Genetic linkage analysis of familial amyotrophic lateral sclerosis using human chromosome 21 microsatellite DNA markers

Variability in Clinical Phenotype in TARDBP Mutations: Amyotrophic Lateral Sclerosis Case Description and Literature Review

Mutations in the 43 kDa transactive-response (TAR)-DNA-binding protein (TARDBP) are associated with 2-5% of familial Amyotrophic Lateral Sclerosis (ALS) cases. TAR DNA-Binding Protein 43 (TDP-43) is an RNA/DNA-binding protein involved in several cellular mechanisms (e.g., transcription, pre-mRNA processing, and splicing). Many ALS-linked TARDBP mutations have been described in the literature, but few phenotypic data on monogenic TARDBP-mutated ALS are available. In this paper, (1) we describe the clinical features of ALS patients carrying mutations in the TARDBP gene evaluated at the Tertiary ALS Center at Maggiore della Carità University Hospital, Novara, Italy, from 2010 to 2020 and (2) present the results of our review of the literature on this topic, analyzing data obtained for 267 patients and highlighting their main clinical and demographic features.

Status of ALS Treatment, Insights into Therapeutic Challenges and Dilemmas

Amyotrophic lateral sclerosis (ALS) is an extremely heterogeneous disease of motor neurons that eventually leads to death. Despite impressive advances in understanding the genetic, molecular, and pathological mechanisms of the disease, the only drug approved to date by both the FDA and EMA is riluzole, with a modest effect on survival. In this opinion view paper, we will discuss how to address some challenges for drug development in ALS at the conceptual, technological, and methodological levels. In addition, socioeconomic and ethical issues related to the legitimate need of patients to benefit quickly from new treatments will also be addressed. In conclusion, this brief review takes a more optimistic view, given the recent approval of two new drugs in some countries and the development of targeted gene therapies.

Contribution of astrocytes to neuropathology of neurodegenerative diseases

Classically, the loss of vulnerable neuronal populations in neurodegenerative diseases was considered to be the consequence of cell autonomous degeneration of neurons. However, progress in the understanding of glial function, the availability of improved animal models recapitulating the features of the human diseases, and the development of new approaches to derive glia and neurons from induced pluripotent stem cells obtained from patients, provided novel information that altered this view. Current evidence strongly supports the notion that non-cell autonomous mechanisms contribute to the demise of neurons in neurodegenerative disorders, and glia causally participate in the pathogenesis and progression of these diseases. In addition to microglia, astrocytes have emerged as key players in neurodegenerative diseases and will be the focus of the present review. Under the influence of pathological stimuli present in the microenvironment of the diseased CNS, astrocytes undergo morphological, transcriptional, and functional changes and become reactive. Reactive astrocytes are heterogeneous and exhibit neurotoxic (A1) or neuroprotective (A2) phenotypes. In recent years, single-cell or single-nucleus transcriptome analyses unraveled new, disease-specific phenotypes beyond A1/A2. These investigations highlighted the complexity of the astrocytic responses to CNS pathology. The present review will discuss the contribution of astrocytes to neurodegenerative diseases with particular emphasis on Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis and frontotemporal dementia. Some of the commonalties and differences in astrocyte-mediated mechanisms that possibly drive the pathogenesis or progression of the diseases will be summarized. The emerging view is that astrocytes are potential new targets for therapeutic interventions. A comprehensive understanding of astrocyte heterogeneity and disease-specific phenotypic complexity could facilitate the design of novel strategies to treat neurodegenerative disorders.

Beyond the Traditional Clinical Trials for Amyotrophic Lateral Sclerosis and The Future Impact of Gene Therapy

Amyotrophic lateral sclerosis (ALS) is a devastating and incurable motor neuron (MN) disorder affecting both upper and lower MNs. Despite impressive advances in the understanding of the disease’s pathological mechanism, classical pharmacological clinical trials failed to provide an efficient cure for ALS over the past twenty years. Two different gene therapy approaches were recently approved for the monogenic disease Spinal muscular atrophy, characterized by degeneration of lower MNs. This milestone suggests that gene therapy-based therapeutic solutions could be effective for the treatment of ALS. This review summarizes the possible reasons for the failure of traditional clinical trials for ALS. It provides then a focus on the advent of gene therapy approaches for hereditary forms of ALS. Specifically, it describes clinical use of antisense oligonucleotides in three familial forms of ALS, caused by mutations in SOD1, C9orf72 and FUS genes, respectively.. Clinical and pre-clinical studies based on AAV-mediated gene therapy approaches for both familial and sporadic ALS cases are presented as well. Overall, this overview highlights the potential of gene therapy as a transforming technology that will have a huge impact on treatment perspective for ALS patients and on the design of future clinical trials.

Glial Cells-The Strategic Targets in Amyotrophic Lateral Sclerosis Treatment

Amyotrophic lateral sclerosis (ALS) is a fatal neurological disease, which is characterized by the degeneration of motor neurons in the motor cortex and the spinal cord and subsequently by muscle atrophy. To date, numerous gene mutations have been linked to both sporadic and familial ALS, but the effort of many experimental groups to develop a suitable therapy has not, as of yet, proven successful. The original focus was on the degenerating motor neurons, when researchers tried to understand the pathological mechanisms that cause their slow death. However, it was soon discovered that ALS is a complicated and diverse pathology, where not only neurons, but also other cell types, play a crucial role via the so-called non-cell autonomous effect, which strongly deteriorates neuronal conditions. Subsequently, variable glia-based in vitro and in vivo models of ALS were established and used for brand-new experimental and clinical approaches. Such a shift towards glia soon bore its fruit in the form of several clinical studies, which more or less successfully tried to ward the unfavourable prognosis of ALS progression off. In this review, we aimed to summarize current knowledge regarding the involvement of each glial cell type in the progression of ALS, currently available treatments, and to provide an overview of diverse clinical trials covering pharmacological approaches, gene, and cell therapies.

