Apelin deficiency accelerates the progression of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the selective loss of motor neurons. Recent studies have implicated that chronic hypoxia and insufficient vascular endothelial growth factor (VEGF)-dependent neuroprotection may lead to the degeneration of motor neurons in ALS. Expression of apelin, an endogenous ligand for the G protein-coupled receptor APJ, is regulated by hypoxia. In addition, recent reports suggest that apelin protects neurons against glutamate-induced excitotoxicity. Here, we examined whether apelin is an endogenous neuroprotective factor using SOD1(G93A) mouse model of ALS. In mouse CNS tissues, the highest expressions of both apelin and APJ mRNAs were detected in spinal cord. APJ immunoreactivity was observed in neuronal cell bodies located in gray matter of spinal cord. Although apelin mRNA expression in the spinal cord of wild-type mice was not changed from 4 to 18 weeks age, that of SOD1(G93A) mice was reduced along with the paralytic phenotype. In addition, double mutant apelin-deficient and SOD1(G93A) displayed the disease phenotypes earlier than SOD1(G93A) littermates. Immunohistochemical observation revealed that the number of motor neurons was decreased and microglia were activated in the spinal cord of the double mutant mice, indicating that apelin deficiency pathologically accelerated the progression of ALS. Furthermore, we showed that apelin enhanced the protective effect of VEGF on H(2)O(2)-induced neuronal death in primary neurons. These results suggest that apelin/APJ system in the spinal cord has a neuroprotective effect against the pathogenesis of ALS.     

Overexpression of Abeta is associated with acceleration of onset of motor impairment and superoxide dismutase 1 aggregation in an amyotrophic lateral sclerosis mouse model

Transgenic mice carrying mutant Cu/Zn superoxide dismutase (SOD1) recapitulate the motor impairment of human amyotrophic lateral sclerosis (ALS). The amyloid-beta (Abeta) peptide associated with Alzheimer's disease is neurotoxic. To investigate the potential role of Abeta in ALS development, we generated a double transgenic mouse line that overexpresses SOD1(G93A) and amyloid precursor protein (APP)-C100. The transgenic mouse C100.SOD1(G93A) overexpresses Abeta and shows earlier onset of motor impairment but has the same lifespan as the single transgenic SOD1(G93A) mouse. To determine the mechanism associated with this early-onset phenotype, we measured copper and zinc levels in brain and spinal cord and found both significantly elevated in the single and double transgenic mice compared with their littermate control mice. Increased glial fibrillary acidic protein and decreased APP levels in the spinal cord of C100.SOD1(G93A) mice compared with the SOD1(G93A) mice agree with the neuronal damage observed by immunohistochemical analysis. In the spinal cords of C100.SOD1(G93A) double transgenic mice, soluble Abeta was elevated in mice at end-stage disease compared with the pre-symptomatic stage. Buffer-insoluble SOD1 aggregates were significantly elevated in the pre-symptomatic mice of C100.SOD1(G93A) compared with the age-matched SOD1(G93A) mice, correlating with the earlier onset of motor impairment in the C100.SOD1(G93A) mice. This study supports abnormal SOD1 protein aggregation as the pathogenic mechanism in ALS, and implicates a potential role for Abeta in the development of ALS by exacerbating SOD1(G93A) aggregation.     

Human neural stem cell replacement therapy for amyotrophic lateral sclerosis by spinal transplantation

Background

Mutation in the ubiquitously expressed cytoplasmic superoxide dismutase (SOD1) causes an inherited form of Amyotrophic Lateral Sclerosis (ALS). Mutant synthesis in motor neurons drives disease onset and early disease progression. Previous experimental studies have shown that spinal grafting of human fetal spinal neural stem cells (hNSCs) into the lumbar spinal cord of SOD1^G93A rats leads to a moderate therapeutical effect as evidenced by local α-motoneuron sparing and extension of lifespan. The aim of the present study was to analyze the degree of therapeutical effect of hNSCs once grafted into the lumbar spinal ventral horn in presymptomatic immunosuppressed SOD1^G93A rats and to assess the presence and functional integrity of the descending motor system in symptomatic SOD1^G93A animals.

