Project description:Bis-2-chloroethyl sulfide (sulfur mustard, SM) is a potent alkylating agent and vesicant. Exposure to SM results in activation of numerous signaling cascades, including mitogen-activated protein kinase (MAPK) signaling pathways. These pathways include the Erk, p38, and JNK pathways, which are involved in cell growth, inflammation, and stress signaling. However, the precise roles of these pathways in SM toxicity have not been fully elucidated. We used Western blotting and microarray analysis to examine the activation and role of each pathway following SM exposure in primary human epidermal keratinocytes. Western blotting revealed increased phosphorylation of p38 and JNK following SM exposure; however, phosphorylation of Erk was equivocal, suggesting that growth conditions may impact activation of Erk by SM. We used pharmacologic inhibitors to target each MAPK and then compared the gene expression profiles to identify SM-induced gene networks regulated by each MAPK. Cells were pretreated with 10 µM SB 203580 (p38 inhibitor), PD 98059 (Erk inhibitor), or SP 600125 (JNK inhibitor) 60 minutes before exposure to 200 µM SM. Cells were harvested at 1h, 4h, and 8h post-exposure, and RNA was extracted for synthesis of microarray probes. Probes were hybridized to Affymetrix U133 Plus 2.0 arrays for gene expression profiling. Analysis of variance was performed to identify genes significantly modulated due to pharmacologic inhibition in SM-exposed cells. Pathway mapping confirmed alterations in SM-induced Erk, JNK, and p38 MAPK signaling due to pharmacologic inhibition. SM-induced expression of IL-8, IL-6, and TNF-alpha was decreased by p38 MAPK inhibition, but not by inhibition of other MAPKs. Based on the number of significant pathways mapped to each MAPK in the presence and absence of inhibitors, the p38 MAPK pathway appeared to be the MAPK pathway most responsive to SM exposure. Interestingly, pathway mapping of the microarray data identified potential cross-talk between MAPK signaling pathways and other pathways involved in SM-induced signaling. Mining of these results will increase our understanding of the role of MAPK pathways in SM-induced signal transduction and may identify potential therapeutic targets for medical countermeasure development.

Project description:Three major MAP kinase signaling cascades, ERK, p38 and JNK, play significant roles in the development of cardiac hypertrophy and heart failure in response to external stress and neural/hormonal stimuli. In order to study the specific function of each MAP kinase branch in adult heart, we have generated three transgenic mouse models with cardiac specific and temporally regulated expression of activated mutants of Ras, MKK3 and MKK7, which are selective upstream activators for ERK, p38 and JNK, respectively. Gene expression profiles in transgenic adult hearts were determined using cDNA microarrays at both early (4-7 days) and late (2-4 weeks) time points following transgene induction. From this study, we revealed common changes in gene expression among the three models, particularly involving extracellular matrix remodeling. However, distinct expression patterns characteristic for each pathway were also identified in cell signaling, growth and physiology. In addition, genes with dynamic expression differences between early vs. late stages illustrated primary vs. secondary changes upon MAP kinase activation in adult hearts. These results provide an overview to both short term and long term effects of MAP kinase activation in heart and support some common as well as unique roles for each MAP kinase cascade in the development of heart failure. Experiment Overall Design:MHC-floxed-HRas-v12/MKK3bE/MKK7D transgenic mice were bred with MHC-Mer-Cre-Mer (MCM) mice (from Dr. J. Molkentin, Cincinnati Children's Hospital) to generate double transgenic animals harboring both floxed transgenes and Mer-Cre-Mer transgene. At 12 weeks of age the double transgenic mice and non-transgenic littermate controls were treated via i.p. injection of tamoxifen at a dosage of 20mg/kgBW once a day for 3 consecutive days as reported. The hearts were harvested at an early (4-7 days post first tamoxifen injection) and a late (2-4 weeks) time point. Left ventricles were dissected and rapidly frozen in liquid nitrogen and stored at -80C prior to protein and RNA analysis. Transcription profiling of

Project description:Astroglia, the star-shaped cells found throughout the central nervous system are the most numerous cell type in the brain. The astroglial response to injury, generically termed reactive astrogliosis, is classically defined by cellular hypertrophy and process extension, increased glial filament production, and some degree of proliferation. Astrogliosis and its functional outcomes, glial scar formation and neuroinflammation, are often viewed as detrimental to recovery. However, increasing evidence points to neuroprotective roles of reactive astroglia in the setting of brain injury. Therapeutic modulation of this double-edged sword will require detailed knowledge of mechanisms by which specific signals induce detrimental and beneficial phenotypes. This proposal is is a logical extension of a published, peer reviewed study (Heffron DS and Mandell JW, Opposing roles of ERK and p38 MAP kinases in FGF2-induced astroglial process extension. Mol Cell Neurosci 2005, 28:779-90). The downstream gene expression changes underlying these pathway-specific responses are largely unknown. The data generated from the proposed project will delineate pathway-specific gene expression responses of astroglia to fibroblast growth factors. This information will allow a rational approach to pharmacological approaches to modulate reactive astrogliosis in brain and spinal cord injury. Determine the astroglial gene expression program elicited by fibroblast growth factor-2, and dissect specific contributions of the ERK and p38 MAP kinase pathways using highly specific pharmacological inhibitors. FGF2, acting via two distinct intracellular signaling pathways, ERK- and p38 MAPK, leads to pathway-specific gene expression changes in astrocytes which promote the morphological plasticity (ERK-dependent) and pro-inflammatory properties (p38-dependent) of reactive astroglia. Cell culture; Neonatal primary astrocyte cultures are prepared exactly as previously described (Heffron and Mandell, 2005), using slight modifications of established protocols (McCarthy and de Vellis, 1980). Astrocytes prepared with these methods comprised greater than 95% of cell cultures as determined by GFAP staining. Microglia are present as a contaminating cell type at a percentage of 3.6 Â± 0.9% as determined by CD11B staining. For process induction experiments, cells are trypsinized and replated in DMEM with 1% fetal bovine serum. This low serum concentration is necessary for good adhesion of the cells. Pharmacological inhibitors are dissolved in DMSO and added 2 h later. P38 MAP kinase inhibitors SB202190 (Calbiochem) and the MEK inhibitor U0126 (Promega) are used at 20 ÂµM. We previously determined that the inactive analog of SB 202190, SB202474 (Calbiochem) had no effects on pathway activation or astrocyte morphology. Therefore, the inactive drug analog will not be used in the array experiments. Final DMSO concentration in the drug treatments and vehicle controls is 0.2%. Human recombinant FGF2 (obtained from the National Cancer Institute Preclinical Repository) is used at 25 ng/ml, based on extensive dose/response analyses in our published work.

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