Dysregulation of Transcription Factors: A Key Culprit Behind Neurodegenerative Disorders

Neurodegenerative diseases (NDs) are considered heterogeneous disorders characterized by progressive pathological changes in neuronal systems. Transcription factors are protein molecules that are important in regulating the expression of genes. Although the clinical manifestations of NDs vary, the pathological processes appear similar with regard to neuroinflammation, oxidative stress, and proteostasis, to which, as numerous studies have discovered, transcription factors are closely linked. In this review, we summarized and reviewed the roles of transcription factors in NDs, and then we elucidated their functions during pathological processes, and finally we discussed their therapeutic values in NDs.

Participation in Physical Activity and Risk for Amyotrophic Lateral Sclerosis Mortality Among Postmenopausal Women

IMPORTANCE

Amyotrophic lateral sclerosis (ALS) is a progressive, fatal disease with no known cause. Case studies primarily of athletes and several case-control studies have suggested that high levels of strenuous physical activity (PA) may increase the risk for ALS. This relationship has yet to be evaluated among women in population-based cohort studies.

OBJECTIVE

To evaluate the relationship between PA and risk for ALS mortality in a large cohort of postmenopausal women.

DESIGN, SETTING, AND PARTICIPANTS

The Women's Health Initiative (WHI) enrolled 161 809 postmenopausal women, aged 50 to 79 years (mean [SD] age, 63.6 [7.24] years), between 1993 and 1998 into either a clinical trial or an observational study at 40 clinical research centers across the United States. We conducted a cohort study from November 2014 to September 2015 using baseline and mortality data during an average of 9.6 years of follow-up from the entire WHI cohort, through September 1, 2013 (with 1.1% lost to follow-up), to address whether there is a relationship between PA and ALS mortality.

EXPOSURES

The WHI assessed frequency and duration of mild, moderate, and strenuous PA at baseline via self-administered questionnaire.

MAIN OUTCOMES AND MEASURES

Underlying cause of death from ALS collected from death certificates.

RESULTS

The WHI enrolled 161 809 women, of whom 165 died of ALS; women who died of ALS were older (median age, 66 years; interquartile range, 61-69 years) compared with the total WHI study population (median age, 63 years; interquartile range, 57-69 years). Age-adjusted ALS mortality rates varied from 7.4 (95% CI, 5.5-9.9)/100 000 person-years for no strenuous PA to 10.6 (95% CI, 5.6-20.0)/100 000 person-years for strenuous PA 3 or more days per week (P = .07). Adjusted for age and body mass index (calculated as weight in kilograms divided by height in meters squared), the odds ratio for death from ALS for participants with strenuous PA 3 or more days per week compared with no reported strenuous PA was 1.56 (95% CI, 1.02-2.37; P = .04).

CONCLUSIONS AND RELEVANCE

To our knowledge, this is the first cohort study to report an increased risk for ALS mortality associated with strenuous PA in postmenopausal women. The association between strenuous PA and ALS risk observed does not compromise the overall benefit of strenuous PA for total mortality, coronary heart disease, and breast cancer reported in other WHI investigations, but it may provide an important clue to the etiology of ALS, if replicated by other studies.

Compartment-dependent mitochondrial alterations in experimental ALS, the effects of mitophagy and mitochondriogenesis

Amyotrophic lateral sclerosis (ALS) is characterized by massive loss of motor neurons. Data from ALS patients and experimental models indicate that mitochondria are severely damaged within dying or spared motor neurons. Nonetheless, recent data indicate that mitochondrial preservation, although preventing motor neuron loss, fails to prolong lifespan. On the other hand, the damage to motor axons plays a pivotal role in determining both lethality and disease course. Thus, in the present article each motor neuron compartment (cell body, central, and peripheral axons) of G93A SOD-1 mice was studied concerning mitochondrial alterations as well as other intracellular structures. We could confirm the occurrence of ALS-related mitochondrial damage encompassing total swelling, matrix dilution and cristae derangement along with non-pathological variations of mitochondrial size and number. However, these alterations occur to a different extent depending on motor neuron compartment. Lithium, a well-known autophagy inducer, prevents most pathological changes. However, the efficacy of lithium varies depending on which motor neuron compartment is considered. Remarkably, some effects of lithium are also evident in wild type mice. Lithium is effective also in vitro, both in cell lines and primary cell cultures from the ventral spinal cord. In these latter cells autophagy inhibition within motor neurons in vitro reproduced ALS pathology which was reversed by lithium. Muscle and glial cells were analyzed as well. Cell pathology was mostly severe within peripheral axons and muscles of ALS mice. Remarkably, when analyzing motor axons of ALS mice a subtotal clogging of axoplasm was described for the first time, which was modified under the effects of lithium. The effects induced by lithium depend on several mechanisms such as direct mitochondrial protection, induction of mitophagy and mitochondriogenesis. In this study, mitochondriogenesis induced by lithium was confirmed in situ by a novel approach using [2-³H]-adenosine.

Downregulated AEG-1 together with inhibited PI3K/Akt pathway is associated with reduced viability of motor neurons in an ALS model

Astrocyte elevated gene-1 (AEG-1) has been reported to regulate the phosphatidylinositol 3-kinase (PI3K)/Akt pathway and is also regulated by it. This study investigated how AEG-1 participates in the survival pathway of motor neurons in amyotrophic lateral sclerosis (ALS). We found reduced levels of AEG-1 in ALS motor neurons, both in vivo and in vitro, compared to wild type controls. Moreover, AEG-1 silencing demonstrated inhibition of the PI3K/Akt pathway and increased cell apoptosis. Additionally, the PI3K/Akt pathway in mSOD1 cells was unresponsive under serum deprivation conditions compared to wtSOD1 cells. These results suggest that AEG-1 deficiency, together with the inhibited PI3K/Akt pathway was associated with decreased viability of ALS motor neurons. However, the mRNA levels of AEG-1 were still lower in mSOD1 cells compared to the control groups, though the signaling pathway was activated by application of a PI3-K activator. This suggests that in ALS motor neurons, some unknown interruption exists in the PI3K/Akt/CREB/AEG-1 feedback loop, thus attenuating the protection by this signaling pathway. Together, these findings support that AEG-1 is a critical factor for cell survival, and the disrupted PI3K/Akt/CREB/AEG-1cycle is involved in the death of injured motor neurons and pathogenesis of ALS.

