Splicing factor 1 modulates dietary restriction and TORC1 pathway longevity in C. elegans
ABSTRACT: RNA-seq of C.elegans strain N2 (wt) with and without sfa-1 RNAi at adult day 3 and day 15, C. elegans strain DA1116 (eat-2(ad1116)) with and without sfa-1 RNAi at adult day 3, day 15, and day 27, C. elegans strain SS104 (glp-4(bn2)) with and without hrp-2 RNAi at adult day 1, and HeLa cells with and without SF1 siRNA.
Project description:Expression data from Caenorhabditis elegans let-418(RNAi), mep-1(RNAi) and gfp(RNAi) L1 larvae. The C. elegans genome encodes two homologs of the human protein Mi-2, namely LET-418 and CHD-3. LET-418 plays an essential role during development; its depletion leads to a pleiotropic and lethal phenotype that includes larval arrest, an everted vulva and sterility. Without maternal contribution, let-418 mutants stop their development at the L1 larval stage (von Zelewsky et al., 2000). We further characterized this arrest and showed that it is very similar to the L1 diapause induced by starvation; both germline and somatic cells remain in a quiescent state in let-418 L1 arrested larvae, indicating that LET-418 activity is required to bypass the L1 arrest in presence of food. The let-418 L1 larvae express ectopically the P granule component PGL-1 in somatic cells (Unhavaithaya et al., 2002). Interestingly, the phenotype of mep-1 mutants is remarkably similar to that of let-418: RNAi targeting mep-1 also induced an L1 arrest phenotype; furthermore, MEP-1 and LET-418 have been shown to physically interact (Unhavaithaya et al., 2002 and M. Passannante). The null allele mep-1(q660) is temperature sensitive and shows a more severe phenotype at higher temperatures. At 20°C, about 10% of mep-1 homozygotes derived from heterozygous mothers arrest as young larvae, whereas the remaining 90% develop into sterile adults (Belfiore et al., 2002). Later in development, the somatic gonad is affected in mep-1(q660) mutants. This results in an abnormal and disorganized gonad, a phenotype also observed in let-418(s1617) mutants. Both let-418 and mep-1 mutants produce a very limited number of oocytes and have pseudovulvae derived from P8.p (Belfiore et al., 2002; von Zelewsky et al., 2000 and C. Wicky, personal communication). Preliminary quantitative real-time PCR revealed that the expression of genes coding for P granule components was deregulated in both mep-1(RNAi) and let-418(RNAi) L1 larvae (data not shown). To further investigate this issue, we performed a complete gene expression analysis. Given the fact that mep-1(q660) mutants are sterile, we used RNA interference to generate mep-1 depleted worms. Bacteria expressing gfp dsRNA (pPE128.110 in HT115) were used as reference, since RNA interference may induce gene expression changes by itself. C. elegans L1 larvae treated with RNA interference were selected for RNA extraction and hybridization on Affymetrix microarrays. Synchronized wild type L4 animals were grown at 25° on bacteria expressing either gfp, let-418 or mep-1 dsRNA. Eggs were collected by bleaching gravid adults and allowed to hatch in the absence of food at 25°C. Newly hatched L1 larvae were fed on bacteria expressing the different dsRNA for three hours to recover from starvation. Three replicates per RNAi.
Project description:Epigenetic modifications are thought to be important for gene expression changes during development and aging. However, besides the Sir2 histone deacetylase in somatic tissues and H3K4 trimethylation in germlines, there is scant evidence implicating epigenetic regulations in aging. The insulin/IGF-1 signaling (IIS) pathway is a major lifespan regulatory pathway. Here we show that progressive increases in gene expression and loss of H3K27me3 on IIS components are due, at least in part, to increased activity of the H3K27 demethylase UTX-1 during aging. RNAi of the utx-1 gene extended the mean lifespan of C. elegans by ~30%, dependent on DAF-16 activity and not additive in daf-2 mutants. The loss of utx-1 increased H3K27me3 on the Igf1r/daf-2 gene and decreased IIS activity leading to a more "naive" epigenetic state. Like stem cell reprogramming, our results suggest that reestablishing epigenetic marks lost during aging might help "reset" the developmental age of animal cells. Examination of H3K27me3 in young and old worms without or with Utx-1 RNAi.
Project description:This SuperSeries is composed of the following subset Series:; GSE9896: Expression data from wildtype and gas-1 mitochondrial mutant C. elegans; GSE9897: Expression data from 2 wildtype and 8 C. elegans ETC mutants Experiment Overall Design: Refer to individual Series
Project description:Utilizing C. elegans as a model of mitochondrial dysfunction provides insight into cellular adaptations which occur as a consequence of genetic alterations causative of human disease. We characterized genome-wide expression profiles of hypomorphic C. ele; Our goal was to detect concordant changes among clusters of genes that comprise defined metabolic pathways utilizing gene set enrichment analysis. Experiment Overall Design: 3 biological replicates of each C. elegans strain were used as sources of total RNA combined for hybridization to a single Affymetrix whole-genome microarray. Comparison of the data was intended to reveal metabolic pathways downstream of the mutation.
