Type 2 Diabetes, obesity and metabolic syndrome are pathologies impacting a large population worldwide where insulin resistance plays a central role. These pathologies are usually associated to a dysregulation of insulin secretion leading to a chronic exposure of the tissues to high insulin levels (i.e. hyperinsulinemia) what diminishes the concentration of key downstream elements causing insulin resistance. The complexity of the study of insulin resistance relies on the heterogeneity of the metabolic states where it’s observed. In consequence, animal models for the study of insulin resistance, can not completely recapitulate the metabolic status of insulin resistant humans, what is translated in contradictory observations. To contribute to the understanding of the mechanisms triggering insulin resistance we have developed a zebrafish model to study insulin metabolism and its associated disorders. Zebrafish embryos appeared to be sensitive to human recombinant insulin, becoming insulin resistant when exposed to a high dose of the hormone, as confirmed by glucose measurements. Moreover RNAseq-based transcriptomic profiling of these embryos revealed a strong down regulation of a number of immune relevant genes as a consequences of the exposure to hyperinsulinemia. Interestingly, as an exception, the negative immune modulator ptpn6 appeared to be up regulated in insulin resistant embryos. Knockdown of ptpn6 showed to counteract the observed down regulation of the immune system and insulin signalling pathways effects at the transcriptional level caused by hyperinsulinemia. These results show that ptpn6 is a mediator of the metabolic switch between insulin sensitive and insulin resistant states. Our zebrafish model for hyperinsulinemia has therefore demonstrated it suitability to discover novel regulators of insulin resistance. In addition, our data will be very useful to further study the function of immunological determinants in a non-obese model system. Overall design: 16 samples in total were analyzed. 4 replicates from control samples (injected with PBS) and 4 replicates of insulin injected samples at 0.5 hpi and 4 hpi. In each sample 10 embryos were pooled.
Hyperinsulinemia induces insulin resistance and immune suppression via Ptpn6/Shp1 in zebrafish.
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View SamplesScavenger receptors on the cell surface of macrophages play an important role in host defence through their ability to bind microbial ligands and induce phagocytosis. Concurrently, signal transduction pathways are initiated that aid in defence mechanisms against the invading microbe. Here we report on the function of scavenger receptor Marco (macrophage receptor with collagenous structure) during infection of zebrafish embryos with Mycobacterium marinum, a close relative of Mycobacterium tuberculosis. Morpholino knockdown demonstrates that Marco is required for the rapid phagocytosis of M. marinum following intravenous infection. Furthermore, gene expression analysis shows that Marco controls the initial transient pro-inflammatory response to M. marinum and remains a determining factor for the immune response signature at later stages of infection. Increased bacterial burden following marco knockdown indicates that this scavenger receptor is important for control of M. marinum growth, likely due to delayed phagocytosis and reduced pro-inflammatory signalling observed under conditions of Marco deficiency Overall design: Embryos were injected at the one cell stage with a morpholino targeting marco, or with the standard control morpholino from GeneTools for comparison. Subsequently, at 24 hours post fertilization (hpf) the morphants and their controls were manually dechorionated at 24 hpf and at 28 hpf they were infected by injecting 200 colony forming units of M. marinum Mma20 into the caudal vein, or mock-injected with PBS/2%PVP. After injections embryos were transferred into fresh egg water containing 0.003% 1-phenyl-2-thiourea (Sigma-Aldrich) to prevent melanization and incubated for 4 days at 28°C. After the incubation period, infected and uninfected morphants, mutants and their controls were imaged and groups of 30 embryos were snap-frozen in liquid nitrogen and RNA was isolated for Illumina RNAseq analysis.
Phagocytosis of mycobacteria by zebrafish macrophages is dependent on the scavenger receptor Marco, a key control factor of pro-inflammatory signalling.
