Browsing by Subject "Mitogen-activated protein kinases"

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    Anthrax Lethal Toxin Impairs CD1d-Mediated Antigen Presentation by Targeting the Extracellular Signal-Related Kinase 1/2 Mitogen-Activated Protein Kinase Pathway
    (American Society for Microbiology, 2010-05) Khan, Masood A.; Gallo, Richard M.; Brutkiewicz, Randy R.; Microbiology and Immunology, School of Medicine
    Lethal toxin (LT) is a critical virulence factor of Bacillus anthracis and an important means by which this bacterium evades the host's immune system. In this study, we demonstrate that CD1d-expressing cells treated with LT have reduced CD1d-mediated antigen presentation. We earlier showed an important role for the mitogen-activated protein kinase extracellular signal-regulated kinase 1/2 (ERK1/2) in the regulation of CD1d-mediated antigen presentation, and we report here that LT impairs antigen presentation by CD1d in an ERK1/2-dependent manner. Similarly, LT and the ERK1/2 pathway-specific inhibitor U0126 caused a decrease in major histocompatibility complex (MHC) class II-mediated antigen presentation. Confocal microscopy analyses revealed altered intracellular distribution of CD1d and LAMP-1 in LT-treated cells, similar to the case for ERK1/2-inhibited cells. These results suggest that Bacillus anthracis has the ability to evade the host's innate immune system by reducing CD1d-mediated antigen presentation through targeting the ERK1/2 pathway.
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    Impaired Annulus Fibrosus Development and Vertebral Fusion Cause Severe Scoliosis in Mice with Deficiency of c-Jun NH2-Terminal Kinases 1 and 2
    (Elsevier, 2019-04) Ulici, Veronica; Kelley, Kathryn L.; Longobardi, Lara; McNulty, Margaret A.; Livingston, Eric W.; Bateman, Ted A.; Séguin, Cheryle A.; Louer, Craig R.; Loeser, Richard F.; Anatomy and Cell Biology, School of Medicine
    Mitogen-activated protein kinases, including c-Jun NH2-terminal kinase (JNK), play an important role in the development and function of a large variety of tissues. The skeletal phenotype of JNK1 and JNK2 double-knockout (dKO) mice (JNK1fl/flCol2-Cre/JNK2−/−) and control genotypes were analyzed at different embryonic and postnatal stages. JNK1/2 dKO mice displayed a severe scoliotic phenotype beginning during development that was grossly apparent around weaning age. Alcian blue staining at embryonic day 17.5 showed abnormal fusion of the posterior spinal elements. In adult mice, fusion of vertebral bodies and of spinous and transverse processes was noted by micro–computed tomography, Alcian blue/Alizarin red staining, and histology. The long bones developed normally, and histologic sections of growth plate and articular cartilage revealed no significant abnormalities. Histologic sections of the vertebral column at embryonic days 15.5 and 17.5 revealed an abnormal organization of the annulus fibrosus in the dKOs, with chondrocyte-like cells and fusion of dorsal processes. Spinal sections in 10-week–old dKO mice showed replacement of intervertebral disk structures (annulus fibrosus and nucleus pulposus) by cartilage and bone tissues, with cells staining for markers of hypertrophic chondrocytes, including collagen X and runt-related transcription factor 2. These findings demonstrate a requirement for both JNK1 and JNK2 in the normal development of the axial skeleton. Loss of JNK signaling results in abnormal endochondral bone formation and subsequent severe scoliosis.
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    Tsg-6 : an inducible mediator of paracrine anti-inflammatory and myeloprotective effects of adipose stem cells
    (2014-01-29) Xie, Jie; March, Keith Leonard, 1963-; Petrache, Irina; Clauss, Matthias A.; Broxmeyer, Hal E.
    Tumor necrosis factor-induced protein 6 (TSG-6) has been shown to mitigate inflammation. Its presence in the secretome of adipose stem / stromal cells (ASC) and its role in activities of ASC have been overlooked. This thesis described for the first time the release of TSG-6 from ASC, and its modulation by endothelial cells. It also revealed that protection of endothelial barrier function was a novel mechanism underlying the anti-inflammatory activity of both ASC and TSG-6. Moreover, TSG-6 was found to inhibit mitogen-activated lymphocyte proliferation, extending the understanding of its pleiotropic effects on major cell populations involved in inflammation. Next, enzyme-linked immunosorbent assays (ELISA) were established to quantify secretion of TSG-6 from human and murine ASC. To study the importance of TSG-6 to specific activities of ASC, TSG-6 was knocked down in human ASC by siRNA. Murine ASC from TSG-6-/- mice were isolated and the down-regulation of TSG-6 was verified by ELISA. The subsequent attempt to determine the efficacy of ASC in ameliorating ischemic limb necrosis and the role of TSG-6, however, was hampered by the highly variable ischemic tissue necrosis in the BALB/c mouse strain. Afterwards in a mouse model of cigarette smoking (CS), in which inflammation also plays an important role, it was observed, for the first time, that 3-day CS exposure caused an acute functional exhaustion and cell cycle arrest of hematopoietic progenitor cells; and that 7-week CS exposure led to marked depletion of phenotypic bone marrow stem and progenitor cells (HSPC). Moreover, a dynamic crosstalk between human ASC and murine host inflammatory signals was described, and specifically TSG-6 was identified as a necessary and sufficient mediator accounting for the activity of the ASC secretome to ameliorate CS-induced myelotoxicity. These results implicate TSG-6 as a key mediator for activities of ASC in mitigation of inflammation and protection of HSPC from the myelotoxicity of cigarette smoke. They also prompt the notion that ASC and TSG-6 might potentially play therapeutic roles in other scenarios involving myelotoxicity.