Project description:MyD88 is an adaptor protein in Toll-like receptor and interleukin 1 receptor mediated signaling pathways that plays an essential role in activation of immune responses following pathogen recognition. We investigate that role in the zebrafish embryo model by using a zebrafish mutant line that contains a premature stop condon in the gene encoding MyD88, leading to a truncated protein that lacks domains important for its normal function. We infected these MyD88 mutants and wildtype individuals with S Mycobacterium marinum to compare the resulting immune response by transcriptome profiling on total RNA isolated from single embryos. Autophagy regulator dram1 was identified as one of the MyD88-dependent genes.
Project description:MyD88 is an adaptor protein in Toll-like receptor and interleukin 1 receptor mediated signaling pathways that plays an essential role in activation of immune responses following pathogen recognition. We investigate that role in the zebrafish embryo model by using a zebrafish mutant line that contains a premature stop condon in the gene encoding MyD88, leading to a truncated protein that lacks domains important for its normal function. We infected these MyD88 mutants and wildtype individuals with Mycobacterium marinum to compare the resulting immune response by transcriptome profiling on total RNA isolated from single embryos. Autophagy regulator dram1 was identified as one of the MyD88-dependent genes.
Project description:MyD88 is an adaptor protein in Toll-like receptor and interleukin 1 receptor mediated signaling pathways that plays an essential role in activation of immune responses following pathogen recognition. We investigate that role in the zebrafish embryo model by using a zebrafish mutant line that contains a premature stop condon in the gene encoding MyD88, leading to a truncated protein that lacks domains important for its normal function. We infected these MyD88 mutants and wildtype individuals with Salmonella typhimurium and Edwardsiella tarda to compare the resulting immune response by transcriptome profiling on total RNA isolated from single embryos. The data derived from these microarray experiments confirms the vital role of MyD88 in pathogen recognition and provides many leads for further research.
Project description:Inflammation has pleiotropic effects on carcinogenesis and tumor progression. Signaling through the adaptor protein MyD88 promotes carcinogenesis in several chemically induced cancer models. Interestingly, we observed a protective role for MyD88 in the development of AOM/DSS colitis-associated cancer. The inability of Myd88-/- mice to heal ulcers generated upon injury creates an inflammatory environment that increases the frequency of mutations and results in a dramatic increase in adenoma formation and cancer progression. Susceptibility to colitis development and enhanced polyp formation were also observed in Il18-/- mice upon AOM/DSS treatment, suggesting that the phenotype of MyD88 knockouts is in part due to their inability to signal through the IL-18 receptor. This study revealed a previously unknown level of complexity surrounding MyD88 activities downstream of different receptors that differentially impact tissue homeostasis and carcinogenesis.
Project description:Inflammation has pleiotropic effects on carcinogenesis and tumor progression. Signaling through the adaptor protein MyD88 promotes carcinogenesis in several chemically induced cancer models. Interestingly, we observed a protective role for MyD88 in the development of AOM/DSS colitis-associated cancer. The inability of Myd88-/- mice to heal ulcers generated upon injury creates an inflammatory environment that increases the frequency of mutations and results in a dramatic increase in adenoma formation and cancer progression. Susceptibility to colitis development and enhanced polyp formation were also observed in Il18-/- mice upon AOM/DSS treatment, suggesting that the phenotype of MyD88 knockouts is in part due to their inability to signal through the IL-18 receptor. This study revealed a previously unknown level of complexity surrounding MyD88 activities downstream of different receptors that differentially impact tissue homeostasis and carcinogenesis. The Myd88 knockout mice were backcrossed to obtain at least 98% congenicity to B6NCr background. As control groups, wild type mice of identical background were used. Ten biological repeats were performed for the treated wild type and Myd88 samples. Six biological repeats were performed for the untreated wild type and Myd88 samples.
