Mild ALS in Japan associated with novel SOD mutation

Updated Genetic Analysis of Japanese Familial ALS Patients Carrying SOD1 Variants Revealed Phenotypic Differences for Common Variants

Background and Objectives

Amyotrophic lateral sclerosis (ALS) is an adult-onset progressive neurodegenerative disease. Approximately 10% of ALS cases are familial, and more than 20 causative genes have been identified. As we have previously reported, SOD1 variants are the most common causes of familial ALS in Japan. Because antisense oligonucleotides for SOD1-linked ALS are being used in practical applications, the types of variants and the clinical features of patients need to be updated.

Methods

We consecutively recruited 160 families with familial ALS in Japan. We performed genetic analyses, focusing on SOD1-linked ALS as the most common in our cohort, updated their genotypes, and characterized clinical phenotypes.

Results

A total of 26 SOD1 variants in 56 patients and 49 families (30.6%) were collected, with the 3 most common (p.His47Arg [the conventional numbering; H46R], p.Leu127Ser [L126S], p.Asn87Ser [N86S]) accounting for 38.8% of all families. We also identified 2 novel variants (p.Ile36Phe [I35F] and p.Asn132Argfs*3 [N131Rfs*3]). The mean age at onset was 48.9 ± 12.2 (mean ± SD) years for all patients with SOD1-linked ALS. Lower limb onset comprised 70% of cases. The mean disease duration was 64.7 ± 82 months, and the median survival was 71.5 months. Some variants led to a relatively homogeneous phenotype, although clinical characteristics differed among types of variants and families. Patients with p.His47Arg (H46R) showed slower progression with lower limb onset and a predominance of lower motor neuron involvement. The p.Leu127Ser (L126S) variant led to varying degrees of progression in heterozygous or homozygous states and presented incomplete penetrance. Intrafamilial phenotypic differences were observed in families carrying p.Asn87Ser (N86S). Four variants (p.Cys7Gly [C6G], p.His44Arg [H43R], p.Leu85Val [L84V], and p.Cys147Arg [C146R]) were found to be associated with rapid disease progression.

Discussion

The genetic basis of familial ALS, at least for SOD1 variants, still differed by geographic and ethnic background. Understanding these clinical profiles will help optimize evaluation in targeted gene therapy worldwide and benefit efficient diagnosis, leading to precise application in clinical practice.

Current progress in microRNA profiling of circulating extracellular vesicles in amyotrophic lateral sclerosis: A systematic review

INTRODUCTION

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease affecting upper and lower motor neurons, leading to death resulting mainly from respiratory failure, for which there is currently no curative treatment. Underlying pathological mechanisms for the development of ALS are diverse and have yet to be elucidated. Non-invasive testing to isolate circulating molecules including microRNA to diagnose ALS has been reported, but circulating extracellular vesicle (EV)-derived microRNA has not been fully studied in the ALS population.

METHODS

A systematic literature review to explore studies investigating the profile of microRNAs in EVs from blood samples of ALS patients was carried out according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guideline.

RESULTS

Eleven studies including a total of 263 patients with ALS were included in the present systematic review. The majority of patients had sporadic ALS, though a small number of patients with ALS having genetic mutations were included. Seven studies used plasma-derived EVs, and the remaining four studies used serum-derived EVs. RNA sequencing or microarrays were used in eight studies, and quantitative PCR was used in eight studies, of which five studies used RNA sequencing or microarrays for screening and quantitative PCR for validation. There was overlap of miR-199a-3p and miR-199a-5p in three studies.

CONCLUSIONS

Overall, the systematic review addressed the current advances in the profiling of microRNAs in circulating EVs of ALS patients. Blood samples, isolation of EVs, and microRNA analysis were diverse. Although there was an overlap of miR-199a-3p and miR-199a-5p, collection of further evidence is warranted.

Profiling tofersen as a treatment of superoxide dismutase 1 amyotrophic lateral sclerosis

INTRODUCTION

Amyotrophic lateral sclerosis (ALS) is a rapidly progressive motor neuron disorder with a fatal outcome 3-5 years after disease onset due to respiratory complications. Superoxide dismutase 1 (SOD1) mutations are found in about 2% of all patients. Tofersen is a novel oligonucleotide antisense drug specifically developed to treat SOD1-ALS patients.

AREAS COVERED

Our review covers and discusses tofersen pharmacological properties and its phase I/II and III clinical trials results. Other available drugs and their limitations are also addressed.

EXPERT OPINION

VALOR study failed to meet the primary endpoint (change in the revised Amyotrophic Lateral Sclerosis Functional Rating Scale score from baseline to week 28, tofersen arm vs. placebo), but a significant reduction in plasma neurofilament light chain (NfL) levels was observed in tofersen arm (60% vs. 20%). PrefALS study has proposed plasma NfL has a potential biomarker for presymptomatic treatment, since it increases 6-12 months before phenoconversion. There is probably a delay between plasma NfL reduction and the clinical benefit. ATLAS study will allow more insights regarding tofersen clinical efficacy in disease progression rate, survival, and even disease onset delay in presymptomatic SOD1 carriers.

Update on Antioxidant Therapy with Edaravone: Expanding Applications in Neurodegenerative Diseases

The brain is susceptible to oxidative stress, which is associated with various neurological diseases. Edaravone (MCI-186, 3-methyl-1 pheny-2-pyrazolin-5-one), a free radical scavenger, has promising effects by quenching hydroxyl radicals (∙OH) and inhibiting both ∙OH-dependent and ∙OH-independent lipid peroxidation. Edaravone was initially developed in Japan as a neuroprotective agent for acute cerebral infarction and was later applied clinically to treat amyotrophic lateral sclerosis (ALS), a neurodegenerative disease. There is accumulating evidence for the therapeutic effects of edaravone in a wide range of diseases related to oxidative stress, including ischemic stroke, ALS, Alzheimer's disease, and placental ischemia. These neuroprotective effects have expanded the potential applications of edaravone. Data from experimental animal models support its safety for long-term use, implying broader applications in various neurodegenerative diseases. In this review, we explain the unique characteristics of edaravone, summarize recent findings for specific diseases, and discuss its prospects for future therapeutic applications.

