Littérature scientifique sur le sujet « G93A-SOD1 mice »

Amyotrophic lateral sclerosis (ALS) is a complex systemic disease that primarily involves motor neuron dysfunction and skeletal muscle atrophy. One commonly used mouse model to study ALS was generated by transgenic expression of a mutant form of human superoxide dismutase 1 (SOD1) gene harboring a single amino acid substitution of glycine to alanine at codon 93 (G93A*SOD1). Although mutant-SOD1 is ubiquitously expressed in G93A*SOD1 mice, a detailed analysis of the skeletal muscle expression pattern of the mutant protein and the resultant muscle pathology were never performed. Using different skeletal muscles isolated from G93A*SOD1 mice, we extensively characterized the pathological sequelae of histological, molecular, ultrastructural, and biochemical alterations. Muscle atrophy in G93A*SOD1 mice was associated with increased and differential expression of mutant-SOD1 across myofibers and increased MuRF1 protein level. In addition, high collagen deposition and myopathic changes sections accompanied the reduced muscle strength in the G93A*SOD1 mice. Furthermore, all the muscles in G93A*SOD1 mice showed altered protein levels associated with different signaling pathways, including inflammation, mitochondrial membrane transport, mitochondrial lipid uptake, and antioxidant enzymes. In addition, the mutant-SOD1 protein was found in the mitochondrial fraction in the muscles from G93A*SOD1 mice, which was accompanied by vacuolized and abnormal mitochondria, altered OXPHOS and PDH complex protein levels, and defects in mitochondrial respiration. Overall, we reported the pathological sequelae observed in the skeletal muscles of G93A*SOD1 mice resulting from the whole-body mutant-SOD1 protein expression.

(1) Background: Amyotrophic lateral sclerosis (ALS) is a multifactorial non-cell autonomous disease where activation of microglia and astrocytes largely contributes to motor neurons death. Heat shock proteins have been demonstrated to promote neuronal survival and exert a strong anti-inflammatory action in glia. Having previously shown that the pharmacological increase of the histamine content in the central nervous system (CNS) of SOD1-G93A mice decreases neuroinflammation, reduces motor neuron death, and increases mice life span, here we examined whether this effect could be mediated by an enhancement of the heat shock response. (2) Methods: Heat shock protein expression was analyzed in vitro and in vivo. Histamine was provided to primary microglia and NSC-34 motor neurons expressing the SOD1-G93A mutation. The brain permeable histamine precursor histidine was chronically administered to symptomatic SOD1-G93A mice. Spine density was measured by Golgi-staining in motor cortex of histidine-treated SOD1-G93A mice. (3) Results: We demonstrate that histamine activates the heat shock response in cultured SOD1-G93A microglia and motor neurons. In SOD1-G93A mice, histidine augments the protein content of GRP78 and Hsp70 in spinal cord and cortex, where the treatment also rescues type I motor neuron dendritic spine loss. (4) Conclusion: Besides the established histaminergic neuroprotective and anti-inflammatory effects, the induction of the heat shock response in the SOD1-G93A model by histamine confirms the importance of this pathway in the search for successful therapeutic solutions to treat ALS.

In vivo 1H magnetic resonance spectroscopy (1H-MRS) investigations of amyotrophic lateral sclerosis (ALS) mouse brain may provide neurochemical profiles and alterations in association with ALS disease progression. We aimed to longitudinally follow neurochemical evolutions of striatum, brainstem and motor cortex of mice transgenic for G93A mutant human superoxide dismutase type-1 (G93A-SOD1), an ALS model. Region-specific neurochemical alterations were detected in asymptomatic G93A-SOD1 mice, particularly in lactate (−19%) and glutamate (+8%) of brainstem, along with γ-amino-butyric acid (−30%), N-acetyl-aspartate (−5%) and ascorbate (+51%) of motor cortex. With disease progression towards the end-stage, increased numbers of metabolic changes of G93A-SOD1 mice were observed (e.g. glutamine levels increased in the brainstem (>+66%) and motor cortex (>+54%)). Through ALS disease progression, an overall increase of glutamine/glutamate in G93A-SOD1 mice was observed in the striatum ( p < 0.01) and even more so in two motor neuron enriched regions, the brainstem and motor cortex ( p < 0.0001). These 1H-MRS data underscore a pattern of neurochemical alterations that are specific to brain regions and to disease stages of the G93A-SOD1 mouse model. These neurochemical changes may contribute to early diagnosis and disease monitoring in ALS patients.