Methods/Principal Findings

Presymptomatic SOD1^G93A rats (60–65 days old) received spinal lumbar injections of hNSCs. After cell grafting, disease onset, disease progression and lifespan were analyzed. In separate symptomatic SOD1^G93A rats, the presence and functional conductivity of descending motor tracts (corticospinal and rubrospinal) was analyzed by spinal surface recording electrodes after electrical stimulation of the motor cortex. Silver impregnation of lumbar spinal cord sections and descending motor axon counting in plastic spinal cord sections were used to validate morphologically the integrity of descending motor tracts. Grafting of hNSCs into the lumbar spinal cord of SOD1^G93A rats protected α-motoneurons in the vicinity of grafted cells, provided transient functional improvement, but offered no protection to α-motoneuron pools distant from grafted lumbar segments. Analysis of motor-evoked potentials recorded from the thoracic spinal cord of symptomatic SOD1^G93A rats showed a near complete loss of descending motor tract conduction, corresponding to a significant (50–65%) loss of large caliber descending motor axons.

Conclusions/Significance

These data demonstrate that in order to achieve a more clinically-adequate treatment, cell-replacement/gene therapy strategies will likely require both spinal and supraspinal targets.     

Late stage treatment with arimoclomol delays disease progression and prevents protein aggregation in the SOD1 mouse model of ALS

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder characterized by motoneuron degeneration, resulting in muscle paralysis and death, typically within 1-5 years of diagnosis. Although the pathogenesis of ALS remains unclear, there is evidence for the involvement of proteasome dysfunction and heat shock proteins in the disease. We have previously shown that treatment with a co-inducer of the heat shock response called arimoclomol is effective in the SOD(G93A) mouse model of ALS, delaying disease progression and extending the lifespan of SOD(G93A) mice (Kieran et al. 2004). However, this previous study only examined the effects arimoclomol when treatment was initiated in pre- or early symptomatic stages of the disease. Clearly, to be of benefit to the majority of ALS patients, any therapy must be effective after symptom onset. In order to establish whether post-symptomatic treatment with arimoclomol is effective, in this study we carried out a systematic assessment of different treatment regimes in SOD(G93A) mice. Treatment with arimoclomol from early (75 days) or late (90 days) symptomatic stages significantly improved muscle function. Treatment from 75 days also significantly increased the lifespan of SOD(G93A) mice, although treatment from 90 days has no significant effect on lifespan. The mechanism of action of arimoclomol involves potentiation of the heat shock response, and treatment with arimoclomol increased Hsp70 expression. Interestingly, this up-regulation in Hsp70 was accompanied by a decrease in the number of ubiquitin-positive aggregates in the spinal cord of treated SOD(G93A) mice, suggesting that arimoclomol directly effects protein aggregation and degradation.     

The Omega-3 Fatty Acid Eicosapentaenoic Acid Accelerates Disease Progression in a Model of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive fatal neurodegenerative disease characterised by loss of motor neurons that currently has no cure. Omega-3 polyunsaturated fatty acids, such as eicosapentaenoic acid (EPA), have many health benefits including neuroprotective and myoprotective potential. We tested the hypothesis that a high level of dietary EPA could exert beneficial effects in ALS. The dietary exposure to EPA (300 mg/kg/day) in a well-established mouse model of ALS expressing the G93A superoxide dismutase 1 (SOD1) mutation was initiated at a pre-symptomatic or symptomatic stage, and the disease progression was monitored until the end stage. Daily dietary EPA exposure initiated at the disease onset did not significantly alter disease presentation and progression. In contrast, EPA treatment initiated at the pre-symptomatic stage induced a significantly shorter lifespan. In a separate group of animals sacrificed before the end stage, the tissue analysis showed that the vacuolisation detected in G93A-SOD1 mice was significantly increased by exposure to EPA. Although EPA did not alter motor neurone loss, EPA reversed the significant increase in activated microglia and the astrocytic activation seen in G93A-SOD1 mice. The microglia in the spinal cord of G93A-SOD1 mice treated with EPA showed a significant increase in 4-hydroxy-2-hexenal, a highly toxic aldehydic oxidation product of omega-3 fatty acids. These data show that dietary EPA supplementation in ALS has the potential to worsen the condition and accelerate the disease progression. This suggests that great caution should be exerted when considering dietary omega-3 fatty acid supplements in ALS patients.     