Roscovitine treatment caused impairment of fertilizing ability in mice

OBJECTIVE

To explore the adverse effect of roscovitine on reproductive system of male mice.

MATERIALS AND METHODS

Male hSOD1(G93A) transgenetic mice received roscovitine 72 nmol/day (d) for 4 weeks (w), with normal control and dimethyl sulfoxide (DMSO)-treated animals served as controls (n=4). Male C57BL/6 mice were treated with roscovitine at either 72 nmol/d or 144 nmol/d for 4 w or 8 w, and normal control and DMSO treated mice served as controls. Fertility of male mice, sperm quality parameters, histological and related pathological changes of seminiferous tubules associated with roscovitine treatment were evaluated.

RESULTS

In male hSOD1(G93A) transgenetic mice treated with 72 nmol/d roscovitine for 4 w and C57BL/6 male mice treated with 72 nmol/d roscovitine for 8w and 144 nmol/d roscovitine for 4 w and 8 w, sperm counts and sperm motility rates decreased and sperm abnormality rates increased, and damage of seminiferous tubules were detected. Roscovitine treatment induced inhibition of CDK5 activities and decrease of BrdU-positive tubuler cells.

CONCLUSION

These results demonstrated that roscovitine treatment induced interference of male reproductive system and caused impairment of fertilizing ability. Reproductive system of ALS male mice was more susceptible to roscovitine induced impaired fertilizing ability.

iPSC-Based Models to Unravel Key Pathogenetic Processes Underlying Motor Neuron Disease Development

Motor neuron diseases (MNDs) are neuromuscular disorders affecting rather exclusively upper motor neurons (UMNs) and/or lower motor neurons (LMNs). The clinical phenotype is characterized by muscular weakness and atrophy leading to paralysis and almost invariably death due to respiratory failure. Adult MNDs include sporadic and familial amyotrophic lateral sclerosis (sALS-fALS), while the most common infantile MND is represented by spinal muscular atrophy (SMA). No effective treatment is ccurrently available for MNDs, as for the vast majority of neurodegenerative disorders, and cures are limited to supportive care and symptom relief. The lack of a deep understanding of MND pathogenesis accounts for the difficulties in finding a cure, together with the scarcity of reliable in vitro models. Recent progresses in stem cell field, in particular in the generation of induced Pluripotent Stem Cells (iPSCs) has made possible for the first time obtaining substantial amounts of human cells to recapitulate in vitro some of the key pathogenetic processes underlying MNDs. In the present review, recently published studies involving the use of iPSCs to unravel aspects of ALS and SMA pathogenesis are discussed with an overview of their implications in the process of finding a cure for these still orphan disorders.

Peptides that activate the 20S proteasome by gate opening increased oxidized protein removal and reduced protein aggregation

The proteasome is a multicatalytic protease that is responsible for the degradation of the majority of intracellular proteins. Its role is correlated with several major regulatory pathways that are involved in cell cycle control, signaling, and antigen presentation, as well as in the removal of oxidatively damaged proteins. Although several proteasomal catalytic inhibitors have been described, very few activators have been reported to date. Some reports in the literature highlight the cellular protective effects of proteasome activation against oxidative stress and its effect on increased life span. In this work, we describe a peptide named proteasome-activating peptide 1 (PAP1), which increases the chymotrypsin-like proteasomal catalytic activity and, consequently, proteolytic rates both in vitro and in culture. PAP1 proteasomal activation is mediated by the opening of the proteasomal catalytic chamber. We also demonstrate that the observed proteasomal activation protected cells from oxidative stress; further, PAP1 prevented protein aggregation in a cellular model of amyotrophic lateral sclerosis. The role of 20SPT gate opening underlying protection against oxidative stress was also explored in yeast cells. The present data indicate the importance of proteasomal activators as potential drugs for the treatment of pathologies associated with the impaired removal of damaged proteins, which is observed in many neurodegenerative diseases.

Genetic Modifiers for Neuromuscular Diseases

Neuromuscular diseases, which encompass disorders that affect muscle and its innervation, are highly heritable. Genetic diagnosis now frequently pinpoints the primary mutation responsible for a given neuromuscular disease. However, the results from genetic testing indicate that neuromuscular disease phenotypes may vary widely, even in individuals with the same primary disease-causing mutation. Clinical variability arises from both genetic and environmental factors. Genetic modifiers can now be identified using candidate gene as well as genomic approaches. The presence of genetic modifiers for neuromuscular disease helps define the clinical outcome and also highlights pathways of potential therapeutic utility. Herein, we will focus on single gene neuromuscular disorders, including muscular dystrophy, spinal muscular atrophy, and amyotrophic lateral sclerosis, and the methods that have been used to identify modifier genes. Animal models have been an invaluable resource for modifier gene discovery and subsequent mechanistic studies. Some modifiers, identified using animal models, have successfully translated to the human counterpart. Furthermore, in a few instances, modifier gene discovery has repetitively uncovered the same pathway, such as TGFβ signaling in muscular dystrophy, further emphasizing the relevance of that pathway. Knowledge of genetic factors that influence disease can have direct clinical applications for prognosis and predicted outcome.

