Project description:Sequencing-based profiling of ribose methylations is a new approach that allows for experiments adrressing dynamic changes on a large scale. Here, we apply such a method to spliceosomal snRNAs present in human whole cell RNA. Analysis of solid tissue samples confirmed all previously known sites and demonstrated close to full methylation at almost all sites. Methylation changes were revealed in biological experimental settings, using T cell activation as an example, and in the T cell leukemia model, Jurkat cells. Such changes could impact the dynamics of snRNA interactions during the spliceosome cycle and affect mRNA splicing efficiency and splicing patterns.
Project description:A sequencing-based profiling method (RiboMeth-seq) for ribose methylations was used to study methylation patterns in mouse adult tissues and during development. In contrast to previous reports based on studies of human cancer cell lines, almost all methylation sites were close to fully methylated in adult tissues. A subset of sites was differentially modified in developing tissues compared to their adult counterparts and showed clear developmental dynamics. This provides the first evidence for ribosome heterogeneity at the level of rRNA modifications during mouse development. In a prominent example, the expression levels of SNORD78 during development appeared to be regulated by alternative splicing of the Gas5 host-gene and to correlate with the methylation level of its target site at LSU-G4593. The results are discussed in the context of the specialized ribosome hypothesis.
Project description:Exogenous signals from drug-stressed cancer cells accelerate the proliferation of neighboring tumor cells and promote to acquire a more aggressive phenotype. We have recently found an exciting phenomenon: drug-stressed cancer cells secrete various components of the spliceosome: proteins and a number of snRNAs. We have observed this phenomenon both in vitro (culture media from cancer cell lines [Pavluykov M. et al., 2018]) and in vivo (ovarian cancer ascites after chemotherapy [Shender V. et al., 2014]). The aim of this study was to elucidate the role of secreted spliceosomal snRNAs in intercellular communication. We constructed synthetic U12 and U6atac snRNAs close to the natural structure, including some non-canonical nucleotides imitating post-transcriptional RNA modifications. RNAseq analysis of SKOV3 cells transfected with U6atac or U12 snRNA analogs has shown that both exogenous snRNAs lead to an increase of abundance of proteins related to cell cycle regulation and M phase. It has been recently shown that a number of spliceosomal proteins affect regulation of the cell cycle, in particular the M phase [Maslon et al., 2014]. Here we demonstrated that not only spliceosomal proteins but also spliceosomal snRNAs (U12 and U6atac) affect cell cycle gene expression. This study revealed previously unknown signaling molecules in the microenvironment of ovarian cancer that have potential clinical significance.
Project description:The major information-carrying macromolecules in the cell, DNA, RNA, and protein, carry an additional layer of information on top of their sequence in the form of modifications of residues. The modifications provide additional functional groups and impact the structure and function of the molecules. Cellular RNA molecules contain more than 100 different modifications and are found in all domains of life and in all major classes of RNA in eukaryotic organisms. Together these modifications constitute the epitranscriptome of which two-thirds are methylations with 2’-O methylation of the ribose moiety of the nucleotide as the most abundant. Many aspects of ribose methylation are underexplored because the existing methods for their detection are laborious and can only address a few modification sites at a time. Here, we introduce RiboMeth-Seq, a high-throughput sequencing based method and applies it to yeast ribosomal RNA. We detect all of the known as well as one new methylation site and provide evidence for hypomethylation at specific residues. Furthermore we demonstrate that many methylation events are interdependent and outline the timing of modifications during ribosome biogenesis. Our results demonstrate a novel and efficient approach to understanding of the role of modifications in ribosomal RNA folding and ribosome function. Recent evidence point to changes in ribose methylation patterns in cancer ribosomes and we anticipate that RiboMeth-Seq can be applied here as well as to other diseases in which ribosomes are affected, including the heritable ribosomopathies. Yeast RNA was degraded at denaturing conditions into small fragments, long enough to be mapped by sequence alignment to the reference genome (20-40 nucleotides). The fragments were ligated to RNA oligos using a tRNA ligase that was mutated to remove its kinase activity, reverse transcribed and the cDNA used as input for Ion semiconductor sequencing. The first and last nucleotides of the inserts were recorded using the full sequence for mapping and the read-ends plotted against the sequence. 2'-O-Methylated RNA positions are protected from cleavage, and read ends from such positions are therefore underrepresented compared to the surrounding positions.
