Project description:Flp-In T-REx-293 cells transfected with non-targeting control siRNA or UPF1-specific siRNA as indicated and used for total RNA-seq.
Project description:To identify high-confidence NMD targets in mouse N2A neuroblastoma cells, we used our established transcriptome-wide RNA sequencing (RNA-seq) methodologies. Through parallel analyses of RNA-seq upon UPF1-knockdown (KD) and RNA immunoprecipitation (RIP-seq) footprinting of p-UPF1-bound RNAs, we identified 1027 high-confidence neuronal NMD targets.
Project description:Human myoblast cell line 54-1 is transfected with either a srambled control siRNA or siRNA against UPF1. Two days after transfection, cell were induced to differentiate by changing grow meida to differentiation media. 2 days after induction of differentiation, cells are collected for extraction of RNA.
Project description:In addition to its role in translation termination, eRF3 has been implicated in the nonsense-mediated mRNA decay (NMD) pathway through its interaction with Upf1. NMD is a RNA quality control mechanism, which detects and degrades aberrant mRNAs as well as some normal transcripts including those that harbor upstream open reading frames in their 5' leader sequence and long 3′ UTR. In this study, we used RNA-sequencing and ribosome profiling to perform a genome wide analysis of the effect of either eRF3 or Upf1 depletion in human cells. Our bioinformatics analyses allow to delineate the features of the transcripts controlled by eRF3 and Upf1 and to compare the effect of each of these factors on gene expression. We show that eRF3 and Upf1 have very different impact on the human transcriptome, only ~250 transcripts being targeted by both factors. We also show that in contrast to Upf1, eRF3a depletion globally derepressed the expression of mRNAs containing translated uORFs. Finally, we find that eRF3a and Upf1 have opposite effects on ribosome protein gene expression. Together, our results provide important elements for understanding the impact of translation termination and NMD on the human transcriptome and reveal novel determinants of ribosome biogenesis regulation.
Project description:Pancreatic adenosquamous carcinoma (PASC) is an aggressive cancer whose mutational origins are poorly understood. An early study reported high-frequency somatic mutations affecting UPF1, a core nonsense-mediated mRNA decay (NMD) factor, in PASC, but subsequent studies did not observe these lesions. The corresponding controversy about whether UPF1 mutations are important contributors to PASC has been exacerbated by a paucity of functional studies. Here, we modeled two UPF1 mutations to find no significant effects on pancreatic cancer growth, acquisition of adenosquamous features, UPF1 splicing, UPF1 protein levels, or NMD efficiency. We subsequently discovered that ~40% of UPF1 mutations reportedly present in PASCs are identical to standing genetic variants in the human population, suggesting that they may be non-pathogenic inherited variants rather than pathogenic mutations. Our data suggest that UPF1 is not a common functional driver of PASC and motivate further attempts to identify unique genetic features defining these malignancies.
Project description:UPF1 is an ATP-driven RNA helicase required for efficient nonsense mediated mRNA decay in eukaryotes. Although it is currently understood that UPF1 primarily acts on the 3’UTR of translating mRNAs in the cytoplasm, our data indicates that this is a highly dynamic protein that is rapidly shuttling between nucleus and cytoplasm in Drosophila. Additionally, ChIP-seq analysis in different cell types demonstrates genome-wide association of UPF1 with nascent RNAs at most of the active Pol II transcription sites, and at some specific Pol III genes. Notably, intron recognition appears to interfere with association and translocation of UPF1 on nascent transcripts. Cells depleted of UPF1 show defects in nuclear processes such as mRNA export and transcription site retention. These data, thus redefine UPF1 as a global player in mRNA based processes in the nucleus as well as the cytoplasm.
Project description:RNA helicases are important regulators of gene expression that act by remodeling RNA secondary structures and as RNA-protein interactions. Here, we demonstrate that MOV10 has an ATP-dependent 5' to 3' in vitro RNA unwinding activity and determine the RNA-binding sites of MOV10 and its helicase mutants using PAR-CLIP. We find that MOV10 predominantly binds to 3' UTRs upstream of regions predicted to form local secondary structures and provide evidence that MOV10 helicase mutants are impaired in their ability to translocate 5' to 3' on their mRNA targets. MOV10 interacts with UPF1, the key component of the nonsense-mediated mRNA decay pathway. PAR-CLIP of UPF1 reveals that MOV10 and UPF1 bind to RNA in close proximity. Knockdown of MOV10 resulted in increased mRNA half-lives of MOV10-bound as well as UPF1-regulated transcripts, suggesting that MOV10 functions in UPF1-mediated mRNA degradation as an RNA clearance factor to resolve structures and displace proteins from 3' UTRs. Flp-In T-REx HEK293 cells expressing FLAG/HA-tagged MOV10 WT, MOV10 K530A, MOV10 D645N and UPF1 were sequenced. mRNA half-life data under GSE56751.
