Amyotrophic lateral sclerosis on Guam.

EAAT2 is a high affinity, Na+-dependent glutamate transporter with predominant astroglial localization. It accounts for the clearance of the bulk of glutamate released at central nervous system synapses and therefore has a crucial role in shaping glutamatergic neurotransmission and limiting excitotoxicity. Caspase-3 activation and impairment in expression and activity of EAAT2 are two distinct molecular mechanisms occurring in human amyotrophic lateral sclerosis (ALS) and in the transgenic rodent model of the disease. Excitotoxicity caused by down-regulation of EAAT2 is thought to be a contributing factor to motor neuron death in ALS. In this study, we report the novel evidence that caspase-3 cleaves EAAT2 at a unique site located in the cytosolic C-terminal domain of the transporter, a finding that links excitotoxicity and activation of caspase-3 as converging mechanisms in the pathogenesis of ALS. Caspase-3 cleavage of EAAT2 leads to a drastic and selective inhibition of this transporter. Heterologous expression of mutant SOD1 proteins linked to the familial form of ALS leads to inhibition of EAAT2 through a mechanism that largely involves activation of caspase-3 and cleavage of the transporter. In addition, we found evidence in spinal cord homogenates of mutant SOD1 ALS mice of a truncated form of EAAT2, likely deriving from caspase-3-mediated proteolytic cleavage, which appeared concurrently to the loss of EAAT2 immunoreactivity and to increased expression of activated caspase-3. Taken together, our findings suggest that caspase-3 cleavage of EAAT2 is one mechanism responsible for the impairment of glutamate uptake in mutant SOD1-linked ALS.

Reduced MTR in the corticospinal tract and normal T 2 in amyotrophic lateral sclerosis

Objective To study the effect of intestinal bacteria on motor ability of amyotrophic lateral sclerosis (ALS) mice models and its mechanism. Methods Twenty wild type C57BL/6J mice (WT group) and 20 SOD1-G93A transgenic ALS mice (ALS group) were selected as the research subjects. (1) Ten mice in both WT group and ALS group were selected, respectively; 5 mice in each group were fed in SPF environment, and the remaining 5 mice were fed in aseptic environment; they were defined as WT+SPF group, WT+aseptic group, ALS+SPF group and ALS+aseptic group. (2) Ten mice in WT group and ALS group were fed in sterile environment; 5 mice in each group were transplanted with fecal bacteria, and the remaining 5 mice were not interfered; they were defined as WT+transplantation group, WT+non-transplantation group, ALS+transplantation group and ALS+non transplantation group. The grip strength of mice was measured by grip force meter, the motor coordination ability of mice was tested by roller treadmill and rotating rod test, the number of motor neurons in the anterior horn of spinal cord was measured by Nissl staining, the expression of microglia activation marker ionic calcium junction protein (IBA-1) in spinal cord tissues was detected by immunohistochemical staining, and the expressions of tumor necrosis factor (TNF)-α and interleukin (IL)-6 in spinal cord tissues were detected by Western blotting; the β-N-methylamino-L-alanine (BMAA) expression was detected by high performance liquid chromatography-tandem mass spectrometry. Results (1) The grip strength, drop latency and drop time of ALS+aseptic mice were significantly higher than those of ALS+SPF mice, the number of Nissl-stained positive cells was significantly larger than that of ALS+SPF mice, the number of IBA-1 positive cells was significantly smaller than that of ALS+SPF mice, the levels of TNF-α and IL-6 protein expressions and BMAA concentration were statistically lower than those of ALS+SPF mice (P<0.05). (2) The grip strength, drop latency and drop time of ALS+transplantion mice were significantly lower than those of ALS+non-transplantation mice, the number of Nissl-stained positive cells was significantly smaller than that of ALS+non-transplantation mice, the number of IBA-1 positive cells was significantly larger than that of ALS+non-transplantation mice, the TNF-α and IL-6 protein expressions and BMAA concentration were significantly higher than those of ALS+non-transplantation mice (P<0.05). Conclusion Imbalance of intestinal bacteria homeostasis can decrease the motor ability of ALS mice, which is related to the activation of microglia. Key words: Amyotrophic lateral sclerosis; Intestinal bacteria; Motor ability; Motor neuron; Microglia

