Age-dependent degeneration of an identified adult leg motor neuron in a Drosophila SOD1 model of ALS

ABSTRACTMutations in superoxide dismutase 1 (SOD1) cause familial amyotrophic lateral sclerosis (ALS) in humans. ALS is a neurodegenerative disease characterized by progressive motor neuron loss leading to paralysis and inevitable death in affected individuals. Using a gene replacement strategy to introduce disease mutations into the orthologous Drosophila sod1 (dsod1) gene, here, we characterize changes at the neuromuscular junction using longer-lived dsod1 mutant adults. Homozygous dsod1H71Y/H71Y or dsod1null/null flies display progressive walking defects with paralysis of the third metathoracic leg. In dissected legs, we assessed age-dependent changes in a single identified motor neuron (MN-I2) innervating the tibia levitator muscle. At adult eclosion, MN-I2 of dsod1H71Y/H71Y or sod1null/null flies is patterned similar to wild-type flies indicating no readily apparent developmental defects. Over the course of 10 days post-eclosion, MN-I2 shows an overall reduction in arborization with bouton swelling and loss of the post-synaptic marker discs-large (dlg) in mutant dsod1 adults. In addition, increases in polyubiquitinated proteins correlate with the timing and extent of MN-I2 changes. Because similar phenotypes are observed between flies homozygous for either dsod1H71Y or dsod1null alleles, we conclude these NMJ changes are mainly associated with sod loss-of-function. Together these studies characterize age-related morphological and molecular changes associated with axonal retraction in a Drosophila model of ALS that recapitulate an important aspect of the human disease.This article has an associated First Person interview with the first author of the paper.

Download Full-text

Loss of TBK1 activity leads to TDP-43 proteinopathy through lysosomal dysfunction in human motor neurons

10.1101/2021.10.11.464011 ◽

2021 ◽

Author(s):

Jin Hao ◽

Michael F Wells ◽

Gengle Niu ◽

Irune Guerra San Juan ◽

Francesco Limone ◽

...

Keyword(s):

Motor Neuron ◽

Neurodegenerative Disease ◽

Motor Neurons ◽

Inhibition Mechanism ◽

Loss Of Function ◽

Neurodegenerative Process ◽

Lysosomal Dysfunction ◽

Human Motor ◽

Lateral Sclerosis ◽

Lysosomal Acidification

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by motor neuron loss accompanied by cytoplasmic localization of TDP-43 proteins and their insoluble accumulations. Haploinsufficiency of TBK1 has been found to associate with or cause ALS. However, the cell-autonomous mechanisms by which reduced TBK1 activity contributes to human motor neuron pathology remain elusive. Here, we generated a human cellular model harboring loss-of-function mutations of TBK1 by gene editing and found that TBK1 deficiency was sufficient to cause TDP-43 pathology in human motor neurons. In addition to its functions in autophagy, we found that TBK1 interacted with endosomes and was required for normal endosomal maturation and subsequent lysosomal acidification. Surprisingly, TDP-43 pathology resulted more from the dysfunctional endo-lysosomal pathway than the previously recognized autophagy inhibition mechanism. Restoring TBK1 levels ameliorated lysosomal dysfunction and TDP-43 pathology and maintained normal motor neuron homeostasis. Notably, using patient-derived motor neurons, we found that haploinsufficiency of TBK1 sensitized neurons to lysosomal stress, and chemical regulators of endosomal maturation rescued the neurodegenerative process. Together, our results revealed the mechanism of TBK1 in maintaining TDP-43 and motor neuron homeostasis and suggested that modulating endosomal maturation was able to rescue neurodegenerative disease phenotypes caused by TBK1 deficiency.

