Transcriptional responses of Dictyostelium discoideum exposed to different classes of bacteria
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ABSTRACT: Dictyostelium discoideum amoebae feed by ingesting bacteria, then killing them in phagosomes. Ingestion and killing of different bacteria have been shown to rely on largely different molecular mechanisms. One would thus expect that D. discoideum adapts its ingestion and killing machinery when encountering different bacteria. In this study, we investigated by RNA sequencing if and how D. discoideum amoebae respond to the presence of different bacteria by modifying their gene expression patterns. Each bacterial species analyzed induced a specific modification of the transcriptome. Bacteria such as Bacillus subtilis, Klebsiella pneumoniae, or Mycobacterium marinum induced a specific and different transcriptional response, while Micrococcus luteus did not trigger a significant gene regulation. Although folate has been proposed to be one of the key molecules secreted by bacteria and recognized by hunting amoebae, it elicited a very specific and restricted transcriptional signature, distinct from that triggered by any bacteria analyzed here. Our results indicate that D. discoideum amoebae respond in a highly specific, almost non-overlapping manner to different species of bacteria. We additionally identify specific sets of genes that can be used as reporters of the response of D. discoideum to different bacteria.
Project description:Transcriptional profiling of D. discoideum revealed sets of genes whose expression is enriched in amoebae interacting with different species of bacteria, including sets that appear specific to amoebae interacting with Gram(+), or with Gram(-) bacteria. In a genetic screen utilizing the growth of mutant amoebae on a variety of bacteria as a phenotypic readout, we identified amoebal genes that are only required for growth on Gram(+) bacteria, including one that encodes the cell surface protein gp130, as well as several genes that are only required for growth on Gram(-) bacteria including one that encodes a putative lysozyme, AlyL. These genes are required for parts of the transcriptional response of wild-type amoebae, and this allowed their classification into potential response pathways.
Project description:Transcriptional profiling of D. discoideum revealed sets of genes whose expression is enriched in amoebae interacting with different species of bacteria, including sets that appear specific to amoebae interacting with Gram(+), or with Gram(-) bacteria. In a genetic screen utilizing the growth of mutant amoebae on a variety of bacteria as a phenotypic readout, we identified amoebal genes that are only required for growth on Gram(+) bacteria, including one that encodes the cell surface protein gp130, as well as several genes that are only required for growth on Gram(-) bacteria including one that encodes a putative lysozyme, AlyL. These genes are required for parts of the transcriptional response of wild-type amoebae, and this allowed their classification into potential response pathways. Transcriptional profiling of amoebal response to different bacteria.
Project description:Purpose: To filter genes that may contribute to introcellualr survival of B. bronchiseptica inside Dictyostelium discoideum, the genes that differently expressed when bacteria inside amoebae or in culture medium are selected as target genes.
Project description:In human volunteers, we evaluated changes in gene expression profiles, immunological indices, and intestinal microbiota of blood cells in subjects consuming a S.reticulata extract. Thirty healthy Japanese males were split randomly into a group ingesting 240 mg/day of S.reticulata extract -containing tablets for 4 weeks and a control group ingesting placebo tablets. Ingestion of the S.reticulata extract improved T cell proliferation and other immunological indices, and changed intestinal microbiota, increasing Bifidobacterium and Lactobacillales and decreasing Clostridium bacteria. Expression levels of many immuno-relevant genes were altered. We have shown the S.reticulata extract to enhance human immune functions.
Project description:Diabetes and Arteriosclerosis progression are frequently observed in borderline Type 2 diabetes cases. Onset of complications (arteriosclerosis and renal damage) due to Type 2 diabetes is well documented; it is extremely important to prevent or delay their progression. Type 2 diabetes onset and progression has been controlled through dietary habits and exercise, although these remain insufficient. Chlorella ingestion improves blood glucose and cholesterol concentrations in mice and humans, although no reports have evaluated Chlorella effects in borderline diabetics. Therefore, we conducted a randomized, placebo-controlled trial for borderline diabetics using laboratory results and comprehensive gene analysis as outcomes. Chlorella ingestion suppressed resistin gene expression, suggesting that Chlorella may be useful for preventing diabetes onset and ameliorating arteriosclerosis. Subjects were randomly divided into two groups: Chlorella group (n = 28) ingesting Chlorella powder (8.0 g/day) and placebo group (n = 29) ingesting lactose formulation (8.0 g/day) for 12 weeks. Blood and urine were collected every 4 weeks for laboratory tests. Gene expression analysis used RNA extracted from peripheral blood samples before and after 12 weeks of Chlorella or lactose ingestion.
