The Ski2-family helicase Obelus regulates Crumbs alternative splicing and cell polarity
Ontology highlight
ABSTRACT:
ORGANISM(S): Drosophila melanogaster
PROVIDER: GSE74545 | GEO | 2015/12/01
SECONDARY ACCESSION(S): PRJNA300677
REPOSITORIES: GEO
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Project description:RNA helicases perform essential housekeeping and regulatory functions in all domains of life by binding and unwinding RNA molecules. The Ski2-like proteins are primordial helicases that play an active role in eukaryotic RNA homeostasis pathways, with multiple homologs having specialized functions. The significance of the expansion and diversity of Ski2-like proteins in Archaea, the third domain of life, has not yet been established. Here, by studying the phylogenetic diversity of Ski2-like helicases among archaeal genomes and the enzymatic activities of those in Thermococcales, we provide further evidence of the function of this protein family in archaeal metabolism of nucleic acids. We show that, in the course of evolution, ASH-Ski2 and Hel308-Ski2, the two main groups of Ski2-like proteins, have diverged in their biological functions. Whereas Hel308 has been shown to mainly act on DNA, we show that ASH-Ski2, previously described to be associated with the 5′-3′ aRNaseJ exonuclease, acts on RNA by supporting an efficient annealing activity, but also an RNA unwinding with a 3′-5′ polarity. To gain insights into the function of Ski2, we also analyse the transcriptome of Thermococcus barophilus ASH-Ski2 mutant strain and provide evidence of the importance of ASH-Ski2 in cellular metabolism pathways related to translation.
2024-03-04 | GSE229955 | GEO
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2007-07-31 | GSE7682 | GEO
Project description:Post-transcriptional gene silence (PTGS) is employed in plants to shut down transgenes, invading viral genes and a certain group of endogenous genes. Meanwhile, it is not clear how the risk of expansive PTGS from endogenous genes featured by transitive siRNA production is minimized. Here we demonstrate two essential components of the SKI complex in cytoplasmic 3’-5’ mRNA decay pathway, SKI2 and SKI3, function as negative regulators of transgene PTGS in Arabidopsis. The ski2 mutants manifested severe synthetic phenotypes with a 5’-3’ exoribonuclease mutant, ein5, which were substantially suppressed by the PTGS mutants, rdr6 and ago1. RDR6 is essential for the altered gene expression in ein5 ski2 on a transcriptome-wide scale. mRNA-seq approach was used to investigate the physiological relevance veiled by the myriad developmental phenotypes in Col-0 (C), ein5-1 (e), ski2-3 (s), ein5-1 ski2-3 (es), rdr6-11 (r) and rdr6-11 ein5-1 ski2-3 (res). Compared with Col-0, 4394 genes exhibited differential expression in ein5-1 ski2-3, much more than those in the ein5-1 (1138 genes) or ski2-3 (1040 genes) single mutant (2-fold cutoff, p < 0.01, FDR < 0.05), suggesting a largely disturbed transcriptome in the absence of both EIN5 and SKI2. While a small overlap was found between the differentially expressed genes in e/C and s/C comparisons, the gene lists from es/C, es/e and es/s comparisons (2-fold cutoff, p < 0.01, FDR < 0.05) largely overlapped with each other, indicating a collaborative function of EIN5 and SKI2 on a transcriptome-wide scale. The 1670 genes overlapped in the es/C, es/e and es/s comparisons included 1306 upregulated genes and 360 downregulated genes with only 4 genes as exception. 994 of the 1306 upregulated genes (76.1%) and 273 of the 360 downregulated genes (75.8%) were differentially expressed in the es/res comparison like that in es/C, es/e and es/s, indicating a substantial supression of the redundant function of EIN5 and SKI2 by RDR6. Taken together, our study brings to light a dual-safeguard system in preventing the expansive siRNA production by the 5’-3’ and 3’-5’ cytoplasmic mRNA decay pathways. Examination of transcriptomes in 6 genotypes.
