Project description:We compare transcriptomic profiles of human induced pluripotent stem cells (iPSCs), motor neurons (MNs) in vitro differentiated from iPSCs or human ESCs containing a HB9::GFP reporter for MNs, and human fetal spinal cords. The purpose of this comparison is to assess the extent of molecular similarities between in vitro differentiated MNs and in vivo fetal or adult spinal cord MNs. Data for adult spinal cord MNs are published from other studies: GSE3526, GSE19332, GSE20589, and GSE40438. Human induced pluripotent stem cells, pluripotent stem cell derived motor neurons, and fetal spinal cords for RNA extraction and hybridization on Affymetrix arrays.
Project description:We compare transcriptomic profiles of human induced pluripotent stem cells (iPSCs), motor neurons (MNs) in vitro differentiated from iPSCs or human ESCs containing a HB9::GFP reporter for MNs, and human fetal spinal cords. The purpose of this comparison is to assess the extent of molecular similarities between in vitro differentiated MNs and in vivo fetal or adult spinal cord MNs. Data for adult spinal cord MNs are published from other studies: GSE3526, GSE19332, GSE20589, and GSE40438.
Project description:We performed RNA-seq experiments on two samples (cortical neurons and spinal motor neurons) from normal induced pluripotent stem cells (iPSCs), and another two samples (cortical neurons and spinal motor neurons) derived from SPG3A (an early onset form of hereditary spastic paraplegia) iPSCs. This initial experiment is to test the system and set up a baseline for future studies. Cortical projection neurons and spinal motor neurons were differentiated from same batch of iPSCs in parallel to minimize variations. The differentiation of cortical neurons and spinal motor neurons are based on protocols well-established in our group.
Project description:Human pluripotent stem cells are a promising source of diverse cells for developmental studies, cell transplantation, disease modeling, and drug testing. However, their widespread use even for intensely studied cell types like spinal motor neurons, is hindered by the long duration and low yields of existing protocols for in vitro differentiation and by the molecular heterogeneity of the populations generated. We report a combination of small molecules that induce up to 50% motor neurons within 3 weeks from human pluripotent stem cells with defined subtype identities that are relevant to neurodegenerative diseases. Despite their accelerated differentiation, motor neurons expressed combinations of HB9, ISL1 and column-specific markers that mirror those observed in vivo in human fetal spinal cord. They also exhibited spontaneous and induced activity, and projected axons towards muscles when grafted into developing chick spinal cord. Strikingly, this novel protocol preferentially generates motor neurons expressing markers of limb-innervating lateral motor column motor neurons (FOXP1+/LHX3-). Access to high-yield cultures of human limb-innervating motor neuron subtypes will facilitate in-depth study of motor neuron subtype-specific properties, disease modeling, and development of large-scale cell-based screening assays. We analyze 3 samples including 2 positive samples and 1 negative sample. Descriptions are as follow: a) Positive Sample 1: SHH-derived, day 21 GFP-high FACS purified motor neurons.b) Positive Sample 2: S+P-derived, day 21 GFP-high FACS purified motor neurons. c) Negative: S+P condition, day 21 no GFP FACS purified motor neurons
Project description:Human fibroblasts can be directly converted into cholinergic neurons by Neurogenin 2 (Neurog2 or NGN2) under the treatments of small molecules. Genome-wide analysis of gene expression was performed to examine the similarity of converted neurons to samples from human brain or spinal cord. Total RNA obtained from isolated human fetal lung fibroblasts or converted neurons at 21 days. Commercially available total RNAs from adult human brains and spinal cords were used as controls.
Project description:RNA sequence was performed using mRNAs of motor neurons derived from iPSCs of four patients of spinal bulbar muscular atrophy (SBMA) and four age- and sex- matched controls. The analysis was performed using purified motor neurons by flowcytometry and cell sorting based on the expression of HB9e438::Venus reporter gene (P4) or unpurified motor neurons (NT).