Project description:This study details the content and dynamics of the long non-coding transcriptome during D. discoideum development, providing an important compendium to the well-characterized protein coding transcriptome. Applying a novel sample preparation method, we isolated antisense and long intergenic non-coding RNAs in addition to mRNAs. We describe the behavior of these different classes of RNAs that have been shown to play important regulatory roles in numerous model systems. Our analyses contribute a wholly different perspective to the most widely appreciated and compelling aspect of Dictyostelium biology—the change in life style from solitary amoebae to differentiated multicellular organisms.
Project description:Dictyostelium discoideum behavior depends on nutrients1. When sufficient food is present these amoebae exist in a unicellular state, but upon starvation they aggregate into a multicellular organism2,3. This unique biology makes D. discoideum an ideal model for investigating how fundamental metabolic pathways command cell differentiation and function. We show here that reactive oxygen species (ROS), generated as a consequence of nutrient limitation, lead to the sequestration of the amino acid cysteine in the antioxidant glutathione, limiting the use of its sulfur atom for processes such as protein translation and FeS cluster-containing enzyme activity that contribute to mitochondrial metabolism and cellular proliferation. Such regulated sulfur sequestration maintains D. discoideum in a non-proliferating state that paves the way for multicellular development. This new mechanism of ROS signaling highlights oxygen and sulfur as simple, early evolutionary signaling molecules dictating cell fate, with implications for responses to nutrient fluctuations in higher eukaryotes.
Project description:Dictyostelium discoideum behavior depends on nutrients1. When sufficient food is present these amoebae exist in a unicellular state, but upon starvation they aggregate into a multicellular organism2,3. This unique biology makes D. discoideum an ideal model for investigating how fundamental metabolic pathways command cell differentiation and function. We show here that reactive oxygen species (ROS), generated as a consequence of nutrient limitation, lead to the sequestration of the amino acid cysteine in the antioxidant glutathione, limiting the use of its sulfur atom for processes such as protein translation and FeS cluster-containing enzyme activity that contribute to mitochondrial metabolism and cellular proliferation. Such regulated sulfur sequestration maintains D. discoideum in a non-proliferating state that paves the way for multicellular development. This new mechanism of ROS signaling highlights oxygen and sulfur as simple, early evolutionary signaling molecules dictating cell fate, with implications for responses to nutrient fluctuations in higher eukaryotes.
Project description:Dictyostelium discoideum behavior depends on nutrients. When sufficient food is present these amoebae exist in a unicellular state (vegetative growth), but upon starvation they aggregate into a multicellular organism (developmental growth). For proteomics 30 minutes and eight hour cultures of D. discoideum under vegetative and starved growth conditions were compared by DIA-LFQ. This unique biology makes D. discoideum an ideal model for investigating how fundamental metabolism commands cell differentiation and function. We show here that reactive oxygen species (ROS), generated as a consequence of nutrient limitation, lead to the sequestration of the amino acid cysteine in the antioxidant glutathione, limiting the use of its sulfur atom for processes such as protein translation and FeS cluster-containing enzyme activity that contribute to mitochondrial metabolism and cellular proliferation. Such regulated sulfur sequestration maintains D. discoideum in a non-proliferating state that paves the way for multicellular development. This new mechanism of ROS signaling highlights oxygen and sulfur as simple, early evolutionary signaling molecules dictating cell fate, with implications for responses to nutrient fluctuations in higher eukaryotes.
Project description:Dictyostelium discoideum is a professional phagocyte and it uses phagocytosis as a way to get food. However, there are a number of bacteria that subvert this professional phagocyte. In this study we investigated whether Salmonella typhimurium is also pathogenic for D. discoideum.