<p>ER-associated degradation (ERAD) targets misfolded proteins in the endoplasmic reticulum (ER) for proteasomal degradation. Mutations in its most conserved branch involving the SEL1L-HRD1 complex cause ERAD-associated neurodevelopmental disorders with onset in infancy (ENDI), characterized by developmental delay, microcephaly, and locomotor dysfunction. Its most severe form, ENDI with agammaglobulinemia (ENDI-A), results from a bi-allelic SEL1L-Cys141Tyr (C141Y) mutation within its fibronectin II (FNII) domain and currently lacks effective treatment. Here, we find that knock-in mouse models carrying the C141Y mutation are unexpectedly rescued via increased use of an alternative splice donor within exon 4 leading to bypass of the mutant FNII-encoding region. The resulting SEL1L variant restores ERAD activity, and rescues perinatal lethality, B cell deficiency, and neurodevelopmental defects. Leveraging this mechanism, we demonstrate that antisense oligonucleotide-mediated exon skipping in patient-derived fibroblasts generates a truncated yet functional SEL1L protein that fully restores ERAD function and ER proteostasis. These results establish RNA splicing-modulation as a viable therapeutic strategy for ERAD deficiency and broaden the clinical potential of exon-skipping therapy to diseases of protein misfolding.</p>

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Functional rescue of a disease-linked ERAD pathway mutation via alternative splicing

  • Huilun Helen Wang,
  • Zhihong Wang,
  • Liangguang Leo Lin,
  • Sunil K Verma,
  • Weronika Gniadzik,
  • Hui Wang,
  • Zexin Jason Li,
  • Emily Whitestone,
  • Lulu Jiang,
  • Muge N Kuyumcu-Martinez,
  • Shengyi Sun,
  • Ling Qi

摘要

ER-associated degradation (ERAD) targets misfolded proteins in the endoplasmic reticulum (ER) for proteasomal degradation. Mutations in its most conserved branch involving the SEL1L-HRD1 complex cause ERAD-associated neurodevelopmental disorders with onset in infancy (ENDI), characterized by developmental delay, microcephaly, and locomotor dysfunction. Its most severe form, ENDI with agammaglobulinemia (ENDI-A), results from a bi-allelic SEL1L-Cys141Tyr (C141Y) mutation within its fibronectin II (FNII) domain and currently lacks effective treatment. Here, we find that knock-in mouse models carrying the C141Y mutation are unexpectedly rescued via increased use of an alternative splice donor within exon 4 leading to bypass of the mutant FNII-encoding region. The resulting SEL1L variant restores ERAD activity, and rescues perinatal lethality, B cell deficiency, and neurodevelopmental defects. Leveraging this mechanism, we demonstrate that antisense oligonucleotide-mediated exon skipping in patient-derived fibroblasts generates a truncated yet functional SEL1L protein that fully restores ERAD function and ER proteostasis. These results establish RNA splicing-modulation as a viable therapeutic strategy for ERAD deficiency and broaden the clinical potential of exon-skipping therapy to diseases of protein misfolding.