Altered macroautophagy in the spinal cord of SOD1 mutant mice

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease caused by selective loss of motor neurons (MNs). About 20% familial cases of ALS (fALS) carried the Cu, Zn-superoxide dismutase (SOD1) gene mutation, which plays a crucial role in the pathogenesis of fALS. There is evidence suggesting that macroautophagy can degrade mutated SOD1 in vitro. To investigate whether the mutant SOD1 can induce macroautophagy in vivo, we examined the LC3 processing in spinal cord and the activation status of macroautophagy in MNs of SOD1(G93A) transgenic mice at different stages. Our data demonstrated that autophagy was activated in spinal cord of SOD1(G93A) mice indicating a possible role of macroautophagy in the pathogenesis of ALS.     

Influence of Methylene Blue on Microglia-Induced Inflammation and Motor Neuron Degeneration in the SOD1(G93A) Model for ALS

Mutations in SOD1 cause hereditary variants of the fatal motor neuron disease amyotrophic lateral sclerosis (ALS). Pathophysiology of the disease is non-cell-autonomous, with toxicity deriving also from glia. In particular, microglia contribute to disease progression. Methylene blue (MB) inhibits the effect of nitric oxide, which mediates microglial responses to injury. In vivo 2P-LSM imaging was performed in ALS-linked transgenic SOD1(G93A) mice to investigate the effect of MB on microglia-mediated inflammation in the spinal cord. Local superfusion of the lateral spinal cord with MB inhibited the microglial reaction directed at a laser-induced axon transection in control and SOD1(G93A) mice. In vitro, MB at high concentrations inhibited cytokine and chemokine release from microglia of control and advanced clinical SOD1(G93A) mice. Systemic MB-treatment of SOD1(G93A) mice at early preclinical stages significantly delayed disease onset and motor dysfunction. However, an increase of MB dose had no additional effect on disease progression; this was unexpected in view of the local anti-inflammatory effects. Furthermore, in vivo imaging of systemically MB-treated mice also showed no alterations of microglia activity in response to local lesions. Thus although systemic MB treatment had no effect on microgliosis, instead, its use revealed an important influence on motor neuron survival as indicated by an increased number of lumbar anterior horn neurons present at the time of disease onset. Thus, potentially beneficial effects of locally applied MB on inflammatory events contributing to disease progression could not be reproduced in SOD1(G93A) mice via systemic administration, whereas systemic MB application delayed disease onset via neuroprotection.     

DREAM-Dependent Activation of Astrocytes in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease of unknown origin and characterized by a relentless loss of motor neurons that causes a progressive muscle weakness until death. Among the several pathogenic mechanisms that have been related to ALS, a dysregulation of calcium-buffering proteins in motor neurons of the brain and spinal cord can make these neurons more vulnerable to disease progression. Downstream regulatory element antagonist modulator (DREAM) is a neuronal calcium-binding protein that plays multiple roles in the nucleus and cytosol. The main aim of this study was focused on the characterization of DREAM and glial fibrillary acid protein (GFAP) in the brain and spinal cord tissues from transgenic SOD1^G93A mice and ALS patients to unravel its potential role under neurodegenerative conditions. The DREAM and GFAP levels in the spinal cord and different brain areas from transgenic SOD1^G93A mice and ALS patients were analyzed by Western blot and immunohistochemistry. Our findings suggest that the calcium-dependent excitotoxicity progressively enhanced in the CNS in ALS could modulate the multifunctional nature of DREAM, strengthening its apoptotic way of action in both motor neurons and astrocytes, which could act as an additional factor to increase neuronal damage. The direct crosstalk between astrocytes and motor neurons can become vulnerable under neurodegenerative conditions, and DREAM could act as an additional switch to enhance motor neuron loss. Together, these findings could pave the way to further study the molecular targets of DREAM to find novel therapeutic strategies to fight ALS.     