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View SamplesBoth embryonic and adult zebrafish Mycobacterium marinum infection studies have contributed to our knowledge of the development and function of tuberculous granulomas, which are typical for mycobacterial pathogenesis. In this review we discuss how transcriptome profiling studies have helped to characterize this infection process and we include new RNA sequencing (RNA-Seq) data that reveals three main phases in the host response to M. marinum during the early stages of granuloma development in zebrafish embryos and larvae. The late-phase response shares common components with the strong and acute host transcriptome response that has previously been reported for S. typhimurium infection in zebrafish embryos. In contrast, the early/mid-phase response to M. marinum infection, characterized by suppressed pro-inflammatory signaling, is strikingly different from the acute response to S. typhimurium infection. Furthermore, M. marinum infection shows a collective and strongly fluctuating regulation of lipoproteins, while S. typhimurium infection has pronounced effects on amino acid metabolism and glycolysis. Overall design: Embryos were infected at 28 hpf by injecting 250 colony forming units of M. marinum Mma20 in 2%PVP into the caudal vein, or mock-injected with PBS/2%PVP. After injections, embryos were transferred into fresh egg water containing 0.003% 1-phenyl-2-thiourea (Sigma-Aldrich) to prevent melanization and incubated at 28°C. After the incubation period, infected and uninfected groups of 30 embryos were snap-frozen in liquid nitrogen and RNA was isolated for Illumina RNAseq analysis. Samples were taken at the following timepoints: 2, 4, 6, 8 hpi and 1, 2, 3, 4, 5 dpi.
Transcriptomic Approaches in the Zebrafish Model for Tuberculosis-Insights Into Host- and Pathogen-specific Determinants of the Innate Immune Response.
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View SamplesWe use the zebrafish embryo model to study the innate immune response against polystyrene particles. Therefore, we injected 700nm polystyrene into the yolk at 2 dpf and took samples at 1 and 3 days post injection. Overall design: This deep sequence study was designed to determine the gene expression profile by polystyrene particle toxicity. RNA was isolated from embryos at 1 and 3 days post injection. Wildtypes zebrafish embryos were micro-injected into the yolk (2dpf) with 1nl of 5mg/ml of 700nm red fluorescent polystyrene particles suspended in PVP (Polyvinylpyrrolidone) (n=3), mock injected with pvp (n=2), or Non-injected as a control (n=3). After injections embryos were transferred into fresh egg water and incubated at 28°C. At 1 and 3 days post injection 10 embryos per group were snap-frozen in liquid nitrogen, and total RNA was isolated using TRIZOL reagent.
Pathway analysis of systemic transcriptome responses to injected polystyrene particles in zebrafish larvae.
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View SamplesCardiomyopathies-associated metabolic pathologies (e.g. T2D and insulin resistance) are a leading cause of mortality. It is known that the association between the pathologies works in both directions, where heart failure can lead to metabolic derangements such as insulin resistance. This intricate crosstalk exemplifies the importance of a fine coordination between one of the most energy demanding organs and an equilibrated carbohydrate metabolism. In this light, to assist in the understanding of the role of insulin regulated glucose transporters and the development of cardiomyopathies, we set out to study GLUT12. GLUT12 is a novel insulin regulated GLUT expressed in the main insulin sensitive tissues such as cardiac and skeletal muscle and adipose tissue. This study investigates the role of GLUT12 in heart failure and diabetes by developing a model for glut12 deficiency in zebrafish. Overall design: 6 samples in total were analyzed. 3 replicates from control samples (injected with contol MO) and 3 replicates from glut12 morphant samples (injected with glut12 splice MO). In each sample 10 embryos were pooled.
GLUT12 deficiency during early development results in heart failure and a diabetic phenotype in zebrafish.
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View SamplesHost pathways mediating changes in immune states elicited by intestinal microbial colonization are incompletely characterized. Here we describe alterations of the host immune state induced by colonization of germ-free zebrafish larvae with an intestinal microbial community or single bacterial species. We show that microbiota-induced changes in intestinal leukocyte subsets and whole-body host gene expression are dependent on the innate immune adaptor gene myd88. Similar patterns of gene expression are elicited by colonization with conventional microbiome, as well as mono-colonization with two different zebrafish commensal bacterial strains. By studying loss-of-function myd88 mutants, we find that colonization suppresses Myd88 at the mRNA level. Tlr2 is essential for microbiota-induced effects on myd88 transcription and intestinal immune cell composition. Overall design: Zebrafish embryos were sterilized to generate germ-free groups. Transcriptomic responses in germ-free embryos were were assessed relative to colonized embryos, either colonized by complex and in characterized microbial communities (Conventionalozation) or by specefic single commensal bacterial species (monoassociation, Exiguobacterium/Chryseobacterium)
Intestinal microbiome adjusts the innate immune setpoint during colonization through negative regulation of MyD88.
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View SamplesWe use the Tlr2 mutant of zebrafish embryos model to study the transcriptome response to Mycobacterium marinum infection. We injected M.marinum into the caudal vein at 28 hours post fertilization and took samples at 4 days post infection. Overall design: This deep sequence study was designed to determine the gene expression profile in the Tlr2 mutant and heterozygote by M.marinum infection. RNA was isolated at 4 days post infection. Tlr2 mutants and heterozygotes zebrafish embryos were micro-injected into the caudal vein with 150CFU M.marinum, or PBS as a control at 28 hours post fertilization. After injections embryso were transerred into fresh egg water and incubated at 28 degree. At 4 days post infection triplicateds of 10 embryos per condition were snapfrozen in liquid nitogen, and total RNA was isolated using TRIZOL reagent.