Background: Myelination, degeneration and regeneration are implicated in crucial responses to injury in the peripheral nervous system. Considering the progression of amyotrophic lateral sclerosis (ALS), we used the superoxide dismutase 1 (SOD1)-G93A transgenic mouse model of ALS to investigate the effects of mutant SOD1 on the peripheral nerves. Methods: Changes in peripheral nerve morphology were analyzed in SOD1 mutant mice at various stages of the disease by toluidine blue staining and electron microscopy (EM). Schwann cell proliferation and recruitment of inflammatory factors were detected by immunofluorescence staining and quantitative reverse transcription PCR and were compared between SOD1 mutant mice and control mice. Furthermore, western blotting (WB) and TUNEL staining were used to investigate axonal damage and Schwann cell survival in the sciatic nerves of mice in both groups. Results: An analysis of the peripheral nervous system in SOD1-G93A mice revealed the following novel features: (i) Schwann cells and axons in mutant mice underwent changes that were similar to those seen in the control mice during the early development of peripheral nerves. (ii) The peripheral nerves of SOD1-G93A mice developed progressive neuropathy, which presented as defects in axons and myelin, leading to difficulty in walking and reduced locomotor capacity at a late stage of the disease. (iii) Macrophages were recruited and accumulated, and nerve injury and a deficit in the blood-nerve barrier were observed. (iv) Proliferation and the inflammatory micro-environment were inhibited, which impaired the regeneration and remyelination of axons after crush injury in the SOD1-G93A mice. Conclusions: The mutant human SOD1 protein induced axonal and myelin degeneration during the progression of ALS and participated in axon remyelination and regeneration in response to injury.

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease affecting motor neurons. In ALS mice, neurodegeneration is associated with the proliferative restorative attempts of ependymal stem progenitor cells (epSPCs) that normally lie in a quiescent in the spinal cord. Thus, modulation of the proliferation of epSPCs may represent a potential strategy to counteract neurodegeneration. Recent studies demonstrated that FM19G11, a hypoxia-inducible factor modulator, induces epSPC self-renewal and proliferation. The aim of the study was to investigate whether FM19G11-loaded gold nanoparticles (NPs) can affect self-renewal and proliferation processes in epSPCs isolated from G93A-SOD1 mice at disease onset. We discovered elevated levels of SOX2, OCT4, AKT1, and AKT3, key genes associated with pluripotency, self-renewal, and proliferation, in G93A-SOD1 epSPCs at the transcriptional and protein levels after treatment with FM19G11-loaded NPs. We also observed an increase in the levels of the mitochondrial uncoupling protein (UCP) gene in treated cells. FM19G11-loaded NPs treatment also affected the expression of the cell cycle-related microRNA (miR)-19a, along with its target gene PTEN, in G93A-SOD1 epSPCs. Overall our findings establish the significant impact of FM19G11-loaded NPs on the cellular pathways involved in self-renewal and proliferation in G93A-SOD1 epSPCs, thus providing an impetus to the design of novel tailored approaches to delay ALS disease progression.

Mice engineered to express a transgene encoding a human Cu/Zn superoxide dismutase (SOD1) with a Gly93 → Ala (G93A) mutation found in patients who succumb to familial amyotrophic lateral sclerosis (FALS) develop a rapidly progressive and fatal motor neuron disease (MND) similar to amyotrophic lateral sclerosis (ALS). Hallmark ALS lesions such as fragmentation of the Golgi apparatus and neurofilament (NF)-rich inclusions in surviving spinal cord motor neurons as well as the selective degeneration of this population of neurons were also observed in these animals. Since the mechanism whereby mutations in SOD1 lead to MND remains enigmatic, we asked whether NF inclusions in motor neurons compromise axonal transport during the onset and progression of MND in a line of mice that contained ∼30% fewer copies of the transgene than the original G93A (Gurney et al., 1994). The onset of MND was delayed in these mice compared to the original G93A mice, but they developed the same neuropathologic abnormalities seen in the original G93A mice, albeit at a later time point with fewer vacuoles and more NF inclusions. Quantitative Western blot analyses showed a progressive decrease in the level of NF proteins in the L5 ventral roots of G93A mice and a concomitant reduction in axon caliber with the onset of motor weakness. By ∼200 d, both fast and slow axonal transports were impaired in the ventral roots of these mice coincidental with the appearance of NF inclusions and vacuoles in the axons and perikarya of vulnerable motor neurons. This is the first demonstration of impaired axonal transport in a mouse model of ALS, and we infer that similar impairments occur in authentic ALS. Based on the temporal correlation of these impairments with the onset of motor weakness and the appearance of NF inclusions and vacuoles in vulnerable motor neurons, the latter lesions may be the proximal cause of motor neuron dysfunction and degeneration in the G93A mice and in FALS patients with SOD1 mutations.

