Project description:The exosome-independent exoribonuclease DIS3L2 is mutated in Perlman syndrome. Here we used extensive global transcriptomic and targeted biochemical analyses to identify novel DIS3L2 substrates in human cells. We show that DIS3L2 regulates pol II transcripts, comprising selected canonical and histone-coding mRNAs, and a novel FTL_short RNA from the ferritin mRNA 5' UTR. Importantly, DIS3L2 contributes to surveillance of pre-snRNAs during their cytoplasmic maturation. Among pol III transcripts, DIS3L2 particularly targets vault and Y RNAs and an Alu-like element BC200 RNA, but not Alu repeats, which are removed by exosome-associated DIS3. Using 3' RACE-Seq, we demonstrate that all novel DIS3L2 substrates are uridylated in vivo by TUT4/TUT7 poly(U) polymerases. Uridylation-dependent DIS3L2-mediated decay can be recapitulated in vitro, thus reinforcing the tight cooperation between DIS3L2 and TUTases. Together these results indicate that catalytically inactive DIS3L2, characteristic of Perlman syndrome, can lead to deregulation of its target RNAs to disturb transcriptome homeostasis. To investigate DIS3L2 functions genome-wide, total RNA samples were collected from model cell lines producing either WT or mut DIS3L2 three days after induction with doxycycline. The RNA samples were rRNA-depleted before preparation of strand-specific total RNA libraries according to the standard TruSeq (Illumina) protocol. TruSeq library preparation favours RNA molecules longer than 200 nt, and shorter transcripts are suboptimal for sequencing via this protocol. Thus, to obtain information about potential DIS3L2 RNA substrates with lengths between 20 and 220 nt, another RNA-Seq was carried out in parallel (with size selection through gel purification). The stable inducible HEK293 cell lines producing DIS3L2 variants were obtained using âpAL_01â and âpAL_02â plasmid constructs and the Flp-In⢠T-REx⢠system according to the manufacturerâs guidelines. âpAL_01â and âpAL_02â plasmids are vectors for co-expression of recoded C-terminal FLAG-tagged DIS3L2 [wild type (WT) variant or its catalytic mutant counterpart (mut), respectively] and sh-miRNAs directed against endogenous DIS3L2 mRNA.
Project description:The exosome-independent exoribonuclease DIS3L2 is mutated in Perlman syndrome. Here we used extensive global transcriptomic and targeted biochemical analyses to identify novel DIS3L2 substrates in human cells. We show that DIS3L2 regulates pol II transcripts, comprising selected canonical and histone-coding mRNAs, and a novel FTL_short RNA from the ferritin mRNA 5' UTR. Importantly, DIS3L2 contributes to surveillance of pre-snRNAs during their cytoplasmic maturation. Among pol III transcripts, DIS3L2 particularly targets vault and Y RNAs and an Alu-like element BC200 RNA, but not Alu repeats, which are removed by exosome-associated DIS3. Using 3' RACE-Seq, we demonstrate that all novel DIS3L2 substrates are uridylated in vivo by TUT4/TUT7 poly(U) polymerases. Uridylation-dependent DIS3L2-mediated decay can be recapitulated in vitro, thus reinforcing the tight cooperation between DIS3L2 and TUTases. Together these results indicate that catalytically inactive DIS3L2, characteristic of Perlman syndrome, can lead to deregulation of its target RNAs to disturb transcriptome homeostasis.
Project description:The post-transcriptional addition of nucleotides to the 3´ end of RNA regulates the maturation, function, and stability of RNA species in all domains of life. Here, we show that, in flies, 3´ terminal RNA uridylation triggers the processive, 3´-to-5´ exoribonucleolytic decay via the RNase II/R enzyme CG16940, a homolog of the human Perlman syndrome exoribonuclease Dis3l2. Together with the TUTase Tailor, dmDis3l2 forms the cytoplasmic, uridylation-triggered RNA processing (TRUMP) complex, that functionally cooperates in the degradation of structured RNA. RNA-immunoprecipitation and high-throughput sequencing reveals a variety of TRUMP complex substrates, including abundant non-coding RNA, such as 5S rRNA, tRNA, snRNA, snoRNA, and the essential RNase MRP, uncovering a key function of the TRUMP complex in the cytoplasmic quality control of RNA polymerase III transcripts. Together with high-throughput biochemical characterization of dmDis3l2 and bacterial RNase R our results imply a conserved molecular function of RNase II/R enzymes as 'readers' of destabilizing post-transcriptional marks - uridylation in eukaryotes and adenylation in prokaryotes - that play important roles in RNA surveillance.