Yeast Models of Amyotrophic Lateral Sclerosis Type 8 Mimic Phenotypes Seen in Mammalian Cells Expressing Mutant VAPBP56S

Amyotrophic lateral sclerosis (ALS) is a complex neurodegenerative disease that results in the loss of motor neurons and can occur sporadically or due to genetic mutations. Among the 30 genes linked to familial ALS, a P56S mutation in VAPB, an ER-resident protein that functions at membrane contact sites, causes ALS type 8. Mammalian cells expressing VAPBP56S have distinctive phenotypes, including ER collapse, protein and/or membrane-containing inclusions, and sensitivity to ER stress. VAPB is conserved through evolution and has two homologs in budding yeast, SCS2 and SCS22. Previously, a humanized version of SCS2 bearing disease-linked mutations was described, and it caused Scs2-containing inclusions when overexpressed in yeast. Here, we describe a yeast model for ALS8 in which the two SCS genes are deleted and replaced with a single chromosomal copy of either wild-type or mutant yeast SCS2 or human VAPB expressed from the SCS2 promoter. These cells display ER collapse, the formation of inclusion-like structures, and sensitivity to tunicamycin, an ER stress-inducing drug. Based on the phenotypic similarity to mammalian cells expressing VAPBP56S, we propose that these models can be used to study the molecular basis of cell death or dysfunction in ALS8. Moreover, other conserved ALS-linked genes may create opportunities for the generation of yeast models of disease.

Genetics of amyotrophic lateral sclerosis: seeking therapeutic targets in the era of gene therapy

Amyotrophic lateral sclerosis (ALS) is an intractable disease that causes respiratory failure leading to mortality. The main locus of ALS is motor neurons. The success of antisense oligonucleotide (ASO) therapy in spinal muscular atrophy (SMA), a motor neuron disease, has triggered a paradigm shift in developing ALS therapies. The causative genes of ALS and disease-modifying genes, including those of sporadic ALS, have been identified one after another. Thus, the freedom of target choice for gene therapy has expanded by ASO strategy, leading to new avenues for therapeutic development. Tofersen for superoxide dismutase 1 (SOD1) was a pioneer in developing ASO for ALS. Improving protocols and devising early interventions for the disease are vital. In this review, we updated the knowledge of causative genes in ALS. We summarized the genetic mutations identified in familial ALS and their clinical features, focusing on SOD1, fused in sarcoma (FUS), and transacting response DNA-binding protein. The frequency of the C9ORF72 mutation is low in Japan, unlike in Europe and the United States, while SOD1 and FUS are more common, indicating that the target mutations for gene therapy vary by ethnicity. A genome-wide association study has revealed disease-modifying genes, which could be the novel target of gene therapy. The current status and prospects of gene therapy development were discussed, including ethical issues. Furthermore, we discussed the potential of axonal pathology as new therapeutic targets of ALS from the perspective of early intervention, including intra-axonal transcription factors, neuromuscular junction disconnection, dysregulated local translation, abnormal protein degradation, mitochondrial pathology, impaired axonal transport, aberrant cytoskeleton, and axon branching. We simultaneously discuss important pathological states of cell bodies: persistent stress granules, disrupted nucleocytoplasmic transport, and cryptic splicing. The development of gene therapy based on the elucidation of disease-modifying genes and early intervention in molecular pathology is expected to become an important therapeutic strategy in ALS.

Therapeutic Strategies and Metal-Induced Oxidative Stress: Application of Synchrotron Radiation Microbeam to Amyotrophic Lateral Sclerosis in the Kii Peninsula of Japan

A series of extensive gene-environment studies on amyotrophic lateral sclerosis (ALS) and Parkinsonism–dementia complex (PDC) in Guam Island, USA, and the Kii Peninsula of Japan, including Auyu Jakai, West New Guinea, have led us to hypothesize that a prolonged low calcium (Ca) and magnesium (Mg) intake, especially over generation, may cause oxidative stress to motor and nigral neurons by an increased uptake of environment metallic elements, i.e., aluminum (Al), manganese (Mn), and iron (Fe). Otherwise, 5–10% of total ALS cases are familial ALS (fALS), of which 20% of the fALS cases linked to a point mutation of Cu/Zn superoxide dismutase (SOD1). In the vicinity of the Kii Peninsula, about 7% of the ALS cases are also linked to the SOD1 mutation. Using synchrotron radiation (SR) microbeam, conglomerate inclusion (SOD1 aggregates) within a spinal motor neuron of the fALS case in the vicinity revealed a loss of copper (Cu) in contrast to extremely high contents of Zinc (Zn) and Ca. That means an exceptionally low Cu/Zn ratio with an increased Ca content, indicating the abnormalities of the active site of SOD1 protein of the fALS. Furthermore, sALS in the southernmost high incidence areas of the Kii Peninsula showed a low Cu/Zn ratio within a motor neuron, suggesting a fragility of SOD1 proteins. From the perspective of gene–environment interactions, the above two research trends may show a common oxidative stress underlying the neuronal degenerative process of ALS/PDC in the Kii Peninsula of Japan. Therefore, it is a crucial point for the prospect of therapeutic strategy to clarify a role of transition metals in the oxidative process in both ALS/PDC, including ALS elsewhere in the world. This paper reviews a history of the genetic epidemiological studies, especially from the aspect of gene–environment interaction, on ALS/PDC in the Kii and Guam high incidence foci and the results of a series of analytical research on trace metallic elements within neurons of both sALS and fALS cases, especially using a synchrotron radiation (SR) microbeam of Spring-8 and Photon Factory of Japan. The SR microbeam is an ideal X-ray source, which supplies an extremely high brilliance (high-intensity photon) and tunability (energy variability) to investigate trace metallic elements contained in biological specimens at the cellular level, even more without any damages. This research will provide a valuable information about the mechanism of oxidative stress involved in neuronal cell death in ALS and related neurodegenerative disorders. To elucidate the physicochemical mechanism of the oxidative process in neuronal degeneration, it will shed a new light on the therapeutic strategies for ALS/PDC in near future.

An ALS-associated KIF5A mutant forms oligomers and aggregates and induces neuronal toxicity

KIF5A is a kinesin superfamily motor protein that transports various cargos in neurons. Mutations in Kif5a cause familial amyotrophic lateral sclerosis (ALS). These ALS mutations are in the intron of Kif5a and induce mis-splicing of KIF5A mRNA, leading to splicing out of exon 27, which in human KIF5A encodes the cargo-binding tail domain of KIF5A. Therefore, it has been suggested that ALS is caused by loss of function of KIF5A. However, the precise mechanisms regarding how mutations in KIF5A cause ALS remain unclear. Here, we show that an ALS-associated mutant of KIF5A, KIF5A(Δexon27), is predisposed to form oligomers and aggregates in cultured mouse cell lines. Interestingly, purified KIF5A(Δexon27) oligomers showed more active movement on microtubules than wild-type KIF5A in vitro. Purified KIF5A(∆exon27) was prone to form aggregates in vitro. Moreover, KIF5A(Δexon27)-expressing Caenorhabditis elegans neurons showed morphological defects. These data collectively suggest that ALS-associated mutations of KIF5A are toxic gain-of-function mutations rather than simple loss-of-function mutations.

