suggesting that the neurons in both sites might be interdependent and might decrease proportionally.