Project description:Root exudates are composed of primary and secondary metabolites known to modulate the rhizosphere microbiota. Glucosinolates are defense compounds present in the Brassicaceae family capable of deterring pathogens, herbivores and biotic stressors in the phyllosphere. In addition, traces of glucosinolates and their hydrolyzed byproducts have been found in the soil, suggesting that these secondary metabolites could play a role in the modulation and establishment of the rhizosphere microbial community associated with this family. We used Arabidopsis thaliana mutant lines with disruptions in the indole glucosinolate pathway, liquid chromatography-tandem mass spectrometry (LC-MS/MS) and 16S rRNA amplicon sequencing to evaluate how disrupting this pathway affects the root exudate profile of Arabidopsis thaliana, and in turn, impacts the rhizosphere microbial community. Chemical analysis of the root exudates from the wild type Columbia (Col-0), a mutant plant line overexpressing the MYB transcription factor ATR1 (atr1D) which increases glucosinolate production, and the loss-of-function cyp79B2cyp79B3 double mutant line with low levels of glucosinolates confirmed that alterations to the indole glucosinolate biosynthetic pathway shifts the root exudate profile of the plant. We observed changes in the relative abundance of exuded metabolites. Moreover, 16S rRNA amplicon sequencing results provided evidence that the rhizobacterial communities associated with the plant lines used were directly impacted in diversity and community composition. This work provides further information on the involvement of secondary metabolites and their role in modulating the rhizobacterial community. Root metabolites dictate the presence of different bacterial species, including plant growth-promoting rhizobacteria. Our results suggest that alterations in the indole glucosinolate pathway cause disruptions beyond the endogenous levels of the plant, significantly changing the abundance and presence of different metabolites in the root exudates of the plants as well as the microbial rhizosphere community.
Project description:Plants have evolved tightly regulated signaling networks to respond and adapt to environmental perturbations, but the nature of the signaling hub(s) involved have remained an enigma. We have previously established that methylerythritol cyclodiphosphate (MEcPP), a precursor of plastidial isoprenoids and a stress-specific retrograde signaling metabolite, enables cellular readjustments for high-order adaptive functions. Here, we specifically show that MEcPP promotes two Brassicaceae-specific traits, namely endoplasmic reticulum (ER) body formation and induction of indole glucosinolate (IGs) metabolism selectively, via transcriptional regulation of key regulators NAI1 for ER body formation and MYB51/122 for IGs biosynthesis). The specificity of MEcPP is further confirmed by the lack of induction of wound-inducible ER body genes as well as IGs by other altered methylerythritol phosphate pathway enzymes. Genetic analyses revealed MEcPP-mediated COI1-dependent induction of these traits. Moreover, MEcPP signaling integrates the biosynthesis and hydrolysis of IGs through induction of nitrile-specifier protein1 and reduction of the suppressor, ESM1, and production of simple nitriles as the bioactive end product. The findings position the plastidial metabolite, MEcPP, as the initiation hub, transducing signals to adjust the activity of hard-wired gene circuitry to expand phytochemical diversity and alter the associated subcellular structure required for functionality of the secondary metabolites, thereby tailoring plant stress responses.
Project description:Altered tryptophan catabolism has been identified in inflammatory diseases like rheumatoid arthritis (RA) and spondyloarthritis (SpA), but the causal mechanisms linking tryptophan metabolites to disease are unknown. Using the collagen-induced arthritis (CIA) model we identify alterations in tryptophan metabolism, and specifically indole, that correlate with disease. We demonstrate that both bacteria and dietary tryptophan are required for disease, and indole supplementation is sufficient to induce disease in their absence. When mice with CIA on a low-tryptophan diet were supplemented with indole, we observed significant increases in serum IL-6, TNF, and IL-1β; splenic RORγt+CD4+ T cells and ex vivo collagen-stimulated IL-17 production; and a pattern of anti-collagen antibody isotype switching and glycosylation that corresponded with increased complement fixation. IL-23 neutralization reduced disease severity in indole-induced CIA. Finally, exposure of human colon lymphocytes to indole increased expression of genes involved in IL-17 signaling and plasma cell activation. Altogether, we propose a mechanism by which intestinal dysbiosis during inflammatory arthritis results in altered tryptophan catabolism, leading to indole stimulation of arthritis development. Blockade of indole generation may present a novel therapeutic pathway for RA and SpA.
Project description:Purpose: The goal of this study was to identify transcriptional changes in HCT-8 cells treated with indole for 4 or 12 hours. Methods: Confluent HCT-8 monolayers were infected with excysted Cryptosporidium parvum sporozoites for 4 h, after which cells were washed to remove extracellular parasites. Cells were then treated with 1% DMSO in cell culture medium with or without 880 uM indole. RNA was collected in triplicate for each treatment type after 4 h and 12 h of treatment (8 and 16 hours post infection, respectively). Results: When the two time points were combined, indole significantly upregulated 57 genes and downregulated 11 genes. Of the upregulated genes,16 genes were primarily upregulated in cells exposed to indole for 4 h and then went back down by 12 h of exposure. These genes were primarily involved in pathways related to ER stress and the unfolded protein response (UPR). Conversely, 41 genes had higher gene expression after 12 h of indole exposure and were predominantly involved in membrane transport of carboxylic acids and amino acids. Conclusions: Indole treatment causes ER stress and upregulation of membrane transporters in a human adenocarcinoma cell line infected with Cryptosporidium parvum.
Project description:Indole-3-carbinol (I3C) is a natural anti-carcinogenic compound found at high concentrations in Brassica vegetables. ER-positive cell lines demonstrated the greatest sensitivity to the anti-tumor effects of I3C compared to ER-negative breast cancer cell lines. Gene expression analysis was performed to identify genes and pathways that accounted for sensitivity to I3C. Microarray analysis performed using Illumina HT-12 v4 expression arrays
Project description:Indole-3-carbinol (I3C) is a natural anti-carcinogenic compound found at high concentrations in Brassica vegetables. ER-positive cell lines demonstrated the greatest sensitivity to the anti-tumor effects of I3C compared to ER-negative breast cancer cell lines. Gene expression analysis was performed to identify genes and pathways that accounted for sensitivity to I3C. Microarray analysis performed using Illumina HT-12 v4 expression arrays A total of 36 samples were analyzed with six breast cancer cell lines treated with either the vehicle control or the drug Indole-3-carbinol in triplicate. The cell lines were: MCF-7, T47D, ZR751(sensitive to the drug, apoptosis/growth arrest) and MDA-MB-231, MDA-MB-157, and MDA-MB-436 (insensitive to the drug). Sensitive cell lines are of the luminal subtype and insensitive cell lines are of the basal subtype.
Project description:Transcriptional profiling of Salmonella Typhimurium SL1344 wild type grown to OD600=1 in LB alone or in LB supplemented with 2mM Indole, or with 2mM indole for 15 min (called shock). The goal is to determine Salmonella response to indole at different time points.
Project description:Transcriptional profiling of P. putida KT2440 cells comparing untreated cells with 1 mM indole or 50 μg/ml ampicillin or 1 mM indole plus 50 μg/ml ampicillin treated cells