In Vivo Imaging of Oxidative and Hypoxic Stresses in Mice Model of Amyotrophic Lateral Sclerosis

Oxidative and hypoxic stresses are associated with the degeneration of both motor neurons and skeletal muscles in amyotrophic lateral sclerosis (ALS). In vivo bioluminescent imaging is used to monitor cellular responses to oxidative and hypoxic stresses in living ALS model mice bearing G93A-human Cu/Zn superoxide dismutase (SOD1) longitudinally using the IVIS spectrum imaging system. Double transgenic mice bearing both Keap1-dependent oxidative stress detector No-48 (OKD48) and G93A-SOD1 are useful for in vivo imaging of oxidative stress in ALS. We developed a bioluminescence resonance energy transfer (BRET) probe that is regulated by HIF-1α-specific ubiquitin-proteasome system. G93A-SOD1 mice injected with the BRET probe are useful to investigate the spatiotemporal responses to hypoxic stress in ALS. In this chapter, we introduce a practical protocol of in vivo imaging of both oxidative and hypoxic stress in ALS model mice.

Non-Tumorigenic Pluripotent Reparative Muse Cells Provide a New Therapeutic Approach for Neurologic Diseases

Muse cells are non-tumorigenic endogenous reparative pluripotent cells with high therapeutic potential. They are identified as cells positive for the pluripotent surface marker SSEA-3 in the bone marrow, peripheral blood, and connective tissue. Muse cells also express other pluripotent stem cell markers, are able to differentiate into cells representative of all three germ layers, self-renew from a single cell, and are stress tolerant. They express receptors for sphingosine-1-phosphate (S1P), which is actively produced by damaged cells, allowing circulating cells to selectively home to damaged tissue. Muse cells spontaneously differentiate on-site into multiple tissue-constituent cells with few errors and replace damaged/apoptotic cells with functional cells, thereby contributing to tissue repair. Intravenous injection of exogenous Muse cells to increase the number of circulating Muse cells enhances their reparative activity. Muse cells also have a specific immunomodulatory system, represented by HLA-G expression, allowing them to be directly administered without HLA-matching or immunosuppressant treatment. Owing to these unique characteristics, clinical trials using intravenously administered donor-Muse cells have been conducted for myocardial infarction, stroke, epidermolysis bullosa, spinal cord injury, perinatal hypoxic ischemic encephalopathy, and amyotrophic lateral sclerosis. Muse cells have the potential to break through the limitations of current cell therapies for neurologic diseases, including amyotrophic lateral sclerosis. Muse cells provide a new therapeutic strategy that requires no HLA-matching or immunosuppressant treatment for administering donor-derived cells, no gene introduction or differentiation induction for cell preparation, and no surgery for delivering the cells to patients.

Therapeutic benefit of Muse cells in a mouse model of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by progressive motor neuron loss. Muse cells are endogenous reparative pluripotent-like stem cells distributed in various tissues. They can selectively home to damaged sites after intravenous injection by sensing sphingosine-1-phosphate produced by damaged cells, then exert pleiotropic effects, including tissue protection and spontaneous differentiation into tissue-constituent cells. In G93A-transgenic ALS mice, intravenous injection of 5.0 × 10⁴ cells revealed successful homing of human-Muse cells to the lumbar spinal cords, mainly at the pia-mater and underneath white matter, and exhibited glia-like morphology and GFAP expression. In contrast, such homing or differentiation were not recognized in human mesenchymal stem cells but were instead distributed mainly in the lung. Relative to the vehicle groups, the Muse group significantly improved scores in the rotarod, hanging-wire and muscle strength of lower limbs, recovered the number of motor neurons, and alleviated denervation and myofiber atrophy in lower limb muscles. These results suggest that Muse cells homed in a lesion site-dependent manner and protected the spinal cord against motor neuron death. Muse cells might also be a promising cell source for the treatment of ALS patients.

A Systematic Review of Genotype-Phenotype Correlation across Cohorts Having Causal Mutations of Different Genes in ALS

Amyotrophic lateral sclerosis is a rare and fatal neurodegenerative disease characterised by progressive deterioration of upper and lower motor neurons that eventually culminates in severe muscle atrophy, respiratory failure and death. There is a concerning lack of understanding regarding the mechanisms that lead to the onset of ALS and as a result there are no reliable biomarkers that aid in the early detection of the disease nor is there an effective treatment. This review first considers the clinical phenotypes associated with ALS, and discusses the broad categorisation of ALS and ALS-mimic diseases into upper and lower motor neuron diseases, before focusing on the genetic aetiology of ALS and considering the potential relationship of mutations of different genes to variations in phenotype. For this purpose, a systematic review is conducted collating data from 107 original published clinical studies on monogenic forms of the disease, surveying the age and site of onset, disease duration and motor neuron involvement. The collected data highlight the complexity of the disease's genotype-phenotype relationship, and thus the need for a nuanced approach to the development of clinical assays and therapeutics.

Cortical Circuit Dysfunction as a Potential Driver of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease that affects selected cortical and spinal neuronal populations, leading to progressive paralysis and death. A growing body of evidences suggests that the disease may originate in the cerebral cortex and propagate in a corticofugal manner. In particular, transcranial magnetic stimulation studies revealed that ALS patients present with early cortical hyperexcitability arising from a combination of increased excitability and decreased inhibition. Here, we discuss the possibility that initial cortical circuit dysfunction might act as the main driver of ALS onset and progression, and review recent functional, imaging and transcriptomic studies conducted on ALS patients, along with electrophysiological, pathological and transcriptomic studies on animal and cellular models of the disease, in order to evaluate the potential cellular and molecular origins of cortical hyperexcitability in ALS.

Omics Approach to Axonal Dysfunction of Motor Neurons in Amyotrophic Lateral Sclerosis (ALS)

Amyotrophic lateral sclerosis (ALS) is an intractable adult-onset neurodegenerative disease that leads to the loss of upper and lower motor neurons (MNs). The long axons of MNs become damaged during the early stages of ALS. Genetic and pathological analyses of ALS patients have revealed dysfunction in the MN axon homeostasis. However, the molecular pathomechanism for the degeneration of axons in ALS has not been fully elucidated. This review provides an overview of the proposed axonal pathomechanisms in ALS, including those involving the neuronal cytoskeleton, cargo transport within axons, axonal energy supply, clearance of junk protein, neuromuscular junctions (NMJs), and aberrant axonal branching. To improve understanding of the global changes in axons, the review summarizes omics analyses of the axonal compartments of neurons in vitro and in vivo, including a motor nerve organoid approach that utilizes microfluidic devices developed by this research group. The review also discusses the relevance of intra-axonal transcription factors frequently identified in these omics analyses. Local axonal translation and the relationship among these pathomechanisms should be pursued further. The development of novel strategies to analyze axon fractions provides a new approach to establishing a detailed understanding of resilience of long MN and MN pathology in ALS.