2015-04-13 | E-GEOD-52407 | biostudies-arrayexpress
Project description:Post-transcriptional gene silence (PTGS) is employed in plants to shut down transgenes, invading viral genes and a certain group of endogenous genes. Meanwhile, it is not clear how the risk of expansive PTGS from endogenous genes featured by transitive siRNA production is minimized. Here we demonstrate two essential components of the SKI complex in cytoplasmic 3’-5’ mRNA decay pathway, SKI2 and SKI3, function as negative regulators of transgene PTGS in Arabidopsis. The ski2 mutants manifested severe synthetic phenotypes with a 5’-3’ exoribonuclease mutant, ein5, which were substantially suppressed by the PTGS mutants, rdr6 and ago1. RDR6 is essential for the altered gene expression in ein5 ski2 on a transcriptome-wide scale. mRNA-seq approach was used to investigate the physiological relevance veiled by the myriad developmental phenotypes in Col-0 (C), ein5-1 (e), ski2-3 (s), ein5-1 ski2-3 (es), rdr6-11 (r) and rdr6-11 ein5-1 ski2-3 (res). Compared with Col-0, 4394 genes exhibited differential expression in ein5-1 ski2-3, much more than those in the ein5-1 (1138 genes) or ski2-3 (1040 genes) single mutant (2-fold cutoff, p < 0.01, FDR < 0.05), suggesting a largely disturbed transcriptome in the absence of both EIN5 and SKI2. While a small overlap was found between the differentially expressed genes in e/C and s/C comparisons, the gene lists from es/C, es/e and es/s comparisons (2-fold cutoff, p < 0.01, FDR < 0.05) largely overlapped with each other, indicating a collaborative function of EIN5 and SKI2 on a transcriptome-wide scale. The 1670 genes overlapped in the es/C, es/e and es/s comparisons included 1306 upregulated genes and 360 downregulated genes with only 4 genes as exception. 994 of the 1306 upregulated genes (76.1%) and 273 of the 360 downregulated genes (75.8%) were differentially expressed in the es/res comparison like that in es/C, es/e and es/s, indicating a substantial supression of the redundant function of EIN5 and SKI2 by RDR6. Taken together, our study brings to light a dual-safeguard system in preventing the expansive siRNA production by the 5’-3’ and 3’-5’ cytoplasmic mRNA decay pathways.
2015-04-13 | GSE52407 | GEO
Project description:Alternative splicing can have profound consequences for protein activity, but the functions of most alternative splicing regulators are not known. We show that Obelus, a conserved Ski2-family helicase, is required for cell polarity and adherens junction organization in the Drosophila melanogaster embryo. In obelus mutants, epithelial cells display an expanded apical domain, aggregation of adherens junctions at the cell membrane, and microtubule-dependent defects in centrosome positioning. Through whole-genome transcriptome analysis, we found that Obelus is required for the alternative splicing of a small number of transcripts in the early embryo, including the pre-mRNA that encodes the apical polarity protein Crumbs. In obelus mutants, inclusion of an alternative exon results in increased expression of a Crumbs isoform that contains an additional epidermal growth factor-like repeat in the extracellular domain. Overexpression of this alternative Crumbs isoform recapitulates the junctional aggregation and centrosome positioning defects of obelus mutants. These results indicate that regulation of Crumbs alternative splicing by the Obelus helicase modulates epithelial polarity during development.
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Project description:Post-transcriptional gene silence (PTGS) is employed in plants to shut down transgenes, invading viral genes and a certain group of endogenous genes. Meanwhile, it is not clear how the risk of expansive PTGS from endogenous genes featured by transitive siRNA production is minimized. Here we demonstrate two essential components of the SKI complex in cytoplasmic 3’-5’ mRNA decay pathway, SKI2 and SKI3, function as negative regulators of transgene PTGS in Arabidopsis. The ski2 mutants manifested severe synthetic phenotypes with a 5’-3’ exoribonuclease mutant, ein5, which were substantially suppressed by the PTGS mutants, rdr6 and ago1. RDR6 is essential for the altered gene expression in ein5 ski2 on a transcriptome-wide scale. mRNA-seq approach was used to investigate the physiological relevance veiled by the myriad developmental phenotypes in Col-0 (C), ein5-1 (e), ski2-3 (s), ein5-1 ski2-3 (es), rdr6-11 (r) and rdr6-11 ein5-1 ski2-3 (res). A number of endogenous genes, including many miRNA target genes, manifest transitive 21-22 nt siRNA production and compromised gene expression in ein5 ski2 in an RDR6-dependent manner. Taken together, our study brings to light a dual-safeguard system in preventing the expansive siRNA production by the 5’-3’ and 3’-5’ cytoplasmic mRNA decay pathways.
