Project description:In higher eukaryotes, an important mechanism to tune translation in different tissues and conditions is mTORC1-dependent regulation of tRNAs transcription by RNA polymerase III (Pol III), as the relative amount of tRNAs tightly coordinates with the translational needs of the cell. mTORC1 contributes to regulate protein synthesis through its direct substrate MAF1, which functions as a negative regulator of Pol III transcription in response to stimuli such as serum starvation or rapamycin treatment. Here, we applied ChIP-seq to examine the Pol III occupancy profile in human fibroblasts and report evidence of a genome wide, MAF1-dependent coordinated response to favorable or stress growth conditions. Strikingly, while a set of genes is extremely responsive in terms of Pol III binding, other genes are mostly unperturbed, yet associated with transcriptionally engaged polymerases as revealed by nascent EU-labeled RNA-seq (neuRNA-seq). As shown by DamIP-seq, the responsiveness of a subset of genes is tightly connected to the rapid and transient interaction of MAF1 with DNA-bound Pol III. We performed duplicate ChIP-seq experiments for the Rpc4 (POLR3D) subunit of RNA polymerase III in IMR90hTert cells grown in the presence of fetal bovine serum (FBS), serum starved (SS), serum starved and treated with insulin (SS+I), serum starved and treated with insulin and rapamycin (SS+R+I). Additional ChIP-seq profiles were generated in cells treated with MAF1 siRNAs and serum starved. MAF1 binding was addressed by DamIP-seq, using two replicates per clone of IMR90hTert cells expressing HA-tagged MAF1-DamK9A (2 different clones) or EGFP-DamK9A (2 different clones). To monitor dynamic transcription profiles we did neusRNA-seq in IMR90hTert cells EU-labeled or mock (DMSO)-labeled. For both DamIP-seq and neusRNA-seq, cells were either unperturbed or serum starved.
Project description:In higher eukaryotes, an important mechanism to tune translation in different tissues and conditions is mTORC1-dependent regulation of tRNAs transcription by RNA polymerase III (Pol III), as the relative amount of tRNAs tightly coordinates with the translational needs of the cell. mTORC1 contributes to regulate protein synthesis through its direct substrate MAF1, which functions as a negative regulator of Pol III transcription in response to stimuli such as serum starvation or rapamycin treatment. Here, we applied ChIP-seq to examine the Pol III occupancy profile in human fibroblasts and report evidence of a genome wide, MAF1-dependent coordinated response to favorable or stress growth conditions. Strikingly, while a set of genes is extremely responsive in terms of Pol III binding, other genes are mostly unperturbed, yet associated with transcriptionally engaged polymerases as revealed by nascent EU-labeled RNA-seq (neuRNA-seq). As shown by DamIP-seq, the responsiveness of a subset of genes is tightly connected to the rapid and transient interaction of MAF1 with DNA-bound Pol III. We performed duplicate ChIP-seq experiments for the Rpc4 (POLR3D) subunit of RNA polymerase III in IMR90hTert cells grown in the presence of fetal bovine serum (FBS), serum starved (SS), serum starved and treated with insulin (SS+I), serum starved and treated with insulin and rapamycin (SS+R+I). Additional ChIP-seq profiles were generated in cells treated with MAF1 siRNAs and serum starved. MAF1 binding was addressed by DamIP-seq, using two replicates per clone of IMR90hTert cells expressing HA-tagged MAF1-DamK9A (2 different clones) or EGFP-DamK9A (2 different clones). To monitor dynamic transcription profiles we did neusRNA-seq in IMR90hTert cells EU-labeled or mock (DMSO)-labeled. For both DamIP-seq and neusRNA-seq, cells were either unperturbed or serum starved.
Project description:Ubiquitin ligation is typically executed by hallmark E3 catalytic domains. Two such domains, "cullin-RING" and "RBR", are individually found in several hundred E3 ligases in humans, and collaborate with E2 enzymes to catalyze ubiquitylation. However, the vertebrate-specific CUL9 complex with RBX1 (also called ROC1), of interest due to its tumor suppressive interaction with TP53, uniquely encompasses both cullin-RING and RBR domains. Here, cryo-EM, biochemistry, and cellular assays elucidate a 1.8 MDa hexameric CUL9-RBX1 assembly. Within one dimeric subcomplex, an E2-bound RBR domain is activated by neddylation of its own cullin domain and positioning from the adjacent CUL9-RBX1 in trans. Our data show CUL9 as unique amongst RBX1-bound cullins in dependence on the metazoan-specific UBE2F neddylation enzyme, while the RBR domain protects from deneddylation. Mono-ubiquitylation of TP53 relies on both CUL9's neddylated cullin and RBR domains achieving self-assembled and chimeric cullin-RING/RBR E3 ligase activity.
