Project description:Pseudouridine synthases (PUSs) are responsible for the installation of pseudouridine (Ψ) modification in RNA. However, the activity and function of the PUS enzymes remain largely unexplored. Here we focus on human PUS10 and find that it co-expresses with the microprocessor (DROSHA–DGCR8 complex). Depletion of PUS10 results in a marked reduction of the expression level of a large number of mature miRNAs and concomitant accumulation of unprocessed primary microRNAs (pri-miRNAs) in multiple human cells. Mechanistically, PUS10 directly binds to pri-miRNAs and interacts with the microprocessor to promote miRNA biogenesis. Unexpectedly, this process is independent of the catalytic activity of PUS10. Additionally, we develop a sequencing method to profile Ψ in the tRNAome and report PUS10-dependent Ψ sites in tRNA. Collectively, our findings reveal differential functions of PUS10 in nuclear miRNA processing and in cytoplasmic tRNA pseudouridylation.
Project description:H/ACA small nucleolar RNAs (snoRNAs) guide pseudouridylation as part of a small nucleolar ribonucleoprotein complex (snoRNP). Disruption of H/ACA snoRNA expression in stem cells impairs pluripotency, yet it remains unclear how H/ACA snoRNAs contribute to differentiation. To determine if H/ACA snoRNA expression is dynamic during differentiation, we comprehensively profiled H/ACA snoRNA expression in multiple murine cell types and during differentiation in three cellular models, including mouse embryonic stem cells and mouse myoblasts. We determined that H/ACA snoRNA expression is cell-type specific, and we identified a subset of snoRNAs that are specifically regulated during differentiation. Additionally, we demonstrated that a decrease in Snora27 expression upon differentiation corresponds to a decrease in pseudouridylation of its target site within the E-site transfer RNA (tRNA) binding region of the 28S ribosomal RNA (rRNA) in the large ribosomal subunit. Many of the snoRNAs regulated during differentiation have target nucleotides in the 28S rRNA, and we found that pre-rRNA processing of large subunit precursors is altered during differentiation. Together, these data suggest a model in which H/ACA snoRNAs are specifically regulated during differentiation to potentially alter pseudouridylation and fine tune ribosome function.
Project description:H/ACA small nucleolar RNAs (snoRNAs) guide pseudouridylation as part of a small nucleolar ribonucleoprotein complex (snoRNP). Disruption of H/ACA snoRNA expression in stem cells impairs pluripotency, yet it remains unclear how H/ACA snoRNAs contribute to differentiation. To determine if H/ACA snoRNA expression is dynamic during differentiation, we comprehensively profiled H/ACA snoRNA expression in multiple murine cell types and during differentiation in three cellular models, including mouse embryonic stem cells and mouse myoblasts. We determined that H/ACA snoRNA expression is cell-type specific, and we identified a subset of snoRNAs that are specifically regulated during differentiation. Additionally, we demonstrated that a decrease in Snora27 expression upon differentiation corresponds to a decrease in pseudouridylation of its target site within the E-site transfer RNA (tRNA) binding region of the 28S ribosomal RNA (rRNA) in the large ribosomal subunit. Many of the snoRNAs regulated during differentiation have target nucleotides in the 28S rRNA, and we found that pre-rRNA processing of large subunit precursors is altered during differentiation. Together, these data suggest a model in which H/ACA snoRNAs are specifically regulated during differentiation to potentially alter pseudouridylation and fine tune ribosome function.