Amyotrophic Lateral Sclerosis (ALS) is a devastating neurodegenerative disease caused in 10% of cases by inherited mutations considered “familial”. An ever-increasing amount of evidence is showing a fundamental role for RNA metabolism in ALS pathogenesis, and long non-coding RNAs (lncRNAs) appear to play a role in ALS development. Here, we aim to investigate the expression of a panel of lncRNAs (linc-Enc1, linc–Brn1a, linc–Brn1b, linc-p21, Hottip, Tug1, Eldrr, and Fendrr) which could be implicated in early phases of ALS. Via Real-Time PCR, we assessed their expression in a murine familial model of ALS (SOD1-G93A mouse) in brain and spinal cord areas of SOD1-G93A mice in comparison with that of B6.SJL control mice, in asymptomatic (week 8) and late-stage disease (week 18). We highlighted a specific area and pathogenetic-stage deregulation in each lncRNA, with linc-p21 being deregulated in all analyzed tissues. Moreover, we analyzed the expression of their human homologues in SH-SY5Y-SOD1-WT and SH-SY5Y-SOD1-G93A, observing a profound alteration in their expression. Interestingly, the lncRNAs expression in our ALS models often resulted opposite to that observed for the lncRNAs in cancer. These evidences suggest that lncRNAs could be novel disease-modifying agents, biomarkers, or pathways affected by ALS neurodegeneration.

ALS (amyotrophic lateral sclerosis) is an adult-onset and deadly neurodegenerative disease characterized by a progressive and selective loss of motoneurons. Transgenic mice overexpressing a mutated human gene (G93A) coding for the enzyme SOD1 (Cu/Zn superoxide dismutase) develop a motoneuron disease resembling ALS in humans. In this generally accepted ALS model, we tested the electrophysiological properties of individual embryonic and neonatal spinal motoneurons in culture by measuring a wide range of electrical properties influencing motoneuron excitability during current clamp. There were no differences in the motoneuron resting potential, input conductance, action potential shape, or afterhyperpolarization between G93A and control motoneurons. The relationship between the motoneuron's firing frequency and injected current (f-I relation) was altered. The slope of the f-I relation and the maximal firing rate of the G93A motoneurons were much greater than in the control motoneurons. Differences in spontaneous synaptic input were excluded as a cause of increased excitability. This finding identifies a markedly elevated intrinsic electrical excitability in cultured embryonic and neonatal mutant G93A spinal motoneurons. We conclude that the observed intrinsic motoneuron hyperexcitability is induced by the SOD1 toxic gain-of-function through an aberration in the process of action potential generation. This hyperexcitability may play a crucial role in the pathogenesis of ALS as the motoneurons were cultured from presymptomatic mice.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by a substantial loss of motor neurons in the spinal cord, brain stem, and motor cortex. Previous evidence showed that in a mouse model of a familial form of ALS expressing high levels of the human mutated protein Cu,Zn superoxide dismutase (Gly93→Ala, G93A), the firing properties of single motor neurons are altered to induce neuronal hyperexcitability. To determine whether the functionality of the macroscopic voltage-dependent Na+ currents is modified in G93A motor neurons, in the present work their physiological properties were examined. The voltage-dependent sodium channels were studied in dissociated motor neurons in culture from nontransgenic mice (Control), from transgenic mice expressing high levels of the human wild-type protein [superoxide dismutase 1 (SOD1)], and from G93A mice, using the whole cell configuration of the patch-clamp recording technique. The voltage dependency of activation and of steady-state inactivation, the kinetics of fast inactivation and slow inactivation of the voltage-dependent Na+ channels were not modified in the mutated mice. Conversely, the recovery from fast inactivation was significantly faster in G93A motor neurons than that in Control and SOD1. The recovery from fast inactivation was still significantly faster in G93A motor neurons exposed for different times (3–48 h) and concentrations (5–500 μM) to edaravone, a free-radical scavenger. Clarification of the importance of these changes in membrane ion channel functionality may have diagnostic and therapeutic implications in the pathogenesis of ALS.

