Project description:Amyotrophic lateral sclerosis (ALS) is characterized by dysfunction and loss of upper and lower motor neurons. Several studies have identified structural and functional alterations in the motor neurons before the manifestation of symptoms, yet the underlying cause of such alterations and how they contribute to the progressive degeneration of affected motor neuron networks remain unclear. Importantly, the short and long-term spatiotemporal dynamics of neuronal network activity make it challenging to discern how ALS-related network reconfigurations emerge and evolve. To address this, we systematically monitored the structural and functional dynamics of motor neuron networks with a confirmed endogenous C9orf72 mutation. We show that ALS patient-derived motor neurons display time-dependent neural network dysfunction, specifically reduced firing rate and spike amplitude, impaired bursting, but higher overall synchrony in network activity. These changes coincided with altered neurite outgrowth and branching within the networks. Moreover, transcriptional analyses revealed dysregulation of molecular pathways involved in synaptic development and maintenance, neurite outgrowth and cell adhesion, suggesting impaired synaptic stabilization. This study identifies early synaptic dysfunction as a contributing mechanism resulting in network-wide structural and functional compensation, which may over time render the networks vulnerable to neurodegeneration.
Project description:Amyotrophic lateral sclerosis (ALS) is characterized by motor neuron degeneration. We demonstrate that ALS-associated RNA-binding proteins (RBPs)—MATR3, FUS, and hnRNPA1—regulate UNC13A transcription via REST mRNA stabilization. Loss of these RBPs increases REST levels, repressing UNC13A transcription and implicating synaptic dysfunction in ALS pathogenesis.
Project description:Gene expression changes in spinal motor neurons of the SOD1G93A-transgenic model for ALS after treatment with G-CSF. To gain insight into the mode of action of G-CSF, we performed gene expression profiling on isolated lumbar motor neurons from SOD1G93A mice, the most frequently studied animal model for ALS, with and without G-CSF treatment. A first group of SOD1G93A and WT mice was included in the study at week 11 of age when SOD1G93A mice present no signs of motor dysfunction but subtle signs of denervation detectable by electromyography. The second cohort of mice was treated with G-CSF or vehicle from week 11 to week 15. At the time of study completion, SOD1G93A mice presented clear motor impairment and motor neuron degeneration is documented. This design should provide information on genes altered in motor neurons of SOD1G93A mice from the clinically non-symptomatic to an early symptomatic stage, and give insight into genes influenced by G-CSF treatment. We sampled 300 motoneurons per mouse spinal cord by laser microdissection.
Project description:Approximately 10% of Amyotrophic lateral sclerosis (ALS) cases have a positive family history (familial ALS) and appear clinically indistinguishable from sporadic cases. ALS and frontotemporal dementia (FTD) are fatal neurodegenerative disorders that have common molecular and pathogenic characteristics; however, their biological mechanisms remain poorly understood. We have previously identified CCNF missense mutations in cohorts of familial and sporadic ALS and FTD cases [ref]. CCNF encodes cyclin F, a component of an E3 ubiquitin-protein ligase (SCFCyclin F) complex that is responsible for ubiquitinating proteins for degradation by the Ubiquitin-Proteasome System (UPS). The SCFCyclin F complex is essential for maintaining cellular homeostasis in cells; but mutations appear to lead to aberrant motor neuron development and neuron degeneration. We revealed elevated Lys48-specific ubiquitination of proteins in neuronal cells expressing mutant CCNFS621G compared to the CCNFWT control, which is consistent with increased Lys48-specific E3 ligase activity of cyclin FS621G (>1.3-fold). Different subsets of immunoprecipitated Lys48-ubiquitinated proteins were identified between CCNFWT and CCNFS621G cells indicating that transfected cyclin F contribute to the protein ubiquitination profile. These findings provide mechanistic insights into the effects of CCNF gene mutations on the function of the SCFcyclin F complex on neuronal proteostasis.
Project description:Amyotrophic Lateral Sclerosis (ALS) results from the selective and progressive degeneration of motor neurons. Although the underlying disease mechanisms remain unknown, glial cells have been implicated in ALS disease progression. Here we examine the effects of glial cell/motor neuron interactions on gene expression, using the hSOD1G93A mouse model of ALS. We detect striking cell autonomous and non-autonomous changes in gene expression in co-cultured motor neurons and glia, revealing that the two cell types profoundly affect each other. In addition, we found a remarkable concordance between the cell culture data, expression profiles of whole spinal cords, and of acutely isolated spinal cord cells, during disease progression in the G93A mouse model, providing validation of the cell culture approach. Bioinformatics analyses identified changes in the expression of specific genes and signaling pathways that may contribute to motor neuron degeneration in ALS, among which are TGF-b signaling pathways. RNA-seq profiles of: 1) 43 Sandwich culture samples at 3 different time points (3, 7 and 14 days), in duplicate, in different combinations of genetic background WT/SOD1_G93A mutant glia and WT/SOD1_G93A mutant neurons; 2) 16 spinal cord samples at 4 different time points, WT and SOD1_G93A mutant.
