ABSTRACT: Deep Sequencing of Human Nuclear and Cytoplasmic Small RNAs Reveals an Unexpectedly Complex Subcellular Distribution of miRNAs and tRNA 3' Trailers
Project description:Background: MicroRNAs (miRNAs) are 22-nt small non-coding regulatory RNAs that have generally been considered to regulate gene expression at the post-transcriptional level in the cytoplasm. However, recent studies have reported that some miRNAs localize to and function in the nucleus. Methodology/Principal Findings: To determine the number of miRNAs localized to the nucleus, we systematically investigated the subcellular distribution of small RNAs (sRNAs) by independent deep sequencing the nuclear and cytoplasmic pools of 18- to 30-nucleotide sRNAs from human cells. We identified 339 nuclear and 324 cytoplasmic known miRNAs, 300 of which overlap, suggesting that the majority of miRNAs are imported into the nucleus. With the exception of a few miRNAs evidently enriched in the nuclear pool, such as the mir-29b, the ratio of miRNA abundances in the nuclear fraction versus in the cytoplasmic fraction vary to some extent. Moreover, our results revealed that a large number of tRNA 3' trailers are exported from the nucleus and accumulate in the cytoplasm. These tRNA 3' trailers accumulate in a variety of cell types, implying that the biogenesis of tRNA 3' trailers is conserved and that they have a potential functional role in vertebrate cells. Conclusion/Significance: Our results provide the first comprehensive view of the subcellular distribution of diverse sRNAs and new insights into the roles of miRNAs and tRNA 3' trailers in the cell Discovery and characterization of small RNA species through deep sequencing of nuclear and cytoplasmic small RNA fractions from 5-8F cells, a nasopharyngeal carcinoma cell line.
Project description:Background: MicroRNAs (miRNAs) are 22-nt small non-coding regulatory RNAs that have generally been considered to regulate gene expression at the post-transcriptional level in the cytoplasm. However, recent studies have reported that some miRNAs localize to and function in the nucleus. Methodology/Principal Findings: To determine the number of miRNAs localized to the nucleus, we systematically investigated the subcellular distribution of small RNAs (sRNAs) by independent deep sequencing the nuclear and cytoplasmic pools of 18- to 30-nucleotide sRNAs from human cells. We identified 339 nuclear and 324 cytoplasmic known miRNAs, 300 of which overlap, suggesting that the majority of miRNAs are imported into the nucleus. With the exception of a few miRNAs evidently enriched in the nuclear pool, such as the mir-29b, the ratio of miRNA abundances in the nuclear fraction versus in the cytoplasmic fraction vary to some extent. Moreover, our results revealed that a large number of tRNA 3' trailers are exported from the nucleus and accumulate in the cytoplasm. These tRNA 3' trailers accumulate in a variety of cell types, implying that the biogenesis of tRNA 3' trailers is conserved and that they have a potential functional role in vertebrate cells. Conclusion/Significance: Our results provide the first comprehensive view of the subcellular distribution of diverse sRNAs and new insights into the roles of miRNAs and tRNA 3' trailers in the cell
Project description:We detect the small RNAs subcellular distribution in breast cancer cell lines MCF-7 and MDA-MB-231, and normal cell line MCF-10A. Each cell line, we detected the nuclear and cytoplasmic small RNAs expression intensity; and then we could get the nuclear-cytoplasmic-ratio.
Project description:RNA deep sequencing efforts have revealed abundant expression of small RNAs derived from small nucleolar (sno) RNAs. We employ here spatial RNA deep sequencing to assess the expression of 10-40 nt small RNAs in subcellular compartments of HeLa cells. Total cellular, cytoplasmic, nuclear and nucleolar fractions were isolated, RNA was purified and size-fractionated in a two-step process to yield 10-40 nt RNA fractions. cDNA libraries were constructed and sequenced on a Ion Torrent platform. Vast majority of cellular, cytoplasmic and nuclear small RNA reads were identified as miRNAs. We found the expression of eleven ten miRNAs in the nucleolar preparations using a cut-off rate of 10 reads. Several miRNAs had a greater relative abundance in the nucleolus compared to the other compartments. The nucleolar small RNAs had a unique size distribution consisting of 19-20 and 25 nt RNAs, which were predominantly composed of small snoRNA-derived box C/D RNAs (termed as sdRNA). Sequences from 47 sdRNAs were identified, which mapped both 5M-bM-^@M-^Y and 3M-bM-^@M-^Y ends of the snoRNAs, and retained conserved box C or D motifs. SdRNA reads from SNORD44 comprised 74% of all nucleolar sdRNAs, and were confirmed by Northern blotting as 20 and 25 nt RNAs. This study reveals a rich representation of cell-compartment specific expression of small RNAs and the distinctive unique composition of the nucleolar small RNAs. Examination of small RNAs in cellular subcompartments
Project description:RNA deep sequencing efforts have revealed abundant expression of small RNAs derived from small nucleolar (sno) RNAs. We employ here spatial RNA deep sequencing to assess the expression of 10-40 nt small RNAs in subcellular compartments of HeLa cells. Total cellular, cytoplasmic, nuclear and nucleolar fractions were isolated, RNA was purified and size-fractionated in a two-step process to yield 10-40 nt RNA fractions. cDNA libraries were constructed and sequenced on a Ion Torrent platform. Vast majority of cellular, cytoplasmic and nuclear small RNA reads were identified as miRNAs. We found the expression of eleven ten miRNAs in the nucleolar preparations using a cut-off rate of 10 reads. Several miRNAs had a greater relative abundance in the nucleolus compared to the other compartments. The nucleolar small RNAs had a unique size distribution consisting of 19-20 and 25 nt RNAs, which were predominantly composed of small snoRNA-derived box C/D RNAs (termed as sdRNA). Sequences from 47 sdRNAs were identified, which mapped both 5’ and 3’ ends of the snoRNAs, and retained conserved box C or D motifs. SdRNA reads from SNORD44 comprised 74% of all nucleolar sdRNAs, and were confirmed by Northern blotting as 20 and 25 nt RNAs. This study reveals a rich representation of cell-compartment specific expression of small RNAs and the distinctive unique composition of the nucleolar small RNAs.
