Altered mRNA Splicing in SMN-Depleted Motor Neuron-Like Cells

• Published in: PloS one 2016-10, Vol.11 (10), p.e0163954-e0163954
• Main Authors: Custer, Sara K, Gilson, Timra D, Li, Hongxia, Todd, A Gary, Astroski, Jacob W, Lin, Hai, Liu, Yunlong, Androphy, Elliot J
• Format: Article
• Language: English
• Subjects: Aberration; Animals; Atrophy; Axonogenesis; Biological effects; Biology and Life Sciences; Biomarkers; Cell Line; Depletion; Dermatology; Disease Models, Animal; Exons; Female; Gene Expression Regulation; Gene sequencing; Genes; Introns; Localization; Male; Medical treatment; Medicine; Medicine and Health Sciences; Messenger RNA; Mice; Mice, Transgenic; Motor neuron diseases; Motor Neurons - metabolism; Motor Neurons - pathology; mRNA processing; Muscular Atrophy, Spinal - genetics; Muscular Atrophy, Spinal - pathology; Mutation; Nervous system diseases; Neuromuscular diseases; Neurons; Neurosciences; Pathology; Proteins; Research and Analysis Methods; Ribonucleic acid; RNA; RNA polymerase; RNA sequencing; RNA Splicing; RNA, Messenger - genetics; Rodents; SMN protein; Spinal cord; Spinal Cord - metabolism; Spinal Cord - pathology; Spinal muscular atrophy; Splicing; Survival of Motor Neuron 1 Protein - genetics; Survival of Motor Neuron 2 Protein - genetics; Transcription; Transcriptome
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0163954

Spinal muscular atrophy (SMA) is an intractable neurodegenerative disease afflicting 1 in 6-10,000 live births. One of the key functions of the SMN protein is regulation of spliceosome assembly. Reduced levels of the SMN protein that are observed in SMA have been shown to result in aberrant mRNA splicing. SMN-dependent mis-spliced transcripts in motor neurons may cause stresses that are particularly harmful and may serve as potential targets for the treatment of motor neuron disease or as biomarkers in the SMA patient population. We performed deep RNA sequencing using motor neuron-like NSC-34 cells to screen for SMN-dependent mRNA processing changes that occur following acute depletion of SMN. We identified SMN-dependent splicing changes, including an intron retention event that results in the production of a truncated Rit1 transcript. This intron-retained transcript is stable and is mis-spliced in spinal cord from symptomatic SMA mice. Constitutively active Rit1 ameliorated the neurite outgrowth defect in SMN depleted NSC-34 cells, while expression of the truncated protein product of the mis-spliced Rit1 transcript inhibited neurite extension. These results reveal new insights into the biological consequence of SMN-dependent splicing in motor neuron-like cells.