Project description:Using high-throughput sequencing of histone mRNAs and degradation intermediates, we find that knockdown of TUT7 reduces both the uridylation at the 3’ end as well as uridylation pattern at the 3’ end, and only had a small effect on the uridylation in the stemloop uridylation of the major during histone mRNA degradation. Knockdown of 3’ hEXO also altered the uridylation of histone mRNAs, revealing a dynamic equilibrium between 3’ hEXO digestion and TUT7 uridylation, suggesting that TUT7 and 3’ hExo function together in trimming and uridylating histone mRNAs.
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.
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:The precise control of microRNA (miRNA) biogenesis is important for various cellular functions, and its dysregulation is often associated with human diseases. We previously reported that Terminal uridylyl transferase 4 (TUT4) down-regulates let-7 miRNA biogenesis by oligo-uridylating let-7 precursor (pre-let-7) in mouse embryonic stem cells and that a pluripotency marker Lin28 promotes a processivity of TUT4. Here we find that TUT4 positively controls let-7 biogenesis by adding a uridine residue to the 3’ end of pre-let-7 in the absence of Lin28. Such mono-uridylation enhances Dicer processing by generating an optimal end structure of pre-let-7 for Dicer recognition and may protect pre-miRNA from trimming. Moreover, TUT7, TUT4 and TUT2 redundantly regulate pre-let-7 processing and simultaneous knock down of these TUTs leads to the decrease of mature let-7 and the accumulation of pre-let-7 in cells. This study provides a novel regulation mechanism of miRNA biogenesis, which may function in development and tumorigenesis. HeLa cells were transfected with siRNA two times over a 4~5 day period.
Project description:The precise control of microRNA (miRNA) biogenesis is important for various cellular functions, and its dysregulation is often associated with human diseases. We previously reported that Terminal uridylyl transferase 4 (TUT4) down-regulates let-7 miRNA biogenesis by oligo-uridylating let-7 precursor (pre-let-7) in mouse embryonic stem cells and that a pluripotency marker Lin28 promotes a processivity of TUT4. Here we find that TUT4 positively controls let-7 biogenesis by adding a uridine residue to the 3’ end of pre-let-7 in the absence of Lin28. Such mono-uridylation enhances Dicer processing by generating an optimal end structure of pre-let-7 for Dicer recognition and may protect pre-miRNA from trimming. Moreover, TUT7, TUT4 and TUT2 redundantly regulate pre-let-7 processing and simultaneous knock down of these TUTs leads to the decrease of mature let-7 and the accumulation of pre-let-7 in cells. This study provides a novel regulation mechanism of miRNA biogenesis, which may function in development and tumorigenesis. HeLa cells were transfected with siRNA two times over a 4~5 day period.
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:Recent small RNA sequencing data has uncovered extensive modification of the 3’ end of mature microRNAs (miRNAs). This non-templated nucleotide addition can impact miRNA gene regulatory networks through the control of miRNA stability or by interfering with the repression of target mRNAs. The miRNA modifying enzymes responsible for this regulation remain largely uncharacterized. Here we describe the ability for two related terminal uridyl transferases (TUTases), Zcchc6 (TUT7) and Zcchc11 (TUT4), to 3’ mono-uridylate a specific subset of miRNAs involved in cell differentiation and Hox gene control. Zcchc6/11 selectively uridylate these miRNAs in vitro, and we biochemically define a bipartite sequence motif that is necessary and sufficient to confer Zcchc6/11 catalyzed uridylation. Depletion of these TUTases in cultured cells causes the selective loss of 3’ mono-uridylation of many of the same miRNAs. Interestingly, upon TUTase dependent loss of uridylation we observe a concomitant increase in non-templated 3’ mono-adenylation. Our results uncover the molecular basis for sequence specific miRNA mono-uridylation by Zcchc6/11, highlight the precise control of different 3’ miRNA modifications in cells, and have implications for miRNA regulation during development. small RNA profiles in TUTases knock-down and control HeLa cells were generated by Illumina deep sequencing