Unknown,Transcriptomics,Genomics,Proteomics

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Pathways Disrupted in Human ALS Motor Neurons Identified Through Genetic Correction of Mutant SOD1

ABSTRACT: Although many distinct mutations in a variety of genes are known to cause Amyotrophic Lateral Sclerosis (ALS), it remains poorly understood how they selectively impact motor neuron biology and whether they converge on common pathways to cause neural degeneration. Here, we have combined reprogramming and stem cell differentiation approaches with genome engineering and RNA sequencing to define the transcriptional changes that are induced in human motor neurons by mutant SOD1. Mutant SOD1 protein induced a transcriptional signature indicative of increased oxidative stress, reduced mitochondrial function, altered sub-cellular transport as well as activation of the ER stress and unfolded protein response pathways. Functional studies demonstrated that perturbations in these pathways were indeed the source of altered transcript levels. 5 samples, 2 patient-derived SOD1A4V and 3 isogenic control samples where the mutation has been corrected. All samples are motor neurons derived from induced pluripotent stem cells (iPSCs), and isolated after lentiviral infection with an Hb9:RFP construct and FACS purification. Each sample is a separate biological replicate.

ORGANISM(S): Homo sapiens

SUBMITTER: Kevin Eggan

PROVIDER: E-GEOD-54409 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Pathways disrupted in human ALS motor neurons identified through genetic correction of mutant SOD1.

Kiskinis Evangelos E Sandoe Jackson J Williams Luis A LA Boulting Gabriella L GL Moccia Rob R Wainger Brian J BJ Han Steve S Peng Theodore T Thams Sebastian S Mikkilineni Shravani S Mellin Cassidy C Merkle Florian T FT Davis-Dusenbery Brandi N BN Ziller Michael M Oakley Derek D Ichida Justin J Di Costanzo Stefania S Atwater Nick N Maeder Morgan L ML Goodwin Mathew J MJ Nemesh James J Handsaker Robert E RE Paull Daniel D Noggle Scott S McCarroll Steven A SA Joung J Keith JK Woolf Clifford J CJ Brown Robert H RH Eggan Kevin K

Cell stem cell 20140403 6

Although many distinct mutations in a variety of genes are known to cause Amyotrophic Lateral Sclerosis (ALS), it remains poorly understood how they selectively impact motor neuron biology and whether they converge on common pathways to cause neuronal degeneration. Here, we have combined reprogramming and stem cell differentiation approaches with genome engineering and RNA sequencing to define the transcriptional and functional changes that are induced in human motor neurons by mutant SOD1. Muta ...[more]

