TY - JOUR T1 - Sam68 splicing regulation contributes to motor unit establishment in the postnatal skeletal muscle JF - Life Science Alliance JO - Life Sci. Alliance DO - 10.26508/lsa.201900637 VL - 3 IS - 10 SP - e201900637 AU - Elisa De Paola AU - Laura Forcina AU - Laura Pelosi AU - Simona Pisu AU - Piergiorgio La Rosa AU - Eleonora Cesari AU - Carmine Nicoletti AU - Luca Madaro AU - Neri Mercatelli AU - Filippo Biamonte AU - Annalisa Nobili AU - Marcello D’Amelio AU - Marco De Bardi AU - Elisabetta Volpe AU - Daniela Caporossi AU - Claudio Sette AU - Antonio Musarò AU - Maria Paola Paronetto Y1 - 2020/10/01 UR - https://www.life-science-alliance.org/content/3/10/e201900637.abstract N2 - RNA-binding proteins orchestrate the composite life of RNA molecules and impact most physiological processes, thus underlying complex phenotypes. The RNA-binding protein Sam68 regulates differentiation processes by modulating splicing, polyadenylation, and stability of select transcripts. Herein, we found that Sam68−/− mice display altered regulation of alternative splicing in the spinal cord of key target genes involved in synaptic functions. Analysis of the motor units revealed that Sam68 ablation impairs the establishment of neuromuscular junctions and causes progressive loss of motor neurons in the spinal cord. Importantly, alterations of neuromuscular junction morphology and properties in Sam68−/− mice correlate with defects in muscle and motor unit integrity. Sam68−/− muscles display defects in postnatal development, with manifest signs of atrophy. Furthermore, fast-twitch muscles in Sam68−/− mice show structural features typical of slow-twitch muscles, suggesting alterations in the metabolic and functional properties of myofibers. Collectively, our data identify a key role for Sam68 in muscle development and suggest that proper establishment of motor units requires timely expression of synaptic splice variants. ER -