Altered localization, abnormal modification and loss of function of Sigma receptor-1 in amyotrophic lateral sclerosis

Intracellular accumulations of mutant, misfolded proteins are major pathological hallmarks of amyotrophic lateral sclerosis (ALS) and related disorders. Recently, mutations in Sigma receptor 1 (SigR1) have been found to cause a form of ALS and frontotemporal lobar degeneration (FTLD). Our goal was to pinpoint alterations and modifications of SigR1 in ALS and to determine how these changes contribute to the pathogenesis of ALS. In the present study, we found that levels of the SigR1 protein were reduced in lumbar ALS patient spinal cord. SigR1 was abnormally accumulated in enlarged C-terminals and endoplasmic reticulum (ER) structures of alpha motor neurons. These accumulations co-localized with the 20s proteasome subunit. SigR1 accumulations were also observed in SOD1 transgenic mice, cultured ALS-8 patient's fibroblasts with the P56S-VAPB mutation and in neuronal cell culture models. Along with the accumulation of SigR1 and several other proteins involved in protein quality control, severe disturbances in the unfolded protein response and impairment of protein degradation pathways were detected in the above-mentioned cell culture systems. Furthermore, shRNA knockdown of SigR1 lead to deranged calcium signaling and caused abnormalities in ER and Golgi structures in cultured NSC-34 cells. Finally, pharmacological activation of SigR1 induced the clearance of mutant protein aggregates in these cells. Our results support the notion that SigR1 is abnormally modified and contributes to the pathogenesis of ALS.

Defective neuromuscular transmission in the SOD1 G93A transgenic mouse improves after administration of human umbilical cord blood cells

To assess the effect of human umbilical cord blood (hUCB) transplantation on neuromuscular transmission in SOD1(G93A) transgenic mice, we studied the probability of neuromuscular transmission (PNMT), a relevant physiological indicator of motor nerve function, in 3 SOD1(G93A) mice transplanted with hUCB and compared to PNMT in 4 SOD1(G93A) mice without cell transplantation and 3 non-mutant SOD1 transgenic mice. For preparations isolated from non-mutant SOD1 transgenic mice, PNMT was 0.93 and 0.84 during the first 5 s of 70 and 90 Hz trains, respectively. PNMT gradually declined to 0.77 and 0.42 at the end of the trains. In striking contrast, PNMT for preparations from non-treated mutant SOD1(G93A) mice was 0.52 and 0.36 in the first 5 s of 70 and 90 Hz trains, respectively (p<0.05). Treatment with hUCB significantly (p<0.05) improved PNMT in SOD1(G93A) preparations. That is, the initial 5 s PNMT was 0.88 and 0.68 for the 70 and 90 Hz stimuli, respectively. We concluded that hUCB transplantation significantly improved PNMT for muscles removed from SOD1(G93A) mice. Testing PNMT in the SOD1(G93A) mouse model could be used as a simple in vitro protocol to detect a positive cellular response to therapeutic interventions in ALS.

Mitochondrial dynamics and bioenergetic dysfunction is associated with synaptic alterations in mutant SOD1 motor neurons

Mutations in Cu,Zn superoxide dismutase (SOD1) cause familial amyotrophic lateral sclerosis (FALS), a rapidly fatal motor neuron disease. Mutant SOD1 has pleiotropic toxic effects on motor neurons, among which mitochondrial dysfunction has been proposed as one of the contributing factors in motor neuron demise. Mitochondria are highly dynamic in neurons; they are constantly reshaped by fusion and move along neurites to localize at sites of high-energy utilization, such as synapses. The finding of abnormal mitochondria accumulation in neuromuscular junctions, where the SOD1-FALS degenerative process is though to initiate, suggests that impaired mitochondrial dynamics in motor neurons may be involved in pathogenesis. We addressed this hypothesis by live imaging microscopy of photo-switchable fluorescent mitoDendra in transgenic rat motor neurons expressing mutant or wild-type human SOD1. We demonstrate that mutant SOD1 motor neurons have impaired mitochondrial fusion in axons and cell bodies. Mitochondria also display selective impairment of retrograde axonal transport, with reduced frequency and velocity of movements. Fusion and transport defects are associated with smaller mitochondrial size, decreased mitochondrial density, and defective mitochondrial membrane potential. Furthermore, mislocalization of mitochondria at synapses among motor neurons, in vitro, correlates with abnormal synaptic number, structure, and function. Dynamics abnormalities are specific to mutant SOD1 motor neuron mitochondria, since they are absent in wild-type SOD1 motor neurons, they do not involve other organelles, and they are not found in cortical neurons. Together, these results suggest that impaired mitochondrial dynamics may contribute to the selective degeneration of motor neurons in SOD1-FALS.

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.

Nutrition, sirtuins and aging

Beyond our inherited genetic make-up environmental factors are central for health and disease and finally determine our life span. Amongst the environmental factors nutrition plays a prominent role in affecting a variety of degenerative processes that are linked to aging. The exponential increase of non-insulin-dependent diabetes mellitus in industrialized nations as a consequence of a long-lasting caloric supernutrition is an expression of this environmental challenge that also affects aging processes. The most consistent effects along the environmental factors that slow down aging - from simple organisms to rodents and primates - have been observed for caloric restriction. In the yeast Saccharomyces cerevisiae, the fruit fly Drosophila melanogaster and the nematode Caenorhabditis elegans, sirtuins (silencing information regulators) have been identified to mediate as "molecular sensors" the effects of caloric restriction on aging processes. Sirtuins are NAD(+)-dependent deacetylases that are activated when e.g. cell energy status is low and the NAD(+) over NADH ratio is high. As a consequence transcription rates of a variety of genes including that of the apoptosis inducing p(53) gene are reduced. Moreover, in C. elegans, sirtuins were shown to interact with proteins of the insulin/IGF-1 signaling cascade of which several members are known to extend life span of the nematodes when mutated. Downstream targets of this pathway include genes that encode antioxidative enzymes such as Superoxide dismutase (SOD) whose transcription is activated when receptor activation by insulin/IGF is low or when sirtuins are active and the ability of cells to resist oxidative damage appears to determine their life span. Amongst dietary factors that activate sirtuins are certain polyphenols such as quercetin and resveratrol. Whereas their ability to affect life span has been demonstrated in simple organisms, their efficacy in mammals awaits proof of principle.

