Repetitive sequences derived from transposons make up a large fraction of eukaryotic genomes and must be silenced to protect genome integrity. Repetitive elements are often found in heterochromatin; however, the roles and interactions of heterochromatin proteins in repeat regulation are poorly understood. Here we show that a diverse set of C. elegans heterochromatin proteins act together with the piRNA and nuclear RNAi pathways to silence repetitive elements and prevent genotoxic stress in the germ line. Mutants in genes encoding HPL-2/HP1, LIN-13, LIN-61, LET-418/Mi-2, and H3K9me2 histone methyltransferase MET-2/SETDB1 also show functionally redundant sterility, increased germline apoptosis, DNA repair defects, and interactions with small RNA pathways. Remarkably, fertility of heterochromatin mutants could be partially restored by inhibiting cep-1/p53, endogenous meiotic double strand breaks, or the expression of MIRAGE1 DNA transposons. Functional redundancy among these factors and pathways underlies the importance of safeguarding the genome through multiple means. Overall design: Synchronized, starved L1 stage worms were grown on NGM plates under one of two conditions. Condition 1: growth was at 20°C (hpl-2, let-418, lin-61, met-2 set-25, and wild-type N2) until the L4 stage and then worms were shifted to 25°C for 15-18 hours until they reached young adult stage. Condition 2: growth was at 15°C (lin-13, prg-1, nrde-2, nrde-2; let-418, and wild-type N2) until the L4 stage, and then worms were shifted to 25°C for 15-18 hours until they reached young adult stage. Worms were then washed off plates, flash frozen in liquid nitrogen, and stored at -80°C until use. RNA was extracted from frozen worms using TriPure (Roche). RNA was purified with Zymo Research RNA Clean and Concentrator-5 (Cambridge Bioscience) following DNase I digestion. Ribosomal RNA was depleted using Ribo-Zero rRNA Removal Kit (Human/Mouse/Rat) (Illumina). Libraries were prepared using the NEBNext Ultra Directional RNA Library Prep Kit for Illumina (New England Biolabs). Two biological replicates were prepared for each strain.
A team of heterochromatin factors collaborates with small RNA pathways to combat repetitive elements and germline stress.
Specimen part, Subject
View SamplesFOXO transcription factors control cellular formation of reactive oxygen species (ROS), which critically contribute to cell survival and cell death in neuroblastoma. Here, we report that C10orf10, also named Decidual Protein induced by Progesterone (DEPP), is a direct transcriptional target of FOXO3 in human neuroblastoma. As FOXO3-mediated apoptosis involves a biphasic ROS accumulation, we analyzed cellular ROS levels in DEPP-knockdown cells by live-cell imaging. Knockdown of DEPP prevented the primary and secondary ROS accumulation during FOXO3 activation and attenuates FOXO3-induced apoptosis, whereas its overexpression raises cellular ROS levels and sensitizes to cell death. In neuronal cells, cellular steady state ROS are mainly detoxified in peroxisomes by the enzyme CAT/catalase. As DEPP contains a peroxisomal-targeting-signal-type-2 (PTS2) sequence at its N-terminus that enables protein import into peroxisomes, we analyzed the effect of DEPP on peroxisomal function by measuring the catalase enzyme activity. Catalase activity was reduced by conditional DEPP overexpression and significantly increased in DEPP-knockdown cells. Using live cell imaging and fluorescent peroxisomal and mitochondrial probes we demonstrate that DEPP localizes to peroxisomes and mitochondria in neuroblastoma cells. The combined data indicate that DEPP reduces peroxisomal activity and thereby impairs the cellular ROS detoxification capacity and contributes to death sensitization.
C10ORF10/DEPP, a transcriptional target of FOXO3, regulates ROS-sensitivity in human neuroblastoma.
Cell line, Treatment
View SamplesYoung adult N2 Caenorhabditis elegans were infected with Enterococcus faecalis or Enterococcus faecium for 8 h to determine the transcriptional host response to each enterococcal species.
Both live and dead Enterococci activate Caenorhabditis elegans host defense via immune and stress pathways.
Specimen part, Treatment
View SamplesN2 young adult animals were analyzed four hours after exposure to wild-type Candida albicans DAY185, heat-killed C. albicans DAY185 and heat-killed Escherichia coli OP50, all on Brain Heart Infusion (BHI) agar. It was necessary to use heat-killed E. coli OP50 as a control for these experiments because live E. coli OP50 (the normal nematode food source) is pathogenic to nematodes on BHI agar. These data identify the C. elegans genes that are differentially regulated during nematode infection with a human fungal pathogen.