Infection and RNA-seq analysis of a zebrafish tlr2 mutant shows a broad function of this toll-like receptor in transcriptional and metabolic control and defense to Mycobacterium marinum infection.
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View SamplesIn this study, zebrafish ZF4 and PAC2 cells were seeded in 0.5% or 1% FCS, respectively, and grown to 85% confluence and subsequently cultured for 24 hours without serum. Then they were treated with either medium without serum or medium with serum (ZF4 in 10% FCS and PAC2 in 15% FCS).After 6 hours, RNA was extracted from the cells and analyzed using the Affymetrix GeneChip Zebrafish Genome Array (GeneChip 430). There are 15502 oligonucleotide sets on each Affymetrix chip, 14895 of which can be linked to a UniGene assignment (Unigene data set 06-12-2005).
Genetic and transcriptome characterization of model zebrafish cell lines.
Cell line, Compound
View SamplesTranscriptional profiling of the zebrafish embryonic host response to a systemic bacterial infection with Salmonella typhimurium (strain SL1027); comparison between traf6 knock-down and control morpholino treated embryos. Overall design: All infection experiments were performed using mixed egg clutches of ABxTL strain zebrafish. Embryos injected with traf6 morpholino or a 5bp mismatch control morpholino were staged at 27 hours post fertilization (hpf) by morphological criteria and approximately 250 cfu of DsRed expressing Salmonella bacteria were injected into the caudal vein close to the urogenital opening. As a control an equal volume of PBS was likewise injected. Pools of 20-40 infected and control embryos were collected 8 hours post infection (hpi). The whole procedure was preformed in triplicate on separate days. Total RNA of the biological triplicates was pooled using equal amounts of RNA prior to RNAseq library preparation.
Transcriptome analysis of Traf6 function in the innate immune response of zebrafish embryos.
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View SamplesMacrophage expressed gene 1 (MPEG1) encodes an evolutionary conserved protein with a predicted Membrane Attack Complex/Perforin domain associated with host defence against invading pathogens. In vertebrates, MPEG1 is an integral membrane protein of macrophages, but how it contributes to the macrophage defence mechanisms remains unknown. Zebrafish have three copies of MPEG1, two of which (mpeg1 and mpeg1.2) are expressed in macrophages whereas the third could be a pseudogene. The mpeg1 and mpeg1.2 genes show differential regulation during infection of zebrafish embryos with the bacterial pathogens, Mycobacterium marinum and Salmonella typhimurium. While mpeg1 is down-regulated during infection with both pathogens, mpeg1.2 is infection inducible. Up-regulation of mpeg1.2 is partially dependent on the presence of functional Mpeg1, and requires the Toll-like receptor adaptor molecule MyD88 and transcription factor NF?B. Knockdown of mpeg1 alters the immune response to M. marinum infection and results in increased bacterial burden. In S. typhimurium infection, both mpeg1 and mpeg1.2 knockdown increase bacterial burdens, but mpeg1 morphants show an increased survival rate. The combined results of these two in vivo infection models support the anti-bacterial function of the Mpeg1 family and indicate that the intricate cross-regulation of the two mpeg1 copies aids the zebrafish host in combatting infection Overall design: Embryos were injected at the one cell stage with a morpholino targeting mpeg1, or with the standard control morpholino from GeneTools, or with a morpholino targeting ptpn6 (Kanwal et al., 2013, J. Immunol 190:1631-45) for comparison. Subsequently, at 24 hours post fertilisation (hpf) the morphants and their controls were manually dechorionated at 24 hpf and at 28 hpf they were infected by injecting 200 colony forming units of M. marinum Mma20 into the caudal vein, or mock-injected with PBS/2%PVP. After injections embryos were transferred into fresh egg water containing 0.003% 1-phenyl-2-thiourea (Sigma-Aldrich) to prevent melanisation and incubated for 4 days at 28°C. After the incubation period, infected and uninfected morphants, mutants and their controls were imaged and groups of 30 embryos were snap-frozen in liquid nitrogen and RNA was isolated for Illumina RNAseq analysis.
Macrophage-expressed perforins mpeg1 and mpeg1.2 have an anti-bacterial function in zebrafish.
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