Abstract
Hotspot mutations in the spliceosome gene SF3B1 are reported in ∼20% of uveal melanomas. SF3B1 is involved in 3'-splice site (3'ss) recognition during RNA splicing; however, the molecular mechanisms of its mutation have remained unclear. Here we show, using RNA-Seq analyses of uveal melanoma, that the SF3B1(R625/K666) mutation results in deregulated splicing at a subset of junctions, mostly by the use of alternative 3'ss. Modelling the differential junctions in SF3B1(WT) and SF3B1(R625/K666) cell lines demonstrates that the deregulated splice pattern strictly depends on SF3B1 status and on the 3'ss-sequence context. SF3B1(WT) knockdown or overexpression do not reproduce the SF3B1(R625/K666) splice pattern, qualifying SF3B1(R625/K666) as change-of-function mutants. Mutagenesis of predicted branchpoints reveals that the SF3B1(R625/K666)-promoted splice pattern is a direct result of alternative branchpoint usage. Altogether, this study provides a better understanding of the mechanisms underlying splicing alterations induced by mutant SF3B1 in cancer, and reveals a role for alternative branchpoints in disease.
Highlights
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not
SF3B1 mutations were found in 16 tumours affecting two hotspots p.R625 and p.K666 (Supplementary Table 1)
Here, we addressed the consequences of SF3B1 hotspot mutations on splicing in uveal melanoma (UM) and its underlying mechanisms
Summary
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. We show, using RNA-Seq analyses of uveal melanoma, that the SF3B1R625/K666 mutation results in deregulated splicing at a subset of junctions, mostly by the use of alternative 30ss. Alterations in SF3B1 were initially discovered in myelodysplastic syndromes (MDSs) and chronic lymphocytic leukemia (CLL), together with other mutations of splicing factors, such as U2AF1, SRSF2 and ZRSR2 (refs 1–3). These genes encode proteins that are all involved in 30-splice site recognition during RNA splicing[4]. Introns contain consensus sequences that define the 50 donor splice site (50ss), branchpoint (BP) and 30 acceptor splice site (30ss), which are initially recognized by the U1 snRNP, SF1 protein and U2AF, respectively. The 50ss and 30ss are ligated together and the branched intron is discarded[10]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