PMID: 24704492

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Project description:Familial amyotrophic lateral sclerosis (ALS) represents about 10% of ALS cases. In about 20% of familial ALS patients, a mutation in superoxide dismutase-1 (SOD1) can be found. The ubiquitous SOD1 protein converts superoxide radical anions to oxygen and hydrogen peroxide. Patients with familial ALS caused by mutations in SOD1 can show comorbidity with frontotemporal dementia and develop cognitive impairment, including apathy, inattention, verbal deficits, and hypersexuality. At the cellular level, pathological signs of ALS may include tau immunoreactive astrocytic and neuronal inclusions, suggesting that cognitive dysfunction in ALS may also reflect abnormal protein metabolism of the microtubule associated protein (MAP), tau. To identify cell-specific expression changes, we performed laser capture microdissection (LCM) to isolate anterior horn motor neurons and surrounding cells. To determine common pathways for the development of ALS due to dysfunction of SOD1 or TAU, we performed whole transcriptome analysis in SOD1 and TAU mouse models. Because ALS is a neurodegenerative disease that specifically affects motor neurons, these cells were the main investigative target. Global transcriptomes of glial cells surrounding the motor neurons were also assessed, because these cells have been implicated as triggers of neurodegeneration. Mouse experiments were performed at the presymptomatic stage, prior to the onset of cell loss, in order to reduce false positive signals due to tissue reactive changes. Lumbar anterior horn anterior horn motor neurons and surrounding cells (glia) were isolated from presymptomatic TAU-P301L and SOD1-G93A transgenic mice using laser capture microdissection (LCM; PixCellÂ® IIe LCM System, Arcturus, Molecular Devices, CA). On average, 500 motor neuron bodies or surrounding glial cells from 20 tissue sections per animal were collected. RNA isolation from LCM collected cells was performed using the Qiagen RNeasy Micro Kit. Only RNA with RNA Integrity Numbers (RIN) above 7.5 were taken for further analysis (Agilent Bioanalyzer 2100). A two-round T7-based amplification and labeling protocol (Agilent Low RNA Input Linear Amplification Kit PLUS) was used to generate high quality labeled cRNA. Agilent Whole Mouse Genome Microarray comparisons of motor neurons and surrounding glia were performed between transgenic (SOD1G93A and TAUP301L) and corresponding nontransgenic (control) littermate animals, producing four independent comparison groups: SOD1G93A motor neurons versus control motor neurons (SOD1mn), SOD1G93A motor neuron surrounding glia versus control glia (SOD1gl), TAUP301L motor neurons versus control motor neurons (TAUmn) and TAUP301L glia versus control glia (TAUgl). Each comparison used four pairs of transgenic (SOD1G93A or TAUP301L) vs. corresponding control littermate animals, producing four biological replicates. Raw microarray data were acquired using the Agilent DNA Microarray scanner and processed with the accompanying Agilent Feature Extraction 10.5 Image Analysis software using default settings. Normalized signal intensities were used to identify gene expression changes in SOD1G93A and TAUP301L motor neurons and surrounding glial cells, generating four partially overlapping sets of data. For the identification of differential expression, the genes were required to pass two conservative criteria: a ratio beyond the 99.5% confidence interval observed in homotypic comparisons, which corresponded to an approximately 1.5-fold expression change, and a paired t-test (P<0.01) computed using 100 permutations of the data for each gene. Correction for multiple comparisons was performed using the adjusted Bonferroni test. The analysis was performed in the TM4: Microarray Software Suite. These techniques identified 251 transcripts representing 186 known genes for which expression was altered in at least one of the four comparisons. Four-condition experiment, SOD1G93A motor neurons versus control motor neurons (SODmn), SOD1G93A motor neuron surrounding glia versus control glia (SODgl), TAUP301L motor neurons versus control motor neurons (TAUmn) and TAUP301L glia versus control glia (TAUgl). Each comparison used four pairs of transgenic (SOD1G93A or TAUP301L) vs. corresponding control littermate animals, producing four biological replicates. Biological replicates: 4 SOD1G93A motor neurons (SODmn), 4 non SOD littermate motor neurons (nonSODmn), 4 SOD1G93A motor neuron surrounding glia (SODgl), 4 non SOD littermate motor neuron surrounding glia (nonSODgl), 4 TAUP301L motor neurons (TAUmn), 4 non TAU littermate motor neurons (nonTAUmn), 4 TAUP301L motor neuron surrounding glia (TAUgl), 4 non TAU littermate motor neuron surrounding glia (nonTAUgl). Four independent comparison groups were generated: SOD1G93A motor neurons versus control nonSOD motor neurons, SOD1G93A motor neuron surrounding glia versus control nonSOD glia, TAUP301L motor neurons versus control nonTAU motor neurons and TAUP301L glia versus control nonTAU glia. Each comparison used four pairs of transgenic (SOD1G93A or TAUP301L) vs. corresponding control littermate animals, producing four biological replicates. Each replicate was repeated twice with dye flip to correct for unequal dye incorporation rates. Therefore, eight microarray hybridizations were performed for each biological comparison, for a total of 32 microarray slides and generating four groups of differentially expressed genes in SOD1G93A motor neurons (SODmn), SOD1G93A motor neuron surrounding glial cells (SODgl), TAUP301L motor neurons (TAUmn), and TAUP301L surrounding glial cells (TAUgl).

Project description:Aims: Loss of nuclear TDP-43 characterises sporadic and most familial forms of amyotrophic lateral sclerosis (ALS). TDP-43 (encoded by TARDBP) has multiple roles in RNA processing. We aimed to determine whether 1) RNA splicing dysregulation is present in lower motor neurons in ALS and in a motor neuron-like cell model, and 2) TARDBP mutations (mtTARDBP) are associated with aberrant RNA splicing using patient-derived fibroblasts. Methods: Affymetrix exon arrays were used to study mRNA expression and splicing in lower motor neurons obtained by laser capture microdissection of autopsy tissue from individuals with sporadic ALS and TDP-43 proteinopathy. Findings were confirmed by qRT-PCR and in NSC34 motor neuronal cells following shRNA-mediated TDP-43 depletion. Exon arrays and immunohistochemistry were used to study mRNA splicing and TDP-43 expression in fibroblasts from patients with mtTARDBP-associated, sporadic and mutant SOD1-associated ALS. Results: We found altered expression of spliceosome components in motor neurons and widespread aberrations of mRNA splicing that specifically affected genes involved in ribonucleotide binding. This was confirmed in TDP-43 depleted NSC34 cells. Fibroblasts with mtTARDBP showed loss of nuclear TDP-43 protein and demonstrated similar changes in splicing and gene expression, that were not present in fibroblasts from patients with sporadic or SOD1-related ALS. Conclusion: Loss of nuclear TDP-43 is associated with RNA processing abnormalities in ALS motor neurons, patient-derived cells with mtTARDBP, and following artificial TDP-43 depletion, suggesting that splicing dysregulation directly contributes to disease pathogenesis. Key functional pathways affected include those central to RNA metabolism. RNA was extracted from lower motor neurons obtained by laser capture microdissection from autopsy material from neurologically healthy controls (n=6) and cases of sporadic ALS (n=3) and ALS due to C9ORF72 mutations (n=3).

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Pathways Disrupted in Human ALS Motor Neurons Identified Through Genetic Correction of Mutant SOD1

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Pathways disrupted in human ALS motor neurons identified through genetic correction of mutant SOD1.

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