Project description:microRNAs are frequently modified by addition of untemplated nucleotides to the 3' end, but the role of this tailing is often unclear. Here we characterize the prevalence and functional consequences of microRNA tailing in vivo, using Caenorhabditis elegans. MicroRNA tailing in C. elegans consists mostly of mono-uridylation of mature microRNA species, with rarer mono-adenylation which is likely added to microRNA precursors. Through a targeted RNAi screen, we discover that the TUT4/TUT7 gene family member CID-1/CDE-1/PUP-1 is required for uridylation, whereas the GLD2 gene family member F31C3.2-here named GLD-2-related 2 (GLDR-2)-is required for adenylation. Thus, the TUT4/TUT7 and GLD2 gene families have broadly conserved roles in miRNA modification. We specifically examine the role of tailing in microRNA turnover. We determine half-lives of microRNAs after acute inactivation of microRNA biogenesis, revealing that half-lives are generally long (median = 20.7 h), as observed in other systems. Although we observe that the proportion of tailed species increases over time after biogenesis, disrupting tailing does not alter microRNA decay. Thus, tailing is not a global regulator of decay in C. elegans. Nonetheless, by identifying the responsible enzymes, this study lays the groundwork to explore whether tailing plays more specialized context- or miRNA-specific regulatory roles.
Project description:Many microRNAs (miRNAs) exist alongside abundant miRNA isoforms (isomiRs), most of which arise from post-maturation sequence modifications, such as 3’ uridylation and adenylation. However, the ways in which these sequence modifications affect miRNA function remain poorly understood. To this aim, we have generated single knock-out cell lines of TUT4, TUT7 and TENT2 (TUT2), as well as double knock-out (DKO) and triple knock-out (TKO) cell lines. Here, using these different cell lines, we have discovered that some of the redundant functions and specific functions of each tailing enzyme. Our study provides a comprehensive characterization of tailing on miRNAs.
Project description:To analyse the impact of URT1-mediated uridylation on miRNA and siRNA tailing, we deep-sequenced small RNA libraries for WT and urt1 duplicate samples at the same developmental stage that was analyzed by TAIL-seq, i.e., two-week-old seedlings. Examination of miRNA and siRNA tailing in WT and urt1 samples.
Project description:Many microRNAs (miRNAs) exist alongside abundant miRNA isoforms (isomiRs), most of which arise from post-maturation sequence modifications, such as 3’ uridylation and adenylation. However, the ways in which these sequence modifications affect miRNA function remain poorly understood. To this aim, we have generated knock-out cell lines of TUT4, TUT7 and TENT2 (TUT2), and rescued with plasmids expressing the cDNA of such enzymes. Here, using these different cell lines, we have discovered that some of the redundant functions and specific functions of each tailing enzyme. Our study provides a comprehensive characterization of tailing on miRNAs.
Project description:Many microRNAs (miRNAs) exist alongside abundant miRNA isoforms (isomiRs), most of which arise from post-maturation sequence modifications, such as 3’ uridylation and adenylation. However, the ways in which these sequence modifications affect miRNA function remain poorly understood. To this aim, we have generated knock-out cell lines of TUT4, TUT7 and TENT2 (TUT2), and obtained miRNA profiles from total RNA, AGO1, and AGO2 immunoprecipitations. Here, using these different cell lines, we have discovered that some of the redundant functions and specific functions of each tailing enzyme. Our study provides a comprehensive characterization of tailing on miRNAs.
Project description:MicroRNAs (miRNAs) act in concert with Argonaute (AGO) proteins to broadly repress mRNA targets. After AGO loading, miRNAs generally exhibit slow turnover. An important exception occurs when miRNAs encounter targets with extensive complementarity, which can trigger a process termed target-directed microRNA degradation (TDMD). Prevailing models of TDMD invoke miRNA tailing and trimming as an essential step in the decay mechanism. Here, a genome-wide screen revealed a novel cullin-RING ubiquitin ligase, which we named the DECAY complex, that mediates TDMD. The DECAY complex interacts with AGO proteins, mediates TDMD induced by multiple transcripts, and does not require tailing and trimming to elicit miRNA turnover. Based upon these findings, we propose a model in which the DECAY complex mediates TDMD by promoting proteasomal decay of miRNA-containing complexes.
Project description:MicroRNAs (miRNAs) act in concert with Argonaute (AGO) proteins to broadly repress mRNA targets. After AGO loading, miRNAs generally exhibit slow turnover. An important exception occurs when miRNAs encounter targets with extensive complementarity, which can trigger a process termed target-directed microRNA degradation (TDMD). Prevailing models of TDMD invoke miRNA tailing and trimming as an essential step in the decay mechanism. Here, a genome-wide screen revealed a novel cullin-RING ubiquitin ligase, which we named the DECAY complex, that mediates TDMD. The DECAY complex interacts with AGO proteins, mediates TDMD induced by multiple transcripts, and does not require tailing and trimming to elicit miRNA turnover. Based upon these findings, we propose a model in which the DECAY complex mediates TDMD by promoting proteasomal decay of miRNA-containing complexes.