2016-11-15 | GSE52408 | GEO
Project description:SAP18 is a highly evolutionarily conserved protein found in all eukaryotic organisms from Saccharomycces cerevisiae to humans. It has been proposed to be involved in multiple cellular processes, from gene regulation to mRNA processing, playing different cellular functions, such as cell fate control during development or regulation of apoptosis or salt stress responses. Previous studies found SAP18 capable of repressing transcription when tethered directly to a promoter region. To gain further insight into the role of Drosophila SAP18, we performed genome-wide expression profiling of a dSAP18 mutant allele and found that dSAP18 is required for the expression of several immune-related genes, amongst others. To provide an updated view of the transcriptome, the probe sequences from the platform used (GPL3797) were matched to FlyBase Genome Release 5.5 and the corresponding gene names and identifiers were obtained. In the cases where one probe matched more than one gene, all of them were obtained. A total of four microarrays were hybridized in biological replicate pairs, such that the total RNA from dsap18 mutant animals (dsap18^117/Df(3R)sbd^45 0-24h staged embryos) and control animals (rescued dsap18^117/Df(3R)sbd^45 0-24h embryos containing a dsap18-HA transgene) used as starting material came from different extractions. Both arrays from each pair were hybridized with the same amplified RNA from sample and common reference (obtained using the Amino-Allyl Messageamp II aRNA Amplification Kit from Ambion, Inc) but with dyes (Cy3 and Cy5 from Amersham, Inc) swapped to take dye-bias into account.
2011-01-18 | E-GEOD-17066 | biostudies-arrayexpress
Project description:A loss-of-function mutant in the SKI2 helicase in Arabidopsis was shown to accumulate 5'-cleavage fragments of several miRNA targets. Small RNAs in ski2 single and ski2/rdr6 double mutants (two biological replicates of each genotype) were next analysed by NGS. The data show that several miRNA targets produce RDR6-dependent siRNAs upon inactivation of SKI2. Files containing these NGS data are deposited here. Seeds were surface sterilized and germinated on MS medium for 2 weeks. The seedlings were grown on soil until flowering stage in a 16h light period. The inflorescences were harvested and used to prepare RNA. Small RNA libraries were prepared using the NEBnext Multiplex small RNA library prep kit for Illumina sequencing.
2015-10-20 | E-MTAB-3781 | biostudies-arrayexpress
Project description:Hemizygous ato[1]/Df(3R)p[13] null mutants lack Johnston organ (JO) in their 2nd antennal segment. We screened for genes that are expressed in JO by comparing the 2nd antennal segment transcriptomes between ato[1]/Df(3R)p[13] mutants and balanced Df(3R)p[13]/TM3 and ato[1]/TM3 controls. To assess transcriptomes, we isolated the 2nd antennal segments of ~50 flies per strain and extracted their total RNA. Because about half of the JO cells are sensory neurons, we also isolated RNA from the brains of ato[1]/TM3 controls to delineate neuronal JO genes. cRNA was hybridized to Affymetrix Drosophila Genome 2.0 arrays. For each experiment, three biological replicates were run.
2012-08-31 | E-MEXP-3609 | biostudies-arrayexpress
Project description:Post-transcriptional gene silence (PTGS) is employed in plants to shut down transgenes, invading viral genes and a certain group of endogenous genes. Meanwhile, it is not clear how the risk of expansive PTGS from endogenous genes featured by transitive siRNA production is minimized. Here we demonstrate two essential components of the SKI complex in cytoplasmic 3 -5 mRNA decay pathway, SKI2 and SKI3, function as negative regulators of transgene PTGS in Arabidopsis. The ski2 mutants manifested severe synthetic phenotypes with a 5 -3 exoribonuclease mutant, ein5, which were substantially suppressed by the PTGS mutants, rdr6 and ago1. RDR6 is essential for the altered gene expression in ein5 ski2 on a transcriptome-wide scale. mRNA-seq approach was used to investigate the physiological relevance veiled by the myriad developmental phenotypes in Col-0 (C), ein5-1 (e), ski2-3 (s), ein5-1 ski2-3 (es), rdr6-11 (r) and rdr6-11 ein5-1 ski2-3 (res). A number of endogenous genes, including many miRNA target genes, manifest transitive 21-22 nt siRNA production and compromised gene expression in ein5 ski2 in an RDR6-dependent manner. Taken together, our study brings to light a dual-safeguard system in preventing the expansive siRNA production by the 5 -3 and 3 -5 cytoplasmic mRNA decay pathways. In this experiment, we did three replicates in sequencing that help increase the power in identify the differentially represented genes.The sequencing depth was also increased. Therefore we identified more siRNA-generating loci than that in previous study (GSE52408) (441 vs. 200 loci). Examination of small RNA profiles in 4 genotypes with 3 biological replicates each.
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