The Role of Microglial Cells in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is an adult motor neuron disease characterized by premature death of upper and lower motor neurons. Two percent of ALS cases are caused by the dominant mutations in the gene for superoxide dismutase 1 (SOD1) through a gain of toxic property of mutant protein. Genetic and chimeric mice studies using SOD1 models indicate that non-neuronal cells play important roles in neurodegeneration through non-cell autonomous mechanism. We review the contribution of each glial cell type in ALS pathology from studies of the rodent models and ALS patients. Astrogliosis and microgliosis are not only considerable hallmarks of the disease, but the intensity of microglial activation is correlated with severity of motor neuron damage in human ALS. The impaired astrocytic functions such as clearance of extracellular glutamate and release of neurotrophic factors are implicated in disease. Further, the damage within astrocytes and microglia is involved in accelerated disease progression. Finally, other glial cells such as NG2 cells, oligodendrocytes and Schwann cells are under the investigation to determine their contribution in ALS. Accumulating knowledge of active role of glial cells in the disease should be carefully applied to understanding of the sporadic ALS and development of therapy targeted for glial cells.

Background: Amyotrophic lateral sclerosis (ALS) is a rare neurodegener-ative disease characterized by the degeneration of upper and lower motor neurons in the central and peripheral nervous systems. Several patholog-ical conditions, including neuroinflammation, oxidative stress, and mito-chondrial dysfunction, contribute to the degeneration of motor neurons. Despite extensive research, no current drug therapies have proven effec-tive in treating ALS. Purpose: This study explores the therapeutic potential of Persea americana (PA) Mill, commonly known as avocado, in the treatment of ALS. Methods: The review draws on pre-clinical and clinical studies that have demonstrated the neuroprotective effects of PA extracts (PAE) in diseas-es such as Alzheimer’s and Parkinson’s, highlighting the potential mechanisms that may be relevant to ALS. Results: Although no studies have directly investigated the effects of PA on ALS, the bioactive compounds in PA have shown promising results in mitigating neurodegenerative processes through their diverse biological activities. Conclusion: Based on existing evidence from related neurodegenerative conditions and the mechanisms involved in ALS pathology, it is hypothesized that PA extracts may offer a novel therapeutic avenue for ALS. Further research is required to validate the efficacy of PAE in man-aging ALS symptoms and slowing disease progression.

A list of genes have been identified to carry mutations causing familial ALS such as SOD1, TARDBP, C9orf72. But for sporadic ALS, which is 90% of all ALS cases, the underlying genetic variants are still largely unknown. There are multiple genome-wide association study (GWAS) for sporadic ALS, but usually a large number nominated SNP can hardly be replicated in larger cohort analysis. Also majority of GWAS SNP lie within noncoding region of genome, imposing a huge challenge to study their biological role in ALS pathology. With the rapid development of next-generation sequencing technology, we are able to sequence exome and whole-genome of a large number of ALS patients to search for novel genetic variants and their potential biological function. Here by analyzing exam data, we discovered two novel or extremely rare missense mutations of DPP6 from a Mestizo Mexican ALS family. We showed the two mutations could exert loss-of-function effect by affecting electrophysiological properties of Potassium channels as well as the membrane localization of DPP6. To our knowledge this is the first report of DPP6 nonsynonymous mutations in familial ALS patients. In addition, by analyzing whole-genome data, we discovered strong linkage disequilibrium between SNP rs12608932, a repeatedly significant ALS GWAS signal, and one polymorphic TGGA tetra-nucleotide tandem repeat, which is further flanked by large TGGA repetitive sequences. We also demonstrated rs12608932 risk allele is associated with reduced UNC13A expression level in human cerebellum and UNC13A knockout could lead to shorter survival in SOD1-G93A ALS mice. Thus the TGGA repeat might be the real underlying genetic variation that confer risk to sporadic ALS.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by progressive and selective degeneration of motor neurons in the motor cortex of brain and spinal cord. Ferroptosis is a newly discovered form of cell death and reported to mediate selective motor neuron death in the mouse model of ALS. The growing awareness of ferroptosis and iron metabolism dysfunction in ALS prompted us to investigate the expression pattern of ferroptosis and iron metabolism-related genes (FIRGs) in ALS. Here, we performed a conjoint analysis of bulk-RNA sequence and single-nucleus RNA sequence data using the datasets from Gene Expression Omnibus (GEO) to reveal the role of FIRGs in ALS, especially in selective motor neuron death of ALS. We first investigated the differentially expressed genes (DEGs) between ALS and non-neurological controls. Weighted gene co-expression network analysis constructed the gene co-expression network and identified three modules closely associated with ALS. Fifteen FIRGs was identified as target genes based on least absolute shrinkage and selection operator regression analysis as follows: ACSL4, ANO6, ATP6V0E1, B2M, CD44, CHMP5, CYBB, CYBRD1, HIF1A, MOSPD1, NCF2, SDCBP, STEAP2, TMEM14C, ULK1. These genes could differentiate ALS patients from non-neurological controls (p < 2.2e−16) and had a valid value in predicting and diagnosing ALS (AUC = 0.881 in primary dataset and AUC = 0.768 in validation dataset). Then we performed the functional enrichment analysis of DEGs between ALS cases, the most significantly influenced by target genes, and non-neurological controls. The result indicated that the most significantly influenced functions in ALS pathogenesis by these identified FIRGs are synapse pathways, calcium signaling pathway, cAMP signaling pathway, and phagosome and several immune pathways. At last, the analysis of single- nuclear seq found that CHMP5, one of the 15 FIRGs identified by bulk single-nucleus RNA-seq data, was expressed significantly higher in ALS than pathologically normal (PN), specifically in excitatory neuron populations with layer 2 and layer 3 markers (Ex L2_L3), layer 3 and layer 5 markers (Ex L3_L5). Taken together, our study indicates the positive correlation between FIRGs and ALS, presents potential markers for ALS diagnosis and provides new research directions of CHMP5 function in selective motor neuron death in ALS.

