Next Generation Sequencing of human SMA and healthy control Motor Neurons

Spinal muscular atrophy (SMA) is a motor neuron (MN) disorder caused by mutations in SMN1. The reasons of MNs selective vulnerability linked to SMN reduction remain unclear. To address this question, we performed deep RNA sequencing on SMA human MNs to detect specific altered splicing/expressed genes and to identify the presence of a common sequence motif in these genes. Many deregulated genes, such as Neurexin and Synaptotagmin families, are implicated in critical MN-function like axonogenesis and synapses. Motif-enrichment analyses of differentially expressed/spliced genes, including Neurexin2 (NRXN2), revealed a common Motif, Motif-7, which is target of SYNCRIP protein. Interestingly, SYNCRIP interacts only with full-length SMN, binding and modulating several MN transcripts, including SMN itself. SYNCRIP overexpression rescued SMA-MNs, due to the consequent increase of SMN and their down-stream target NRXN2, through a positive loop mechanism. SMN/SYNCRIP complex through motif-7 might account for selective MN degeneration and represent a potential therapeutic target. total RNA collected from control iPSC and patient iPSC derived spinal motor neurons