scholarly journals Loss of Activity-Induced Mitochondrial ATP Production Underlies the Synaptic Defects in a Drosophila model of ALS

2021 ◽  
Author(s):  
Nicholas E Karagas ◽  
Kai Li Tan ◽  
Hugo J. Bellen ◽  
Kartik Venkatachalam ◽  
Ching-On Wong
Keyword(s):  
Motor Neurons ◽  
Morphological Changes ◽  
Gene Encoding ◽  
Atp Production ◽  
Root Cause ◽  
Familial Form ◽  
Presynaptic Boutons ◽  
Related Variant ◽  
Larval Neuromuscular Junction ◽  
Induced Changes

Mutations in the gene encoding VAPB (vesicle-associated membrane protein B) cause a familial form of Amyotrophic Lateral Sclerosis (ALS). Expression of an ALS-related variant of vapb (vapbP58S) in Drosophila motor neurons results in morphological changes at the larval neuromuscular junction (NMJ) characterized by the appearance of fewer, but larger, presynaptic boutons. Although diminished microtubule stability is known to underlie these morphological changes, a mechanism for the loss of presynaptic microtubules has been lacking. Here, we demonstrate the suppression of vapbP58S-induced changes in NMJ morphology by either the loss of ER Ca2+ release channels or the inhibition Ca2+/calmodulin (CaM)-activated kinase II (CaMKII). These data suggest a model in which decreased stability of presynaptic microtubules at vapbP58S NMJs result from hyperactivation of CaMKII due to elevated cytosolic [Ca2+]. We attribute the Ca2+ dyshomeostasis to delayed extrusion of cytosolic Ca2+ stemming from a paucity of activity-induced mitochondrial ATP production coupled with elevated rates of ATP consumption. Taken together, our data point to bioenergetic dysfunction as the root cause for the synaptic defects in vapbP58S-expressing Drosophila motor neurons.

scholarly journals Mutant VAPB: Culprit or Innocent Bystander of Amyotrophic Lateral Sclerosis?

Contact ◽  
2021 ◽  
Vol 4 ◽  
pp. 251525642110225
Author(s):  
Nica Borgese ◽  
Francesca Navone ◽  
Nobuyuki Nukina ◽  
Tomoyuki Yamanaka
Keyword(s):  
Amyotrophic Lateral Sclerosis ◽  
Motor Neuron ◽  
Motor Neurons ◽  
Dominant Negative ◽  
Negative Effects ◽  
Membrane Contact Sites ◽  
Familial Form ◽  
Main Driver ◽  
Mechanistic Basis ◽  
Lateral Sclerosis

Nearly twenty years ago a mutation in the VAPB gene, resulting in a proline to serine substitution (p.P56S), was identified as the cause of a rare, slowly progressing, familial form of the motor neuron degenerative disease Amyotrophic Lateral Sclerosis (ALS). Since then, progress in unravelling the mechanistic basis of this mutation has proceeded in parallel with research on the VAP proteins and on their role in establishing membrane contact sites between the ER and other organelles. Analysis of the literature on cellular and animal models reviewed here supports the conclusion that P56S-VAPB, which is aggregation-prone, non-functional and unstable, is expressed at levels that are insufficient to support toxic gain-of-function or dominant negative effects within motor neurons. Instead, insufficient levels of the product of the single wild-type allele appear to be required for pathological effects, and may be the main driver of the disease. In light of the multiple interactions of the VAP proteins, we address the consequences of specific VAPB depletion and highlight various affected processes that could contribute to motor neuron degeneration. In the future, distinction of specific roles of each of the two VAP paralogues should help to further elucidate the basis of p.P56S familial ALS, as well as of other more common forms of the disease.

scholarly journals Neurotoxic Effect of Flavonol Myricetin in the Presence of Excess Copper

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 845
Author(s):  
Anja Sadžak ◽  
Ignacija Vlašić ◽  
Zoran Kiralj ◽  
Marijana Batarelo ◽  
Nada Oršolić ◽  
...  
Keyword(s):  
Cell Death ◽  
Intracellular Signaling ◽  
Chromatin Condensation ◽  
Membrane Integrity ◽  
Toxic Effects ◽  
Trypan Blue Exclusion ◽  
Atp Production ◽  
Mtt Method ◽  
Biophysical Approach ◽  
Induced Changes