Disease-related regressive alterations of forebrain cholinergic system in SOD1 mutant transgenic mice

Transgenic mice carrying the human mutated SOD1 gene with a glycine/alanine substitution at codon 93 (G93A) are a widely used model for the fatal human disease amyotrophic lateral sclerosis (ALS). In these transgenic mice, we carried out a neurochemical study not only restricted to the primarily affected regions, the cervical and lumbar segments of the spinal cord, but also to several other brain regions. At symptomatic (110 and 125 days of age), but not at pre-symptomatic (55 days of age) stages, we found significant decreases in catalytic activity of the cholinergic enzyme, choline acetyltransferase (ChAT) in the hippocampus, olfactory cortex and fronto-parietal cortex. In parallel, we observed a decreased number of basal forebrain cholinergic neurons projecting to these areas. No alterations of the cholinergic markers were noticed in the striatum and the cerebellum. A widespread marker for GABAergic neurons, glutamate decarboxylase (GAD), was unaffected in all the areas examined. Alteration of cholinergic markers in forebrain areas was paralleled by concomitant alterations in the spinal cord and brainstem, as a consequence of progressive apoptotic elimination of cholinergic motor neuron. Gestational supplementation of choline, while able to result in long-term enhancement of cholinergic activity, did not improve transgenic mice lifespan nor counteracted cholinergic impairment in brain regions and spinal cord.     

Death receptor 6 (DR6) antagonist antibody is neuroprotective in the mouse SOD1G93A model of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the death of motor neurons, axon degeneration, and denervation of neuromuscular junctions (NMJ). Here we show that death receptor 6 (DR6) levels are elevated in spinal cords from post-mortem samples of human ALS and from SOD1^G93A transgenic mice, and DR6 promotes motor neuron death through activation of the caspase 3 signaling pathway. Blocking DR6 with antagonist antibody 5D10 promotes motor neuron survival in vitro via activation of Akt phosphorylation and inhibition of the caspase 3 signaling pathway, after growth factor withdrawal, sodium arsenite treatment or co-culture with SOD1^G93A astrocytes. Treatment of SOD1^G93A mice at an asymptomatic stage starting on the age of 42 days with 5D10 protects NMJ from denervation, decreases gliosis, increases survival of motor neurons and CC1⁺ oligodendrocytes in spinal cord, decreases phosphorylated neurofilament heavy chain (pNfH) levels in serum, and promotes motor functional improvement assessed by increased grip strength. The combined data provide clear evidence for neuroprotective effects of 5D10. Blocking DR6 function represents a new approach for the treatment of neurodegenerative disorders involving motor neuron death and axon degeneration, such as ALS.     

Insoluble mutant SOD1 is partly oligoubiquitinated in amyotrophic lateral sclerosis mice

Mutations in the Cu,Zn-superoxide dismutase (SOD1) gene cause a familial form of amyotrophic lateral sclerosis (ALS) through an unknown gain-of-function mechanism. Mutant SOD1 aggregation may be the toxic property. In fact, proteinaceous inclusions rich in mutant SOD1 have been found in tissues from the familial form of ALS patients and in mutant SOD1 animals, before disease onset. However, very little is known of the constituents and mechanism of formation of aggregates in ALS. We and others have shown that there is a progressive accumulation of detergent-insoluble mutant SOD1 in the spinal cord of G93A SOD1 mice. To investigate the mechanism of SOD1 aggregation, we characterized by proteome technologies SOD1 isoforms in a Triton X-100-insoluble fraction of spinal cord from G93A SOD1 mice at different stages of the disease. This showed that at symptomatic stages of the disease, part of the insoluble SOD1 is unambiguously mono- and oligoubiquitinated, in spinal cord and not in hippocampus, and that ubiquitin branches at Lys(48), the major signal for proteasome degradation. At presymptomatic stages of the disease, only insoluble unmodified SOD1 is recovered. Partial ubiquitination of SOD1-rich inclusions was also confirmed by immunohistochemical and electron microscopy analysis of lumbar spinal cord sections from symptomatic G93A SOD1 mice. On the basis of these results, we propose that ubiquitination occurs only after SOD1 aggregation and that oligoubiquitination may underline alternative mechanisms in disease pathogenesis.     