Project description:Progressive dysfunction and death of photoreceptors occurs in blinding diseases such as age-related macular degeneration and retinitis pigmentosa. The MyD88 protein is a central adaptor molecule for innate immune system Toll-like receptors (TLR) and interleukin-1 receptor (IL-1R), which are active in retinal disease and induce cytokine secretion from inflammatory cells. We recently demonstrated that inhibiting MyD88 in mouse models of retinal degeneration led to increased rod photoreceptor survival, which was associated with altered cytokine expression and increased neuroprotective microglia. However, additional molecular changes associated with MyD88 inhibitor-mediated neuroprotection are not known. Quantitative proteomics using iTRAQ LC-MS/MS is a high-throughput method ideal for providing new information about the molecular mechanisms contributing to photoreceptor protection. In this study, we used isobaric tags for relative and absolute quantification (iTRAQ) labeling followed by liquid chromatography–tandem mass spectrometry (LC-MS/MS) for quantitative proteomic analysis on the rd10 mouse model of retinal degeneration to identify protein pathways changed by MyD88 inhibition. A total of 42 proteins were differentially expressed in retinas from mice treated with MyD88 inhibitor compared with control. Notably, increased expression of multiple crystallins and chaperones that respond to cellular stress and have anti-apoptotic properties were identified in the MyD88 inhibited mice. Additional differentially expressed biological processes included pyrophosphatase activity and peptide biosynthesis. These data suggest that inhibiting MyD88 may enhance chaperone-mediated tissue protective pathways. Therefore, this study provides new insight into molecular events that contribute to photoreceptor protection from modulating inflammation.
Project description:Lipopolysaccharide (LPS), a Toll-like receptor (TLR) 4 ligand, activates intracellular signaling via adaptors, MyD88 and TRIF, leading to the expression of various genes including proinflammatory cytokines. We used microarrays to examine influence of MyD88 or TRIF deficiency in LPS-inducible gene expression. Experiment Overall Design: Peritoneal macrophages from wild-type, MyD88-/- and TRIF-/- mice were stimulated with LPS for 0, 1 and 4 hours, followed by RNA extraction. Then hybridization on affymetrix microarrays was performed.
Project description:Interleukin 33 (IL33) is an inflammatory cytokine released during necrotic cell death. The epithelium and stroma of the intestine express large amounts of IL33 and its receptor St2. IL33 is therefore continuously released during homeostatic turnover of the intestinal mucosa. Although IL33 can prevent colon cancer associated with inflammatory colitis, the contribution of IL33 signaling to sporadic colon cancer remains unknown. Here, we utilized a mouse model of sporadic colon cancer to investigate the contribution of IL33 signaling to tumorigenesis in the absence of pre-existing inflammation. We demonstrated that genetic ablation of St2 enhanced colon tumor development. In reciprocal bone marrow (BM) chimeras, the concurrent loss of IL33 signaling within radioresistant nonhematopoietic, and the radiosensitive hematopoietic, compartments was associated with increased tumor burden. To elucidate the molecular mechanisms underpinning the tumor-suppressing effect of IL33 signaling in sporadic colon cancer, we performed whole transcriptome analysis of tumors collected from each of the four cohorts of the 6xAOM-treated BM chimeras. We discovered that St2 deficiency within the nonhematopoietic compartment coincided with suppression of an IFN gene expression signature. The decrease of this IFN gene expression signature was associated with more aggressive disease in human colon cancer patients, suggesting that lack of IL33 signaling impaired the generation of a potent IFN-mediated antitumor immune response. Collectively, our data reveal that IL33 functions as a tumor suppressor in sporadic colon cancer.
Project description:Nitric oxide (NO) produced by macrophages (MØs) is toxic to both host tissues and invading pathogens and its regulation is therefore essential to suppress host cytotoxicity. MØ arginase 1 (Arg1) inhibits NO production by competing with NO synthases for arginine, the common substrate of NO synthases and arginases. Two signal transduction pathways control Arg1 expression in MØs. First, a MyD88-dependent pathway induces Arg1 in intracellular infections, while a second Stat6-dependent pathway is required for Arg1 expression in alternativelyactivated MØs. We found that mycobacteria-infected MØs produce soluble factors that induce Arg1 in an autocrine-paracrine manner via Stat3. We identify these factors as IL-6, IL-10 and GCSF. We further establish that Arg1 expression is controlled by the MyD88-dependent production of IL-6, IL-10 and G-CSF rather than cell intrinsic MyD88 signaling to Arg1. Our data reveal the MyD88-dependent pathway of Arg1induction following BCG infection requires Stat3 activation and may result in the development of an immunosuppressive niche in granulomas due to the induced Arg1 production in surrounding uninfected MØs We used microarrays to perform genome wide expression analysis in mycobacteria-infected macrophages from C57Bl/6 WT and MyD88-knockout mice.