Oxidative stress (OS) induced by the disturbed homeostasis of metal ions is one of the pivotal factors contributing to neurodegeneration. The aim of the present study was to investigate the effects of flavonoid myricetin on copper-induced toxicity in neuroblastoma SH-SY5Y cells. As determined by the MTT method, trypan blue exclusion assay and measurement of ATP production, myricetin heightened the toxic effects of copper and exacerbated cell death. It also increased copper-induced generation of reactive oxygen species, indicating the prooxidative nature of its action. Furthermore, myricetin provoked chromatin condensation and loss of membrane integrity without caspase-3 activation, suggesting the activation of both caspase-independent programmed cell death and necrosis. At the protein level, myricetin-induced upregulation of PARP-1 and decreased expression of Bcl-2, whereas copper-induced changes in the expression of p53, p73, Bax and NME1 were not further affected by myricetin. Inhibitors of ERK1/2 and JNK kinases, protein kinase A and L-type calcium channels exacerbated the toxic effects of myricetin, indicating the involvement of intracellular signaling pathways in cell death. We also employed atomic force microscopy (AFM) to evaluate the morphological and mechanical properties of SH-SY5Y cells at the nanoscale. Consistent with the cellular and molecular methods, this biophysical approach also revealed a myricetin-induced increase in cell surface roughness and reduced elasticity. Taken together, we demonstrated the adverse effects of myricetin, pointing out that caution is required when considering powerful antioxidants for adjuvant therapy in copper-related neurodegeneration.

scholarly journals The Emerging Role of DNA Damage in the Pathogenesis of the C9orf72 Repeat Expansion in Amyotrophic Lateral Sclerosis

2018 ◽  
Vol 19 (10) ◽  
pp. 3137 ◽  
Author(s):  
Anna Konopka ◽  
Julie Atkin
Keyword(s):  
Dna Damage ◽  
Amyotrophic Lateral Sclerosis ◽  
Motor Neurons ◽  
Repeat Expansion ◽  
Chromosome 9 ◽  
Gene Encoding ◽  
C9orf72 Repeat Expansion ◽  
Reading Frame ◽  
Early Onset Dementia ◽  
Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal, rapidly progressing neurodegenerative disease affecting motor neurons, and frontotemporal dementia (FTD) is a behavioural disorder resulting in early-onset dementia. Hexanucleotide (G4C2) repeat expansions in the gene encoding chromosome 9 open reading frame 72 (C9orf72) are the major cause of familial forms of both ALS (~40%) and FTD (~20%) worldwide. The C9orf72 repeat expansion is known to form abnormal nuclei acid structures, such as hairpins, G-quadruplexes, and R-loops, which are increasingly associated with human diseases involving microsatellite repeats. These configurations form during normal cellular processes, but if they persist they also damage DNA, and hence are a serious threat to genome integrity. It is unclear how the repeat expansion in C9orf72 causes ALS, but recent evidence implicates DNA damage in neurodegeneration. This may arise from abnormal nucleic acid structures, the greatly expanded C9orf72 RNA, or by repeat-associated non-ATG (RAN) translation, which generates toxic dipeptide repeat proteins. In this review, we detail recent advances implicating DNA damage in C9orf72-ALS. Furthermore, we also discuss increasing evidence that targeting these aberrant C9orf72 confirmations may have therapeutic value for ALS, thus revealing new avenues for drug discovery for this disorder.

scholarly journals Murine models of Parkinson’s disease caused by an increased concentration of α‑synuclein

2019 ◽  
Vol 73 ◽  
pp. 38-46
Author(s):  
Adriana Wawer ◽  
Ilona Joniec-Maciejak ◽  
Anna Sznejder-Pachołek ◽  
Dagmara Mirowska-Guzel
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Viral Vectors ◽  
Disease Model ◽  
Lewy Bodies ◽  
Dopamine Metabolism ◽  
Pathological Process ◽  
Gene Encoding ◽  
Familial Form ◽  
Activity Of Enzymes

Parkinson’s disease (PD) is a chronic, progressive neurodegenerative disease of central nervous system. Despite many years of research its pathogenesis remains elusive. The main pathological process observed in PD is the degeneration of dopaminergic neurons in the substantia nigra and the reduction in the concentration of dopamine and its metabolites in the striatum and basal ganglia. In addition, a reduction in the activity of enzymes involved in the synthesis and metabolism of dopamine (e.g. tyrosine hydroxylase) is observed. The process of neurodegeneration is accompanied by the development of inflammatory reaction and the formation of intraneuronal inclusions - Lewy’s bodies, which containing mainly of α‑synuclein (ASN). The presence of ASN in Lewy bodies and the association of mutations in the gene encoding ASN with the familial form of the disease indicates the important role of this protein in the pathogenesis of PD. ASN is a small protein widely distributed in the brain. Under physiological conditions it is involved, among others, in dopamine metabolism. Changes in ASN levels due to its aggregation, overexpression or decreased expression may disrupt dopaminergic system functions and contribute to the neurodegeneration process observed in PD. Our paper is focused on murine ASN-based models of PD. In this review we describe models based on transgenic mice, viral vectors containing the ASN gene, and those in which elevated ASN levels are obtained by intracerebral protein administration. We briefly discuss the advantages of developed models and their numerous limitations We also highlight the need for further search for the ideal disease model.