The biophysics of superoxide dismutase-1 and amyotrophic lateral sclerosis

Few proteins have come under such intense scrutiny as superoxide dismutase-1 (SOD1). For almost a century, scientists have dissected its form, function and then later its malfunction in the neurodegenerative disease amyotrophic lateral sclerosis (ALS). We now know SOD1 is a zinc and copper metalloenzyme that clears superoxide as part of our antioxidant defence and respiratory regulation systems. The possibility of reduced structural integrity was suggested by the first crystal structures of human SOD1 even before deleterious mutations in the sod1 gene were linked to the ALS. This concept evolved in the intervening years as an impressive array of biophysical studies examined the characteristics of mutant SOD1 in great detail. We now recognise how ALS-related mutations perturb the SOD1 maturation processes, reduce its ability to fold and reduce its thermal stability and half-life. Mutant SOD1 is therefore predisposed to monomerisation, non-canonical self-interactions, the formation of small misfolded oligomers and ultimately accumulation in the tell-tale insoluble inclusions found within the neurons of ALS patients. We have also seen that several post-translational modifications could push wild-type SOD1 down this toxic pathway. Recently we have come to view ALS as a prion-like disease where both the symptoms, and indeed SOD1 misfolding itself, are transmitted to neighbouring cells. This raises the possibility of intervention after the initial disease presentation. Several small-molecule and biologic-based strategies have been devised which directly target the SOD1 molecule to change the behaviour thought to be responsible for ALS. Here we provide a comprehensive review of the many biophysical advances that sculpted our view of SOD1 biology and the recent work that aims to apply this knowledge for therapeutic outcomes in ALS.

Systemic overexpression of SQSTM1/p62 accelerates disease onset in a SOD1H46R-expressing ALS mouse model

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterized by a selective loss of upper and lower motor neurons. Recent studies have shown that mutations in SQSTM1 are linked to ALS. SQSTM1 encodes SQSTM1/p62 that regulates not only autophagy via the association with MAP1LC3/LC3 and ubiquitinated proteins but also the KEAP1-NFE2L2/Nrf2 anti-oxidative stress pathway by interacting with KEAP1. Previously, we have demonstrated that loss of SQSTM1 exacerbates disease phenotypes in a SOD1^H46R-expressing ALS mouse model. To clarify the effects of SQSTM1 overexpression in this model, we generated SQSTM1 and SOD1 ^H46R double-transgenic (SQSTM1;SOD1 ^H46R ) mice. SQSTM1;SOD1 ^H46R mice exhibited earlier disease onset and shorter lifespan than did SOD1 ^H46R mice. Conversely, disease progression after the onset rather slightly but significantly slowed in SQSTM1;SOD1 ^H46R mice. However, there were observable differences neither in the number of Nissl positive neurons nor in the distribution of ubiquitin-positive and/or SQSTM1-positive aggregates between SOD1 ^H46R and SQSTM1;SOD1 ^H46R mice. It was noted that these protein aggregates were mainly observed in neuropil, and partly localized to astrocytes and/or microglia, but not to MAP2-positive neuronal cell bodies and dendrites at the end-stage of disease. Nonetheless, the biochemically-detectable insoluble SQSTM1 and poly-ubiquitinated proteins were significantly and progressively increased in the spinal cord of SQSTM1;SOD1 ^H46R mice compared to SOD1 ^H46R mice. These results suggest that overexpression of SQSTM1 in SOD1 ^H46R mice accelerates disease onset by compromising the protein degradation pathways.

[An early history of Japanese amyotrophic lateral sclerosis (ALS)-related diseases and the current development]

The present review focuses an early history of Japanese amyotrophic lateral sclerosis (ALS)-related diseases and the current development. In relation to foreign previous reports, five topics are introduced and discussed on ALS with dementia, ALS/Parkinsonism dementia complex (ALS/PDC), familial ALS (FALS), spinal bulbar muscular atrophy (SBMA), and multisystem involvement especially in cerebellar system of ALS including ALS/SCA (spinocerebellar ataxia) crossroad mutation Asidan. This review found the great contribution of Japanese reports on the above five topics, and confirmed the great development of ALS-related diseases over the past 120 years.

Unraveling ALS due to SOD1 mutation through the combination of brain and cervical cord MRI

OBJECTIVE

To explore structural and functional changes of the brain and cervical cord in patients with amyotrophic lateral sclerosis (ALS) due to mutation in the superoxide dismutase (SOD1) gene compared with sporadic ALS.

METHODS

Twenty patients with SOD1 ALS, 11 with sporadic ALS, and 33 healthy controls underwent clinical evaluation and brain MRI. Cortical thickness analysis, diffusion tensor MRI of the corticospinal tracts (CST) and corpus callosum, and resting-state functional connectivity were performed. Patients with ALS also underwent cervical cord MRI to evaluate cord cross-sectional area and magnetization transfer ratio (MTR).

RESULTS

Patients with SOD1 ALS showed longer disease duration and slower rate of functional decline relative to those with sporadic ALS. No cortical thickness abnormalities were found in patients with ALS compared with controls. Fractional anisotropy showed that sporadic ALS patients had significant CST damage relative to both healthy controls (p = 0.001-0.02) and SOD1-related ALS (p = 0.05), although the latter showed alterations that were intermediate between controls and sporadic ALS. Functional hyperconnectivity of the motor cortex in the sensorimotor network was observed in patients with sporadic ALS relative to controls. Conversely, patients with SOD1 ALS showed lower cord cross-sectional area along the whole cervical cord relative to those with sporadic ALS (p < 0.001). No cord MTR differences were found between patient groups.

CONCLUSIONS

Patients with SOD1 ALS showed cervical cord atrophy relative to those with sporadic ALS and a relative preservation of brain motor structural and functional networks. Neurodegeneration in SOD1 ALS is likely to occur primarily in the spinal cord. An objective and accurate estimate of spinal cord damage has potential in the future assessment of preventive SOD1 ALS therapies.

Molecular epidemiological study of familial amyotrophic lateral sclerosis in Japanese population by whole-exome sequencing and identification of novel HNRNPA1 mutation

To elucidate the genetic epidemiology of familial amyotrophic lateral sclerosis (FALS) in the Japanese population, we conducted whole-exome sequencing analysis of 30 FALS families in whom causative mutations have not been identified in previous studies. Consequently, whole-exome sequencing analysis revealed novel mutations in HNRNPA1, TBK1, and VCP. Taken together with our previous results of mutational analyses by direct nucleotide sequencing analysis, a microarray-based resequencing method, or repeat-primed PCR analysis, causative mutations were identified in 41 of the 68 families (60.3%) with SOD1 being the most frequent cause of FALS (39.7%). Of the mutations identified in this study, a novel c.862/1018C>G (p.P288A/340A) mutation in HNRNPA1 located in the nuclear localization signal domain of hnRNPA1, enhances the recruitment of mutant hnRNPA1 into stress granules, indicating that an altered nuclear localization signal activity plays an essential role in amyotrophic lateral sclerosis pathogenesis.