Integrative role of cPLA with COX-2 and the effect of non-steriodal anti-inflammatory drugs in a transgenic mouse model of amyotrophic lateral sclerosis

Cyclooxygenase-2 (COX-2) is a key molecule in the inflammatory pathway in amyotrophic lateral sclerosis (ALS). Cytosolic phospholipase A (cPLA2) is an important enzyme providing substrate for cyclooxygenases. We therefore examined cPLA2 expression in human ALS and mutant Cu/Zn superoxide dismutase (SOD1) transgenic mice and its relation to COX-2. Immunohistochemistry and real-time RT-PCR revealed elevated cPLA2 protein and its mRNA levels in the lumbar spinal cord of mutant SOD1 mice. COX-2 immunoreactivity was increased in lumbar spinal cord sections from both familial ALS (FALS) and sporadic ALS (SALS) as compared to controls, and cPLA2 immunoreactivity was increased in a patient with FALS. Oral administration of the non-selective cyclooxygenase (COX) inhibitor, sulindac, extended the survival (by 10%) of G93A SOD1 mice as compared to littermate controls. Sulindac, as well as the selective COX-2 inhibitors, rofecoxib and celecoxib reduced cPLA2 immunoreactivity in the lumbar spinal cord of G93A transgenic mice. Sulindac treatment preserved motor neurons, and reduced microglial activation and astrocytosis, in the spinal cord of G93A SOD1 transgenic mice. These results suggest that cPLA2 plays an important role in supplying arachidonic acid to the COX-2 driven inflammatory pathway in ALS associated with SOD1 mutations.     

Human Motor Neurons Generated from Neural Stem Cells Delay Clinical Onset and Prolong Life in ALS Mouse Model

Amyotrophic lateral sclerosis (ALS) is the most common adult onset motor neuron disease. The etiology and pathogenic mechanisms of the disease remain unknown, and there is no effective treatment. Here we show that intrathecal transplantation of human motor neurons derived from neural stem cells (NSCs) in spinal cord of the SOD1G93A mouse ALS model delayed disease onset and extended life span of the animals. When HB1.F3.Olig2 (F3.Olig2) cells, stable immortalized human NSCs encoding the human Olig2 gene, were treated with sonic hedgehog (Shh) protein for 5–7 days, the cells expressed motor neuron cell type-specific phenotypes Hb9, Isl-1 and choline acetyltransferase (ChAT). These F3.Olig2-Shh human motor neurons were transplanted intrathecally in L5–L6 spinal cord of SOD1G93A mice, and at 4 weeks post-transplantation, transplanted F3.Olig2-Shh motor neurons expressing the neuronal phenotype markers NF, MAP2, Hb9, and ChAT were found in the ventral horn of the spinal cord. Onset of clinical signs in ALS mice with F3.Olig2-Shh motor neuron implants was delayed for 7 days and life span of animals was significantly extended by 20 days. Our results indicate that this treatment modality of intrathecal transplantation of human motor neurons derived from NSCs might be of value in the treatment of ALS patients without significant adverse effects.     

The Legs at odd angles (Loa) Mutation in Cytoplasmic Dynein Ameliorates Mitochondrial Function in SOD1G93A Mouse Model for Motor Neuron Disease