scholarly journals The Comparative Toxicity of 10 Microcystin Congeners Administered Orally to Mice: Clinical Effects and Organ Toxicity

Toxins ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 403 ◽  
Author(s):  
Neil Chernoff ◽  
Donna Hill ◽  
Johnsie Lang ◽  
Judy Schmid ◽  
Thao Le ◽  
...  
Keyword(s):  
Algal Blooms ◽  
Morphological Changes ◽  
Wide Spectrum ◽  
Serum Levels ◽  
Serum Glucose ◽  
Oral Exposure ◽  
Clinical Effects ◽  
Clinical Changes ◽  
Induced Changes ◽  
Dose Response Study

Microcystins (MCs) are common cyanobacterial toxins that occur in freshwaters worldwide. Only two of the >200 MC variants have been tested for potential toxicity after oral exposure. This paper reports on the toxicity of 10 different MC congeners identified in algal blooms, microcystin-LR (MCLR), MCLA, MCLF, MCLW, MCLY, MCRR, [Asp3]MCRR, [Asp3,Dhb7]MCRR, MCWR, and MCYR after single administrations to BALB/c mice. In a preliminary MCLR dose–response study of 3 to 9 mg/kg doses, ≥5 mg/kg induced clinical changes, increased serum levels of ALT, AST, and GLDH, liver congestion, increased liver/body weight ratios, and reduced serum glucose and total protein. Based on the extent of these effects, the 10 congeners were administered as single 7 mg/kg oral doses and toxicity evaluated. The greatest toxicity was observed with MCLA and MCLR including a high percentage of moribundity. In addition to eliciting effects similar to those listed above for MCLR, MCLA also induced serum alterations indicative of jaundice. MCLY, and MCYR induced changes like those noted with MCLR, but to lesser extents. MCLW and MCLF exhibited some serum and morphological changes associated with hepatic toxicity, while there were few indications of toxicity after exposures to MCRR, [Asp3]MCRR, [Asp3,Dhb7]MCRR, or MCWR. These data illustrate a wide spectrum of hepatic effects and different potencies of these MC congeners.

scholarly journals Extensive phenotypic characterisation of a human TDP-43Q331K transgenic mouse model of amyotrophic lateral sclerosis (ALS)

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jodie A. Watkins ◽  
James J. P. Alix ◽  
Pamela J. Shaw ◽  
Richard J. Mead
Keyword(s):  
Transgenic Mouse ◽  
Motor Neurons ◽  
Compound Muscle Action Potential ◽  
Therapeutic Effects ◽  
Gene Encoding ◽  
Cytoplasmic Inclusions ◽  
Hindlimb Muscle ◽  
Phenotypic Characterisation ◽  
Cellular Pathology ◽  
End Stage

AbstractThe majority of preclinical studies in ALS have relied on transgenic models with overexpression of mutant human superoxide dismutase 1 (SOD1), widely regarded to have failed in terms of translation of therapeutic effects. However, there are still no widely accepted models of other genetic subtypes of ALS. The majority of patients show ubiquitinated cytoplasmic inclusions of TAR DNA binding protein of 43 kilodaltons (TDP-43) in spinal motor neurons at the end stage of disease and a small proportion have mutations in TARDBP, the gene encoding TDP-43. TDP-43 transgenic mouse models have been produced, but have not been widely adopted. Here, we characterised one of these models available from the Jackson Laboratory in detail. Compared to TDP-43WT mice, TDP-43Q331K mice had 43% less hindlimb muscle mass at 6 months and a 73% reduction in hindlimb compound muscle action potential at 8 months of age. Rotarod and gait analysis indicated motor system decline with elevated weight gain. At the molecular level, the lack of TDP-43 cellular pathology was confirmed with a surprising increase in nuclear TDP-43 in motor neurons. Power analysis indicated group sizes of 12–14 mice are needed to detect 10–20% changes in measured parameters with a power of 80%, providing valid readouts for preclinical testing. Overall, this model may represent a useful component of multi-model pre-clinical therapeutic studies for ALS.

scholarly journals Oxidants, ATP depletion, and endothelial permeability to macromolecules

Blood ◽  
1990 ◽  
Vol 76 (12) ◽  
pp. 2578-2582 ◽  
Author(s):  
J Wilson ◽  
M Winter ◽  
DM Shasby
Keyword(s):  
Endothelial Cells ◽  
Endothelial Permeability ◽  
Atp Depletion ◽  
Metabolic Inhibitors ◽  
Endothelial Monolayer ◽  
Atp Production ◽  
Endothelial Monolayers ◽  
Induced Changes ◽  
Glucose Reduction ◽  
Porcine Pulmonary Artery

