Matrin3 is an abundant nuclear matrix protein with both DNA and RNA binding domains. Mutations in Matrin3 were recently shown to be associated with Amyotrophic Lateral Sclerosis (Motor Neuron Disease), yet the cellular functions of Matrin3 have remained unclear. Chris Smith's group now report in the EMBO Journal
that Matrin3 is a regulator of alternative pre-mRNA splicing. By carrying out transcriptome-wide analyses of transcript level and splicing changes in response to Matrin3 depletion, and comparing with transcriptome-wide analyses of RNAs bound by Matrin3, they show that Matrin3 acts as a repressor of target exons by binding to an extended region of RNA encompassing the target exon.