Comprehensive targeted next-generation sequencing in Japanese familial amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is an adult-onset neurodegenerative disease characterized by loss of motor neurons. We have recently identified SOD1 and FUS mutations as the most common causes in a consecutive series of 111 familial ALS pedigrees in Japan. To reveal possible genetic causes for the remaining 51 patients with familial ALS (45 pedigrees), we performed targeted next-generation sequencing of 35 known ALS/motor neuron diseases-related genes. Known variants in ANG, OPTN, SETX, and TARDBP were identified in 6 patients. A novel likely pathogenic homozygous variant in ALS2 was identified in 1 patient. In addition, 18 patients harbored 1-3 novel variants of uncertain significance, whereas hexanucleotide repeat expansions in C9ORF72 were not detected using repeat-primed polymerase chain reaction. Collectively, in our Japanese cohort, the frequencies of SOD1, FUS, SETX, TARDBP, ANG, and OPTN variants were 32%, 11%, 2%, 2%, 1%, and 1%, respectively. These findings indicate considerable differences in the genetic variations associated with familial ALS across populations. Further genetic analyses and functional studies of novel variants are warranted.

Functional links between SQSTM1 and ALS2 in the pathogenesis of ALS: cumulative impact on the protection against mutant SOD1-mediated motor dysfunction in mice

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by a selective loss of motor neurons in the brain and spinal cord. Multiple toxicity pathways, such as oxidative stress, misfolded protein accumulation, and dysfunctional autophagy, are implicated in the pathogenesis of ALS. However, the molecular basis of the interplay between such multiple factors in vivo remains unclear. Here, we report that two independent ALS-linked autophagy-associated gene products; SQSTM1/p62 and ALS2/alsin, but not antioxidant-related factor; NFE2L2/Nrf2, are implicated in the pathogenesis in mutant SOD1 transgenic ALS models. We generated SOD1^H46R mice either on a Nfe2l2-null, Sqstm1-null, or Sqstm1/Als2-double null background. Loss of SQSTM1 but not NFE2L2 exacerbated disease symptoms. A simultaneous inactivation of SQSTM1 and ALS2 further accelerated the onset of disease. Biochemical analyses revealed that loss of SQSTM1 increased the level of insoluble SOD1 at the intermediate stage of the disease, whereas no further elevation occurred at the end-stage. Notably, absence of SQSTM1 rather suppressed the mutant SOD1-dependent accumulation of insoluble polyubiquitinated proteins, while ALS2 loss enhanced it. Histopathological examinations demonstrated that loss of SQSTM1 accelerated motor neuron degeneration with accompanying the preferential accumulation of ubiquitin-positive aggregates in spinal neurons. Since SQSTM1 loss is more detrimental to SOD1^H46R mice than lack of ALS2, the selective accumulation of such aggregates in neurons might be more insulting than the biochemically-detectable insoluble proteins. Collectively, two ALS-linked factors, SQSTM1 and ALS2, have distinct but additive protective roles against mutant SOD1-mediated toxicity by modulating neuronal proteostasis possibly through the autophagy-endolysosomal system.

Genotype-phenotype relationships in familial amyotrophic lateral sclerosis with FUS/TLS mutations in Japan

INTRODUCTION

We investigated possible genotype-phenotype correlations in Japanese patients with familial amyotrophic lateral sclerosis (FALS) carrying fused in sarcoma/translated in liposarcoma (FUS/TLS) gene mutations.

METHODS

A consecutive series of 111 Japanese FALS pedigrees were screened for copper/zinc superoxide dismutase 1 (SOD1) and FUS/TLS gene mutations. Clinical data, including onset age, onset site, disease duration, and extramotor symptoms, were collected.

RESULTS

Nine different FUS/TLS mutations were found in 12 pedigrees. Most of the patients with FUS/TLS-linked FALS demonstrated early onset in the brainstem/upper cervical region, and relatively short disease duration. A few mutations exhibited phenotypes that were distinct from typical cases. Frontotemporal dementia was present in 1 patient.

CONCLUSIONS

This study revealed a characteristic phenotype in FUS/TLS-linked FALS patients in Japan. FUS/TLS screening is recommended in patients with FALS with this phenotype. Muscle Nerve 54: 398-404, 2016.

FUS Interacts with HSP60 to Promote Mitochondrial Damage

FUS-proteinopathies, a group of heterogeneous disorders including ALS-FUS and FTLD-FUS, are characterized by the formation of inclusion bodies containing the nuclear protein FUS in the affected patients. However, the underlying molecular and cellular defects remain unclear. Here we provide evidence for mitochondrial localization of FUS and its induction of mitochondrial damage. Remarkably, FTLD-FUS brain samples show increased FUS expression and mitochondrial defects. Biochemical and genetic data demonstrate that FUS interacts with a mitochondrial chaperonin, HSP60, and that FUS translocation to mitochondria is, at least in part, mediated by HSP60. Down-regulating HSP60 reduces mitochondrially localized FUS and partially rescues mitochondrial defects and neurodegenerative phenotypes caused by FUS expression in transgenic flies. This is the first report of direct mitochondrial targeting by a nuclear protein associated with neurodegeneration, suggesting that mitochondrial impairment may represent a critical event in different forms of FUS-proteinopathies and a common pathological feature for both ALS-FUS and FTLD-FUS. Our study offers a potential explanation for the highly heterogeneous nature and complex genetic presentation of different forms of FUS-proteinopathies. Our data also suggest that mitochondrial damage may be a target in future development of diagnostic and therapeutic tools for FUS-proteinopathies, a group of devastating neurodegenerative diseases.

Amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) are two groups of common and devastating neurodegenerative diseases, characterized by losses of selected groups of neurons. Mutations in the FUS gene have been associated with ALS, whereas inclusion bodies containing the FUS protein have been discovered in both ALS and FTLD patients. However, the underlying pathogenic mechanisms of FUS in these diseases remain unclear. Here, we demonstrate that wild-type or ALS-associated mutant FUS can interact with mitochondrial chaperonin HSP60 and that HSP60 mediates FUS localization to mitochondria, leading to mitochondrial damage. Mitochondrial impairment may be an early event in FUS proteinopathies and represent a potential therapeutic target for treating these fatal diseases.