Project description:Post-transcriptional regulatory strategies that involve coupling between terminal uridyltransferase (TUTase) and exoribonuclease enzymes have recently been characterized in diverse species. Of note, the 3' exoribonuclease Dis3L2 has received substantial attention as a factor that metabolizes uridylated substrates in contexts such as general mRNA degradation, turnover of specific miRNAs, and quality control of noncoding RNAs. To date, most studies of Dis3L2 have focused on fungi and mammalian cells. Here, we introduce Drosophila as a system that permits analysis of molecular mechanisms as well as the ability to interrogate organismal phenotypes. We started with a structure-function analysis of the Drosophila TUTase Tailor, which we recently identified to inhibit biogenesis of splicing-derived miRNA hairpins. Next, we show that Tailor/Dis3L2 form a complex via N-terminal domains in the respective proteins that are distinct from their catalytic domains. In vitro, Dis3L2 has nuclease activity, but substrate oligouridylation by Tailor stimulates their degradation by Dis3L2, especially for structured substrates. We analyzed mutants of Tailor and Dis3L2, which are viable and lack overt morphological defects. Instead, these mutants exhibit defects in female and male fertility, implying specific requirements in the germline. Dis3L2 defects are more severe than Tailor, and their requirements appear stronger in males than in females. In particular, loss of Dis3L2 completely blocks productive spermatogenesis, causing male sterility. RNA-seq analysis from single- and double-mutant testes reveals aberrant gene expression programs and suggests that noncoding RNAs may be preferentially affected by Dis3L2. Overall, our studies of a new tailing/trimming complex reveal unexpectedly specific requirements during gametogenesis.
Project description:Mutations in the 3’-5’ exonuclease DIS3L2 are associated with Perlman syndrome and hypersusceptibility to Wilms’ tumorigenesis. Previously, we found that Dis3l2 specifically recognizes and degrades uridylated pre-let-7 microRNA. However, the widespread relevance of Dis3l2-mediated decay of uridylated substrates remains unknown. Here we applied an unbiased RNA immunoprecipitation strategy to identify Dis3l2 targets in mouse embryonic stem cells. The disease-associated long noncoding RNA (lncRNA) Rmrp, 7SL, as well as several other Pol III-transcribed noncoding RNAs (ncRNAs) were among the most highly enriched Dis3l2-bound RNAs. 3’-uridylated Rmrp, 7SL, and snRNA species were highly stabilized in the cytoplasm of Dis3l2-depleted cells. Deep sequencing analysis of Rmrp 3’ ends revealed extensive oligouridylation mainly on transcripts with imprecise ends. We implicate the TUTases Zcchc6/11 in the uridylation of these ncRNAs, and biochemical reconstitution assays demonstrate the sufficiency of TUTase-Dis3l2 for Rmrp decay. This establishes Dis3l2-Mediated Decay (DMD) as a quality control pathway that eliminates aberrant ncRNAs.obtaining over four billion bases of sequence from chromatin immunoprecipitated DNA, we generated genome-wide chromatin-state maps of mouse embryonic stem cells, neural progenitor cells and embryonic fibroblasts. We find that lysine 4 and lysine 27 trimethylation effectively discriminates genes that are expressed, poised for expression, or stably repressed, and therefore reflect cell state and lineage potential. Lysine 36 trimethylation marks primary coding and non-coding transcripts, facilitating gene annotation. Trimethylation of lysine 9 and lysine 20 is detected at satellite, telomeric and active long-terminal repeats, and can spread into proximal unique sequences. Lysine 4 and lysine 9 trimethylation marks imprinting control regions. Finally, we show that chromatin state can be read in an allele-specific manner by using single nucleotide polymorphisms. This study provides a framework for the application of comprehensive chromatin profiling towards characterization of diverse mammalian cell populations.
Project description:Inhibition or genetic deletion of poly(ADP-ribose) polymerase-1 (PARP-1) is profoundly protective against a number of toxic insults in many organ systems1,2. In the brain the molecular mechanisms underlying PARP-1-dependent cell death (parthanatos) involves mitochondrial apoptosis-inducing factor (AIF) release and translocation to the nucleus resulting in chromatinolysis3-5. However, it is not known how AIF induces chromatinolysis and neuronal death in parthanatos3. Here we show through an unbiased screen of a ~16K human protein microarray followed by a second siRNA-based screen for protection against PARP-1- dependent cell death, that macrophage migration inhibitory factor (MIF)6 is an AIF associated nuclease that is required for cell death following N-methyl-D-aspartate (NMDA) glutamate receptor excitotoxicity and N-methyl-N-nitroso-N- nitroguanidine (MNNG) toxicity in primary neuronal cultures and focal stroke in mice. MIF contains a central four stranded mixed β-sheet flanked by two α- helices on both sides with an αβββαβ topology which is the structural core of many proteins belonging to the PD-D/E(X)K nuclease-like superfamily. MIF possesses previously unknown Mg2+/Ca2+-dependent nuclease activity, cleaving genomic DNA into large 20-50 kb fragments. AIF recruits MIF to the nucleus after NMDA treatment to induce DNA damage and cell death. Disruption of the AIF-MIF interaction prevents MIF recruitment to the nucleus and protects neurons from NMDA excitotoxicity and ischemic injury. Mutation of Glu22 to Gln in the catalytic nuclease domain completely blocks MIF’s nuclease activity, which almost completely inhibits DNA damage and cell death in vitro and in vivo. These findings reveal that MIF is recruited by AIF to the nucleus where it functions as a parthanatos dependent AIF associated nuclease that induces chromatinolysis and neuronal death, providing a new therapeutic target for stroke and other disorders involving parthanatos.