Project description:A key step in pre-mRNA splicing is the recognition of 3’ splicing sites by the U2AF large and small subunits, a process regulated by numerous trans-acting splicing factors. How these trans-acting factors interact with U2AF in vivo is unclear. From a screen for suppressors of the temperature-sensitive (ts) lethality of the C. elegans U2AF large subunit gene uaf-1(n4588) mutants, we identified mutations in the RNA binding motif gene rbm-5, a homolog of the tumor suppressor RBM5. rbm-5 mutations can suppress uaf-1(n4588) ts-lethality by loss of function and neuronal expression of rbm-5 was sufficient to rescue the suppression. Transcriptome analyses indicate that uaf-1(n4588) affected the expression of numerous genes and rbm-5 mutations can partially reverse the abnormal gene expression to levels similar to that of wild type. Though rbm-5 mutations did not obviously affect alternative splicing per se, they can suppress or enhance, in a gene-specific manner, the altered splicing of genes in uaf-1(n4588) mutants. Specifically, the recognition of a weak 3’ splice site was more susceptible to the effect of rbm-5. Our findings provide novel in vivo evidence that RBM-5 can modulate UAF-1-dependent RNA splicing and suggest that RBM5 might interact with U2AF large subunit to affect tumor formation.
Project description:The mechanisms underlying molecular targeting to mitochondria remain enigmatic, yet this process is crucial for normal cellular function. The RNA binding proteins U2AF1/2 form a heterodimer (U2AF) that shuttles between the nucleus and cytoplasm, regulating splicing in the nucleus and translation in the cytoplasm. Our study identifies an unexpected role for U2AF in mitochondrial function. We demonstrate that U2AF interacts with nuclear-encoded mitochondrial mRNAs and proteins, inhibits translation, localizes to the mitochondria, and regulates mRNA localization to mitochondria. Moreover, an oncogenic point-mutation in U2AF1(S34F) disrupts this regulation, leading to altered mitochondrial structure, increased translation, large changes in the mitochondria proteome, and OXPHOS-dependent metabolic rewiring, recapitulating changes observed in bone marrow progenitors from patients with myelodysplastic syndromes. These findings reveal a non-canonical role for U2AF, where it modulates multiple aspects of mitochondrial function by regulating the translation and mitochondrial localization of nuclear-encoded mRNAs.
Project description:Characterization of RNA processing events dependent on U2AF-related proteins PUF60 and RBM39. PUF60 (poly-U-binding factor 60 kDa, also known as FIR, Hfp or Ro-bp1) is a splicing factor homologous to the 65 kD subunit of the auxiliary factor of U2 small nuclear ribonucleoprotein (U2AF65). PUF60 has two central RNA recognition motifs and a C-terminal U2AF homology motif (UHM), but lacks the N terminal arginine/serine-rich (RS) and UHM ligand motif (ULM) domains present in U2AF65. PUF60 activity, in conjunction with U2AF, facilitates the association of U2 snRNP with the pre-mRNA. PUF60 and U2AF65 can bind SF3b155 ULMs simultaneously and noncompetitively. RBM39 (also known as CAPERα, HCC1, FSAP59 or RNPC2) is an RNA processing factor and a hormone-dependent transcriptional coactivator. RBM39 domain structure is similar to PUF60, except for the extra N-terminal RS domain with unknown function. To understand function of the two proteins on a genome-wide scale, each protein was individually depleted from human embryonic kidney cell line 293 using RNAi to systematically characterize the PUF60- and RBM39-dependent exon usage.
Project description:The U2AF heterodimer has been well studied for its role in defining functional 3’ splice sites in pre-mRNA splicing, but many fundamental questions still remain unaddressed regarding the function of U2AF in mammalian genomes. Through genome-wide analysis of U2AF-RNA interactions, we report that U2AF has the capacity to directly define ~88% of functional 3’ splice sites in the human genome, but numerous U2AF binding events also occur in intronic locations. Mechanistic dissection reveals that upstream intronic binding events interfere with the immediate downstream 3’ splice site associated with either the alternative exon to cause exon skipping or with the competing constitutive exon to induce exon inclusion. We further demonstrate partial functional impairment with mutations in U2AF35, but not U2AF65, in regulated splicing. These findings reveal the genomic function and regulatory mechanism of U2AF in both normal and disease states.
Project description:Heterochromatin, representing the silenced state of transcription, largely consists of transposon-enriched and highly repetitive sequences. Implicated in heterochromatin formation and transcriptional silencing in Drosophila are PIWI and repeat-associated small interfering RNAs (rasiRNAs). Despite this, the role of PIWI in rasiRNA expression and heterochromatic silencing remains unknown. Here we report the identification and characterization of 12,903 PIWI-interacting RNAs (piRNAs) in Drosophila, demonstrating that rasiRNAs represent a subset of piRNAs. Keywords: PIWI, piRNA, epigenetic regulation, heterochromatin
Project description:The U2AF heterodimer has been well studied for its role in defining functional 3M-bM-^@M-^Y splice sites in pre-mRNA splicing, but many fundamental questions still remain unaddressed regarding the function of U2AF in mammalian genomes. Through genome-wide analysis of U2AF-RNA interactions, we report that U2AF has the capacity to directly define ~88% of functional 3M-bM-^@M-^Y splice sites in the human genome, but numerous U2AF binding events also occur in intronic locations. Mechanistic dissection reveals that upstream intronic binding events interfere with the immediate downstream 3M-bM-^@M-^Y splice site associated with either the alternative exon to cause exon skipping or with the competing constitutive exon to induce exon inclusion. We further demonstrate partial functional impairment with mutations in U2AF35, but not U2AF65, in regulated splicing. These findings reveal the genomic function and regulatory mechanism of U2AF in both normal and disease states. Examination of U2AF heterodimer regulated splicing in Hela cells with CLIP-seq (U2AF65), paired-end RNA-seq (si-NC and si-U2AF65) and RASL-seq (respective three biological replicates of WT, si-NC, si-U2AF65, si-U2AF35, si-NC + pcDNA3.0, si-U2AF65 + pcDNA3.0, and si-U2AF65 + Flag-U2AF35)
Project description:Heterochromatin, representing the silenced state of transcription, largely consists of transposon-enriched and highly repetitive sequences. Implicated in heterochromatin formation and transcriptional silencing in Drosophila are PIWI and repeat-associated small interfering RNAs (rasiRNAs). Despite this, the role of PIWI in rasiRNA expression and heterochromatic silencing remains unknown. Here we report the identification and characterization of 12,903 PIWI-interacting RNAs (piRNAs) in Drosophila, demonstrating that rasiRNAs represent a subset of piRNAs. Keywords: PIWI, piRNA, epigenetic regulation, heterochromatin PIWI-associated small RNA cDNA library was sequenced for one time by high-throughput 454 pyrosequencing. Putative small RNA sequences were extracted and BLAST against the Drosophila melanogaster genome release 5. Presented here is a list of non-redundant PIWI-associated small RNAs, which have at least one genome match determined by BLASTn.