Project description:C. elegans nuclear pore protein NPP-13 associates with small RNA genes transcribed by RNA Polymerase III. To test if the nuclear pore-chromatin interactions play a role in large-scale chromatin organization, we determined nuclear membrane-genome interactions and RNA Polymerase II localization in C. elegans embryos depleted for NPP-13. Genome-wide ChIP-seq and ChIP-chip for nuclear membrane protein LEM-2, RNA Polymerase II (AMA-1) and H3K4me3 were performed in mixed-stage C. elegans embryos depleted for NPP-13. As a control, ChIP was also performed in wild-type embryos treated with empty vector.
Project description:Periodic starvation of animals induces large shifts in metabolism, but may also influence many other cellular systems and can lead to adaption to prolonged starvation conditions. To date, there is limited understanding of how starvation affects gene expression, particularly at the protein level. Here, we have used mass spectrometry‐based quantitative proteomics to identify global changes in the C. elegans proteome due to acute starvation of young adult animals. Measuring changes in abundance of up to 7,000 proteins, we show that acute starvation rapidly alters the levels of hundreds of proteins, many involved in central metabolic pathways, highlighting key regulatory responses. Surprisingly, we also detect changes in the abundance of chromatin‐associated proteins including specific linker histones, histone variants and histone post‐translational modifications associated with the epigenetic control of gene expression. A null mutant for one of these proteins, the histone H3.3 variant HIS‐71, identified a subset of proteins whose abundance no longer varied in response to starvation. This mutant also displayed defects in starvation stress resistance and showed a reduced adult lifespan. To maximise community access to these data, they are presented in an online searchable database, the Encyclopedia of Proteome Dynamics (http://www.peptracker.com/epd/).
Project description:Nuclear pores associate with active protein-coding genes in yeast and have been implicated in transcriptional regulation. Here, we show that in addition to transcriptional regulation, key components of C. elegans nuclear pores are required for processing of a subset of small nucleolar RNAs (snoRNAs) and tRNAs transcribed by RNA Polymerase (Pol) III. Chromatin immunoprecipitation of NPP-13 and NPP-3, two integral nuclear pore components, and importin-ß IMB-1, provides strong evidence that this requirement is direct. All three proteins associate specifically with tRNA and snoRNA genes undergoing Pol III transcription. These pore components bind immediately downstream of the Pol III pre-initiation complex, but are not required for Pol III recruitment. Instead, NPP-13 is required for cleavage of tRNA and snoRNA precursors into mature RNAs, whereas Pol II transcript processing occurs normally. Our data suggest that integral nuclear pore proteins act to coordinate transcription and processing of Pol III transcripts in C. elegans. Genome-wide ChIP-seq and ChIP-chip were performed in mixed-stage C. elegans embryos for nuclear pore proteins NPP-13, NPP-3, IMB-1 and chromatin proteins Pol III (RPC-1), TBP-1, TFC-1 (SFC-1), TFC-4 (TAG-315), and Pol II (AMA-1). For RPC-1 and TBP-1 ChIP-seq, embryos depleted for NPP-13 were also used. Total RNAs from wild-type, NPP-13 RNAi, and IMB-1 RNAi embryos were analyzed by RNA-seq.
Project description:Hsp90 is a molecular chaperone involved in the regulation and maturation of kinases and transcription factors. In C. elegans Hsp90 participates in the development of fertility, maintenance of muscle structure and the regulation of stress response and dauer state. To understand the consequences of Hsp90-depletion we studied Hsp90 RNAi-treated nematodes by DNA microarrays and mass spectrometry. We find that upon development of phenotypes the levels of chaperones and cofactors are increased, while specific proteins related to the innate immune response are specifically depleted. We further uncover Hsp90-dependent signatures of gonad development and larval development. Using reporter strains for the responsive genes skr-5, dod-24 and clec-60, we confirm an influence on the innate immune response in intestinal tissues, while alterations to development become evident in strains reporting on the presence of ZIP-8, CAV-1 and SEPA-1 in the gonad arms and very early embryos. These observations add molecular details to the Hsp90-dependent processes during development and stress responses and imply that multiple interactions of this chaperone system are relevant for the nematode’s life and development.
Project description:From a forward genetic screen for C. elegans genes required for RNAi, we identified rde-10 and through proteomic analysis of RDE-10-interacting proteins, we identified a protein complex containing the new RNAi factor RDE-11, the known RNAi factors RSD-2 and ERGO-1, as well as other candidate RNAi factors. The newly identified RNAi defective genes rde-10 and rde-11 encode a novel protein and a RING-type zinc finger domain protein, respectively. Mutations in rde-10 and rde-11 genes cause dosage-sensitive RNAi deficiencies: these mutants are resistant to low dosage, but sensitive to high dosage of double-stranded RNAs. We assessed the roles of rde-10, rde-11, and the dosage-sensitive RNAi defective genes rsd-2, rsd-6 and haf-6 in both exogenous and endogenous small RNA pathways using high-throughput sequencing and qRT-PCR. These genes are required for the accumulation of secondary siRNAs in both exogenous and endogenous RNAi pathways. Small RNA analysis by deep sequencing in various wild type and mutant C. elegans strains.