Modeling the early phenotype at the neuromuscular junction of spinal muscular atrophy using patient-derived iPSCs (RNA-Seq)
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ABSTRACT: Spinal muscular atrophy (SMA) is a neuromuscular disorder caused by mutations of the survival of motor neuron 1 (SMN1) gene. In the pathogenesis of SMA, pathological changes of the neuromuscular junction (NMJ) precede the motor neuronal loss. Therefore, it is critical to evaluate the NMJ formed by SMA patientsM-bM-^@M-^Y motor neurons (MNs), and to identify drugs that can restore the normal condition. We generated NMJ-like structures using motor neurons (MNs) derived from SMA patient-specific induced pluripotent stem cells (iPSCs), and found that the clustering of the acetylcholine receptor (AChR) is significantly impaired. Valproic acid and antisense oligonucleotide treatment ameliorated the AChR clustering defects, leading to an increase in the level of full-length SMN transcripts. Thus, the current in vitro model of AChR clustering using SMA patient-derived iPSCs is useful to dissect the pathophysiological mechanisms underlying the development of SMA, and to evaluate the efficacy of new therapeutic approaches.M-bM-^@M-^C to evaluate the effects of VPA on the expression profiles of the MNs
Project description:Spinal muscular atrophy (SMA) is a neuromuscular disorder caused by mutations of the survival of motor neuron 1 (SMN1) gene. In the pathogenesis of SMA, pathological changes of the neuromuscular junction (NMJ) precede the motor neuronal loss. Therefore, it is critical to evaluate the NMJ formed by SMA patientsM-bM-^@M-^Y motor neurons (MNs), and to identify drugs that can restore the normal condition. We generated NMJ-like structures using motor neurons (MNs) derived from SMA patient-specific induced pluripotent stem cells (iPSCs), and found that the clustering of the acetylcholine receptor (AChR) is significantly impaired. Valproic acid and antisense oligonucleotide treatment ameliorated the AChR clustering defects, leading to an increase in the level of full-length SMN transcripts. Thus, the current in vitro model of AChR clustering using SMA patient-derived iPSCs is useful to dissect the pathophysiological mechanisms underlying the development of SMA, and to evaluate the efficacy of new therapeutic approaches.M-bM-^@M-^C To compare the gene expression pattern between control and patient derived iPSCs
Project description:Spinal muscular atrophy (SMA) is a neuromuscular disorder caused by mutations of the survival of motor neuron 1 (SMN1) gene. In the pathogenesis of SMA, pathological changes of the neuromuscular junction (NMJ) precede the motor neuronal loss. Therefore, it is critical to evaluate the NMJ formed by SMA patients’ motor neurons (MNs), and to identify drugs that can restore the normal condition. We generated NMJ-like structures using motor neurons (MNs) derived from SMA patient-specific induced pluripotent stem cells (iPSCs), and found that the clustering of the acetylcholine receptor (AChR) is significantly impaired. Valproic acid and antisense oligonucleotide treatment ameliorated the AChR clustering defects, leading to an increase in the level of full-length SMN transcripts. Thus, the current in vitro model of AChR clustering using SMA patient-derived iPSCs is useful to dissect the pathophysiological mechanisms underlying the development of SMA, and to evaluate the efficacy of new therapeutic approaches.
Project description:Spinal muscular atrophy (SMA) is a neuromuscular disorder caused by mutations of the survival of motor neuron 1 (SMN1) gene. In the pathogenesis of SMA, pathological changes of the neuromuscular junction (NMJ) precede the motor neuronal loss. Therefore, it is critical to evaluate the NMJ formed by SMA patients’ motor neurons (MNs), and to identify drugs that can restore the normal condition. We generated NMJ-like structures using motor neurons (MNs) derived from SMA patient-specific induced pluripotent stem cells (iPSCs), and found that the clustering of the acetylcholine receptor (AChR) is significantly impaired. Valproic acid and antisense oligonucleotide treatment ameliorated the AChR clustering defects, leading to an increase in the level of full-length SMN transcripts. Thus, the current in vitro model of AChR clustering using SMA patient-derived iPSCs is useful to dissect the pathophysiological mechanisms underlying the development of SMA, and to evaluate the efficacy of new therapeutic approaches.