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.

Improving binding specificity of pharmacological chaperones that target mutant superoxide dismutase-1 linked to familial amyotrophic lateral sclerosis using computational methods

We recently described a set of drug-like molecules obtained from an in silico screen that stabilize mutant superoxide dismutase-1 (SOD-1) linked to familial amyotrophic lateral sclerosis (ALS) against unfolding and aggregation but exhibited poor binding specificity toward SOD-1 in presence of blood plasma. A reasonable but not a conclusive model for the binding of these molecules was proposed on the basis of restricted docking calculations and site-directed mutagenesis of key residues at the dimer interface. A set of hydrogen bonding constraints obtained from these experiments were used to guide docking calculations with compound library around the dimer interface. A series of chemically unrelated hits were predicted, which were experimentally tested for their ability to block aggregation. At least six of the new molecules exhibited high specificity of binding toward SOD-1 in the presence of blood plasma. These molecules represent a new class of molecules for further development into clinical candidates.

Stem cells: comprehensive treatments for amyotrophic lateral sclerosis in conjunction with growth factor delivery

Amyotrophic lateral sclerosis (ALS) is characterized by loss of both upper and lower motor neurons. ALS progression is complex and likely due to cellular dysfunction at multiple levels, including mitochondrial dysfunction, glutamate excitotoxicity, oxidative stress, axonal dysfunction, reactive astrocytosis, and mutant superoxide dismutase expression, therefore, treatment must provide neuronal protection from multiple insults. A significant amount of ALS research focuses on growth factor-based therapies. Growth factors including insulin-like growth factor-I, vascular endothelial growth factor, brain-derived neurotrophic factor, and glial-derived neurotrophic factor exhibit robust neuroprotective effects on motor neurons in ALS models. Issues concerning growth factor delivery, stability and unwanted side effects slow the transfer of these treatments to human ALS patients. Stem cells represent a new therapeutic approach offering both cellular replacement and trophic support for the existing population. Combination therapy consisting of stem cells expressing beneficial growth factors may provide a comprehensive treatment for ALS.

Smoking and risk for amyotrophic lateral sclerosis: analysis of the EPIC cohort

OBJECTIVE

Cigarette smoking has been reported as "probable" risk factor for Amyotrophic Lateral Sclerosis (ALS), a poorly understood disease in terms of aetiology. The extensive longitudinal data of the European Prospective Investigation into Cancer and Nutrition (EPIC) were used to evaluate age-specific mortality rates from ALS and the role of cigarette smoking on the risk of dying from ALS.

METHODS

A total of 517,890 healthy subjects were included, resulting in 4,591,325 person-years. ALS cases were ascertained through death certificates. Cox hazard models were built to investigate the role of smoking on the risk of ALS, using packs/years and smoking duration to study dose-response.

RESULTS

A total of 118 subjects died from ALS, resulting in a crude mortality rate of 2.69 per 100,000/year. Current smokers at recruitment had an almost two-fold increased risk of dying from ALS compared to never smokers (HR = 1.89, 95% C.I. 1.14-3.14), while former smokers at the time of enrollment had a 50% increased risk (HR = 1.48, 95% C.I. 0.94-2.32). The number of years spent smoking increased the risk of ALS (p for trend = 0.002). Those who smoked more than 33 years had more than a two-fold increased risk of ALS compared with never smokers (HR = 2.16, 95% C.I. 1.33-3.53). Conversely, the number of years since quitting smoking was associated with a decreased risk of ALS compared with continuing smoking.

INTERPRETATION

These results strongly support the hypothesis of a role of cigarette smoking in aetiology of ALS. We hypothesize that this could occur through lipid peroxidation via formaldehyde exposure.

Temporal response of neural progenitor cells to disease onset and progression in amyotrophic lateral sclerosis-like transgenic mice

Regenerative medicine through neural stem cells (NSCs) or neural progenitor cells (NPCs) has been proposed as an alterative avenue for restoring neurological dysfunction in amyotrophic lateral sclerosis (ALS). It is critical to understand the organization and distribution of endogenous adult NPCs in response to motor neuron degeneration before regenerative medicine can be applied for ALS therapy. For this reason, we analyzed the temporal response of NPCs to motor neuron degeneration in the spinal cord and brain using nestin enhancer-driven LacZ reporter transgenic mice (pNes-Tg mice, control) and bi-transgenic mice containing both the nestin enhancer-driven LacZ reporter gene and mutant G93A-SOD1 gene (Bi-Tg mice). We observed an increase of NPCs in the dorsal horns of the spinal cord at the disease onset and progression stages in the Bi-Tg mice compared with that of age-matched pNes-Tg control mice. In contrast, an increase of NPCs in the ventral horns was detected at the disease progression stage. On the other hand, an increase of NPCs in the motor cortex at the disease-onset stage, but not at the disease progression stage, was detected. Furthermore, a decrease of NPCs in the lateral ventricle at the disease progression stage was observed, whereas no difference in the number of NPCs in the hippocampus was detected at the disease onset and progression stages. Some of the NPCs differentiate into neuron-like cells in response to motor neuron degeneration. The organization and distribution of endogenous adult NPCs in the ALS-like transgenic mice at the disease onset and progression stages provide fundamental bases for consideration of regenerative therapy of ALS by increasing de novo neurogenesis.