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterised by selective neuronal death in the brain stem and spinal cord. The cause is unknown, but an increasing amount of evidence has firmly certified that neuroinflammation plays a key role in ALS pathogenesis. Neuroinflammation is a pathological hallmark of several neurodegenerative disorders and has been implicated as driver of disease progression. Here, we describe a treatment study demonstrating the therapeutic potential of a tandem version of the well-known all-d-peptide RD2 (RD2RD2) in a transgenic mouse model of ALS (SOD1*G93A). Mice were treated intraperitoneally for four weeks with RD2RD2 vs. placebo. SOD1*G93A mice were tested longitudinally during treatment in various behavioural and motor coordination tests. Brain and spinal cord samples were investigated immunohistochemically for gliosis and neurodegeneration. RD2RD2 treatment in SOD1*G93A mice resulted not only in a reduction of activated astrocytes and microglia in both the brain stem and lumbar spinal cord, but also in a rescue of neurons in the motor cortex. RD2RD2 treatment was able to slow progression of the disease phenotype, especially the motor deficits, to an extent that during the four weeks treatment duration, no significant progression was observed in any of the motor experiments. Based on the presented results, we conclude that RD2RD2 is a potential therapeutic candidate against ALS.

Amyotrophic lateral sclerosis (ALS) is a progressive, fatal, neurodegenerative disorder caused by the degeneration of motor neurons in the CNS, which results in complete paralysis of skeletal muscles. To establish the timeframe of motor neuron degeneration in relation to muscle atrophy in motor neuron disease, we have used MRI to monitor changes throughout disease in brain and skeletal muscle of G93A-SOD1 mice, a purported model of ALS. Longitudinal MRI examination of the same animals indicated that muscle volume in the G93A-SOD1 mice was significantly reduced from as early as week 8 of life, four weeks prior to clinical onset. Progressive muscle atrophy from week 8 onwards was confirmed by histological analysis. In contrast, brain MRI indicated that neurodegeneration occurs later in G93A-SOD1 mice, with hyperintensity MRI signals detected only at weeks 10-18. Neurodegenerative changes were observed only in the motor nuclei areas of the brainstem; MRI changes indicative of neurodegeneration were not detected in the motorcortex where first motor neurons originate, even at the late disease stage. This longitudinal MRI study establishes unequivocally that, in the experimental murine model of ALS, muscle degeneration occurs before any evidence of neurodegeneration and clinical signs, supporting the postulate that motor neuron disease can initiate from muscle damage and result from retrograde dying-back of the motor neurons. In G93A-SOD1 ALS mice the response to neurodegeneration comprises proliferation and migration of ependymal stem progenitor cells (epSPCs), normally present and quiescent in spinal cord. We isolated epSPCs from G93A-SOD1 mice at 8 (asymptomatic) and 18 (symptomatic) weeks of age, and characterized the ability of epSPC cultures to proliferate and differentiate into the three neural cell lineages. G93A epSPCs produced neurospheres of self-renewing cells, and differentiated into more neurons and fewer astrocytes than control epSPCs, whereas oligodendrocytes did not show difference between the examined groups. The G93A-SOD1 neurons were small and the astrocytes were consistently activated. MicroRNA analysis revealed that miR-9 and miR-124a, involved in neural cell fate, were upregulated in differentiating G93A-SOD1 epSPCs, particularly at 18 weeks. miR-19a and miR-19b, implicated in cell-cycle regulation, were differentially expressed during epSPC differentiation in G93A-SOD1 compared with controls. Our findings demonstrated that G93A-SOD1 epSPCs have neurogenic potential constituting a source of multipotent cells useful for understanding the ALS pathogenesis and for identifying new therapeutic targets.