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease characterized by the degeneration of motor neurons. Mutations in the cyclin F (CCNF) and fused in sarcoma (FUS) genes have been associated with ALS pathology. In this study, we aimed to investigate the functional role of CCNF and FUS in ALS by using genome editing techniques to generate zebrafish models with genetic disruptions in these genes. Sequence comparisons showed significant homology between human and zebrafish CCNF and FUS proteins. We used CRISPR/Cas9 and TALEN-mediated genome editing to generate targeted disruptions in the zebrafish ccnf and fus genes. Ccnf-deficient zebrafish exhibited abnormal motor neuron development and axonal outgrowth, whereas Fus-deficient zebrafish did not exhibit developmental abnormalities or axonopathies in primary motor neurons. However, Fus-deficient zebrafish displayed motor impairments in response to oxidative and endoplasmic reticulum stress. The Ccnf-deficient zebrafish were only sensitized to endoplasmic reticulum stress, indicating that ALS genes have overlapping as well as unique cellular functions. These zebrafish models provide valuable platforms for studying the functional consequences of CCNF and FUS mutations in ALS pathogenesis. Furthermore, these zebrafish models expand the drug screening toolkit used to evaluate possible ALS treatments.

Increasing evidence shows that disease spreading in amyotrophic lateral sclerosis (ALS) follows a preferential pattern with more frequent involvement of contiguous regions from the site of symptom onset. The aim of our study was to assess if: (i) the burden of upper (UMN) and lower motor neuron (LMN) involvement influences directionality of disease spreading; (ii) specific patterns of disease progression are associated with motor and neuropsychological features of different ALS subtypes (classic, bulbar, primary lateral sclerosis, UMN-predominant, progressive muscular atrophy, flail arm, flail leg); and (iii) specific clinical features may help identify ALS subtypes, which remain localized to the site of onset for a prolonged time (regionally entrenching ALS).A single-centre, retrospective cohort of 913 Italian ALS patients was evaluated to assess correlations between directionality of the disease process after symptom onset and motor/neuropsychological phenotype. All patients underwent an extensive evaluation including the following clinical scales: Penn Upper Motor Neuron Score (PUMNS), MRC Scale for Muscle Strength and the Edinburgh Cognitive and Behavioural ALS Screen (ECAS).The most frequent initial spreading pattern was that towards adjacent horizontal regions (77.3%), which occurred preferentially in patients with lower MRC scores (P = 0.038), while vertical diffusion (21.1%) was associated with higher PUMNS (P < 0.001) and with reduced survival (P < 0.001). Non-contiguous disease spreading was associated with more severe UMN impairment (P = 0.003), while contiguous disease pattern with lower MRC scores. Furthermore, non-contiguous disease spreading was associated with more severe cognitive impairment in both executive and visuospatial ECAS domains. Individuals with regionally entrenching ALS were more frequently female (45.6% versus 36.9%; P = 0.028) and had higher frequencies of symmetric disease onset (40.3% versus 19.7%; P < 0.001) and bulbar phenotype (38.5% versus 16.4%; P < 0.001).Our study suggests that motor phenotypes characterized by a predominant UMN involvement are associated with a vertical pattern of disease progression reflecting ipsilateral spreading within the motor cortex, while those with predominant LMN involvement display more frequently a horizontal spreading from one side of the spinal cord to the other. These observations raise the hypothesis that one of the mechanisms underlying disease spreading in ALS pathology is represented by diffusion of toxic factors in the neuron microenvironment. Finally, it is possible that in our cohort, regionally entrenching ALS forms are mainly observed in patients with atypical bulbar phenotypes, characterized by a slowly progressive course and relatively benign prognosis.