Depletion of reduced glutathione enhances motor neuron degeneration in vitro and in vivo

The mechanism of selective and age-dependent motor neuron degeneration in human amyotrophic lateral sclerosis (ALS) has not been defined and the role of glutathione (GSH) in association with motor neuron death remains largely unknown. A motor neuron-like cell culture system and a transgenic mouse model were used to study the effect of cellular GSH alteration on motor neuron cell death. Exposure of NSC34 motor neuron-like cells to ethacrynic acid (EA) or l-buthionine sulfoximine (BSO) dramatically reduced the cellular GSH levels, and was accompanied by increased production of reactive oxygen species (ROS) measured by the dichlorofluorescin (DCF) fluorescent oxidation assay. In addition, GSH depletion enhanced oxidative stress markers, AP-1 transcriptional activation, c-Jun, c-Fos and heme oxygenase-1 (HO-1) expression in NSC34 cells analyzed by a luciferase reporter, Western blotting and quantitative PCR assays respectively. Furthermore, depletion of GSH decreased mitochondrial function, facilitated apoptosis inducing factor (AIF) translocation, cytochrome c release, and caspase 3 activation, and consequently led to motor neuron-like cell apoptosis. In an ALS-like transgenic mouse model overexpressing mutant G93A-Cu, Zn-superoxide dismutase (SOD1) gene, we showed that the reduction of GSH in the spinal cord and motor neuron cells is correlated with AIF translocation, caspase 3 activation, and motor neuron degeneration during ALS-like disease onset and progression. Taken together, the in vitro and in vivo data presented in the current report demonstrated that decreased GSH promotes multiple apoptotic pathways contributing, at least partially, to motor neuron degeneration in ALS.

Mitochondrial involvement in amyotrophic lateral sclerosis: trigger or target?

Despite numerous reports demonstrating mitochondrial abnormalities associated with amyotrophic lateral sclerosis (ALS), the role of mitochondrial dysfunction in the disease onset and progression remains unknown. The intrinsic mitochondrial apoptotic program is activated in the central nervous system of mouse models of ALS harboring mutant superoxide dismutase 1 protein. This is associated with the release of cytochrome-c from the mitochondrial intermembrane space and mitochondrial swelling. However, it is unclear if the observed mitochondrial changes are caused by the decreasing cellular viability or if these changes precede and actually trigger apoptosis. This article discusses the current evidence for mitochondrial involvement in familial and sporadic ALS and concludes that mitochondria is likely to be both a trigger and a target in ALS and that their demise is a critical step in the motor neuron death.

Motor neuron degeneration promotes neural progenitor cell proliferation, migration, and neurogenesis in the spinal cords of amyotrophic lateral sclerosis mice

The organization, distribution, and function of neural progenitor cells (NPCs) in the adult spinal cord during motor neuron degeneration in amyotrophic lateral sclerosis (ALS) remain largely unknown. Using nestin promoter-controlled LacZ reporter transgenic mice and mutant G93A-SOD1 transgenic mice mimicking ALS, we showed that there was an increase of NPC proliferation, migration, and neurogenesis in the lumbar region of adult spinal cord in response to motor neuron degeneration. The proliferation of NPCs detected by bromodeoxyurindine incorporation and LacZ staining was restricted to the ependymal zone surrounding the central canal (EZ). Once the NPCs moved out from the EZ, they lost the proliferative capability but maintained migratory function vigorously. During ALS-like disease onset and progression, NPCs in the EZ migrated initially toward the dorsal horn direction and then to the ventral horn regions, where motor neurons have degenerated. More significantly, there was an increased de novo neurogenesis from NPCs during ALS-like disease onset and progression. The enhanced proliferation, migration, and neurogenesis of (from) NPCs in the adult spinal cord of ALS-like mice may play an important role in attempting to repair the degenerated motor neurons and restore the dysfunctional circuitry which resulted from the pathogenesis of mutant SOD1 in ALS.

SOD1 mutations in amyotrophic lateral sclerosis

Amyotrophic Lateral Sclerosis (ALS), the most common form among motoneuron diseases, is characterized by a progressive neurodegenerative process involving motor neurons in the motor cortex, brain stem and spinal cord. Sporadic (SALS) accounts for the majority of patients but in about 10% of ALS cases the disease is inherited (FALS), usually as an autosomal dominant trait. In the present study we show the results of a referred based multicenter study on the distribution of SOD1 gene mutations in the largest cohort of Italian ALS patients described so far. Two hundred and sixty-four patients (39 FALS and 225 SALS) of Italian origin were studied. In 7 out of 39 FALS patients we found the following SOD1 gene mutations: i) a new G12R missense mutation in exon 1, found in a patient with a slowly progressive disease course; ii) the G41S mutation, in four unrelated patients with rapidly progressive course complicated with cognitive decline in two of them; iii) the L114F mutation, in a patient with a slowly progressive phenotype; iv) the D90A mutation, in a heterozygous patient with atypical phenotype. In addition, in one SALS patient a previously reported synonymous variant S59S was identified. In 17 (3 FALS and 14 SALS) out of 264 patients (6.4 %) the polymorphism A-->C at position 34 of intron 3 (IVS3: + 34 A-->C) was found, and in one FALS patient a novel variant IVS3 + 62 T-->C was identified. The frequency of SOD1 gene mutations (17.9 %) in FALS cases was comparable with that found in other surveys with a similar sample size of ALS cases. No SOD1 gene mutations have been identified in SALS cases. Within FALS cases, The most frequent mutation was the G41S identified in four FALS.