Candida albicans infection of Caenorhabditis elegans induces antifungal immune defenses.
No sample metadata fields
View SamplesPluripotent-specific inhibitors (PluriSIns) make a powerful tool for studying the mechanisms that control the survival of human pluripotent stem cells (hPSCs). Here we characterize PluriSIn#2 as a novel selective indirect inhibitor of topoisomerase II alpha (TOP2A). We find that TOP2A is uniquely expressed in undifferentiated hPSCs, and that its inhibition results in their rapid cell death. These findings reveal a dependency of hPSCs on the activity of TOP2A, which can be harnessed for their selective elimination from culture.
Brief reports: Controlling the survival of human pluripotent stem cells by small molecule-based targeting of topoisomerase II alpha.
Specimen part, Cell line, Treatment
View SamplesVery little is known about how animals discriminate pathogens from innocuous microbes. To address this question, we examined infection-response gene induction in the nematode Caenorhabditis elegans. We focused on genes that are induced in C. elegans by infection with the bacterial pathogen Pseudomonas aeruginosa, but are not induced by an isogenic attenuated gacA mutant. Most of these genes are induced independently of known immunity pathways. We generated a GFP reporter for one of these genes, infection response gene 1 (irg-1), which is induced strongly by wild-type P. aeruginosa strain PA14, but not by other C. elegans pathogens or by other wild-type P. aeruginosa strains that are weakly pathogenic to C. elegans. To identify components of the pathway that induces irg-1 in response to infection, we performed an RNA interference screen of C. elegans transcription factors. This screen identified zip-2, a bZIP transcription factor that is required for inducing irg-1, as well as several other genes, and is important for defense against infection by P. aeruginosa. These data indicate that zip-2 is part of a specialized pathogen response pathway that is induced by virulent strains of P. aeruginosa and provides defense against this pathogen.
bZIP transcription factor zip-2 mediates an early response to Pseudomonas aeruginosa infection in Caenorhabditis elegans.
Time
View SamplesAnalysis of differential gene expression in C. elegans adults exposed to three different bacteria: E. coli strain OP50, wild-type P. aeruginosa PA14 and gacA mutant PA14. Samples were analyzed at 4 hours and 8 hours after exposure to the different bacteria. These studies identified C. elegans genes induced by pathogen infection.
p38 MAPK regulates expression of immune response genes and contributes to longevity in C. elegans.
Specimen part
View SamplesAnalysis of genes differentially expressed between daf-2(e1368) and daf-2(e1368);pmk-1(km25) and between daf-2(e1368) and daf-2(e1368);daf-16(mgDf47). These studies identified genes upregulated by wild-type PMK-1 and wild-type DAF-16.
p38 MAPK regulates expression of immune response genes and contributes to longevity in C. elegans.
Specimen part
View SamplesYoung adult fer-15;fem-1 Caenorhabditis elegans were infected with Staphylococcus aureus for 8 h to determine the transcriptional host response to Staphylococcus aureus. Analysis of differential gene expression in C. elegans young adults exposed to two different bacteria: E. coli strain OP50 (control), wild-type Staphylococcus aureus RN6390. Samples were analyzed at 8 hours after exposure to the different bacteria. These studies identified C. elegans genes induced by pathogen infection.
Distinct pathogenesis and host responses during infection of C. elegans by P. aeruginosa and S. aureus.
Disease, Disease stage
View SamplesThe nematode Caenorhabditis elegans offers currently untapped potential for carrying out high-throughput, live-animal screens of low molecular weight compound libraries to identify molecules that target a variety of cellular processes. We previously used a bacterial infection assay in C. elegans to identify 119 compounds that affect host-microbe interactions among 37,214 tested. We subsequently found that one of these small molecules, RPW-24, protects C. elegans from bacterial infection by stimulating the host immune response of the nematode. Using transcriptome profiling, epistasis pathway analyses with C. elegans mutants, and an RNAi screen, we showed that RPW-24 promotes resistance to Pseudomonas aeruginosa infection by inducing the transcription of a remarkably small number of C. elegans genes (~1.3% of all genes) in a manner that partially depends on the evolutionarily-conserved p38 MAP kinase pathway and the transcription factor ATF-7. These data demonstrated that the immunostimulatory activity of RPW-24 is required for its efficacy and define a novel C. elegans-based strategy to identify compounds with activity against antibiotic-resistant bacterial pathogens. Here we present the microarray data that were used to define the genes that are differentially regulated in wild-type nematodes following exposure to RPW-24.
Stimulation of host immune defenses by a small molecule protects C. elegans from bacterial infection.
Specimen part, Treatment
View Samples