Blood Superoxide Dismutase, Catalase and Glutathione Peroxidase Activities in Familial and Sporadic Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is characterized by degeneration of upper and lower motor neurons. In some ALS patients, dementia or aphasia may be present (ALS-D). The dementia is most commonly a frontotemporal dementia (FTD), and many of these cases have ubiquitin-positive, tau-negative inclusions in neurons of the dentate gyrus and superficial layers of the frontal and temporal lobes. Identical inclusions have been found in cases presenting with FTD and have been designated motor neuron disease (MND)-inclusions. Cases of ALS-D without MND-inclusions have been reported to show neocortical gliosis, neuronal loss, and superficial spongiosis, but there have also been scattered case reports of ALS with Alzheimer's disease (AD). To determine whether AD pathology may play a role in the dementia or aphasia syndromes in ALS, we reviewed 30 cases of sporadic ALS diagnosed at the University of Pittsburgh Medical Center. A clinical history of ALS-D was found in 24.1% of the cases, of which 57% had MND-inclusions. Although the ALS-D cases with MND-inclusions typically had amyloid-beta (Abeta) plaques, there were no neuritic plaques. Three cases of ALS-D had no MND-inclusions, and two of these fulfilled pathological criteria for AD. One ALS-D case showed severe amyloid angiopathy but no neuritic plaques or MND-inclusions. MND-inclusions were not found in any ALS case without dementia; however, four patients without dementia or aphasia showed moderate or frequent numbers of neuritic plaques. In conclusion, we found that approximately 30% of ALS cases with dementia have AD and that some ALS cases without frank dementia have significant AD pathology.

Amyotrophic lateral sclerosis (ALS) is a degenerative motor neuron disease that is inherited as an autosomal dominant trait in approximately 10% of cases. Recently we and others identified several single-base mutations in the Cu/Zn superoxide dismutase (SOD1) gene in patients with familial ALS (FALS). Using single-strand conformational polymorphism, we studied the C to G mutation in exon 2 of the SOD1 gene (resulting in a leucine to valine substitution in position 38) in affected and unaffected members of a large Belgian family with FALS. We measured the SOD1 activity in red blood cell lysates in 14 members of this family, including the only surviving clinically affected patient. SOD1 activity of the family members carrying the mutation was less than half that of members without the mutation. In addition, in 11 patients with sporadic ALS and 11 age- and sex-matched controls, red blood cell SOD1 activity was normal. These studies indicate that SOD1 activity is reduced in these FALS patients but not in sporadic ALS patients. Moreover, this SOD1 enzyme abnormality is detectable years before onset of clinical ALS in carriers of this FALS mutation.