Download Full-text

Bisperoxovanadium promotes motor neuron survival and neuromuscular innervation in amyotrophic lateral sclerosis

Molecular Brain ◽

10.1186/s13041-021-00867-7 ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Junmei Wang ◽

Lydia Tierney ◽

Ranjeet Mann ◽

Thomas Lonsway ◽

Chandler L. Walker

Keyword(s):

Amyotrophic Lateral Sclerosis ◽

Motor Neuron ◽

Lumbar Spinal Cord ◽

Therapeutic Effects ◽

Spinal Cord Tissue ◽

Neuron Loss ◽

Neuroprotective Therapy ◽

Motor Neuron Loss ◽

Lateral Sclerosis

AbstractAmyotrophic lateral sclerosis (ALS) is the most common motor neuron (MN) disease, with no present cure. The progressive loss of MNs is the hallmark of ALS. We have previously shown the therapeutic effects of the phosphatase and tensin homolog (PTEN) inhibitor, potassium bisperoxo (picolinato) vanadium (bpV[pic]), in models of neurological injury and demonstrated significant neuroprotective effects on MN survival. However, accumulating evidence suggests PTEN is detrimental for MN survival in ALS. Therefore, we hypothesized that treating the mutant superoxide dismutase 1 G93A (mSOD1G93A) mouse model of ALS during motor neuron degeneration and an in vitro model of mSOD1G93A motor neuron injury with bpV(pic) would prevent motor neuron loss. To test our hypothesis, we treated mSOD1G93A mice intraperitoneally daily with 400 μg/kg bpV(pic) from 70 to 90 days of age. Immunolabeled MNs and microglial reactivity were analyzed in lumbar spinal cord tissue, and bpV(pic) treatment significantly ameliorated ventral horn motor neuron loss in mSOD1G93A mice (p = 0.003) while not significantly altering microglial reactivity (p = 0.701). Treatment with bpV(pic) also significantly increased neuromuscular innervation (p = 0.018) but did not affect muscle atrophy. We also cultured motor neuron-like NSC-34 cells transfected with a plasmid to overexpress mutant SOD1G93A and starved them in serum-free medium for 24 h with and without bpV(pic) and downstream inhibitor of Akt signaling, LY294002. In vitro, bpV(pic) improved neuronal viability, and Akt inhibition reversed this protective effect (p < 0.05). In conclusion, our study indicates systemic bpV(pic) treatment could be a valuable neuroprotective therapy for ALS.

Download Full-text

Longitudinal study of functional spinal alpha motor neuron loss in amyotrophic lateral sclerosis

Muscle & Nerve ◽

10.1002/mus.10067 ◽

2002 ◽

Vol 25 (4) ◽

pp. 520-526 ◽

Cited By ~ 17

Author(s):

K. Arasaki ◽

Y. Kato ◽

A. Hyodo ◽

R. Ushijima ◽

M. Tamaki

Keyword(s):

Amyotrophic Lateral Sclerosis ◽

Longitudinal Study ◽

Motor Neuron ◽

Neuron Loss ◽

Motor Neuron Loss ◽

Alpha Motor Neuron ◽

Lateral Sclerosis

Download Full-text

Spatiotemporal dynamics of molecular pathology in amyotrophic lateral sclerosis

Science ◽

10.1126/science.aav9776 ◽

2019 ◽

Vol 364 (6435) ◽

pp. 89-93 ◽

Cited By ~ 74

Author(s):

Silas Maniatis ◽

Tarmo Äijö ◽

Sanja Vickovic ◽

Catherine Braine ◽

Kristy Kang ◽

...

Keyword(s):

Amyotrophic Lateral Sclerosis ◽

Motor Neuron ◽

Motor Neurons ◽

Molecular Mechanisms ◽

Early Time ◽

Course Of Disease ◽

Molecular Events ◽

Motor Neuron Loss ◽

Als Patients ◽

Lateral Sclerosis

Paralysis occurring in amyotrophic lateral sclerosis (ALS) results from denervation of skeletal muscle as a consequence of motor neuron degeneration. Interactions between motor neurons and glia contribute to motor neuron loss, but the spatiotemporal ordering of molecular events that drive these processes in intact spinal tissue remains poorly understood. Here, we use spatial transcriptomics to obtain gene expression measurements of mouse spinal cords over the course of disease, as well as of postmortem tissue from ALS patients, to characterize the underlying molecular mechanisms in ALS. We identify pathway dynamics, distinguish regional differences between microglia and astrocyte populations at early time points, and discern perturbations in several transcriptional pathways shared between murine models of ALS and human postmortem spinal cords.