Amyotrophic lateral sclerosis (ALS) is a debilitating and fatal late-onset neurodegenerative disease. Familial cases of ALS (FALS) constitute ∼10% of all ALS cases, and mutant superoxide dismutase 1 (SOD1) is found in 15–20% of FALS. SOD1 mutations confer a toxic gain of unknown function to the protein that specifically targets the motor neurons in the cortex and the spinal cord. We have previously shown that the autosomal dominant Legs at odd angles (Loa) mutation in cytoplasmic dynein heavy chain (Dync1h1) delays disease onset and extends the life span of transgenic mice harboring human mutant SOD1^G93A. In this study we provide evidence that despite the lack of direct interactions between mutant SOD1 and either mutant or wild-type cytoplasmic dynein, the Loa mutation confers significant reductions in the amount of mutant SOD1 protein in the mitochondrial matrix. Moreover, we show that the Loa mutation ameliorates defects in mitochondrial respiration and membrane potential observed in SOD1^G93A motor neuron mitochondria. These data suggest that the Loa mutation reduces the vulnerability of mitochondria to the toxic effects of mutant SOD1, leading to improved mitochondrial function in SOD1^G93A motor neurons.     

Characterizing the multiple roles of FGF-2 in SOD1G93A ALS mice in vivo and in vitro

We have previously shown that knockout of fibroblast growth factor-2 (FGF-2) and potential compensatory effects of other growth factors result in amelioration of disease symptoms in a transgenic mouse model of amyotrophic lateral sclerosis (ALS). ALS is a rapidly progressive neurological disorder leading to degeneration of cortical, brain stem, and spinal motor neurons followed by subsequent denervation and muscle wasting. Mutations in the superoxide dismutase 1 (SOD1) gene are responsible for approximately 20% of familial ALS cases and SOD1 mutant mice still are among the models best mimicking clinical and neuropathological characteristics of ALS. The aim of the present study was a thorough characterization of FGF-2 and other growth factors and signaling effectors in vivo in the SOD1^G93A mouse model. We observed tissue-specific opposing gene regulation of FGF-2 and overall dysregulation of other growth factors, which in the gastrocnemius muscle was associated with reduced downstream extracellular-signal-regulated kinases (ERK) and protein kinase B (AKT) activation. To further investigate whether the effects of FGF-2 on motor neuron death are mediated by glial cells, astrocytes lacking FGF-2 were cocultured together with mutant SOD1 ^G93A motor neurons. FGF-2 had an impact on motor neuron maturation indicating that astrocytic FGF-2 affects motor neurons at a developmental stage. Moreover, neuronal gene expression patterns showed FGF-2- and SOD1 ^G93A-dependent changes in ciliary neurotrophic factor, glial-cell-line-derived neurotrophic factor, and ERK2, implying a potential involvement in ALS pathogenesis before the onset of clinical symptoms.     

MTOR-independent,autophagic enhancer trehalose prolongs motor neuron survival and ameliorates the autophagic flux defect in a mouse model of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disorder caused by selective motor neuron degeneration. Abnormal protein aggregation and impaired protein degradation pathways may contribute to the disease pathogenesis. Although it has been reported that autophagy is altered in patients and animal model of ALS, little is known about the role of autophagy in motor neuron degeneration in this disease. Our previous study shows that rapamycin, an MTOR-dependent autophagic activator, accelerates disease progression in the SOD1^G93A mouse model of ALS. In the present report, we have assessed the role of the MTOR-independent autophagic pathway in ALS by determining the effect of the MTOR-independent autophagic inducer trehalose on disease onset and progression, and on motor neuron degeneration in SOD1^G93A mice. We have found that trehalose significantly delays disease onset prolongs life span, and reduces motor neuron loss in the spinal cord of SOD1^G93A mice. Most importantly, we have documented that trehalose decreases SOD1 and SQSTM1/p62 aggregation, reduces ubiquitinated protein accumulation, and improves autophagic flux in the motor neurons of SOD1^G93A mice. Moreover, we have demonstrated that trehalose can reduce skeletal muscle denervation, protect mitochondria, and inhibit the proapoptotic pathway in SOD1^G93A mice. Collectively, our study indicated that the MTOR-independent autophagic inducer trehalose is neuroprotective in the ALS model and autophagosome-lysosome fusion is a possible therapeutic target for the treatment of ALS.     

