Abstract
U12-type (minor) introns are found in most multicellular eukaryotes and constitute ∼0.5% of all introns in species with a minor spliceosome required for their splicing. However, the biological relevance of U12-type introns is not well understood. It is known that mutations resulting in aberrant U12-type intron splicing cause developmental defects in both plants and animals. We recently reported that maize RNA Binding Motif Protein 48 (RBM48) is an essential splicing factor for U12-type introns. Maize rbm48 mutants display aberrant genome-wide U12-type intron splicing. This leads to severe defects in endosperm development, resulting in non-viable seeds. In this report, we use CRISPR/Cas9-mediated ablation of RBM48 in human K-562 cells to establish the evolutionary conservation of RBM48 dependent U12-type intron splicing between maize and humans. Comparative RNA-seq analysis performed on RBM48 deficient human cell lines and maize endosperm defined a subset of orthologous minor U12-type containing genes (MIGs) displaying aberrant splicing of U12-type introns in both species. Mutations in the majority of these MIGs have been reported to cause developmental defects in both plants and animals. Thus, a comparison of RNA-seq data between distantly related species containing mutations in RBM48 identifies candidate genes likely to mediate mutant phenotypes of U12-type splicing defects. Our results elucidate deeply conserved post-transcriptional processing mechanisms that are required for normal growth and development of eukaryotes with a minor spliceosome.
Competing Interest Statement
The authors have declared no competing interest.