Slowly progressing lower motor neuron disease caused by a novel duplication mutation in exon 1 of the SOD1 gene

Familial amyotrophic lateral sclerosis accounts for about 5% of all cases of the neurodegenerative disorder amyotrophic lateral sclerosis. Genetic mutations in Cu/Zn superoxide dismutase (SOD1) have been associated with one kind of familial amyotrophic lateral sclerosis (ALS1). We identified a novel duplication mutation in exon 1 of the SOD1 gene in a Japanese family whose members had lower motor neuron diseases. The patients showed slow disease progression, with the onset of lower limb muscle weakness and exertional dyspnea. Some patients had mild motor and sensory neuropathy and/or bladder dysfunction, which is further evidence that SOD1 mutation results in a predominantly lower motor neuron phenotype.

A clinical variance in familial amyotrophic lateral sclerosis with a point mutation in Cu/Zn superoxide dismutase gene

We report here a novel point mutation in exon 5 of the Cu/Zn superoxide dismutase (SOD) gene resulting in an amino acid substitution of valine(148) by isoleucine (V148I) in a Japanese family with amyotrophic lateral sclerosis (FALS). In this family, the age at onset was young (28.0 ± 3.8 years old, mean ± SD, n = 4) and the disease progression was rapid (22.0 ± 5.9 months, n = 3) with low Cu/Zn SOD activity (56.3 and 59.0% of the controls, n = 2). It is interesting that the clinical features of ALS varied very much among the affected members. One case had weakness of the lower extremities at first, and died without bulbar paresis. The second case first noticed wasting of the upper limbs with bulbar symptoms, but the third had weakness of upper extremities without developing dysarthria nor dysphagia until death. The living remainder first developed fasciculation of the tongue without weakness of extremities. The valine(148) is conserved among different species, and V148I mutation might destabilize dimer formation with another SOD subunit, leading to decrease enzymatic activity. These results suggested that there could be considerable clinical variance among the patients of FALS within one family, carrying the same Cu/Zn SOD mutation such as V148I.

Early and selective reduction of NOP56 (Asidan) and RNA processing proteins in the motor neuron of ALS model mice

OBJECTIVE

There is increasing evidence to support that altered RNA processing is implicated in the pathogenesis of motor neuron degeneration of amyotrophic lateral sclerosis (ALS). We evaluate the expression of three RNA processing-related proteins in ALS model mice in this study.

METHODS

We analyzed expression and distribution patterns of three RNA processing-related proteins, nucleolar protein (NOP) 56 (identified as causative gene for spinocerebellar ataxia (SCA) 36, nicknamed Asidan), TDP-43, and fused in sarcoma/translocated in liposarcoma (FUS) in lumbar and cervical cords, hypoglossal nucleus, cerebral motor cortex, and cerebellum of transgenic (Tg) SOD1 G93A ALS model mice throughout the course of motor neuron degeneration.

RESULTS

Compared to age-matched wild type (WT) mice, Tg mice showed progressive reduction of NOP56 levels in the large motor neurons of lumbar and cervical cords from the early-symptomatic stage (14 weeks of age) to the end stage of the disease (18 weeks). TDP-43 and FUS protein levels showed a later decrease in the nucleus of large motor neuron at 18 weeks (end stage of the disease). These changes were not observed in the primary motor cortex of the cerebrum as well as molecular and granular layers and Purkinje cells in the cerebellum.

DISCUSSION

The present study suggests a progressive loss of these three nuclear proteins and subsequent RNA processing problems including a novel gene relating to ALS (NOP56) under the motor neuron degeneration.

[Clinical genetics of amyotrophic lateral sclerosis in Japan: an update]

Amyotrophic lateral sclerosis (ALS) is an adult onset neurodegenerative disorder characterized by the death of upper and lower motor neurons. In familial ALS kinders with mutations in the SOD1 gene, the age of onset of weakness varies greatly but the duration of illness appears to be characteristic to each mutation. Mutations in the fused in sarcoma/translated in liposarcoma (FUS/TLS) gene have been discovered to be associated with familial ALS. In a Japanese family with familial ALS, we found the R521C FUS mutation, which has been reported to be found in various ethnic backgrounds. The family history revealed 23 patients with ALS among 46 family members, suggesting a 100% penetrance rate. They developed muscle weakness at an average age of 35.3 years, and the average age of death was 37.2 years. Neuropathological examination revealed remarkable atrophy of the brainstem tegmentum characterized by cytoplasmic basophilic inclusion bodies in the neurons of the brainstem. The frequency of a hexanucleotide repeat expansion in C9ORF72 with familial ALS has been estimated as approximately 5% in Japan, although the one Japanese patient was identified as a carrier of the C9ORF72 expansion carried the Finnish risk haplotype.

[Clinical translation of hepatocyte growth factor for amyotrophic lateral sclerosis]

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease characterized by selective loss of motor neurons. Approximately 20% of familial ALS cases are linked to mutations in Cu/Zn superoxide dismutase (SOD1) gene. Previously, we developed a transgenic rat model of ALS overexpressing mutant SOD1 protein. The rat model facilitates preclinical ALS research employing various therapeutic approaches such as intrathecal administration, cell transplantation, and viral vector-mediated gene transduction to the affected central nervous system. Hepatocyte growth factor (HGF) is a pleiotropic growth factor and also a potent survival-promoting factor for motor neurons. To examine its therapeutic effect on ALS, we administered human recombinant HGF (hrHGF) to the transgenic ALS rats. In contrast with vehicle-treated rats, continuous intrathecal infusion of hrHGF attenuated spinal motor neuron degeneration and prolonged the duration of the disease, even with administration from the onset of symptoms. To translate the strategy to human treatment, we performed dose-finding and safety studies using non-human primate model of contusive cervical spinal cord injury. Introducing exogenous HGF protein also revealed a distinct therapeutic effect with functional recovery. Given the therapeutic potential of hrHGF on ALS, we started a novel phase I clinical trial for ALS patients in Tohoku University Hospital.

Impaired hypoxic sensor Siah-1, PHD3, and FIH system in spinal motor neurons of an amyotrophic lateral sclerosis mouse model

We recently reported spinal blood flow-metabolism uncoupling in the Cu/Zn-superoxide dismutase 1 (SOD1)-transgenic (Tg) mouse model of amyotrophic lateral sclerosis (ALS), suggesting relative hypoxia in the spinal cord. However, the hypoxic stress sensor pathway in ALS has not been well studied. In the present work, we examined the temporal and spatial changes of hypoxic stress sensor proteins (Siah-1, PHD3, and FIH) following motor neuron (MN) degeneration in the spinal cord of normoxic ALS mice. The expression of Siah-1 and PHD3 proteins progressively increased in the surrounding glial cells of presymptomatic Tg mice (10 weeks, 10 weeks) compared with the large MN of the anterior horn. In contrast, a significant reduction in Siah-1 and PHD3 protein expression was evident in end-stage ALS mice (18 weeks, 18 weeks). Double-immunofluorescence analysis revealed PHD3 plus Siah-1 double-positive cells in the surrounding glia of symptomatic Tg mice (14-18 weeks), with no change in the large MNs. In contrast, FIH protein expression decreased in the surrounding glial cells of Tg mice at end-stage ALS (18 weeks). The present study suggests a partial loss in the neuroprotective response of spinal MNs in ALS results from a relative hypoxia through the Siah-1, PHD3, and FIH system under normoxic conditions. This response could be an important mechanism of neurodegeneration in ALS.

