Project description:Small molecule splicing modifiers have been extensively described which target the generic splicing machinery and thus have low target specificity. We have identified potent splicing modifiers with unprecedented high selectively, correcting the splicing deficit of the SMN2 (survival motor neuron 2) gene in Spinal Muscular Atrophy (SMA). Here we show that they directly bind to two sites of the SMN2 pre-mRNA, thereby stabilizing a novel ribonucleoprotein (RNP) complex in the SMN2 gene that is critical for the high target specificity of these small molecules over other genes. In addition to the therapeutic potential of these molecules for treatment of SMA, our work may have wide-ranging consequences for further research to identify small molecules that target splicing correction of specific genes by interacting with tertiary RNA structures.
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. Motoneurons derived from induced pluripotent stem cells (iPSC) obtained by reprogramming SMA patient and his healthy father fibroblasts, and genetically corrected SMA-iPSC obtained converting SMN2 into SMN1 with target gene correction (TGC), were used to study gene expression and splicing events linked to pathogenetic mechanisms. Microarray technology was used to assess the global gene expression profile as well as splicing events of iPS-derived motorneurons from SMA patient, unaffected father and TGC-treated cells. The microarray data derived from three different groups: SMA patient, healty father and treated SMA patient's cells. Each population consists of three RNA profiling cell samples.
Project description:Spinal muscular atrophy (SMA) is an autosomal recessive, pediatric-onset disorder caused by the loss of spinal motor neurons thereby leading to generalized muscle atrophy. SMA is caused by the loss of or mutations in the survival motor neuron 1 (SMN1) gene. SMN1 is duplicated only in human to give rise to the paralogous SMN2 gene. These paralogs are nearly identical except for a cytosine to thymine (C-to-T) transition within an exonic splicing enhancer (ESE) element within exon 7. As a result, the majority of SMN2 transcripts lack exon 7 (SMNΔ7) which produces a truncated and unstable SMN protein. Since SMN2 copy number is inversely related to disease severity, it is a well-established target for SMA therapeutics development. 5-(N-ethyl-N-isopropyl)amiloride (EIPA), an inhibitor of sodium/proton exchangers (NHEs), has previously been shown to increase exon 7 inclusion and SMN protein levels in SMA cells. In this study several different types of NHE inhibitors were evaluated for their ability to modulate SMN2 expression. EIPA as well as 5-(N,N-hexamethylene)amiloride (HMA) increase exon 7 inclusion in SMN2 splicing reporter lines as well as in SMA fibroblasts. The EIPA-induced exon 7 inclusion occurs via a mechanism unique from that used by RG7800, another SMN2 splicing modulator, and does not involve previously identified splicing factors. Transcriptome analysis identified novel targets, including TIA1 and FABP3, for further characterization. EIPA and HMA are more selective at inhibiting the NHE5 isoform, which is expressed in fibroblasts as well as in neuronal cells. These results show that NHE5 inhibition increases SMN2 expression and may be a novel target for therapeutics development.
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. Motoneurons derived from induced pluripotent stem cells (iPSC) obtained by reprogramming SMA patient and his healthy father fibroblasts, and genetically corrected SMA-iPSC obtained converting SMN2 into SMN1 with target gene correction (TGC), were used to study gene expression and splicing events linked to pathogenetic mechanisms. Microarray technology was used to assess the global gene expression profile as well as splicing events of iPS-derived motorneurons from SMA patient, unaffected father and TGC-treated cells.
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 an autosomal recessive motor neuron disease and is the second most common genetic disorder leading to death in childhood. Motoneurons derived from induced pluripotent stem cells (iPS cells) obtained by reprogramming SMA patient and his healthy father fibroblasts, and genetically corrected SMA-iPSC obtained converting SMN2 into SMN1 with target gene correction (TGC), were used to study gene expression and splicing events linked to pathogenetic mechanisms. Microarray technology was used to assess global gene expression profiles of iPSC from SMA patient, unaffected father and iPS 19.9 (Prof. J. Thomson's lab) compared to transcriptomic data obtained by corresponding fibroblasts.
Project description:Spinal Muscular Atrophy (SMA) is a motor-neuron disease caused by mutations of the SMN1 gene. The human paralog SMN2, whose exon 7 (E7) is predominantly skipped cannot compensate for the lack of SMN1. Nusinersen is an antisense oligonucleotide that upregulates E7 inclusion and SMN protein levels by displacing the splicing repressors hnRNPA1/A2 from their target site in intron 7. We show that, by promoting transcriptional elongation, the histone deacetylase inhibitor VPA cooperates with nusinersen to promote E7 inclusion. Surprisingly, nusinersen promotes the deployment of the silencing histone mark H3K9me2 on the SMN2 gene, creating a roadblock to PolII elongation that inhibits E7 inclusion. By removing the roadblock, VPA counteracts the undesired chromatin effects of nusinersen, resulting in higher E7 inclusion, without large pleiotropic effects, as assessed by genome-wide analyses. Combined administration of nusinersen and VPA in SMA mice strongly synergized in SMN expression, growth, survival, and neuromuscular function.
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. Motoneurons derived from induced pluripotent stem cells (iPS cells) obtained by reprogramming SMA patient and his healthy father fibroblasts, and genetically corrected SMA-iPSC obtained converting SMN2 into SMN1 with target gene correction (TGC), were used to study gene expression and splicing events linked to pathogenetic mechanisms. Microarray technology was used to assess global gene expression profiles of iPSC from SMA patient, unaffected father and iPS 19.9 (Prof. J. Thomson's lab) compared to transcriptomic data obtained by corresponding fibroblasts. The microarray data derived from three different individuals: SMA patient, healthy father and control iPS cells (19.9). We analyzed iPSC from SMA patient (n=2), iPS- from healthy father (n=1) and iPS-19.9 from Prof. Thomson's lab (n=3). The expression profile was compared to SMA patient's fibroblasts (n=2) and healthy father's fibroblasts (n=1)