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: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 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 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: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:In this study, we demonstrated the use of the RNA Antisense Purification by Mass Spectrometry (RAP-MS) method to identify proteins involved in specific alternative splicing events. Specifically, we applied the RAP-MS method to identify proteins that interact with the Tau pre-mRNA around its exon 10 region.
Project description:Antisense oligonucleotide (ASO) nusinersen (Spinraza®) modulates the pre–mRNA splicing of the SMN2 gene, allowing rebalance of biologically active SMN. It is administered intrathecally via lumbar puncture after removing an equal amount of cerebrospinal fluid (CSF). Its effect was proven beneficial and approved since 2017 for SMA treatment. Since the direct effect of nusinersen on RNA metabolism, the aim of this project was to evaluate cell-free RNA (cfRNA) in CSF of SMA patients under ASOs treatment for biomarker discovery.
Project description:While there are many human skeletal muscle disorders, very few therapies have been developed. It has not been possible to generate large amounts of purified skeletal muscle cells from pluripotent stem cells, and to test therapies quantitatively. We therefore devised conditions for generating and expanding purified human myogenic progenitors from induced pluripotent stem (iPS) cells. The progenitors retained the capacity to differentiate into multinucleated myotubes and showed a normal karyotype throughout the expansion phase. We applied this method to Pompe disease, a metabolic myopathy caused by deficiency of the lysosomal enzyme acid alpha-glucosidase (GAA). In a screen, we identified sequences that suppressed aberrant GAA exon 2 splicing caused by the frequent c.-32-13T>G (IVS1) GAA variant. Antisense oligonucleotides (AONs) that blocked these sequences promoted exon 2 inclusion in patient-derived myotubes. As this raised GAA enzymatic activity above the disease threshold, AON-mediated splicing correction may provide a treatment option for Pompe disease.
Project description:We performed a transcriptomic and epigenomic study in patient-derived B-cell lines to investigate the genome-scale effects of DNMT3B dysfunction. We highlighted that altered intragenic CpG-methylation impairs multiple aspects of transcriptional regulation, like alternative TSS usage, antisense transcription and exon splicing.
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.