Project description:Egr3 is a zinc-finger transcription factor involved in growth and development. Egr3-deficient mice have severe sensory ataxia due to failed development of muscle spindle stretch receptors. Sensory and motor neurons that normally innervate spindles are absent in Egr3-deficient mice, presumably as a secondary consequence to the loss of trophic signals produced by spindles during development that are required for innervation and neuron survival. The molecular mechanisms involving motor neuron fate specification, target derived growth factor dependencies, and specification of target innervation have been difficult to study since select markers for functionally specific motor neurons are very poorly characterized. A more thorough understanding of the molecular mediators of motor neuron biology will be important to evaluate the efficacy of new strategies devised to thwart neuron death that occurs in a variety of human motor neuronopathies and neuropathies. To identify genes specifically expressed by spinal cord fusimotor neurons: Many motor neuron specific genes have been described over the years. However, none have been described that distinguish fusimotor neurons from skeletomotor neurons despite the fact that they have distinct muscle targets (muscle spindle stretch receptors) and comprise 25-30% of the spinal motor neuron populations. Since these motor neurons have remarkably different target innervation and function, we hypothesize that they express genes that establish their specific phenotypes during development. We hypothesize that fusimotor neurons can be distinguished in the spinal cord by characterizing fusimotor neuron specific gene expression. Once fusimotor neuron specific genes are identified, they will be used as markers to identify fusimotor neurons in complex neuroglial cell populations in vivo and in vitro. We hypothesize that by characterizing fusimotor neuron specific genes, unique marker molecules will be identified for in vivo and in vitro study of this functionally distinct and important motor neuron subtype. Moreover, we hypothesize that many of the genes that are specifically expressed by fusimotor neurons will be involved in mechanisms related to their fate specification, target innervation and growth factor dependent biology. We will use the Affymetrix microarray platform to identify genes that are specifically expressed by fusimotor neurons in mouse spinal cord. The differential expression analysis will be performed on microdissected segments of spinal cord (L3-L5) from wild type and Egr3-deficient mice. Postnatal Egr3-deficient mice lack muscle spindles and fusimotor neurons in their spinal cords. By comparing gene expression from microdissected segments of spinal cord (L3-L5) between wild type and Egr3-deficient mice, we hypothesize that fusimotor neuron selective genes can be identified. We will microdissect L3-L5 segments of spinal cord using precise anatomical landmarks to ensure that comparable spinal cord regions are anlayzed from each animal. For each microarray experiment, total RNA will be extracted from L3-L5 cords (approximately 2 mm length of spinal cord). The integrity of each RNA sample will be verified by gel electrophoresis. The intact RNA samples from mice of similar genotype will be pooled from three (3) 27-day old animals. The intact cord dissection is easier in young animals (eg: 27-day old) and the phenotype is known to exist at this developmental stage. The RNA from each animal of a similar genotype will be pooled into a single sample to minimize false positive gene calls that may represent genes related to the specific state of vigilance of a particular animal at the time of sacrifice (eg: activity dependent genes). Thus, each of the two RNA samples to be analyzed for a particular microarray experiment will represent RNA from three (3) spinal cords of each genotype. RNA amplification for probe synthesis should not be necessary since we will provide 7 ug of intact pooled total RNA for each sample. For statistical analysis, the experiment will be performed twice. Since the RNA samples are precious, they will be provided to the Array Consortium in two shipments with each of the experiments performed independently.
Project description:Amyotrophic lateral sclerosis (ALS) is a severe neurodegenerative condition characterized by loss of motor neurons in the brain and spinal cord. Expansions of a hexanucleotide repeat (GGGGCC) in the noncoding region of the C9ORF72 gene are the most common cause of the familial form of ALS (C9-ALS), as well as frontotemporal lobar degeneration and other neurological diseases. How the repeat expansion causes disease remains unclear, with both loss of function (haploinsufficiency) and gain of function (either toxic RNA or protein products) proposed. We report a cellular model of C9-ALS with motor neurons differentiated from induced pluripotent stem cells (iPSCs) derived from ALS patients carrying the C9ORF72 repeat expansion. No significant loss of C9ORF72 expression was observed, and knockdown of the transcript was not toxic to cultured human motor neurons. Transcription of the repeat was increased, leading to accumulation of GGGGCC repeat–containing RNA foci selectively in C9-ALS iPSC-derived motor neurons. Repeat-containing RNA foci colocalized with hnRNPA1 and Pur-?, suggesting that they may be able to alter RNA metabolism. C9-ALS motor neurons showed altered expression of genes involved in membrane excitability including DPP6, and demonstrated a diminished capacity to fire continuous spikes upon depolarization compared to control motor neurons. Antisense oligonucleotides targeting the C9ORF72 transcript suppressed RNA foci formation and reversed gene expression alterations in C9-ALS motor neurons. These data show that patient-derived motor neurons can be used to delineate pathogenic events in ALS. Transcriptome profiling from iPSC derived motor neurons compared to controls
Project description:Proximal spinal muscular atrophy (SMA) is an early onset, autosomal recessive motor neuron disease caused by loss of or mutation in SMN1 (survival motor neuron 1). Despite understanding the genetic basis underlying this disease, it is still not known why motor neurons (MNs) are selectively affected by the loss of the ubiquitously expressed SMN protein. Using a mouse embryonic stem cell (mESC) model for severe SMA, the RNA transcript profiles (transcriptomes) between control and severe SMA (SMN2+/+;mSmn-/-) mESC-derived MNs were compared in this study using massively parallel RNA sequencing (RNA-Seq). The MN differentiation efficiencies between control and severe SMA mESCs were similar. RNA-Seq analysis identified 3094 upregulated and 6964 downregulated transcripts in SMA mESC-derived MNs when compared against control cells. Pathway and network analysis of the differentially expressed RNA transcripts showed that pluripotency and cell proliferation transcripts were significantly increased in SMA MNs while transcripts related to neuronal development and activity were reduced. The differential expression of selected transcripts such as Crabp1, Crabp2 and Nkx2.2 was validated in a second mESC model for SMA as well as in the spinal cords of low copy SMN2 severe SMA mice. Furthermore, the levels of these selected transcripts were restored in high copy SMN2 rescue mouse spinal cords when compared against low copy SMN2 severe SMA mice. These findings suggest that SMN deficiency affects processes critical for normal development and maintenance of MNs. RNA profiles were generated from FACS-purified control and SMA mESC-derived motor neurons (n=3/genotype) by deep sequencing using Illumina HighSeq 2500
Project description:We used total RNA-sequencing (RNA-seq) to analyze ALS MN-specific gene-expression signatures in laser capture microdissected motor neurons from post-mortem lumbar spinal cords.