F sub(0)F sub(1) ATP synthase harnesses a transmembrane electrochemical gradient for the production of ATP. When operated in reverse, this multiprotein complex catalyzes ATP hydrolysis. In bacteria, ...the epsilon subunit is involved in regulating this ATPase activity. Also, epsilon is essential for coupling ATP hydrolysis (or synthesis) to proton translocation. The epsilon subunit consists of a beta sandwich and two C-terminal helices, alpha 1 and alpha 2. The protein can switch from a compact fold to an alternate conformation where alpha 1 and alpha 2 are separated, resulting in an extended structure. epsilon from the thermophile Bacillus PS3 (T epsilon ) binds ATP with high affinity such that this protein may function as an intracellular ATP level sensor. ATP binding to isolated T epsilon triggers a major conformational transition. Earlier data were interpreted in terms of an ATP + T epsilon sub(extended) arrow right ATP.T epsilon sub(compact) transition that may mimic aspects of the regulatory switching within F sub(0)F sub(1) (Yagi et al. (2007) Proc. Natl. Acad. Sci. U.S.A., 104, 11233-11238). In this work, we employ complementary biophysical techniques for examining the ATP-induced conformational switching of isolated T epsilon . CD spectroscopy confirmed the occurrence of a large-scale conformational transition upon ATP binding, consistent with the formation of stable helical structure. Hydrogen/deuterium exchange (HDX) mass spectrometry revealed that this transition is accompanied by a pronounced stabilization in the vicinity of the ATP-binding pocket. Surprisingly, dramatic stabilization is also seen in the beta 8- beta 9 region, which is remote from the site of ATP interaction. Analytical ultracentrifugation uncovered a previously unrecognized feature of T epsilon : a high propensity to undergo dimerization in the presence of ATP. Comparison with existing crystallography data strongly suggests that the unexpected beta 8- beta 9 HDX protection is due to newly formed protein-protein contacts. Hence, ATP binding to isolated T epsilon proceeds according to 2ATP + 2T epsilon sub(extended) arrow right (ATP.T epsilon sub(compact)) sub(2). Implications of this dimerization propensity for the possible role of T epsilon as an antibiotic target are discussed.
•miR-22 knock-out mice have a blunted interferon response to viral infection.•miR-22 exerts reciprocal effects on megakaryocyte and erythrocyte maintenance during infection.•miR-22 is expressed in ...stage II erythroid progenitors to regulate the pace of differentiation.
MicroRNA-22 (miR-22) is a highly conserved microRNA that can regulate cell proliferation, oncogenesis, and cell maturation, especially during stress. In hematopoietic stem cells (HSCs), miR-22 has been reported to be involved in the regulation of key self-renewal factors, including Tet2. Recent work demonstrates that miR-22 also participates in regulation of the interferon (IFN) response, and expression profiling studies suggest that it is variably expressed at different stages in erythroid differentiation. We thus hypothesized that miR-22 regulates maturation of erythroid progenitors during stress hematopoiesis through its interaction with IFN. We compared the blood and bone marrow of wild-type (WT) and miR-22-deficient mice at baseline and upon infectious challenge with systemic lymphochoriomeningitis (LCMV) virus. miR-22-deficient mice maintained platelet counts better than WT mice during infection, but they showed significantly reduced red blood cells and hemoglobin. Analysis of bone marrow progenitors demonstrated better overall survival and improved HSC homeostasis in infected miR-22-null mice compared with WT, which was attributable to a blunted IFN response to LCMV challenge in the miR-22-null mice. We found that miR-22 was expressed exclusively in stage II erythroid precursors and downregulated upon infection in WT mice. Our results indicate that miR-22 promotes the IFN response to viral infection and that it functions at baseline as a brake to slow erythroid differentiation and maintain adequate erythroid potential. Impaired regulation of erythrogenesis in the absence of miR-22 can lead to anemia during infection.
Fungi in Mucoobstructive Airway Diseases Li, Evan; Landers, Cameron T; Tung, Hui-Ying ...
Annals of the American Thoracic Society,
11/2018, Letnik:
15, Številka:
Suppl 3
Journal Article
Recenzirano
Odprti dostop
Asthma, chronic rhinosinusitis, and related incurable allergic afflictions of the upper and lower airways are medically important because of their association with the disabling symptom of dyspnea ...and, at least for asthma, the potential to cause fatal asphyxiation. Extensive research over the past two decades has uncovered both the physiological basis of airway obstruction in asthma and key governing molecular pathways. Exaggerated airway constriction in response to diverse provocative stimuli, termed airway hyperresponsiveness, is mediated through the cytokines interleukin 4 (IL-4) and IL-13 and the transcription factor signal transducer and activator of transcription 6 (STAT6). Overproduction of mucus has long been known to be an essential second component of airway obstruction and is also mediated in part through the IL-4/IL-13/STAT6 pathway. In this review, we discuss a second major signaling pathway which underlies mucus production that is mediated through proteinase-cleaved fibrinogen signaling through Toll-like receptor 4. Unexpectedly, our analysis of human sputum and paranasal sinus fluid indicates that in most cases of severe allergic airway disease, a unique type of airway fungal infection, termed airway mycosis, is pathogenically linked to these conditions. We further discuss how fungal and endogenous proteinases mediate the fibrinogenolysis that is essential to both Toll-like receptor 4 signaling and fibrin deposition that, together with mucus, contribute to airway obstruction.