Impaired response of hypoxic sensor protein HIF-1α and its downstream proteins in the spinal motor neurons of ALS model mice

We have recently reported spinal blood flow-metabolism uncoupling in an amyotrophic lateral sclerosis (ALS) animal model using Cu/Zn-superoxide dismutase 1 (SOD1)-transgenic (Tg) mice, suggesting a relative hypoxia in the spinal cord. However, the hypoxic stress sensor pathway has not been well studied in ALS. Here, we examined temporal and spatial changes of the hypoxic stress sensor proteins HIF-1α and its downstream proteins (VEGF, HO-1, and EPO) during the normoxiccourse of motor neuron (MN) degeneration in the spinal cord of these ALS model mice. We found that HIF-1α protein expression progressively increased both in the anterior large MNs and the surrounding glial cells in Tg mice from early symptomatic 14 week (W) and end stage 18 W. Double immunofluorescence analysis revealed that HIF-1α, plus GFAP and Iba-1 double-positive surrounding glial cells, progressively increased from 14 W to 18 W, although the immunohistochemistry in large MNs did not change. Expression levels of VEGF and HO-1 also showed a progressive increase but were significant only in the surrounding glial cells at 18 W. In contrast, EPO protein expression was decreased in the surrounding glial cells of Tg mice at 18 W. Because HIF1-α serves as an important mediator of the hypoxic response, these findings indicate that MNs lack the neuroprotective response to hypoxic stress through the HIF-1α system, which could be an important mechanism of neurodegeneration in ALS.

Different human copper-zinc superoxide dismutase mutants, SOD1G93A and SOD1H46R, exert distinct harmful effects on gross phenotype in mice

Amyotrophic lateral sclerosis (ALS) is a heterogeneous group of fatal neurodegenerative diseases characterized by a selective loss of motor neurons in the brain and spinal cord. Creation of transgenic mice expressing mutant Cu/Zn superoxide dismutase (SOD1), as ALS models, has made an enormous impact on progress of the ALS studies. Recently, it has been recognized that genetic background and gender affect many physiological and pathological phenotypes. However, no systematic studies focusing on such effects using ALS models other than SOD1^G93A mice have been conducted. To clarify the effects of genetic background and gender on gross phenotypes among different ALS models, we here conducted a comparative analysis of growth curves and lifespans using congenic lines of SOD1^G93A and SOD1^H46R mice on two different genetic backgrounds; C57BL/6N (B6) and FVB/N (FVB). Copy number of the transgene and their expression between SOD1^G93A and SOD1^H46R lines were comparable. B6 congenic mutant SOD1 transgenic lines irrespective of their mutation and gender differences lived longer than corresponding FVB lines. Notably, the G93A mutation caused severer disease phenotypes than did the H46R mutation, where SOD1^G93A mice, particularly on a FVB background, showed more extensive body weight loss and earlier death. Gender effect on survival also solely emerged in FVB congenic SOD1^G93A mice. Conversely, consistent with our previous study using B6 lines, lack of Als2, a murine homolog for the recessive juvenile ALS causative gene, in FVB congenic SOD1^H46R, but not SOD1^G93A, mice resulted in an earlier death, implying a genetic background-independent but mutation-dependent phenotypic modification. These results indicate that SOD1^G93A- and SOD1^H46R-mediated toxicity and their associated pathogenic pathways are not identical. Further, distinctive injurious effects resulted from different SOD1 mutations, which are associated with genetic background and/or gender, suggests the presence of several genetic modifiers of disease expression in the mouse genome.

Early and progressive impairment of spinal blood flow-glucose metabolism coupling in motor neuron degeneration of ALS model mice

The exact mechanism of selective motor neuron death in amyotrophic lateral sclerosis (ALS) remains still unclear. In the present study, we performed in vivo capillary imaging, directly measured spinal blood flow (SBF) and glucose metabolism, and analyzed whether if a possible flow-metabolism coupling is disturbed in motor neuron degeneration of ALS model mice. In vivo capillary imaging showed progressive decrease of capillary diameter, capillary density, and red blood cell speed during the disease course. Spinal blood flow was progressively decreased in the anterior gray matter (GM) from presymptomatic stage to 0.80-fold of wild-type (WT) mice, 0.61 at early-symptomatic, and 0.49 at end stage of the disease. Local spinal glucose utilization (LSGU) was transiently increased to 1.19-fold in anterior GM at presymptomatic stage, which in turn progressively decreased to 0.84 and 0.60 at early-symptomatic and end stage of the disease. The LSGU/SBF ratio representing flow-metabolism uncoupling (FMU) preceded the sequential pathological changes in the spinal cord of ALS mice and was preferentially found in the affected region of ALS. The present study suggests that this early and progressive FMU could profoundly involve in the whole disease process as a vascular factor of ALS pathology, and could also be a potential target for therapeutic intervention of ALS.

Effect of mitochondrial transcription factor a overexpression on motor neurons in amyotrophic lateral sclerosis model mice

Increasing evidence indicates that oxidative stress is an important mechanism underlying motor neuron (MN) degeneration in amyotrophic lateral sclerosis (ALS). Mitochondrial DNA (mtDNA) is highly susceptible to oxidative damage and has little potential for repair, although mitochondrial transcription factor A (TFAM) plays essential roles in maintaining mitochondrial DNA by reducing oxidative stress, promoting mtDNA transcription, and regulating mtDNA copy number. To analyze a possible therapeutic effect of TFAM on ALS pathology, double transgenic mice overexpressing G93A mutant SOD1 (G93ASOD1) and human TFAM (hTFAM) were newly generated in the present study. Rotarod scores were better in G93ASOD1/hTFAM double-Tg mice than G93ASOD1 single-Tg mice at an early symptomatic stage, 15 and 16 weeks of age, with a 10% extension of the onset age in double-Tg mice. The number of surviving MNs was 30% greater in double-Tg mice with end-stage disease, at 19 weeks, with remarkable reductions in the amount of the oxidative stress marker 8-OHdG and the apoptotic marker cleaved caspase 3 and with preserved COX1 expression. Double-immunofluorescence study showed that hTFAM was expressed specifically in MNs and microglia in the spinal cords of double-Tg mice. The present study suggests that overexpression of TFAM has a potential to reduce oxidative stress in MN and delay onset of the disease in ALS model mice. © 2012 Wiley Priodicals, Inc.

