Authors |
Jackson R, Kroehling L, Khitun A, Bailis W, Jarret A, York AG, Khan OM, Brewer JR, Skadow MH, Duizer C, Harman CCD, Chang L, Bielecki P, Solis AG, Steach HR, Slavoff S, Flavell RA |
Abstract |
The annotation of the mammalian protein-coding genome is incomplete. Arbitrary size restriction of open reading frames (ORFs) and the absolute requirement for a methionine codon as the sole initiator of translation have constrained the identification of potentially important transcripts with non-canonical protein-coding potential 1,2 . Here, using unbiased transcriptomic approaches in macrophages that respond to bacterial infection, we show that ribosomes associate with a large number of RNAs that were previously annotated as 'non-protein coding'. Although the idea that such non-canonical ORFs can encode functional proteins is controversial 3,4 , we identify a range of short and non-ATG-initiated ORFs that can generate stable and spatially distinct proteins. Notably, we show that the translation of a new ORF 'hidden' within the long non-coding RNA Aw112010 is essential for the orchestration of mucosal immunity during both bacterial infection and colitis. This work expands our interpretation of the protein-coding genome and demonstrates that proteinaceous products generated from non-canonical ORFs are crucial for the immune response in vivo. We therefore propose that the misannotation of non-canonical ORF-containing genes as non-coding RNAs may obscure the essential role of a multitude of previously undiscovered protein-coding genes in immunity and disease. |