Tese de mestrado, Neurociências, Faculdade de Medicina, Universidade de Lisboa, 2013
A Esclerose Lateral Amiotrófica (ELA), uma das doenças do neurónio motor mais comum, caracteriza-se pela perda selectiva de neurónios motores do tracto corticoespinhal. Vários estudos sugerem que a degeneração inicia-se na porção distal do axónio com uma progressão retrógrada. Assim, o presente trabalho teve como objectivo avaliar a transmissão sináptica na junção neuromuscular dos animais SOD1(G93A), nos períodos correspondentes às fases pré-sintomática e sintomática da ELA. As experiências foram efectuadas em ratinhos transgénicos SOD1(G93A) e não transgénicos (WT), na fase pré-sintomática (4 a 6 semanas de idade) e fase sintomática (12 a 16 semanas de idade). Após o nascimento, os animais foram genotipados por polymerase chain reaction (PCR). Nas respectivas fases da doença, os animais foram testados no rotarod, e em seguida fizeram-se registos electrofisiologicos: potenciais de placa evocados (EPPs), potenciais de placa miniatura (MEPPs) e MEPPs gigantes (GMEPPs: MEPPs > 1mV). Os registos foram feitos em fibras musculares do diafragma inervado, paralisadas com μ-conotoxina GIIIB. O conteúdo quântico dos EPPs foi calculado através da razão entre a amplitude média dos EPPs e a amplitude média dos MEPPs. Na fase pré-sintomática da doença, os ratos SOD1(G93A) não exibiram alterações na função motora a 10 rpm. Relativamente à transmissão neuromuscular, estes animais apresentaram um aumento significativo da amplitude média dos EPPs e do conteúdo quântico dos EPPs, quando comparados com os animais WT, sugerindo uma maior eficiência da transmissão neuromuscular nos animais SOD1(G93A). Para além disso, o aumento significativo da frequência de GMEPPs, o que pela literatura parece estar associado a uma desregulação dos níveis intracelulares de Ca2+, e as alterações na amplitude e cinética dos MEPPs sugerem a existência de alterações ao nível da junção neuromuscular numa fase pré-sintomatica. Na fase sintomática, os animais SOD1(G93A) apresentaram um défice motor aos 10 rpm. Os registos electrofisiológicos revelaram a existência de dois grupos de junções neuromusculares nos ratos SOD1(G93A): SOD1a e SOD1b. O grupo SOD1a apresentou EPPs e MEPPs com amplitudes significativamente reduzidas bem como um rise-time dos MEPPs aumentado, quando comparado com os grupos SOD1b e WT, sugerindo um enfraquecimento da transmissão neuromuscular, nesse grupo. Pelo contrário, o grupo SOD1b apresentou uma transmissão neuromuscular semelhante tanto à dos animais SOD1(G93A) pré-sintomáticos, como também à dos WT com 12-14 semanas. Em conclusão, este trabalho mostra que a transmissão neuromuscular dos animais SOD1(G93A) encontra-se aumentada na fase pré-sintomática. Na fase sintomática, a presença de uma população mista de junções neuromusculares é consistente com os ciclos de desinervação/ re-inervação, já descritos noutros estudos. As alterações iniciais na transmissão neuromuscular dos animais SOD1(G93A) representam assim mais uma evidência que os mecanismos patológicos da ELA iniciam-se antes do aparecimento dos primeiros sintomas.
Amyotrophic Lateral Sclerosis (ALS) is the most frequent adult-onset motor neuron disease and is characterized by a selective and progressive loss of motor neurons in the corticospinal tract. Growing evidence suggest that degeneration may begin at the distal axon proceeding in a dying-back pattern, increasing the need to focus on neuromuscular junction parameters. It seemed therefore of interest to investigate synaptic transmission at the neuromuscular junction (NMJ) in both pre- and symptomatic phases of the disease. Experiments were performed in SOD1(G93A) mice and in non-transgenic littermates (WT) with 4-6 and 12-14 weeks-old, corresponding respectively to pre- and symptomatic phases. After birth, mice were genotyped through polymerase chain reaction (PCR). At the respective age, mice were submitted rotarod, then low-frequency (0.5 Hz) evoked endplate potentials (EPPs), miniature endplate potentials (MEPPs) and giant MEPPs (GMEPPs: MEPPs >1mV) were recorded from innervated diaphragm muscle fibers, paralyzed with μ-conotoxin GIIIB. The quantal content of EPPs was estimated as the ratio between EPPs amplitude and MEPPs amplitude. In the pre-symptomatic phase, SOD1(G93A) mice did not present motor deficits on the rotarod at 10rpm. However, SOD1(G93A) mice exhibited a significant increase of the mean amplitude of EPPs together with an increase in the mean quantal content of EPPs, suggesting that more acetylcholine is being released into the synaptic cleft. Also, SOD1(G93A) mice presented a higher frequency of GMEPPs, suggestive of intracellular Ca2+ deregulation in nerve terminals. The observed increase in the mean amplitude of MEPPs and the decreased mean rise-time of MEPPs in SOD1(G93A) mice point as well to post-synaptic related changes. In symptomatic phase, SOD1(G93A) mice presented a lower motor balance and coordination. Electrophysiological data showed evidence for two NMJ groups in SOD1(G93A) mice: SOD1a and SOD1b. The SOD1a group presented both mean amplitude of EPPs and of MEPPs reduced. The mean rise-time of MEPPs was increased, when compared to WT and to SOD1b group, indicating an impairment in the neuromuscular transmission. In contrast, the neuromuscular transmission of SOD1b group was not different from age-matched WT or from the pre-symptomatic SOD1(G93A) mice. Altogether these results clearly show that the neuromuscular transmission of SOD1(G93A) mice is enhanced in the pre-symptomatic phase. In the symptomatic phase our results are consistent with the hypothesis that the diaphragm of SOD1(G93A) mice are undergoing cycles of denervation/re-innervation supported by the mixed population of neuromuscular junctions. These early changes in the neuromuscular transmission of SOD1(G93A) mice is a novel proof that the ALS associated events starts long before the symptoms appear.