<p>Genetic and experimental findings point to a crucial role of RNA dysfunction in the pathogenesis of Amyotrophic Lateral Sclerosis (ALS). Evidence suggests that mutations in RNA binding proteins (RBPs) such as FUS, a gene associated with ALS, affect the regulation of alternative splicing. We have previously shown that the overexpression of wild-type FUS in mice, a condition that induces ALS-like phenotypes, impacts the splicing of hnRNP A2/B1, a protein with key roles in RNA metabolism, suggesting that a pathological connection between FUS and hnRNP A2/B1 might promote FUS-associated toxicity. Here we report that the expression and distribution of different hnRNP A2/B1 splice variants are modified in the affected tissues of mice overexpressing wild-type FUS. Notably, degenerating motor neurons are characterized by the cytoplasmic accumulation of splice variants of hnRNP A2/B1 lacking exon 9 (hnRNP A2b/B1b). In vitro studies show that exon 9 skipping affects the nucleocytoplasmic distribution of hnRNP A2/B1, promoting its localization into stress granules (SGs), and demonstrate that cytoplasmic localization is the primary driver of hnRNP A2b recruitment into SGs and cell toxicity. Finally, boosting exon 9 skipping using splicing switching oligonucleotides exacerbates disease phenotypes in wild-type FUS mice. Altogether, these findings reveal that alterations of the nucleocytoplasmic distribution of hnRNP A2/B1, driven by FUS-induced splicing changes, likely contribute to motor neuron degeneration in ALS.</p>

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Cytoplasmic accumulation of a splice variant of hnRNPA2/B1 contributes to FUS-associated toxicity in a mouse model of ALS

  • S. Rossi,
  • M. Milani,
  • I. Della Valle,
  • S. Bisegna,
  • V. Durante,
  • M. Addesse,
  • E. D’Avorio,
  • M. Di Salvio,
  • A. Serafino,
  • G. Cestra,
  • S. Apolloni,
  • N. D’Ambrosi,
  • M. Cozzolino

摘要

Genetic and experimental findings point to a crucial role of RNA dysfunction in the pathogenesis of Amyotrophic Lateral Sclerosis (ALS). Evidence suggests that mutations in RNA binding proteins (RBPs) such as FUS, a gene associated with ALS, affect the regulation of alternative splicing. We have previously shown that the overexpression of wild-type FUS in mice, a condition that induces ALS-like phenotypes, impacts the splicing of hnRNP A2/B1, a protein with key roles in RNA metabolism, suggesting that a pathological connection between FUS and hnRNP A2/B1 might promote FUS-associated toxicity. Here we report that the expression and distribution of different hnRNP A2/B1 splice variants are modified in the affected tissues of mice overexpressing wild-type FUS. Notably, degenerating motor neurons are characterized by the cytoplasmic accumulation of splice variants of hnRNP A2/B1 lacking exon 9 (hnRNP A2b/B1b). In vitro studies show that exon 9 skipping affects the nucleocytoplasmic distribution of hnRNP A2/B1, promoting its localization into stress granules (SGs), and demonstrate that cytoplasmic localization is the primary driver of hnRNP A2b recruitment into SGs and cell toxicity. Finally, boosting exon 9 skipping using splicing switching oligonucleotides exacerbates disease phenotypes in wild-type FUS mice. Altogether, these findings reveal that alterations of the nucleocytoplasmic distribution of hnRNP A2/B1, driven by FUS-induced splicing changes, likely contribute to motor neuron degeneration in ALS.