Project description:Amyotrophic lateral sclerosis (ALS), the most common form of motor neuron disease, is characterized by progressive muscle weakness and paralysis caused by degeneration of upper and lower motor neurons. A major breakthrough in understanding the genetics of ALS was the discovery of a GGGGCC hexanucleotide repeat expansion (HRE) within the non-coding region of chromosome 9 open reading frame 72 (C9orf72) as the most common mutation in both familial and sporadic forms of ALS [25, 80]. We report that C9orf72 loss of function and poly(GP) expression act together to induce motor neuron degeneration and paralysis. These synergistic properties of C9orf72 mutation affect autophagy, thus resulting in poly(GP) and p62 aggregation. In this context, poly(GP) accumulation occurs in motor neurons preferentially, along with swollen mitochondria, a typical signature of mitophagy defects. In motor neurons, accumulated abnormal mitochondria engage caspase cascade, ultimately giving rise to apoptotic cell death of motor neurons that results in paralysis
Project description:Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease causing progressive dysfunction and degeneration of upper and lower motor neurons. An increasing body of evidence has identified synaptic alterations in patients and experimental models of ALS. Importantly, these have been associated with functional impairments in motor neuron networks, suggesting that synaptic impairments are early events in the disease cascade resulting in functional compensatory reconfigurations. The synapse may therefore represent a disease-modifying target to delay disease progression. In this study, we aimed to stabilize synapses and modify structural connectivity to restore network balance in ALS patient-derived motor neuron networks. To this end, we blocked the potassium channels using tetraethylammonium (TEA) which has been shown to induce chemical long-term potentiation (cLTP). The unperturbed ALS patient-derived motor neuron networks developed clear signs of subtle network dysfunction, including increased firing rate and bursting, and accompanying structural abnormalities. These features were partially restored by temporarily blocking the potassium channels. Specifically, the TEA-treated ALS networks were characterized by a reduction in aberrant branching and stabilization of dendritic spines, alongside a temporary reduction in firing rate and bursting. Furthermore, protein expression assays revealed restoration of dysregulated molecular pathways, including protein synthesis and metabolic pathways, and upregulation of pathways involved in synapse organization in the TEA-treated ALS networks. This is one of the first studies to integrate synaptic potentiation, proteomics, and functional network analysis of human ALS motor neurons. Collectively, these findings improve our understanding of the association between synaptic impairments and functional alterations in ALS, and demonstrate the therapeutic potential of targeting neuronal excitability and plasticity to promote network balance.
Project description:RNA sequencing analysis of human iPSC-derived motor neurons generated from one C9ORF72 ALS/FTD patient line, treated with DMSO or Apilimod. The goal of this study is to evaluate the effect of PIKFYVE inhibitor in rescuing ALS motor neuron degeneration.
Project description:Amyotrophic lateral sclerosis (ALS) is caused by the progressive degeneration of motor neurons. Mutations in the Cu/Zn superoxide dismutase (SOD1) are found in about 20% of patients with familial ALS. Mutant SOD1 causes motor neuron death through an acquired toxic property. Although, molecular mechanism underlying this toxic gain-of-function remains unknown, evidence support the role of mutant SOD1 expression in non-neuronal cells in shaping motor neuron degeneration. We have previously found that in contrast to non-transgenic, SOD1G93A-expressing astrocytes induced apoptosis of co-cultured motor neurons. This prompted us to investigate whether the effect on motor neuron survival was related to a change in the gene expression profile. Through high-density oligonucletide microarrays we found changes in the expression of genes involved in transcription, signaling, cell proliferation, extracellular matrix construction, response to stress and steroid and lipid metabolism. Decorin, a small multifunctional proteoglycan, was the most up-regulated gene. Down-regulated genes included the insulin-like growth factor-1 receptor and the RNA binding protein ROD1. We also analyzed the expression of selected genes in purified motor neurons expressing SOD1G93A and in spinal cord of asymptomatic and early symptomatic ALS-rodent model. The expression of mutated SOD1 in astrocytes cause gene expression changes with potential consequences for its interaction with motor neurons. The astrocyte-specific gene expression profile contributes to the identification of possible candidates for cell type-specific therapies in ALS Keywords: Cell type comparison
Project description:RNA sequencing analysis of human induced motor neurons generated from a C9ORF72 ALS patient line and its isogenic control, treated with siRNA targetting SYF2. The goal of this study is to evaluate the process of SYF2 suppression in rescuing ALS motor neuron degeneration.