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bioRxiv · 10.1101/784868

A Distinct Subset of Human Short Introns: U2AF Heterodimer Is Replaced by SPF45 (RBM17) as General Splicing Factor

Fukumura, K.·Yoshimoto, R.·Hirose, T.·Inoue, K.·Mayeda, A.
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Abstract

Human pre-mRNA introns vary in size from under fifty to over a million nucleotides. We searched for essential factors involved in the splicing of human short introns by screening siRNAs against 154 human nuclear proteins. The splicing activity was assayed with a model HNRNPH1 pre-mRNA containing short 56-nucleotide intron. We identified a known alternative splicing regulator SPF45 (RBM17) as a constitutive splicing factor that is required to splice out this 56-nt intron. Whole-transcriptome sequencing of SPF45-deficient cells revealed that SPF45 is essential in the efficient splicing of many short introns. To initiate the spliceosome assembly on a short intron with the truncated poly-pyrimidine tract, the U2AF-homology motif (UHM) of SPF45 competes out that of U2AF65 for binding to the UHM-ligand motif (ULM) of the U2 snRNP protein SF3b155 (SF3B1). We propose that splicing in a distinct subset of human short introns depends on SPF45 but not U2AF heterodimer.

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Fukumura, K., Yoshimoto, R., Hirose, T., Inoue, K., Mayeda, A.. 2019-09-27. A Distinct Subset of Human Short Introns: U2AF Heterodimer Is Replaced by SPF45 (RBM17) as General Splicing Factor. https://doi.org/10.1101/784868

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