Project description:The endogenous RNA substrates of Translin-TRAX complexes (also known as C3POs) and how they regulate diverse biological processes remain unknown. Here we show that Translin and TRAX do not play a significant role in RNAi in the filamentous fungus Neurospora crassa. Instead, the Neurospora C3PO complex functions as a ribonuclease that removes the 5M-bM-^@M-^Y pre-tRNA fragments after the processing of pre-tRNAs by RNase P. In translin and trax mutants, 5M-bM-^@M-^Y pre-tRNA fragments accumulate to very high levels that can be degraded specifically by both recombinant and endogenous Neurospora C3PO and recombinant Drosophila C3PO. In addition, the mutants have elevated tRNA levels and increased levels of protein translation and are more resistant to a programmed cell-death inducing agent. Together, this study identified the endogenous RNA substrates of C3PO and provides a potential explanation for its roles in seemingly diverse biological processes. Examine small RNA population changes in two different strain background
Project description:Pseudouridylation (Ψ) is the most abundant and widespread type of RNA epigenetic modification in living organisms; however, the biological role of Ψ remains poorly understood. Here, we show that a Ψ-driven posttranscriptional program steers translation control to impact stem cell commitment during early embryogenesis. Mechanistically, the Ψ ‘writer’ PUS7 modifies and activates a network of tRNA-derived fragments (tRFs) targeting the translation initiation complex. PUS7 inactivation in embryonic stem cells impairs tRF-mediated translational regulation leading to increased protein biosynthesis and abnormal germ layer specification. Remarkably, dysregulation of PUS7 and tRFs in myeloid malignancies associates with altered translation rates, suggesting a role of Ψ in leukemogenesis. Our findings unveil a critical function of Ψ in directing translational control in stem cells with important implications for human disease.
Project description:H/ACA small nucleolar RNAs (snoRNAs) guide pseudouridylation as part of a small nucleolar ribonucleoprotein complex (snoRNP). Disruption of H/ACA snoRNA expression in stem cells impairs pluripotency, yet it remains unclear how H/ACA snoRNAs contribute to differentiation. To determine if H/ACA snoRNA expression is dynamic during differentiation, we comprehensively profiled H/ACA snoRNA expression in multiple murine cell types and during differentiation in three cellular models, including mouse embryonic stem cells and mouse myoblasts. We determined that H/ACA snoRNA expression is cell-type specific, and we identified a subset of snoRNAs that are specifically regulated during differentiation. Additionally, we demonstrated that a decrease in Snora27 expression upon differentiation corresponds to a decrease in pseudouridylation of its target site within the E-site transfer RNA (tRNA) binding region of the 28S ribosomal RNA (rRNA) in the large ribosomal subunit. Many of the snoRNAs regulated during differentiation have target nucleotides in the 28S rRNA, and we found that pre-rRNA processing of large subunit precursors is altered during differentiation. Together, these data suggest a model in which H/ACA snoRNAs are specifically regulated during differentiation to potentially alter pseudouridylation and fine tune ribosome function.
Project description:Pseudouridylation (Ψ) is the most abundant and widespread type of RNA epigenetic modification in living organisms; however, the biological role of Ψ remains poorly understood. Here, we show that a Ψ-driven posttranscriptional program steers translation control to impact stem cell commitment during early embryogenesis. Mechanistically, the Ψ ‘writer’ PUS7 modifies and activates a network of tRNA-derived fragments (tRFs) targeting the translation initiation complex. PUS7 inactivation in embryonic stem cells impairs tRF-mediated translational regulation leading to high protein biosynthesis and abnormal germ layer specification. Dysregulation of PUS7 and tRFs in myeloid malignancies associates with altered translation rates, suggesting a role of Ψ in tumorigenesis. Our findings unveil a critical function of Ψ in directing translational control in stem cells with promisingly broad implications for human disease.
Project description:The endogenous RNA substrates of Translin-TRAX complexes (also known as C3POs) and how they regulate diverse biological processes remain unknown. Here we show that Translin and TRAX do not play a significant role in RNAi in the filamentous fungus Neurospora crassa. Instead, the Neurospora C3PO complex functions as a ribonuclease that removes the 5’ pre-tRNA fragments after the processing of pre-tRNAs by RNase P. In translin and trax mutants, 5’ pre-tRNA fragments accumulate to very high levels that can be degraded specifically by both recombinant and endogenous Neurospora C3PO and recombinant Drosophila C3PO. In addition, the mutants have elevated tRNA levels and increased levels of protein translation and are more resistant to a programmed cell-death inducing agent. Together, this study identified the endogenous RNA substrates of C3PO and provides a potential explanation for its roles in seemingly diverse biological processes.