Cytoplasmic cleavage of IMPA1 3'UTR is necessary for maintaining axon integrity.

The 3' untranslated regions (3'UTRs) of messenger RNAs (mRNA) are non-coding sequences involved in many aspects of mRNA metabolism, including intracellular localisation and translation. Incorrect processing and delivery of mRNA causes severe developmental defects and has been implicated in many neurological disorders. Here, we use deep sequencing to show that in sympathetic neuron axons, the 3'UTRs of many transcripts undergo cleavage, generating isoforms that express the coding sequence with a short 3'UTR, and stable 3'UTR-derived fragments of unknown function. Cleavage of the long 3'UTR of Inositol Monophosphatase 1 ( IMPA1 ), mediated by a protein complex containing the endonuclease Ago2 and the RNA binding protein HuD, generates a translatable isoform that is necessary for maintaining the integrity of sympathetic neuron axons. Thus, our study provides a new mechanism of mRNA metabolism that simultaneously regulates local protein synthesis and generates a yet undescribed class of non-coding RNAs. Overall design: Bulk 3' end sequencing data from cell body and distal axons of post-mitotic rat sympathetic neurons which distal axons have been exposed either to NGF or to NT3.