Motor neuronal protection by l-arginine prolongs survival of mutant SOD1 (G93A) ALS mice

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by progressive paralysis due to motor neuron degeneration. Despite the fact that many different therapeutic strategies have been applied to prevent disease progression, no cure or effective therapy is currently available for ALS. We found that l-arginine protects cultured motor neurons from excitotoxic injury. We also found that l-arginine supplementation both prior to and after the onset of motor neuron degeneration in mtSOD1 (G93A) transgenic ALS mice significantly slowed the progression of neuropathology in lumbar spinal cord, delayed onset of motor dysfunction, and prolonged life span. Moreover, l-arginine treatment was associated with preservation of arginase I activity and neuroprotective polyamines in spinal cord motor neurons. Our findings show that l-arginine has potent in vitro and in vivo neuroprotective properties and may be a candidate for therapeutic trials in ALS.     

Treatment with arimoclomol, a coinducer of heat shock proteins, delays disease progression in ALS mice

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative condition in which motoneurons of the spinal cord and motor cortex die, resulting in progressive paralysis. This condition has no cure and results in eventual death, usually within 1-5 years of diagnosis. Although the specific etiology of ALS is unknown, 20% of familial cases of the disease carry mutations in the gene encoding Cu/Zn superoxide dismutase-1 (SOD1). Transgenic mice overexpressing human mutant SOD1 have a phenotype and pathology that are very similar to that seen in human ALS patients. Here we show that treatment with arimoclomol, a coinducer of heat shock proteins (HSPs), significantly delays disease progression in mice expressing a SOD1 mutant in which glycine is substituted with alanine at position 93 (SOD1(G93A)). Arimoclomol-treated SOD1(G93A) mice show marked improvement in hind limb muscle function and motoneuron survival in the later stages of the disease, resulting in a 22% increase in lifespan. Pharmacological activation of the heat shock response may therefore be a successful therapeutic approach to treating ALS, and possibly other neurodegenerative diseases.     

MTOR-independent,autophagic enhancer trehalose prolongs motor neuron survival and ameliorates the autophagic flux defect in a mouse model of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disorder caused by selective motor neuron degeneration. Abnormal protein aggregation and impaired protein degradation pathways may contribute to the disease pathogenesis. Although it has been reported that autophagy is altered in patients and animal model of ALS, little is known about the role of autophagy in motor neuron degeneration in this disease. Our previous study shows that rapamycin, an MTOR-dependent autophagic activator, accelerates disease progression in the SOD1^G93A mouse model of ALS. In the present report, we have assessed the role of the MTOR-independent autophagic pathway in ALS by determining the effect of the MTOR-independent autophagic inducer trehalose on disease onset and progression, and on motor neuron degeneration in SOD1^G93A mice. We have found that trehalose significantly delays disease onset prolongs life span, and reduces motor neuron loss in the spinal cord of SOD1^G93A mice. Most importantly, we have documented that trehalose decreases SOD1 and SQSTM1/p62 aggregation, reduces ubiquitinated protein accumulation, and improves autophagic flux in the motor neurons of SOD1^G93A mice. Moreover, we have demonstrated that trehalose can reduce skeletal muscle denervation, protect mitochondria, and inhibit the proapoptotic pathway in SOD1^G93A mice. Collectively, our study indicated that the MTOR-independent autophagic inducer trehalose is neuroprotective in the ALS model and autophagosome-lysosome fusion is a possible therapeutic target for the treatment of ALS.     

Ablation of proliferating cells in the CNS exacerbates motor neuron disease caused by mutant superoxide dismutase

Proliferation of glia and immune cells is a common pathological feature of many neurodegenerative diseases including amyotrophic lateral sclerosis (ALS). Here, to investigate the role of proliferating cells in motor neuron disease, SOD1(G93A) transgenic mice were treated intracerebroventicularly (i.c.v.) with the anti-mitotic drug cytosine arabinoside (Ara-C). I.c.v. delivery of Ara-C accelerated disease progression in SOD1(G93A) mouse model of ALS. Ara-C treatment caused substantial decreases in the number of microglia, NG2+ progenitors, Olig2+ cells and CD3+ T cells in the lumbar spinal cord of symptomatic SOD1(G93A) transgenic mice. Exacerbation of disease was also associated with significant alterations in the expression inflammatory molecules IL-1β, IL-6, TGF-β and the growth factor IGF-1.