Download Full-text

n -butylidenephthalide treatment prolongs life span and attenuates motor neuron loss in SOD1G93A mouse model of amyotrophic lateral sclerosis

CNS Neuroscience & Therapeutics ◽

10.1111/cns.12681 ◽

2017 ◽

Vol 23 (5) ◽

pp. 375-385 ◽

Cited By ~ 13

Author(s):

Qin-Ming Zhou ◽

Jing-Jing Zhang ◽

Song Li ◽

Sheng Chen ◽

Wei-Dong Le

Keyword(s):

Amyotrophic Lateral Sclerosis ◽

Mouse Model ◽

Motor Neuron ◽

Life Span ◽

Neuron Loss ◽

Motor Neuron Loss ◽

Sod1g93a Mouse ◽

Lateral Sclerosis

Download Full-text

Genetic Evidence Linking Age-Dependent Attenuation of the 26S Proteasome with the Aging Process

Molecular and Cellular Biology ◽

10.1128/mcb.01227-08 ◽

2008 ◽

Vol 29 (4) ◽

pp. 1095-1106 ◽

Cited By ~ 164

Author(s):

Ayako Tonoki ◽

Erina Kuranaga ◽

Takeyasu Tomioka ◽

Jun Hamazaki ◽

Shigeo Murata ◽

...

Keyword(s):

Neurodegenerative Diseases ◽

Life Span ◽

Cellular Protein ◽

Proteasome Activity ◽

26S Proteasome ◽

Loss Of Function ◽

Ubiquitinated Proteins ◽

Age Related ◽

Age Dependent ◽

Progressive Neurodegeneration

ABSTRACT The intracellular accumulation of unfolded or misfolded proteins is believed to contribute to aging and age-related neurodegenerative diseases. However, the links between age-dependent proteotoxicity and cellular protein degradation systems remain poorly understood. Here, we show that 26S proteasome activity and abundance attenuate with age, which is associated with the impaired assembly of the 26S proteasome with the 19S regulatory particle (RP) and the 20S proteasome. In a genetic gain-of-function screen, we characterized Rpn11, which encodes a subunit of the 19S RP, as a suppressor of expanded polyglutamine-induced progressive neurodegeneration. Rpn11 overexpression suppressed the age-related reduction of the 26S proteasome activity, resulting in the extension of flies' life spans with suppression of the age-dependent accumulation of ubiquitinated proteins. On the other hand, the loss of function of Rpn11 caused an early onset of reduced 26S proteasome activity and a premature age-dependent accumulation of ubiquitinated proteins. It also caused a shorter life span and an enhanced neurodegenerative phenotype. Our results suggest that maintaining the 26S proteasome with age could extend the life span and suppress the age-related progression of neurodegenerative diseases.

Download Full-text

Microglia influence neurofilament deposition in ALS iPSC-derived motor neurons

10.1101/2021.12.30.474573 ◽

2022 ◽

Author(s):

Reilly L Allison ◽

Jacob W Adelman ◽

Jenica Abrudan ◽

Raul A Urrutia ◽

Michael T Zimmermann ◽

...

Keyword(s):

Motor Neuron ◽

Conditioned Medium ◽

Motor Neurons ◽

Neuron Loss ◽

Secreted Factors ◽

Sporadic Als ◽

Motor Neuron Loss ◽

Induced Pluripotent ◽

Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease in which upper and lower motor neuron loss is the primary phenotype, leading to muscle weakness and wasting, respiratory failure, and death. Although a portion of ALS cases are linked to one of over 50 unique genes, the vast majority of cases are sporadic in nature. However, the mechanisms underlying the motor neuron loss in either familial or sporadic ALS are not entirely clear. Here we used induced pluripotent stem cells derived from a set of identical twin brothers discordant for ALS to assess the role of astrocytes and microglia on the expression and accumulation of neurofilament proteins in motor neurons. We found that motor neurons derived from the affected twin exhibited increased transcript levels of all three neurofilament isoforms and increased expression of phosphorylated neurofilament puncta. We further found that treatment of the motor neurons with astrocyte conditioned medium and microglial conditioned medium significantly impacted neurofilament deposition. Together, these data suggest that glial-secreted factors can alter neurofilament pathology in ALS iPSC-derived motor neurons.

Download Full-text