Project description:The major information-carrying macromolecules in the cell, DNA, RNA, and protein, carry an additional layer of information on top of their sequence in the form of modifications of residues. The modifications provide additional functional groups and impact the structure and function of the molecules. Cellular RNA molecules contain more than 100 different modifications and are found in all domains of life and in all major classes of RNA in eukaryotic organisms. Together these modifications constitute the epitranscriptome of which two-thirds are methylations with 2’-O methylation of the ribose moiety of the nucleotide as the most abundant. Many aspects of ribose methylation are underexplored because the existing methods for their detection are laborious and can only address a few modification sites at a time. Here, we introduce RiboMeth-Seq, a high-throughput sequencing based method and applies it to yeast ribosomal RNA. We detect all of the known as well as one new methylation site and provide evidence for hypomethylation at specific residues. Furthermore we demonstrate that many methylation events are interdependent and outline the timing of modifications during ribosome biogenesis. Our results demonstrate a novel and efficient approach to understanding of the role of modifications in ribosomal RNA folding and ribosome function. Recent evidence point to changes in ribose methylation patterns in cancer ribosomes and we anticipate that RiboMeth-Seq can be applied here as well as to other diseases in which ribosomes are affected, including the heritable ribosomopathies.
Project description:We used a whole-genome microarray based on the sequenced strain Lactobacillus sakei 23K to study ribose catabolism in three Lactobacillus sakei strains by screening for differentially expressed genes when grown on ribose compared to glucose
Project description:Growth of B. breve UCC2003 on ribose leads to the transcriptional induction of the rbsACBDK gene cluster. Generation and phenotypic analysis of an rbsA insertion mutant established that the rbs gene cluster is essential for ribose utilization, and that its transcription is likely regulated by a LacI-type regulator encoded by rbsR, located immediately upstream of rbsA. Gel mobility shift assays using purified RbsRHis indicate that the promoter upstream of rbsABCDK is negatively controlled by RbsRHis binding to an 18-bp inverted repeat and that RbsRHis binding activity is modulated by D-ribose. The rbsK gene of the rbs operon of B. breve UCC2003 was shown to specify a ribokinase (EC 2.7.1.15), which specifically directs its phosphorylating activity towards D-ribose, converting this pentose sugar to ribose-5-phosphate. In order to investigate differences in global gene expression upon growth of B. breve UCC2003 on ribose, or a combination of ribose and glucose, as compared to glucose, DNA microarray experiments were performed. Total RNA was isolated from B. breve UCC2003 cultures grown on ribose, a combination of ribose and glucose, or glucose. All experiments were performed in duplicate. A dye swap was performed in one of the two biological replicates.
Project description:Histone methylations play a major role in regulating the chromatin state and gene expression, yet little is known about their involvement in differential gene expression and function of memory CD8 T cells. Here, we report a genome-wide analysis of two histone H3 methylations (H3K4me3 and H3K27me3) and gene expression in naïve, central (TCM) and effector (TEM) memory CD8 T cells. Analysis of 16,314 annotated genes in CD8 T cell subsets revealed that gene expression were positively correlated with the levels of H3K4me3 and negatively correlated with the levels of H3K27me3 in these gene loci. The correlation between differential H3K4me3 orH3K27me3 levels with gene expressions in memory CD8 T cells displayed four distinct modes: repressive, active, poised, and bivalent, reflecting their complex regulation and different function of these genes. Furthermore, accessible chromatin states of different gene loci were preferentially influenced by different histone modifications as demonstrated here high levels of H3K9ac found in active gene loci without high levels of H3K4me3. These findings reveal a histone methylation based complex regulation of differential gene expression in memory CD8 T cells. Thus, change of chromatin structure mediated by histone methylation may serve a fundamental basis for the rapid transcriptional response of memory CD8 T cells. genome-wide analysis of two histone H3 methylations (H3K4me3 and H3K27me3) in naïve, central (TCM) and effector (TEM) memory CD8 T cells.