Abstract Oxidants can reversibly increase the permeability of endothelium to ions and macromolecules. Oxidants also deplete ATP in cultured endothelial cells. We asked if oxidant-mediated ATP depletion, alone, accounted for the effects of oxidants on endothelial permeability to macromolecules. When porcine pulmonary artery endothelial cells were exposed to 2.5 mmol/LH2O2, ATP was depleted to 31.7% +/- 1.8% of control within 15 minutes and was reduced to 23.1% +/- 2.0% of control after 30 minutes. To determine if this magnitude of ATP depletion could account for the oxidant-induced increase in endothelial permeability to macromolecules, we measured ATP in endothelial cells exposed to metabolic inhibitors of ATP production. We then measured the effects of these metabolic inhibitors on endothelial monolayer permeability to macromolecules. ATP levels were reduced to 44% +/- 4% of control by 12 mmol/L deoxyglucose (DOG) in the absence of glucose and to 2% +/- 1.3% of control by DOG with 25 nmol/L antimycin A in the absence of glucose. Reduction of endothelial cell ATP to these levels with the metabolic inhibitors did not alter the flux of albumin or dextran across the endothelial monolayers. Thus ATP depletion, by itself, does not explain oxidant-induced changes in endothelial permeability to macromolecules.

Afferent-Induced Changes in Rhythmic Motor Programs in the Feeding Circuitry of Aplysia

2004 ◽  
Vol 92 (4) ◽  
pp. 2312-2322 ◽  
Author(s):  
Avniel N. Shetreat-Klein ◽  
Elizabeth C. Cropper
Keyword(s):  
Sensory Neurons ◽  
Motor Neurons ◽  
Rhythmic Activity ◽  
Motor Program ◽  
Firing Frequency ◽  
Afferent Activity ◽  
Motor Programs ◽  
Rhythmic Motor ◽  
Induced Changes ◽  
The Impact

A manipulation often used to determine whether a neuron plays a role in the generation of a motor program involves injecting current into the cell during rhythmic activity to determine whether activity is modified. We perform this type of manipulation to study the impact of afferent activity on feeding-like motor programs in Aplysia. We trigger biting-like programs and manipulate sensory neurons that have been implicated in producing the changes in activity that occur when food is ingested, i.e., when bites are converted to bite-swallows. Sensory neurons that are manipulated are the radula mechanoafferent B21 and the retraction proprioceptor B51. Data suggest that both cells are peripherally activated during radula closing/retraction when food is ingested. We found that phasic subthreshold depolarization of a single sensory neuron can significantly prolong radula closing/retraction, as determined by recording both from interneurons (e.g., B64), and motor neurons (e.g., B15 and B8). Additionally, afferent activity produces a delay in the onset of the subsequent radula opening/protraction, and increases the firing frequency of motor neurons. These are the changes in activity that are seen when food is ingested. These results add to the growing data that implicate B21 and B51 in bite to bite-swallow conversions and indicate that afferent activity is important during feeding in Aplysia.

scholarly journals Disease mechanism, biomarker and therapeutics for spinal and bulbar muscular atrophy (SBMA)

2020 ◽  
Vol 91 (10) ◽  
pp. 1085-1091
Author(s):  
Atsushi Hashizume ◽  
Kenneth H Fischbeck ◽  
Maria Pennuto ◽  
Pietro Fratta ◽  
Masahisa Katsuno
Keyword(s):  
Motor Neurons ◽  
Animal Studies ◽  
Muscular Atrophy ◽  
Neuromuscular Disorder ◽  
Nuclear Accumulation ◽  
Gene Encoding ◽  
Metabolic Switch ◽  
Hand Tremor ◽  
Hormonal Manipulation ◽  
Biochemical Indices

Spinal and bulbar muscular atrophy (SBMA) is a hereditary neuromuscular disorder caused by CAG trinucleotide expansion in the gene encoding the androgen receptor (AR). In the central nervous system, lower motor neurons are selectively affected, whereas pathology of patients and animal models also indicates involvement of skeletal muscle including loss of fast-twitch type 2 fibres and increased slow-twitch type 1 fibres, together with a glycolytic-to-oxidative metabolic switch. Evaluation of muscle and fat using MRI, in addition to biochemical indices such as serum creatinine level, are promising biomarkers to track the disease progression. The serum level of creatinine starts to decrease before the onset of muscle weakness, followed by the emergence of hand tremor, a prodromal sign of the disease. Androgen-dependent nuclear accumulation of the polyglutamine-expanded AR is an essential step in the pathogenesis, providing therapeutic opportunities via hormonal manipulation and gene silencing with antisense oligonucleotides. Animal studies also suggest that hyperactivation of Src, alteration of autophagy and a mitochondrial deficit underlie the neuromuscular degeneration in SBMA and provide alternative therapeutic targets.

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