Project description:Strand selection is a critical step in microRNA (miRNA) biogenesis. Although the dominant strand may alter depending on cellular contexts, the molecular mechanism and physiological significance of such alternative strand selection (or “arm switching”) remain elusive. Here we find miR-324 as one of the strongly regulated miRNAs by arm switching, and identify terminal uridylyl transferases TUT4 and TUT7 as the key regulators. Uridylation of pre-miR-324 by TUT4/7 re-positions DICER on the pre-miRNA and shifts the cleavage site. This alternative processing produces a duplex with a different terminus, from which the 3′ strand (3p) is selected instead of the 5′ strand (5p). In glioblastoma, the TUT4/7 and 3p levels are upregulated while the 5p level is reduced. Manipulation of the strand ratio is sufficient to impair glioblastoma cell proliferation. This study uncovers a role of uridylation as a molecular switch in alternative strand selection and implicates its therapeutic potential.
Project description:Strand selection is a critical step in microRNA (miRNA) biogenesis. Although the dominant strand may alter depending on cellular contexts, the molecular mechanism and physiological significance of such alternative strand selection (or “arm switching”) remain elusive. Here we find miR-324 as one of the strongly regulated miRNAs by arm switching, and identify terminal uridylyl transferases TUT4 and TUT7 as the key regulators. Uridylation of pre-miR-324 by TUT4/7 re-positions DICER on the pre-miRNA and shifts the cleavage site. This alternative processing produces a duplex with a different terminus, from which the 3′ strand (3p) is selected instead of the 5′ strand (5p). In glioblastoma, the TUT4/7 and 3p levels are upregulated while the 5p level is reduced. Manipulation of the strand ratio is sufficient to impair glioblastoma cell proliferation. This study uncovers a role of uridylation as a molecular switch in alternative strand selection and implicates its therapeutic potential.
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: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.
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.