Project description:Uridylation occurs pervasively on mRNAs in mammals, yet its mechanism and significance remain unknown. Here we identify TUT4 and TUT7 (also known as ZCCHC11 and ZCCHC6, respectively) as the enzymes that uridylate mRNAs. Uridylation readily occurs on deadenylated mRNAs that are not associated with poly(A) binding protein (PABPC1) in cells. Consistently, purified TUT4 and TUT7 (TUT4/7) selectively uridylate RNAs with short A tails (< ~25 nt) while PABPC1 antagonizes uridylation of polyadenylated mRNAs in vitro. In cells depleted of TUT4/7, the vast majority of mRNAs lose the U tails, and their half-lives are extended. Suppression of mRNA decay factors leads to the accumulation of uridylated mRNAs. In line with this, microRNA induces uridylation of its targets, and TUT4/7 is required for enhanced decay of microRNA targets. Our study explains the mechanism underlying selective uridylation of deadenylated mRNAs, and demonstrates a fundamental role of the U tail as a molecular mark for global mRNA decay. Thirteen separate sets of TAIL-seq experiments were performed. Each set includes a negative control for transfection, immunoprecipitation, or knockout cell generation. Experimental samples were treated with various conditions including siRNA transfection, transdominant negative protein expression, TALEN-based gene knockout, or immunoprecipitation. The 'README-TAIL-seq.txt' include detailed information about structure of seq entries in FASTQ files and of processed data for 3' end modifications.
Project description:Uridylation occurs pervasively on mRNAs in mammals, yet its mechanism and significance remain unknown. Here we identify TUT4 and TUT7 (also known as ZCCHC11 and ZCCHC6, respectively) as the enzymes that uridylate mRNAs. Uridylation readily occurs on deadenylated mRNAs that are not associated with poly(A) binding protein (PABPC1) in cells. Consistently, purified TUT4 and TUT7 (TUT4/7) selectively uridylate RNAs with short A tails (< ~25 nt) while PABPC1 antagonizes uridylation of polyadenylated mRNAs in vitro. In cells depleted of TUT4/7, the vast majority of mRNAs lose the U tails, and their half-lives are extended. Suppression of mRNA decay factors leads to the accumulation of uridylated mRNAs. In line with this, microRNA induces uridylation of its targets, and TUT4/7 is required for enhanced decay of microRNA targets. Our study explains the mechanism underlying selective uridylation of deadenylated mRNAs, and demonstrates a fundamental role of the U tail as a molecular mark for global mRNA decay. HeLa cells were knocked down of control or TUT4/7, then total RNAs were prepared for RNA-seq on 0, 1, 2, 4h after actinomycin D treatment. The whole processes of experiments were repeated two times.
Project description:MicroRNA induces deadenylation of its targets according to the current model in the scientific community, but this model is based on the studies of a few individual genes. We tested the model by examining the global effect of miRNA on poly(A) tail of the targets. Synthetic miR-1 mimic was transfected into HeLa cells, and the poly(A) length was measured by TAIL-seq. Deadenylation of miR-1 targets was evident as early as 3 hours post-transfection without a significant change in mRNA level. After 6 or 9 hours, target mRNA level was substantially downregulated. Therefore, although there are some exceptions, our result confirms that, in general, miRNA indeed induces deadenylation. Furthermore, our kinetic global analysis confirms that deadenylation precedes mRNA decay. Four culture dishes of HeLa cells were treated with miR-1 all together, then collected and prepared for sequencing after different time of incubation (0, 3, 6, and 9 hours post-transfection)
Project description:Terminal uridylyl transferases (TUTs) function as integral regulators of microRNA (miRNA) biogenesis by modifying the end structure of precursor miRNA (pre-miRNA). Using biochemistry and deep sequencing techniques, we here investigate the mechanism how human TUT7 recognizes and uridylates pre-miRNAs. We show that the overhang of a pre-miRNA is the key structural element that TUT7 and its paralogues, TUT4 and TUT2, recognize. For group II pre-miRNAs which have a 1 nt 3’ overhang, TUT7 restores the canonical end structure (2 nt 3’ overhang) by mono-uridylation, and thereby promotes miRNA biogenesis. Interestingly, once the 3’ end is receded into the stem (3’ trimmed pre-miRNAs such as Ago-cleaved-pre-miRNA), TUT7 effectively generates an oligo-U tail that consequently leads to degradation. Our single-molecule study further suggests that a distributive mode is employed for both pathways, but the overhang length determines the frequency of TUT7-RNA interaction. Our results explain how TUT7 and TUT4 differentiate pre-miRNA species and reveal a role for TUT7 and TUT4 in the oligo-uridylation and removal of defective pre-miRNAs. HeLa cells were knocked down of control or TUT2/4/7, then total RNAs were prepared for RNA-seq
Project description:iCLIP experiment to assess the binding of the highly abundant nuclear RNA-binding protein hnRNP C and core splicing factor U2AF65 on a genomic scale. To investigate how both proteins compete for binding at a subset of sites, U2AF65 iCLIP experiments were performed from both HNRNPC knockdown and control HeLa cells.