Project description:The molecular roles of the dually targeted ElaC domain protein 2 (ELAC2) during nuclear and mitochondrial RNA processing in vivo have not been distinguished. We generated conditional knockout mice of ELAC2 to identify that it is essential for life and its activity is non-redundant. Heart and skeletal muscle-specific loss of ELAC2 causes dilated cardiomyopathy and premature death at 4 weeks. Transcriptome-wide analyses of total RNAs, small RNAs, mitochondrial RNAs and miRNAs identified the nuclear and mitochondrial molecular targets of ELAC2 in vivo. We show that ELAC2 is required for processing of nuclear and mitochondrial tRNAs and for the balanced maintenance of C/D box snoRNAs, a new class of tRNA fragments, and miRNAs. We identify that correct biogenesis of regulatory non-coding RNAs is essential for both cytoplasmic and mitochondrial protein synthesis as well as the assembly of mitochondrial ribosomes and cytoplasmic polysomes. Taken together our data show that nuclear tRNA processing is required for the balanced production of snoRNAs and miRNAs for gene expression and that 3′ tRNA processing follows 5′ tRNA processing but nevertheless is an essential step in the production of all mature mitochondrial RNAs and the majority of nuclear tRNAs.
Project description:The molecular roles of the dually targeted ElaC domain protein 2 (ELAC2) during nuclear and mitochondrial RNA processing in vivo have not been distinguished. We generated conditional knockout mice of ELAC2 to identify that it is essential for life and its activity is non-redundant. Heart and skeletal muscle-specific loss of ELAC2 causes dilated cardiomyopathy and premature death at 4 weeks. Transcriptome-wide analyses of total RNAs, small RNAs, mitochondrial RNAs and miRNAs identified the nuclear and mitochondrial molecular targets of ELAC2 in vivo. We show that ELAC2 is required for processing of nuclear and mitochondrial tRNAs and for the balanced maintenance of C/D box snoRNAs, a new class of tRNA fragments, and miRNAs. We identify that correct biogenesis of regulatory non-coding RNAs is essential for both cytoplasmic and mitochondrial protein synthesis as well as the assembly of mitochondrial ribosomes and cytoplasmic polysomes. Taken together our data show that nuclear tRNA processing is required for the balanced production of snoRNAs and miRNAs for gene expression and that 3′ tRNA processing follows 5′ tRNA processing but nevertheless is an essential step in the production of all mature mitochondrial RNAs and the majority of nuclear tRNAs.
Project description:The molecular roles of the dually targeted ElaC domain protein 2 (ELAC2) during nuclear and mitochondrial RNA processing in vivo have not been distinguished. We generated conditional knockout mice of ELAC2 to identify that it is essential for life and its activity is non-redundant. Heart and skeletal muscle-specific loss of ELAC2 causes dilated cardiomyopathy and premature death at 4 weeks. Transcriptome-wide analyses of total RNAs, small RNAs, mitochondrial RNAs and miRNAs identified the nuclear and mitochondrial molecular targets of ELAC2 in vivo. We show that ELAC2 is required for processing of nuclear and mitochondrial tRNAs and for the balanced maintenance of C/D box snoRNAs, a new class of tRNA fragments, and miRNAs. We identify that correct biogenesis of regulatory non-coding RNAs is essential for both cytoplasmic and mitochondrial protein synthesis as well as the assembly of mitochondrial ribosomes and cytoplasmic polysomes. Taken together our data show that nuclear tRNA processing is required for the balanced production of snoRNAs and miRNAs for gene expression and that 3′ tRNA processing follows 5′ tRNA processing but nevertheless is an essential step in the production of all mature mitochondrial RNAs and the majority of nuclear tRNAs.
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:Characteristics of subcellular localization of RNAs are closely associated with their transcriptional outputs and, therefore, involved in the physiological process of many cases of central nervous system diseases, such as hemorrhagic stroke, which threatens millions of people and causes of death and long-term disability world-wide. Using whole-transcriptome sequencing (RNA-seq), here we report a subcellular gene profiling during hemorrhagic damage. Differentially expressed genes owing to spatial distribution of oxyhemoglobin (oxy-hb) treated-microglial nuclear and cytoplasmic fractions were enriched in biological processes in RNA metabolism and RNA splicing regardless of the duration of stimulation; while hemorrhage-induced differentially expressed genes played roles in inflammation regardless of the duration of stimulation. Interestingly, nuclear-retained intron of microglial nucleocytoplasmic transport genes may result in their down-regulation in 24 hours of oxy-Hb stimulation. This transcriptome study advances our understanding of the contributor of subcellular components, revealing new insights into cytoplasmic non-coding RNAs in response to hemorrhage and provide a resource for investigating comparable diseases.