Project description:Adenosine DeAminases acting on RNA (ADAR) catalyzes adenosine-to-inosine (A-to-I) conversion within RNA duplex structures. While A-to-I editing is often dynamically regulated in a spatial-temporal manner, the mechanisms underlying its tissue-selective restriction remain elusive. We have previously reported that transcripts of voltage-gated calcium channel CaV1.3 are subject to brain-selective A-to-I RNA editing by ADAR2. Here, we show that editing of CaV1.3 mRNA is dependent on a 40 bp RNA duplex formed between exon 41 and an evolutionarily conserved editing site complementary sequence (ECS) located within the preceding intron. Heterologous expression of a mouse minigene that contained the ECS, intermediate intronic sequence and exon 41 with ADAR2 yielded robust editing. Interestingly, editing of CaV1.3 was potently inhibited by serine/arginine-rich splicing factor 9 (SRSF9). Mechanistically, the inhibitory effect of SRSF9 required direct RNA interaction. Selective down-regulation of SRSF9 in neurons provides a basis for the neuron-specific editing of CaV1.3 transcripts.
Project description:Coleoid cephalopods possess a highly complex nervous system and a rich behavioral repertoire that is unique within the invertebrates and is comparable to – but evolved independently from – the vertebrates (Shigeno et al. 2018). To explain this complexity, previous studies have implicated a unusually high level of mRNA editing in transcripts expressed in both the octopus and squid nervous system (Albertin et al. 2015; Alon et al. 2015; Liscovitch-Brauer et al. 2017). We have sequenced RNA across 18 tissues from the octopus O. vulgaris, and analyzed the extent of mRNA isoform usage as well as the expression of microRNAs in the nervous system in comparison to non-neuronal tissues.
Project description:The goal of this study is to identify global changes in gene expression that accompany induction of site-specific RNA editing that targets the SDHB gene in monocyte-enriched peripheral blood mononuclear cell cultures. The results provide important information to understand the function of this programmed SDHB RNA mutation within the context of global gene expression changes that occur in cultured immune cells when the editing is induced. The study also specifically tests whether expression changes occur in SDH subunit genes, cytidine deaminase family of genes and hypoxia-inducible pathways. Overall design includes pairwise comparison of total gene expression profiles from uncultured cold-aggregated PBMCs (day 0), low-editing (culture day 3) and high-editing (culture days 5-8) samples, each from 4 donors. Submitted manuscript reported summary results from comparison of cultured low- and high-editing samples.
Project description:RNA editing by adenosine deamination is well-positioned to diversify proteomes, but it is infrequently used for this purpose. Recent reports have suggested that squid may be an exception. We show that extensive recoding by RNA editing is an invention of the behaviorally sophisticated coleoid cephalopods, with tens of thousands of evolutionarily conserved sites. Editing is enriched in the nervous system and targets excitability and neuronal morphology. Many edited codons are translated into protein and in some cases cause functional changes. The genomic sequence flanking these sites is highly conserved to maintain the structures required for editing, suggesting that the process confers a selective advantage. Due to the large number of sites, the surrounding conservation greatly reduces the number of mutations and genomic polymorphisms that accumulate in protein coding regions. This trade-off between genome evolution and transcriptome plasticity highlights the importance of RNA recoding as a novel strategy for neural complexity.
Project description:Alternative splicing and mRNA editing are known to contribute to transcriptome diversity. Although alternative splicing is pervasive and known to contribute to a variety of pathologies, including cancer, the genetic context for individual differences in isoform usage is still evolving. Similarly, although mRNA editing is ubiquitous and associated with important biological processes such as intracellular viral replication and cancer development, individual variations in and the genetic transmissibility of mRNA editing are equivocal. Here, we have used linkage analysis to show that both mRNA editing and alternative splicing are regulated by the macrophage genetic background and environmental cues. We show that distinct loci, potentially harboring variable splice factors, regulate the splicing of multiple transcripts. Additionally, we show that individual genetic variability at the Apobec1 locus results in differential rates of C-to-U(T) editing in murine macrophages; with mouse strains expressing mostly a truncated isoform of Apobec1 exhibiting lower rates of editing. As a proof of concept, we have used linkage analysis to identify 36 high confidence novel edited sites. These results provide a novel and complementary method that can be used to identify C-to-U editing sites in individuals segregating at specific loci and show that, beyond individual DNA sequence and structural changes, differential isoform usage and mRNA editing can contribute to intra-species genomic and phenotypic diversity. Bone marrow derived macrophages (BMDM) from female AxB/BxA mice were left unstimulated or stimulated with IFNG/TNF, or CpG for 18 hrs or infected with infected with type II (Pru A7) for 8 hrs. The transcriptional response was then measured using the illumina RNA-seq protocol on an illumuna HiSeq 2000.
