TARGETING MALAT1 LNCRNA TO MODULATE AUTOPHAGY AND MYOGENESIS IN IPSC-DERIVED MUSCLE CELLS: A NANO-NUCLEAR STRATEGY FOR C9ORF72-ALS

The G4C2 repeat expansion in the C9orf72 gene is the most common genetic cause of familial and sporadic ALS. Disease mechanisms extend beyond motor neurons, with skeletal muscle actively contributing to ALS onset and progression. Early muscle defects and impaired autophagy suggest that disrupted muscle–motor neuron communication drives C9orf72‑ALS neurodegeneration. This study investigated the molecular mechanisms underlying muscle dysfunction in C9orf72‑ALS and identified potential long non‑coding RNA (lncRNA)–based therapeutic targets using a patient‑specific induced pluripotent stem cell (iPSC)–derived skeletal muscle model. Using a small‑molecule differentiation protocol, we generated contractile iPSC‑derived myotubes from ALS patients and healthy controls. Muscle identity was confirmed through transcriptomic, immunofluorescence, and molecular analyses. The lncRNA profile was assessed by qPCR, and functional validation was performed using a non‑viral nanovector system enabling nuclear siRNA‑mediated knockdown in mature myotubes. Our in vitro model recapitulated key C9orf72‑ALS features, including RNA foci and repeat expansions, validating its use for studying muscle alterations. Transcriptomic profiling revealed significant upregulation of MALAT1, a regulator of autophagy and myogenic pathways. MALAT1 knockdown restored autophagy and increased muscle differentiation marker expression, supporting its role in muscle homeostasis. These findings reveal a previously underappreciated contribution of lncRNA dysregulation to skeletal muscle pathology in C9orf72‑ALS and highlight non‑viral, nucleus‑targeted siRNA delivery as a safe and translatable approach for therapeutic intervention.​​​​
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