Project description:The PAQosome (Particle for Arrangement of Quaternary structure) is a twelve-subunit HSP90 co-chaperone involved in the biogenesis of several human protein complexes. Two mechanisms of client selection have previously been identified, namely the selective recruitment of specific adaptors and the differential use of homologous core subunits. Here, we describe a third client selection mechanism by showing that RPAP3, one of the core PAQosome subunits, is phosphorylated at several Ser residues in HEK293 cells. Affinity purification coupled with mass spectrometry (AP-MS) using expression of tagged RPAP3 with single phospho-null mutations at Ser116, Ser119 or Ser121 reveals binding of the unphosphorylated form to several proteins involved in ribosome biogenesis. In vitro phosphorylation assays indicate that the kinase CK2 phosphorylates these RPAP3 residues. This finding is supported by data showing that pharmacological inhibition of CK2 enhances binding of RPAP3 to ribosome preassembly factors in AP-MS experiments. Moreover, silencing of PAQosome subunits interferes with ribosomal assembly factors’ interactome. Altogether, these results indicate that RPAP3 phosphate group addition/removal at specific residues modulates binding to subunits of preribosomal complexes and allows speculating that PAQosome posttranslational modifications is a mechanism of client selection.
Project description:RNA-seq analysis revealed that genes involved in urea uptake and metabolism were significantly upregulated in the Clo1313_2031 deletion strain, suggesting that deletion of Clo1313_2031 mimics nitrogen starvation in C. thermocellum. Additionally, genes encoding the RNF-complex were also more highly expressed and in turn may have a potential role in increasing ethanol production. Samples for RNA-seq were taken from mid-exponential phase (OD ~ 0.33) batch cultures grown in MTC on 4.5 g/l cellobiose
Project description:Wild-type mouse embryonic stem cells are compared with mutants for components of PRC2 including Ezh2-/-, Eed-/-, and Jarid2-/- cells. Chromatin modifications, Gene expression, Pol-II, small-RNA sequencing, and DNA methylation are compared for both cell types. To study genomic and epigentic control of PRC2 in mESCs, we designed gene expression analysis (RNA-Seq and small RNA-Seq), combining with ChIP-Seq analysis of several factors and histone marks from wild-type and distinct PRC2 mutants including wild-type, Ezh2-/-, Eed-/-, and Jarid2-/-.
Project description:MicroRNAs (miRNAs) have been shown to play an important role in many different cellular, developmental, and physiological processes. Accordingly, numerous methods have been established to identify and quantify miRNAs. The shortness of miRNA sequence results in a high dynamic range of melting temperatures and, moreover, impedes a proper selection of detection probes or optimized PCR primers. While miRNA microarrays allow for massive parallel and accurate relative measurement of all known miRNAs, they have so far been less useful as an assay for absolute quantification. Here, we present a microarray based approach for global and absolute quantification of miRNAs. The method relies on an equimolar pool of about 1000 synthetic miRNAs of known concentration which is used as an universal reference and labeled and hybridized in a dual colour approach on the same array as the sample of interest. Each single miRNA is quantified with respect to the universal reference outbalancing bias related to sequence, labeling, hybridization or signal detection method. We demonstrate the accuracy of the method by various spike in experiments. Further, we quantified miRNA copy numbers in liver samples and CD34(+)CD133(-) hematopoietic stem cells. We analyzed to which extend the universal reference can be used as a tool for the relative quantification of miRNAs across multiple experiments. We compared the results of direct hybridizations i.e. sample vs. sample to those of indirect hybridizations i.e. sample vs. UR. For the direct hybridizations, we hybridized 5µg liver total RNA vs 5 µg brain total RNA (n = 3) and for the indirect hybridization 5 µg liver or brain total RNA vs UR (5 fmol/miRNA) (n = 3). We calculated the so-called re-ratios for the UR experiments by dividing the signal ratios of the liver vs. UR array by the respective brain vs. UR array gaining a liver vs. brain re-ratio. Each RNA sample was mixed with 5 fmol of each of 18 RNA oligonucleotides reverse complement to miRControl 3 probes and subsequently fluorescently labelled. The RNA mix was hybridized in a dual colour approach to microarrays. The mean ratios of all probes were normalized to the median of the ratios detected for the spiked 18 synthetic RNA oligonucleotides reverse complement to miRControl 3 probes.