Project description:We performed RNA-seq experiments on two replicate samples from each HNRNPC knockdown (KD1 and KD2) As well as from control HeLa cells. Library preparation was preformed according to mRNA Sequencing Sample Preparation Guide (Illumina, Part # 1004898 REV. D). Reagents were taken from the Illumina sample preparation kit (Illumina, CAT # RS-930-1001). Knockdown and control samples were sequenced together in one flowcell on one and two lanes, respectively.
Project description:Long noncoding RNAs (lncRNAs) are a major transcriptional output of the mammalian genome, yet their functions are poorly characterized. In this experiment, we used RNA interference (RNAi) and locked nucleic acid antisense oligonucleotides (LNAs) to deplete the lncRNAs LINC00899 and C1QTNF1-AS1 (C1) in HeLa cells. Both of these lncRNAs are of interest as their depletion results in mitotic delay, suggesting a role in mitotic progression. After depletion of each lncRNA with RNAi or LNAs, we performed high-throughput RNA sequencing and tested for differential expression compared to negative control samples (using control siRNAs or negative control LNAs) to identify downstream regulatory targets of each lncRNA. We generated 3-4 replicates for each condition, spread across multiple batches and experiments. Samples with the same batch number were treated at roughly the same time (within the same month), while the experiment number is nested within batch and refers to cells treated on the same day. Samples were pooled and sequenced across multiple lanes, yielding 8-9 technical replicates per sample.
Project description:Poly(A) tails are critical for mRNA stability and translation. However, recent studies have challenged this view, showing that poly(A) tail length and translation efficiency are decoupled in non-embryonic cells. Using TAIL-seq and ribosome profiling, we investigate poly(A) tail dynamics and translational control in the somatic cell cycle. We find dramatic changes in poly(A) tail lengths of cell cycle regulatory genes like CDK1, TOP2A, and FBXO5, explaining their translational repression in M phase. We also find that poly(A) tail length is coupled to translation when the poly(A) tail is <20 nucleotides. However, as most genes have >20 nucleotide poly(A) tails, their translation is regulated mainly via poly(A) tail length-independent mechanisms during the cell cycle. Specifically, we find that terminal oligopyrimidine (TOP) tract-containing transcripts escape global translational suppression in M phase and are actively translated. Our quantitative and comprehensive data provide a revised view of translational control in the somatic cell cycle. HeLa cells were synchronized at S or M phase, and subject to RNA-seq, ribosome profiling and TAIL-seq analysis.
Project description:We have develped a novel method of making siRNAs (named pro-siRNA for prokaryotic siRNA). To evaluate off-targeting of pro-siRNA, we compared the mRNA expression profiles of HeLa-d1EGFP cells transfected with 4 nM EGFP siRNAs and pro-siRNAs by microarray. We used microarray to study the off-target effect of siRNAs in the HeLa-d1EGFP cell line. After transfection of siRNAs for 24 hrs, RNA were extracted using Trizol. Deep sequencing libraries were generated using the NEBNext Ultra RNA Library Prep Kit for Illumina (NEB #E7530).