Involvement of activated microglia in increased vulnerability of motoneurons after facial nerve avulsion in presymptomatic amyotrophic lateral sclerosis model rats

Activated microglia are observed in various neurodegenerative diseases and are thought to be involved in the processes of neuronal cell death. Motoneuron damage in the facial nuclei after facial nerve avulsion is accelerated in presymptomatic transgenic rats expressing human mutant Cu(2+) /Zn(2+) superoxide dismutase 1 (SOD1), compared with that in wild-type rats. To reveal the functional role of microglia in motoneuronal death, we investigated the microglial response after facial nerve avulsion in presymptomatic mutant SOD1(H46R) (mSOD1(H46R) ) rats. At 3 days after avulsion, microglial clusters were observed in the facial nuclei of both wild-type and mSOD1(H46R) rats. The numbers of microglial clusters, proliferating microglia, and microglial attachments to motoneurons were significantly higher in mSOD1(H46R) rats, compared with those in wild-type rats. Immunopositive signals for the phagocytic marker ED1 were significantly stronger in mSOD1(H46R) rats, compared with that in wild-type rats, at 2 weeks after avulsion. Furthermore, primary microglia prepared from mSOD1(H46R) rats showed enhanced phagocytic activity, compared with that in wild-type rats. The expression of P2Y(12) mRNA was higher in the facial nuclei of mSOD1(H46R) rats, compared with that in wild-type rats. A laser microdissection system revealed that the expression of ATF3 mRNA was higher in the motoneurons of mSOD1(H46R) rats, compared with that in wild-type rats, at 2 days after avulsion. These results indicate that microglial activation in response to early neuronal damage increased in mSOD1(H46R) rats and suggest that the enhanced activation of microglia may lead to an increase in the vulnerability of motoneurons after avulsion in mSOD1(H46R) rats.

[Regenerative therapies for amyotrophic lateral sclerosis using hepatocyte growth factor]

Amyotrophic lateral sclerosis (ALS) is an adult onset neurodegenerative disorder characterized by the death of upper and lower motor neurons. Approximately 20% of familial ALS cases are caused by mutations in the superoxide dismutase 1 (SOD1) gene. We have developed rats that express a human SOD1 transgene with two different ALS-associated mutations develop striking motor neuron degeneration and paralysis. The larger size of this rat model as compared with the ALS mice will facilitate studies involving manipulations of spinal fluid (implantation of intrathecal catheters for chronic therapeutic studies; CSF sampling) and spinal cord (e.g., direct administration of viral- and cell-mediated therapies). Hepatocyte growth factor (HGF) is one of the most potent survival-promoting factors for motor neurons. To examine both its protective effect on motor neurons and its therapeutic potential, we administered human recombinant HGF (hrHGF) by continuous intrathecal delivery to the transgenic rats at the onset of paralysis for 4 weeks. Intrathecal administration of hrHGF attenuates motor neuron degeneration and prolonged the duration of the disease by 63%. Our results indicated the therapeutic efficacy of continuous intrathecal administration of hrHGF in ALS rats. These results should prompt further clinical trials in ALS using continuous intrathecal administration of hrHGF.

Impaired antioxydative Keap1/Nrf2 system and the downstream stress protein responses in the motor neuron of ALS model mice

The Kelch-like ECH-associated protein 1 (Keap1)/Nuclear erythroid 2-related factor 2 (Nrf2) system is the major cellular defense mechanism under oxidative stress, but the role in motor neuron degeneration under amyotrophic lateral sclerosis (ALS) pathology has not yet been fully elucidated. Here we examined temporal and spatial changes of Keap1, Nrf2, and their downstream stress response proteins heme oxgenase-1 (HO-1), glutathione, thioredoxin (TRX), and heat shock protein 70 (HSP70) throughout the course of motor neuron (MN) degeneration in the spinal cord of ALS model mice. Keap1 protein levels progressively decreased in the MN and anterior lumbar cord of ALS mice to 63% at early symptomatic 14 weeks and 58% at end symptomatic 18 weeks, while Nrf2 dramatically increased in the anterior lumbar cord with accumulation in the MN nucleus to 229% at 14 weeks and 471% at 18 weeks when glial like cells became also positive. In contrast, downstream stress response proteins such as HO-1, glutathione, TRX, and HSP70 showed only a small increase in MN with a significant increase to 149% to 280% in the number of glial-like cells after symptomatic 14 weeks. Our present observation suggests that MN selectively lost inductions of these important downstream protective proteins without regard to the Keap1/Nrf2 system activation, which could be a pivotal mechanism of neurodegenerative processes of ALS.

Appearance of phagocytic microglia adjacent to motoneurons in spinal cord tissue from a presymptomatic transgenic rat model of amyotrophic lateral sclerosis

Microglial activation occurs early during the pathogenesis of amyotrophic lateral sclerosis (ALS). Recent evidence indicates that the expression of mutant Cu(2+)/Zn(2+) superoxide dismutase 1 (SOD1) in microglia contributes to the late disease progression of ALS. However, the mechanism by which microglia influence the neurodegenerative process and disease progression in ALS remains unclear. In this study, we revealed that activated microglia aggregated in the lumbar spinal cord of presymptomatic mutant SOD1(H46R) transgenic rats, an animal model of familial ALS. The aggregated microglia expressed a marker of proliferating cell, Ki67, and phagocytic marker proteins ED1 and major histocompatibility complex (MHC) class II. The motoneurons near the microglial aggregates showed weak choline acetyltransferase (ChAT) immunoreactivity and contained reduced granular endoplasmic reticulum and altered nucleus electron microscopically. Furthermore, immunopositive signals for tumor necrosis factor-alpha (TNFalpha) and monocyte chemoattractant protein-1 (MCP-1) were localized in the aggregated microglia. These results suggest that the activated and aggregated microglia represent phagocytic features in response to early changes in motoneurons and possibly play an important role in ALS disease progression during the presymptomatic stage.

Disruption of neurovascular unit prior to motor neuron degeneration in amyotrophic lateral sclerosis

Recent reports suggest that functional or structural defect of vascular components are implicated in amyotrophic lateral sclerosis (ALS) pathology. In the present study, we examined a possible change of the neurovascular unit consisting of endothelium (PCAM-1), tight junction (occludin), and basement membrane (collagen IV) in relation to a possible activation of MMP-9 in ALS patients and ALS model mice. We found that the damage in the neurovascular unit was more prominent in the outer side and preferentially in the anterior horn of ALS model mice. This damage occurred prior to motor neuron degeneration and was accompanied by MMP-9 up-regulation. We also found the dissociation between the PCAM-1-positive endothelium and GFAP-positive astrocyte foot processes in both humans and the animal model of ALS. The present results indicate that perivascular damage precedes the sequential changes of the disease, which are held in common between humans and the animal model of ALS, suggesting that the neurovascular unit is a potential target for therapeutic intervention in ALS.