Project description:Motor neurons are selectively vulnerable in spinal muscular atrophy (SMA). However, some brainstem motor neuron groups, including oculomotor and trochlear, which innervate the muscles around the eyes, are for unknown reasons spared. Here, we investigate the transcriptional dynamics in discrete neuronal populations in health and SMA to identify mechanisms of vulnerability and resistance. Such mechanisms could reveal targets for future gene therapy studies aimed towards preserving vulnerable motor neurons.
Project description:Spinal Muscular Atrophy (SMA) is an autosomal recessive motor neuron disease and is the second most common genetic disorder leading to death in childhood. Stem cell transplantation could represent a therapeutic approach for motor neuron diseases such as SMA. We examined the theraputics effects of a spinal cord neural stem cell population and their ability to modify SMA phenotype. Microarray technology was used to assess the global gene expression profile of laser-microdissected motoneurons obtained by transplanted and veichle treated SMA, and wildtype mice. Experiment Overall Design: The microarray data derived from three different groups: wildtype controls (vehicle treated), transgenic SMA (vehicle treated) and transplanted SMA mice. Each population consists of three RNA profiling samples.
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.
Project description:Although spinal muscular atrophy (SMA) is a motor neuron disease caused by the loss of survival of motor neuron protein, there is growing evidence that non-neuronal cells play important roles in SMA pathogenesis. However, transcriptome alterations occurring at the single-cell level in SMA spinal cord remain unknown, preventing us from fully comprehending the role of specific cells. Here, we performed single-cell RNA sequencing of the spinal cord of a severe SMA mouse model, and identified ten cell types as well as their differentially expressed genes.
Project description:<p>Beyond motor neuron degeneration, homozygous mutations in the survival motor neuron 1 (SMN1) gene cause multiorgan and metabolic defects in patients with spinal muscular atrophy (SMA). However, the precise biochemical features of these alterations and the age of onset in the brain and peripheral organs remain unclear. Using untargeted NMR-based metabolomics in SMA mice, we identify cerebral and hepatic abnormalities related to energy homeostasis pathways and amino acid metabolism, emerging already at postnatal day 3 (P3) in the liver. Through HPLC, we find that SMN deficiency induces a drop in cerebral norepinephrine levels in overt symptomatic SMA mice at P11, affecting the mRNA and protein expression of key genes regulating monoamine metabolism, including aromatic L-amino acid decarboxylase (AADC), dopamine beta-hydroxylase (DβH) and monoamine oxidase A (MAO-A). In support of the translational value of our preclinical observations, we also discovered that SMN upregulation increases cerebrospinal fluid norepinephrine concentration in Nusinersen-treated SMA1 patients. Our findings highlight a previously unrecognized harmful influence of low SMN levels on the expression of critical enzymes involved in monoamine metabolism, suggesting that SMN-inducing therapies may modulate catecholamine neurotransmission. These results may also be relevant for setting therapeutic approaches to counteract peripheral metabolic defects in SMA. </p>
Project description:Spinal muscular atrophy (SMA) is a neurodegenerative disease which exhibits selective motor neuron death caused by a ubiquitous deficiency of the survival motor neuron (SMN) protein. It remains unclear how the ubiquitous reduction of SMN lead to death in selective motor neuron pools. Medial motor neuron columns (MMC) are vulnerable, whereas lateral motor columns (LMC) are resistant to motor neuron death in SMA. Here we performed microarray and pathway analysis comparing cholera toxin subunit B (CTb) labeled vulnerable MMC and resistant LMC of pre-symptomatic SMA with corresponding motor neuron columns of control mice to identify pathways involved in selective motor neuron death in SMA. WT is FVB. SMN is Delta7 (SMNΔ7;SMN2;Smn-) on a FVB background.
Project description:Spinal Muscular Atrophy (SMA) is an autosomal recessive motor neuron disease and is the second most common genetic disorder leading to death in childhood. Stem cell transplantation could represent a therapeutic approach for motor neuron diseases such as SMA. We examined the theraputics effects of a spinal cord neural stem cell population and their ability to modify SMA phenotype. Microarray technology was used to assess the global gene expression profile of laser-microdissected motoneurons obtained by transplanted and veichle treated SMA, and wildtype mice. Keywords: Comparative Gene Expression Analysis
Project description:Despite the discovery of many genetic risk factors, the cause of the motor neuron death that drives terminal pathology in Amyotrophic Lateral Sclerosis (ALS) remains unknown. We report that the skeletal muscle of ALS patients secretes exosomal vesicles that are specifically toxic to motor neurons. This could not be attributed to a trivial down-stream consequence of muscle denervation. In a study of muscle biopsies and biopsy-derived denervation-naïve differentiated muscle stem cells (myotubes) from 67 human subjects, including healthy and disease controls, ALS myotubes had a consistent signature of disrupted exosome biogenesis and RNA-processing, and their exosomes induced shortened, less branched, neurites, greater death, and disrupted localization of RNA and RNA-processing proteins in motor neurons. Toxicity was dependent on presence of the FUS protein, which is highly expressed in recipient motor neurons. As part of this work, we carried out gene expression analysis of myotubes (differentiated myoblasts) comparing ALS against two other motor neuron disorders as disease controls (SBMA, Spinal and bulbar muscular atrophy; and Spinal Muscular Atrophy Type 4, SMA-IV) and healthy controls.
Project description:Spinal and bulbar muscular atrophy (SBMA), also known as Kennedy’s Disease, is a slowly progressive adult-onset neuromuscular disease which results from a polyglutamine (polyQ) encoding CAG repeat expansion within the androgen receptor gene (AR). Despite the ubiquitous expression of the androgen receptor, it is unclear why motor neurons selectively degenerate and there are no effective treatments or disease modifying therapies for this debilitating disease. In order to identify potential therapeutic targets, we set out to establish the genes and molecular pathways involved in early motor neuron dysfunction in SBMA. We therefore undertook global transcriptomic profiling of cultured primary embryonic motor neurons from the spinal cord of AR100 mice, which model SBMA.. Four biological replicate samples were used for genome wide analysis using Affymetrix 430 v2.0 mouse arrays. Data was normalised using therobust multichip average (RMA) algorithm.