Project description:The light-organ symbiosis between the squid Euprymna scolopes and the luminous bacterium Vibrio fischeri offers the opportunity to decipher the hour-by-hour events that occur during the natural colonization of an animal's epithelial surface by its microbial partners. To determine the genetic basis of these events, a glass-slide microarray was used to characterize the light-organ transcriptome of juvenile squid in response to the initiation of symbiosis. Patterns of gene expression were compared between animals not exposed to the symbiont, exposed to the wild-type symbiont, or exposed to a mutant symbiont defective in either of two key characters of this association: bacterial luminescence or autoinducer (AI) production. Hundreds of genes were differentially regulated as a result of symbiosis initiation, and a hierarchy existed in the magnitude of the host's response to three symbiont features: bacterial presence > luminescence > AI production. Putative host receptors for bacterial surface molecules known to induce squid development are up-regulated by symbiont light production, suggesting that bioluminescence plays a key role in preparing the host for bacteria-induced development. Further, because the transcriptional response of tissues exposed to AI in the natural context (i.e., with the symbionts) differed from that to AI alone, the presence of the bacteria potentiates the role of quorum signals in symbiosis. Comparison of these microarray data with those from other symbioses, such as germ-free/conventionalized mice and zebrafish, revealed a set of shared genes that may represent a core set of ancient host responses conserved throughout animal evolution. Six experimental treatments of juvenile animals were performed for the microarray matrix: uncolonized (Apo); uncolonized, but supplemented with AI (Apo + AI); colonized by wild-type V. fischeri (wild type); colonized by a mutant defective in luciferase synthesis (luxA); colonized by a mutant defective in AI synthesis (luxI); and, colonized by the luxI mutant, but supplemented with AI (luxI + AI). At 18 h postinoculation, animals were anesthetized in 2% ethanol in HOSW, and the light organs were removed into RNAlater (Ambion Biosystems).
Project description:The light-organ symbiosis between the squid Euprymna scolopes and the luminous bacterium Vibrio fischeri offers the opportunity to decipher the hour-by-hour events that occur during the natural colonization of an animal's epithelial surface by its microbial partners. To determine the genetic basis of these events, a glass-slide microarray was used to characterize the light-organ transcriptome of juvenile squid in response to the initiation of symbiosis. Patterns of gene expression were compared between animals not exposed to the symbiont, exposed to the wild-type symbiont, or exposed to a mutant symbiont defective in either of two key characters of this association: bacterial luminescence or autoinducer (AI) production. Hundreds of genes were differentially regulated as a result of symbiosis initiation, and a hierarchy existed in the magnitude of the host's response to three symbiont features: bacterial presence > luminescence > AI production. Putative host receptors for bacterial surface molecules known to induce squid development are up-regulated by symbiont light production, suggesting that bioluminescence plays a key role in preparing the host for bacteria-induced development. Further, because the transcriptional response of tissues exposed to AI in the natural context (i.e., with the symbionts) differed from that to AI alone, the presence of the bacteria potentiates the role of quorum signals in symbiosis. Comparison of these microarray data with those from other symbioses, such as germ-free/conventionalized mice and zebrafish, revealed a set of shared genes that may represent a core set of ancient host responses conserved throughout animal evolution.
Project description:Correct pairing of amino acids and tRNA is prerequisite for correct translation of genetic information during protein biosynthesis. Here, we present effects of proteome-wide isoleucine mistranslation in Escherichia coli induced by editing-defective isoleucyl-tRNA synthetase (IleRS). Two types of mistranslation were investigated: substitution of isoleucine (Ile) with either canonical (valine) or noncanonical (norvaline) amino acid. The effects of Ile to Val and Ile to Nva mistranslation were explored on proteome level. High level of Ile substitutions were achieved in editing-deficient strain, leading to excessive protein aggregation. Protein aggregates were analized by LC-MS/MS. Also, interaction of mistranslated proteins with DnaK was explored. The DnaK clients were isolated by pull-down, using endogenously expressed His-tagged DnaK.