Project description:MicroRNAs (miRNAs) have been shown to play an important role in many different cellular, developmental, and physiological processes. Accordingly, numerous methods have been established to identify and quantify miRNAs. The shortness of miRNA sequence results in a high dynamic range of melting temperatures and, moreover, impedes a proper selection of detection probes or optimized PCR primers. While miRNA microarrays allow for massive parallel and accurate relative measurement of all known miRNAs, they have so far been less useful as an assay for absolute quantification. Here, we present a microarray based approach for global and absolute quantification of miRNAs. The method relies on an equimolar pool of about 1000 synthetic miRNAs of known concentration which is used as an universal reference and labeled and hybridized in a dual colour approach on the same array as the sample of interest. Each single miRNA is quantified with respect to the universal reference outbalancing bias related to sequence, labeling, hybridization or signal detection method. We demonstrate the accuracy of the method by various spike in experiments. Further, we quantified miRNA copy numbers in liver samples and CD34(+)CD133(-) hematopoietic stem cells. Total liver RNA was mixed with 2.5 fmol of each of 18 RNA oligonucleotides reverse complement to miRControl 3 probes and subsequently fluorescently labelled by 3â ligation. Total RNA mix was hybridized in a dual colour approach to microarrays versus a second labelled synthetic miRNA pool (n = 6). The synthetic miRNA pool consisted of 2.5 fmol of each of 891 non redundant miRNAs sequences and miRControl 3 sequences. The array data was normalized by calculating the median of the miRControl 3 present in the liver and UR sample. The miRNA amount was calculated with respect to the corresponding miRNA in the UR.
Project description:Intracellular bacterial pathogens inject a cocktail of effector proteins into host cells to hijack diverse cellular processes and promote their survival and proliferation. Salmonella enterica serovar Typhimurium (STm) uses two Type 3 secretion system (T3SS) to deliver a suite of effector proteins into host cells, however, knowledge of their host-targets remains sparse. To systematically map STm effector-host protein-protein interactions (PPIs) during active infection, we generated a library of 32 STm strains expressing affinity-tagged effector proteins from their endogenous chromosomal loci. Tagged-effector strains were then used to infect macrophages or epithelial cells, and PPIs were detected by Affinity-Purification Quantitative Mass-Spectrometry (AP-QMS) under both native and cross-linking conditions. We recovered 25 previously described effector-host PPIs, along with 421 novel interactions across the two cell lines tested, as well as several effector-effector PPIs. While effectors converged on specific host cellular processes, which varied across cell types, most had multiple host targets. Using reciprocal co-immunoprecipitations, we could validated 13 out of 22 new PPIs, demonstrating an accuracy of at least 59% for the AP-QMS approach. To illustrate the utility of this resource for discovering novel infection biology, we first showed that SseJ and SseL cooperate to control cholesterol transport at the Salmonella Containing Vacuole (SCV) via the Niemann-Pick C1 protein (NPC1). Second, we uncovered that PipB directly binds and recruits the organelle contact site protein PDZD8 to the SCV. Third, we elucidated a novel mechanism whereby the effector kinase SteC promotes host actin bundling, by directly interacting and phosphorylating formin-like proteins. Overall, we provide a systems-wide host-bacterial pathogen physical interactome resource, to our knowledge the first in an infection context, with broad implications for effector function and cooperation.
Project description:Comparison of ds-cDNA, Indirect and Direct Random Labeling Methods for gene expression analysis on the NimbleGen platform. Expression profiles from artemisinic acid-producing S. cerevisiae strain EPY330 and non-producing strain EPY338 are compared for each labeling method tested. The labeling methods and their comparison are described in detail in Ouellet et al., BMC Biotech 2009. Strains were described in detail previously in Ro et al. BMC Biotechnol 2008, 8(1):83 [PMID: 18983675] RNA pools from strains EPY330 (sample A) and EPY338 (sample B) were reverse-transcribed and labeled in triplicate with the ds-cDNA, the Indirect and the new Direct Random method and hybridized in parallel on NimbleGen 4-plex arrays.