Familial amyotrophic lateral sclerosis with His46Arg mutation in Cu/Zn superoxide dismutase presenting characteristic clinical features and Lewy body-like hyaline inclusions

We evaluated the characteristic clinical features of one family of familial amyotrophic sclerosis (FALS) with a His46Arg mutation in the enzyme Cu/Zn superoxide dismutase (SOD1). Codon 46 encodes the binding site for copper and the His46Arg mutation may result in decreased copper binding and copper toxicity. The disease duration of this family was 17.8+/-13.2 years (mean+/-S.D.) with the age at onset being 42.9+/-4.7 years old (mean+/-S.D.). The initial sign was distal weakness of the unilateral lower limb, extending to the other lower limb. An autopsy was performed on a 62-year-old female member of the family who had the mutation. Her disease duration was 23 years, and she died of tonsillar herniation caused by metastasis of colon cancer in the cerebellum. Neuropathological findings showed marked loss of large anterior horn cells and very mild degeneration of corticospinal tracts as well as posterior columns. The number of nuclei of Clark's column was reduced. Lewy body-like hyaline inclusion bodies (LBHIs) were frequently seen in the remaining anterior horn cells. Astrocytic hyaline inclusions (Ast-HIs) were also seen. This is the first autopsy report of FALS with a His46Arg mutation presenting neuronal LBHIs and Ast-HIs. The formation of LBHIs and Ast-HIs may be dependent on the phenotype of the preferential lower motor neuron involvement in FALS with a SOD mutation and long disease duration.

Issues for Clinical Drug Development in Neurodegenerative Diseases

Neurodegenerative diseases pose specific challenges for drug development. These diseases typically have a slow and variable clinical course, an insidious onset, and symptom expression is only observed when a significant proportion of neurons are already lost. It is important to identify vulnerability factors and other determinants of clinical course in order to be able in the future to select patient populations for clinical trials with a predictable prognosis. The neurodegenerative process itself is not amenable to direct observation and, thus, cannot be monitored in clinical trials. For this reason, surrogate biomarkers are required for use as outcome parameters. In this respect, magnetic resonance imaging has proved valuable for assessing disease activity and progression in multiple sclerosis. Rating scales are of use as outcome measures but, as these generally measure symptom severity, they are most appropriate for use in assessing symptomatic treatments. Survival has been used with success as an outcome measure in trials in amyotrophic lateral sclerosis, where disease progression is rapid. The optimal outcome measure, the sample size required and the treatment duration need to be chosen in relation to the phase of the disease. Potential new treatments can be chosen based upon new knowledge of the genetics and physiopathology of neurodegenerative diseases and, in some cases, screened in transgenic mouse models, although it should be recognised that the validity of these models in terms of treatment response has yet to be established empirically.

Clinical features and neuropathological findings of familial amyotrophic lateral sclerosis with a His46Arg mutation in Cu/Zn superoxide dismutase

We examined the characteristic clinical features of one family of familial amyotrophic lateral sclerosis (FALS) with a His46Arg mutation in the enzyme Cu/Zn superoxide dismutase-1 (SOD1). The disease duration for this family was 18.1 +/- 13.2 (mean +/- S.D.) years, with the age at onset being 39.7 +/- 10.5 years old (mean +/- S.D.). The initial sign was distal weakness of the unilateral lower limb, extending to the lower limb of the other side. A wheel chair became necessary at 9.8 +/- 3.2 years after the onset. Upper limb weakness started at 15.5 +/- 8.9 years following from the onset. An autopsy was performed on a 71-year-old woman of the family with the mutation. Her disease duration was 47 years, and she died of pneumonia. She had no clear upper motor neuron involvement. Bulbar sign and respiratory muscle weakness had developed 2 years before her death. Neuropathological findings showed degeneration of corticospinal tracts, anterior/posterior spinocerebellar tracts, posterior columns, and Clarke's columns. There were few anterior horn cells in the lumbar spinal cord and no Lewy body-like hyaline inclusion bodies in these remaining anterior horn neurons. This is the first autopsy report of FALS with a His46Arg mutation in the SOD1 enzyme.

Inheritance of frontotemporal dementia

BACKGROUND

Previous studies of families with fronto-temporal dementia (FTD) support an autosomal dominant inheritance pattern, but most studies have described genetic transmission in individual families specifically selected for the presence of multiple affected individuals.

OBJECTIVE

To investigate the familial presentation and inheritance of FTD and related disorders among a large group of FTD index cases unselected for family history of dementia.

DESIGN AND SETTING

We interviewed family members and reviewed medical records and autopsy reports at a university hospital and a university-affiliated hospital to determine the frequency of familial FTD and the most likely mode of inheritance. Characteristic families with the disorder are described, along with the history, clinical findings, and neuroimaging results in affected members of these families.

PATIENTS AND PARTICIPANTS

The 42 index cases of FTD had a mean age of onset of 56.1 years (range, 40-69 years). Of these patients, 21 (50%) were women. All but one of the patients were white. Participants included male and female spouses and children of the index cases. family member with an FTD spectrum disorder and were considered familial cases. The majority (17 [89%]) of familial FTD cases showed a pattern consistent with dominant inheritance. If depression is excluded, familial cases decrease from 19 (45%) to 17 (40%), of which 15 (88%) showed a dominant transmission pattern. The initial presentations in the nonindex familial cases varied but most frequently consisted of personality and behavioral changes that preceded cognitive impairment (19 [43%]), followed by psychiatric illness (14 [33%]), dementia without behavioral change (5 [11%]), amyotrophic lateral sclerosis (5 [11%]), and parkinsonism (2[5%]). Two of the affected nonindex cases had dual presenting diagnoses. The average age of onset was 56.1 years and did not differ significantly between familial and nonfamilial cases. Onset of FTD-related symptoms occurred after the age of 65 years in only 4(10%) of 42 index cases and 3 (5%) of 60 affected relatives.

CONCLUSIONS

Familial FTD is usually inherited in an autosomal dominant pattern. The initial onset is insidious, often consisting of mood and behavioral changes occurring in presenile years that are often erroneously attributed to other nonneurologic causes. Although the precise incidence of FTD in North America is not known, it is one of the most common presenile dementias.