Project description:Spinal Muscular Atrophy (SMA) is well-known to be caused by mutations in the gene Survival of Motor Neuron 1 (SMN1). Because this gene is ubiquitously expressed, it remains poorly understood why motor neurons (MNs) are one of the most affected cell types. To begin to address this question, we carried out RNA-sequencing studies using fixed, antibody-labeled and purified MNs produced from control and SMA patient-derived induced pluripotent stem cells (iPSCs). We found SMA-specific changes in MNs, including hyper-activation of the endoplasmic reticulum (ER) stress pathway and enhanced apoptosis. Functional studies demonstrated that inhibition of ER stress improves overall MN health and survival in vitro even in MNs with low SMN levels. In SMA mice, we show that systemic delivery of an ER stress inhibitor that crosses the blood-brain-barrier led to preservation of MNs in the spinal cord and prolonged survival of these mice. Therefore, our study implies that selective activation of ER stress underlies MN death in SMA. Moreover, the approach we have taken would be broadly applicable to studying disease-prone human cells in heterogeneous cultures. total RNA collected from ES cell and patient ES cell derived spinal motor neurons
Project description:Spinal Muscular Atrophy (SMA) is well-known to be caused by mutations in the gene Survival of Motor Neuron 1 (SMN1). Because this gene is ubiquitously expressed, it remains poorly understood why motor neurons (MNs) are one of the most affected cell types. To begin to address this question, we carried out RNA-sequencing studies using fixed, antibody-labeled and purified MNs produced from control and SMA patient-derived induced pluripotent stem cells (iPSCs). We found SMA-specific changes in MNs, including hyper-activation of the endoplasmic reticulum (ER) stress pathway and enhanced apoptosis. Functional studies demonstrated that inhibition of ER stress improves overall MN health and survival in vitro even in MNs with low SMN levels. In SMA mice, we show that systemic delivery of an ER stress inhibitor that crosses the blood-brain-barrier led to preservation of MNs in the spinal cord and prolonged survival of these mice. Therefore, our study implies that selective activation of ER stress underlies MN death in SMA. Moreover, the approach we have taken would be broadly applicable to studying disease-prone human cells in heterogeneous cultures.
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:Spinal muscular atrophy (SMA) is a neuromuscular disease caused by mutations in the survival of motor neuron (SMN) gene. Although the primary manifestation of SMA is degeneration of motor neurons in a dying-back manner, deficient SMN intrinsic to motor neurons does not cause severe motor neuron loss, as is the case in SMA mouse models. Thus, the involvement of non-neuronal cells in the pathogenesis of SMA has been suggested. Here, we report that a novel subset of fibro-adipogenic progenitors expressing Dpp4 (Dpp4+ FAPs) is required for the survival of motor neurons, in which BRCA1-associating protein 1 (Bap1) is crucial for the stabilization of SMN by preventing its ubiquitination-dependent degradation. Inactivation of Bap1 in FAPs decreased SMN levels and accompanied degeneration of the neuromuscular junction, leading to dying-back loss of motor neurons and muscle atrophy, reminiscent of SMA pathogenesis. Overexpression of ubiquitination-resistant SMN variant, SMNK186R, in Bap1-null FAPs completely prevented neuromuscular degenerations. In addition, transplantation of Dpp4+ FAPs, but not Dpp4- FAPs, completely rescued neuromuscular defects in the mutant mice. Our data revealed that Bap1-mediated stabilization of SMN in Dpp4+ FAPs is crucial for the survival of motor neurons and provided a new therapeutic approach to treat SMA.
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.
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:Spinal muscular atrophy (SMA) is a devastating neuromuscular disorder that affects the spinal motor neurons and leads to progressive muscle wasting and atrophy. It is caused by a reduction in SMN protein levels due to the mutations in the survival motor neuron 1 (SMN1) gene. Human are unique as they possess a homologous pseudogene known as survival motor neuron 2 (SMN2) gene. MicroRNAs (miRNAs) play a role in either translational repression or mRNA degradation. It has been highlighted that dysregulation of miRNA has been a common feature of motor neuron disease such as SMA. Moreover, it is speculated that the dysregulation of miRNAs expression contributes to the pathophysiology of SMA and the vulnerability of SMN protein can be altered by the modulation of specific miRNA. However, there are still lacking of studies on the dysregulation of miRNAs in human SMA patients using iPSC cell models and how the miRNAs correlate with the SMN protein. Hence, we utilized miRNA microarray to identify the miRNAs dysregulated in SMA patients as compared to normal controls in both fibroblast and its derivative induced pluripotent stem cells (iPSCs). Human fibroblasts and iPSCs were cultured and their respective RNA were extracted.