Project description:Nonsense-mediated mRNA decay (NMD) is a conserved RNA surveillance pathway that is an important modulator of disease pathology and is required for embryonic development. Despite significant research effort, the rules that govern NMD remain incompletely understood. Here we used a combined¬ approach, integrating RNA-Seq, ribosome footprinting, and CLIP-Seq analysis of the essential NMD factor Upf1, to provide a more complete picture of the role of NMD in modulating gene expression in murine embryonic stem cells (mESCs). We show that presence of an exon-exon junction ?50 nucleotides (nt) downstream of a termination codon (dEJ) contributes to NMD independently of 3' UTR length, but has stronger effects in genes with shorter 3' UTRs. We also map translated upstream open reading frames (uORFs) in mESCs and show that they are associated with NMD regulation, especially of genes encoding transcription factors, and we find that lowly translated mRNAs can escape NMD. Finally, we identify over 200 direct binding targets of Upf1 and describe a pathway of Upf1-dependent gene regulation reliant on Upf1 binding to the 3' UTR and independent of presence of a dEJ. Together, these analyses characterize known and discover novel determinants of NMD and establish a broader role in mESC gene regulation for Upf1. mRNA-Seq analysis of wildtype (2 samples), translationally inhibited (by cycloheximide treatment, 2 samples), control-depleted (2 samples), and Upf1-depleted (4 samples) mouse embryonic stem cells (mESCs); CLIP-Seq analysis of Upf1 (5 samples, and 5 samples of IgG control CLIP-Seq); Ribosome footprint profiling of wildtype (1 sample), control-depleted (1 sample), and Upf1-depleted (1 sample) mESCs
Project description:Nonsense-mediated mRNA decay (NMD) controls the quality of eukaryotic gene expression and also degrades physiologic mRNAs. How NMD targets are identified is incompletely understood. A central NMD factor is the ATP-dependent RNA helicase UPF1. Neither the distance in space between the termination codon and the poly(A) tail nor the binding of steady-state, largely hypophosphorylated UPF1 is a discriminating marker of cellular NMD targets, unlike for PTC-containing reporter mRNAs when compared to their PTC-free counterparts. Here, we map phosphorylated UPF1 (p-UPF1) binding sites using transcriptome-wide footprinting or DNA oligonucleotide-directed mRNA cleavage to report that p-UPF1 provides the first reliable cellular NMD-target marker. p-UPF1 is enriched on NMD target 3'UTRs along with SMG5 and SMG7 but not SMG1 or SMG6. Immunoprecipitations of UPF1 variants deficient in various aspects of the NMD process in parallel with FRET experiments reveal that ATPase/helicase-deficient UPF1 manifests high levels of RNA binding and disregulated hyperphosphorylation, whereas wild-type UPF1 releases from nonspecific RNA interactions in an ATP hydrolysis-dependent mechanism until an NMD target is identified. 3'UTR-associated UPF1 undergoes regulated phosphorylation on NMD targets, providing a binding platform for mRNA degradative activities. p-UPF1 binding to NMD target 3'UTRs is stabilized by SMG5 and SMG7. Our results help to explain why steady-state UPF1 binding is not a marker for cellular NMD substrates and how this binding is transformed to induce mRNA decay. RIP-seq experiments for p-UPF1, control IPs using rabbit IgG and additional control sample without IP were performed in duplicates
Project description:DNA/RNA helicase Upf1 seems to interact with axonal transcripts in response to nerve growth factor (NGF, A. Ludanyi, M. Gaspari and A. Riccio, unpublished data). In order to shed light on Upf1 mechanism of action and to identify potential associations with molecules having cleavage activity, we performed an AP-MS experiment comprising Upf1 immunoprecipitation, on-beads digestion, isotopic labelling (18O) and quantitative LC-MS/MS analysis.