Degeneration of NO-synthesizing cerebrocortical neurons in transgenic mice expressing mutated superoxide dismutase is not due to elevated nitric oxide levels

Nitric oxide (NO) synthase (NOS)-containing cerebrocortical neurons degenerate in patients with amyotrophic lateral sclerosis (ALS) and dementia, and in transgenic mice expressing a mutated superoxide dismutase gene (G93A) associated with familial ALS. The cerebral cortex of transgenic mice displayed decreased NOS activity (p<0.001) and cGMP levels (p<0.01), but no changes in NOS content indicating that less NO is produced. Therefore, NOSN degeneration is not caused by elevated NO.

Retrograde axonal transport of neurotrophins: differences between neuronal populations and implications for motor neuron disease

During development, neurons die if they do not receive neurotrophin support from the target cells they are innervating. Neurotrophins are delivered from the target to the cell bodies of the innervating neurons by interacting with specific receptors located on the nerve terminals and then together are retrogradely transported to the cell body. This process consists of a number of distinct events including endocytosis of neurotrophin and its receptor into coated vesicles; vesicle sorting followed by retrograde axonal transport to the cell body, where interaction of the activated receptor initiates a signalling cascade at the cell body that causes the survival response. It has recently been shown that the signalling molecules associated with retrograde transport differ between neuronal populations. In sympathetic but not sensory neurons, a wortmannin-sensitive molecule (phosphatidylinositol kinase) is essential for the retrograde transport of neurotrophins. In sensory but not sympathetic neurons, a rapamycin-sensitive molecule (pp70S6K) is associated with retrograde transport of neurotrophins. This is strong evidence that sympathetic and sensory neurons utilize different signalling pathways to perform the same cellular function; retrograde transport. These findings may provide clues to understanding neurological diseases, such as motor neuron disease, in which axonal transport is impaired specifically in motor neurons.

Reexamination of the mechanism of hydroxyl radical adducts formed from the reaction between familial amyotrophic lateral sclerosis-associated Cu,Zn superoxide dismutase mutants and H2O2

Amyotrophic lateral sclerosis (ALS) involves the progressive degeneration of motor neurons in the spinal cord and motor cortex. Mutations to Cu,Zn superoxide dismutase (SOD) linked with familial ALS are reported to increase hydroxyl radical adduct formation from hydrogen peroxide as measured by spin trapping with 5, 5'-dimethyl-1-pyrrolline N-oxide (DMPO). In the present study, we have used oxygen-17-enriched water and H2O2 to reinvestigate the mechanism of DMPO/.OH formation from the SOD and SOD mutants. The relative ratios of DMPO/.17OH and DMPO/.16OH formed in the Fenton reaction were 90% and 10%, respectively, reflecting the ratios of H217O2 to H216O2. The reaction of the WT SOD with H217O2 in bicarbonate/CO2 buffer yielded 63% DMPO/.17OH and 37% DMPO/.16OH. Similar results were obtained from the reaction between familial ALS SOD mutants and H217O2: DMPO/.17OH (64%); DMPO/.16OH (36%) from A4V and DMPO/.17OH (62%); and DMPO/.16OH (38%) from G93A. These results were confirmed further by using 5-diethoxyphosphoryl-5-methyl-1-pyrroline N-oxide spin trap, a phosphorylated analog of DMPO. Contrary to earlier reports, the present results indicate that a significant fraction of DMPO/.OH formed during the reaction of SOD and familial ALS SOD mutants with H2O2 is derived from the incorporation of oxygen from water due to oxidation of DMPO to DMPO/.OH presumably via DMPO radical cation. No differences were detected between WT and mutant SODs, neither in the concentration of DMPO/.OH or DEPMPO/.OH formed nor in the relative incorporation of oxygen from H2O2 or water.

Three novel mutations and two variants in the gene for Cu/Zn superoxide dismutase in familial amyotrophic lateral sclerosis

Autosomal dominant inheritance is exhibited by about 10% of cases of amyotrophic lateral sclerosis (ALS), a paralytic disorder characterized by the death of motor neurons in the brain and spinal cord. A subgroup of these familial cases are linked to mutations in the gene which codes for Cu/Zn superoxide dismutase (SOD1). We report three additional mutations occurring in the SOD1 gene in ALS patients and two single base pair variant changes. The single base pair change in an ALS family causes a glycine 93 to valine substitution, which is the fifth distinct amino acid change reported for the glycine 93 residue. One missense mutation in exon 5 would substitute neutral valine for the negatively-charged aspartate 124 (aspartate 124 to valine). An individual with an apparently sporadic case of ALS carries a three base pair deletion in exon 5 of the SOD1 gene. These three mutations bring to 38 the total number of distinct SOD1 mutations associated with familial ALS.

Identification of three novel mutations in the gene for Cu/Zn superoxide dismutase in patients with familial amyotrophic lateral sclerosis

About 10% of cases of amyotrophic lateral sclerosis (ALS), a paralytic disorder characterized by death of motor neurons in the brain and spinal cord, exhibit autosomal dominant inheritance. A subgroup of these familial cases are caused by mutations in the gene encoding Cu/Zn superoxide dismutase (SOD1). We report here three additional mutations occurring in the SOD1 gene in three families with ALS. Two of these changes are missense mutations in exon 5 of the SOD1 gene, resulting in leucine 144 to serine and alanine 145 to threonine substitutions. The third, a single base pair change in intron 4 immediately upstream of exon 5, results in an alternatively spliced mRNA. The alternate transcript conserves the open reading frame of exon 5, producing an SOD1 protein with three amino acids inserted between exons 4 and 5 (following residue 118). These three mutations bring to 29 the total number of distinct SOD1 mutations associated with familial ALS.