title: Basal splicing factors regulate the stability of mature mRNAs in trypanosomes.
abstract: Gene expression in trypanosomes is mainly regulated post-transcriptionally. Genes are transcribed as polycistronic mRNAs that are dissected by the concerted action of trans-splicing and polyadenylation. In trans-splicing, a common exon, the spliced leader, is added to all mRNAs from a small RNA. In this study, we examined by microarray analysis the transcriptome following RNAi silencing of the basal splicing factors U2AF65, SF1, and U2AF35. The transcriptome data revealed correlations between the affected genes and their splicing and polyadenylation signaling properties, suggesting that differential binding of these factors to pre-mRNA regulates trans-splicing and hence expression of specific genes. Surprisingly, all these factors were shown to affect not only splicing but also mRNA stability. Affinity purification of SF1 and U2AF35 complexes supported their role in mRNA stability. U2AF35 but not SF1 was shown to bind to ribosomes. To examine the role of splicing factors in mRNA stability, mutations were introduced into the polypyrimidine tract located in the 3' UTR of a mini-gene, and the results demonstrate that U2AF65 binds to such a site and controls the mRNA stability. We propose that transcripts carrying splicing signals in their 3' UTR bind the splicing factors and control their stability.
authors.affiliation: Mina and Everard Goodman Faculty of Life Sciences, and Advanced Materials and Nanotechnology Institute, Bar-Ilan University, Ramat-Gan 52900, Israel.
authors.forename: Sachin Kumar
authors.initials: SK
authors.lastname: Gupta
authors.forename: Shai
authors.initials: S
authors.lastname: Carmi
authors.forename: Hiba
authors.initials: H
authors.lastname: Waldman Ben-Asher
authors.forename: Itai Dov
authors.initials: ID
authors.lastname: Tkacz
authors.forename: Ilana
authors.initials: I
authors.lastname: Naboishchikov
authors.forename: Shulamit
authors.initials: S
authors.lastname: Michaeli
mesh_terms: D000818:Animals; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000502:physiology*; D015870:Gene Expression; D007891:Leishmania / Q000378:metabolism; D008957:Models, Genetic; D009687:Nuclear Proteins / Q000737:chemistry / Q000502:physiology*; D020411:Oligonucleotide Array Sequence Analysis; D011061:Poly A / Q000378:metabolism; D034622:RNA Interference; D012326:RNA Splicing; D000072260:RNA Splicing Factors; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry*; D012261:Ribonucleoproteins / Q000737:chemistry / Q000502:physiology*; D000072668:Splicing Factor U2AF; D013778:Tetrazolium Salts / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology; D020040:Trans-Splicing; D014157:Transcription Factors / Q000737:chemistry / Q000502:physiology*; D014158:Transcription, Genetic; D014346:Trypanosoma brucei brucei / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D000072260:RNA Splicing Factors; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; C107467:SF1 protein, human; D000072668:Splicing Factor U2AF; D013778:Tetrazolium Salts; D013844:Thiazoles; D014157:Transcription Factors; C076753:U2AF1 protein, human; C000607494:U2AF2 protein, human; D011061:Poly A; C022616:thiazolyl blue