title: Targeting SR proteins improves SMN expression in spinal muscular atrophy cells.
abstract: Spinal muscular atrophy (SMA) is one of the most common inherited causes of pediatric mortality. SMA is caused by deletions or mutations in the survival of motor neuron 1 (SMN1) gene, which results in SMN protein deficiency. Humans have a centromeric copy of the survival of motor neuron gene, SMN2, which is nearly identical to SMN1. However, SMN2 cannot compensate for the loss of SMN1 because SMN2 has a single-nucleotide difference in exon 7, which negatively affects splicing of the exon. As a result, most mRNA produced from SMN2 lacks exon 7. SMN2 mRNA lacking exon 7 encodes a truncated protein with reduced functionality. Improving SMN2 exon 7 inclusion is a goal of many SMA therapeutic strategies. The identification of regulators of exon 7 inclusion may provide additional therapeutic targets or improve the design of existing strategies. Although a number of regulators of exon 7 inclusion have been identified, the function of most splicing proteins in exon 7 inclusion is unknown. Here, we test the role of SR proteins and hnRNP proteins in SMN2 exon 7 inclusion. Knockdown and overexpression studies reveal that SRSF1, SRSF2, SRSF3, SRSF4, SRSF5, SRSF6, SRSF7, SRSF11, hnRNPA1/B1 and hnRNP U can inhibit exon 7 inclusion. Depletion of two of the most potent inhibitors of exon 7 inclusion, SRSF2 or SRSF3, in cell lines derived from SMA patients, increased SMN2 exon 7 inclusion and SMN protein. Our results identify novel regulators of SMN2 exon 7 inclusion, revealing potential targets for SMA therapeutics.
authors.affiliation: Department of Cell Biology and Anatomy, The Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois, United States of America.
authors.forename: Claribel D
authors.initials: CD
authors.lastname: Wee
authors.affiliation: Department of Cell Biology and Anatomy, The Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois, United States of America.
authors.forename: Mallory A
authors.initials: MA
authors.lastname: Havens
authors.affiliation: Department of Cell Biology and Anatomy, The Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois, United States of America.
authors.forename: Francine M
authors.initials: FM
authors.lastname: Jodelka
authors.affiliation: Department of Cell Biology and Anatomy, The Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois, United States of America.
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Hastings
mesh_terms: D002460:Cell Line; D005091:Exons; D005260:Female; D015870:Gene Expression; D055785:Gene Knockdown Techniques; D034441:Heterogeneous-Nuclear Ribonucleoproteins / Q000235:genetics / Q000502:physiology; D006801:Humans; D009134:Muscular Atrophy, Spinal / Q000235:genetics* / Q000503:physiopathology; D009687:Nuclear Proteins / Q000235:genetics / Q000502:physiology*; D012326:RNA Splicing; D016601:RNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D012261:Ribonucleoproteins / Q000235:genetics / Q000502:physiology*; D000068103:Serine-Arginine Splicing Factors / Q000235:genetics / Q000502:physiology; D055540:Survival of Motor Neuron 2 Protein / Q000235:genetics
chemical_list: D034441:Heterogeneous-Nuclear Ribonucleoproteins; D009687:Nuclear Proteins; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; C526477:SMN2 protein, human; C491388:SRSF3 protein, human; D055540:Survival of Motor Neuron 2 Protein; C073288:SRSF2 protein, human; D000068103:Serine-Arginine Splicing Factors