TDP-43 (43-kDa TAR DNA-binding domain protein) is a major constituent of ubiquitin-positive cytoplasmic aggregates present in neurons of patients with fronto-temporal lobular dementia and amyotrophic lateral sclerosis (ALS). The pathologic significance of TDP-43 aggregation is not known; however, dominant mutations in TDP-43 cause a subset of ALS cases, suggesting that misfolding and/or altered trafficking of TDP-43 is relevant to the disease process. Here, we show that the presenilin-binding protein ubiquilin 1 (UBQLN) plays a role in TDP-43 aggregation. TDP-43 interacted with UBQLN both in yeast and in vitro, and the carboxyl-terminal ubiquitin-associated domain of UBQLN was both necessary and sufficient for binding to polyubiquitylated forms of TDP-43. Overexpression of UBQLN recruited TDP-43 to detergent-resistant cytoplasmic aggregates that colocalized with the autophagosomal marker, LC3. UBQLN-dependent aggregation required the UBQLN UBA domain, was mediated by non-overlapping regions of TDP-43, and was abrogated by a mutation in UBQLN previously linked to Alzheimer disease. Four ALS-associated alleles of TDP-43 also coaggregated with UBQLN, and the extent of aggregation correlated with in vitro UBQLN binding affinity. Our findings suggest that UBQLN is a polyubiquitin-TDP-43 cochaperone that mediates the autophagosomal delivery and/or proteasome targeting of TDP-43 aggregates.

Voltage-activated calcium channels are important in controlling motoneuron (MN) excitability and repetitive firing behaviour through their effects on calcium-dependent potassium channels, and the after-hyperpolarization (AHP), in particular the medium AHP (mAHP). Differential expression of voltage-activated calcium channels may therefore be important in establishing the task-specific firing properties of functionally distinct motoneuron pools. Differential expression of these channels may also be involved in the variable susceptibility of MNs to disruptions in calcium homeostasis, which are implicated in the pathology of neurodegenerative diseases such as Amyotrophic Lateral Sclerosis (ALS). To further explore the expression of calcium channels in brainstem MNs and the possibility that differential expression of calcium channels predisposes some MNs to degeneration, we compared voltage-activated calcium channels in hypoglossal (XII) and oculomotor (III) MNs, that differ not only in their firing behaviour, but in their vulnerability to degeneration in ALS. XII MNs, which innervate the genioglossus muscle of the tongue and degenerate in ALS, produce rhythmic bursts of action potentials during inspiration that last ~200–400 ms. Discharge frequency peaks between 25–50 Hz [1]. Oculomotor motoneurons, which innervate extraocular muscles and are resistant to degeneration in ALS, can produce sustained firing rates of 300 Hz during fixation and peak discharge rates of 600 Hz for up to 25 ms during saccades [2]. Voltage-activated calcium channel expression was compared between XII and III MNs electrophysiologically in neonatal rat brain slices using whole-cell patch-clamp recording techniques, and immunohistochemically using antibodies to different channel subtypes. Current densities of low voltage-activated (LVA) calcium currents were similar in XII (-5.9 ± 1.1 pA/pF, n = 9) and III (-4.6 ± 0.8 pA/pF, n = 13) MNs. Immunolabelling for the α1 G subunit of the LVA calcium channel was also similar between MN pools. In contrast, high voltage-activated (HVA) calcium current density was two-fold greater in XII (-38.2 ± 3.0 pA/pF, n = 33) compared with III (-19.5 ± 1.4 pA/pF, n = 40) MNs. Use of HVA calcium channel antagonists (nimodipine and nifedipine for L-type; ω-agatoxin-TK for P/Q-type; ω-conotoxin-GVIA for N-type) revealed that the majority of this difference reflected greater P/Q-type currents in XII MNs (XII: -15.4 ± 0.9 pA/pF, n = 6; III: -4.4 ± 1.2 pA/pF, n = 12). Immunohistochemical analysis of P/Q channel expression supported greater expression in XII MNs. N-type currents were not significantly different in XII (-4.3 ± 1.2 pA/pF, n = 9) and III MNs (-8.0 ± 1.7 pA/pF; n = 11). L-type currents, defined by nimodipine or nifedipine sensitivity, were not detected. These data suggest that differential expression of voltage-activated calcium channels may not contribute to the distinct firing properties of XII and III MNs since activation of the mAHP is primarily associated with calcium flux through N-type channels [3] and these channels do not differ between XII and III MNs. However, our data do support the possibility that greater expression of HVA calcium channels may predispose XII MNs to degeneration during periods of metabolic stress as seen in ALS. The greater density of P/Q-type HVA calcium channels in XII MNs would allow more calcium to enter MNs upon depolarisation and increase the likelihood of interaction with calcium channel antibodies found in some ALS patients.