The allergic airway diseases, including chronic rhinosinusitis (CRS), asthma, allergic bronchopulmonary mycosis (ABPM) and many others, comprise a heterogeneous collection of inflammatory disorders ...affecting the upper and lower airways and lung parenchyma that represent the most common chronic diseases of humanity. In addition to their shared tissue tropism, the allergic airway diseases are characterized by a distinct pattern of inflammation involving the accumulation of eosinophils, type 2 macrophages, innate lymphoid cells type 2 (ILC2), IgE-secreting B cells, and T helper type 2 (Th2) cells in airway tissues, and the prominent production of type 2 cytokines including interleukin (IL-) 33, IL-4, IL-5, IL-13, and many others. These factors and related inflammatory molecules induce characteristic remodeling and other changes of the airways that include goblet cell metaplasia, enhanced mucus secretion, smooth muscle hypertrophy, tissue swelling and polyp formation that account for the major clinical manifestations of nasal obstruction, headache, hyposmia, cough, shortness of breath, chest pain, wheezing, and, in the most severe cases of lower airway disease, death due to respiratory failure or disseminated, systemic disease. The syndromic nature of the allergic airway diseases that now include many physiological variants or endotypes suggests that distinct endogenous or environmental factors underlie their expression. However, findings from different perspectives now collectively link these disorders to a single infectious source, the fungi, and a molecular pathogenesis that involves the local production of airway proteinases by these organisms. In this review, we discuss the evidence linking fungi and their proteinases to the surprisingly wide variety of chronic airway and systemic disorders and the immune pathogenesis of these conditions as they relate to environmental fungi. We further discuss the important implications these new findings have for the diagnosis and future therapy of these common conditions.
Smoking-related emphysema is a chronic inflammatory disease driven by the T.sub.H17 subset of helper T cells through molecular mechanisms that remain obscure. Here we explored the role of the ...microRNA miR-22 in emphysema. We found that miR-22 was upregulated in lung myeloid dendritic cells (mDCs) of smokers with emphysema and antigen-presenting cells (APCs) of mice exposed to smoke or nanoparticulate carbon black (nCB) through a mechanism that involved the transcription factor NF-κB. Mice deficient in miR-22, but not wild-type mice, showed attenuated T.sub.H17 responses and failed to develop emphysema after exposure to smoke or nCB. We further found that miR-22 controlled the activation of APCs and T.sub.H17 responses through the activation of AP-1 transcription factor complexes and the histone deacetylase HDAC4. Thus, miR-22 is a critical regulator of both emphysema and T.sub.H17 responses.
We are using Drosophila as a model system for analysis of immunity and tumor formation and have conducted two types of screens using enhancer detector strains to find genes related to these ...processes: genes expressed in the immune system (type A; hemocytes, lymph glands and fat body) and genes increased in expression by bacterial infection (type B). For type A, tissue-specific reporter gene activity was determined. For type B, a variation of enhancer detection was devised in which beta-galactosidase is assayed spectrophotometrically with and without bacterial infection. Because of immune system involvement in melanotic tumor formation, a third type was hypothesized to be found among types A and B: genes that, when mutated, have a melanotic tumor phenotype. Enhancer detector strains (2800) were screened for type A, 900 for B, and 11 retained for further analysis. Complementation tests, cytological mapping, P-element mobilization, and determination of lethal phase and mutant phenotype have identified six novel genes, Dorothy, wizard, toto, viking, Thor and dappled, and one previously identified gene, Collagen IV. All are associated with reporter gene expression in at least one immune system tissue. Thor has increased expression upon infection. Mutations of wizard and dappled have a melanotic tumor phenotype.
Smoking-related emphysema is a chronic inflammatory disease driven by the T sub(H)17 subset of helper T cells through molecular mechanisms that remain obscure. Here we explored the role of the ...microRNA miR-22 in emphysema. We found that miR-22 was upregulated in lung myeloid dendritic cells (mDCs) of smokers with emphysema and antigen-presenting cells (APCs) of mice exposed to smoke or nanoparticulate carbon black (nCB) through a mechanism that involved the transcription factor NF- Kappa B. Mice deficient in miR-22, but not wild-type mice, showed attenuated T sub(H)17 responses and failed to develop emphysema after exposure to smoke or nCB. We further found that miR-22 controlled the activation of APCs and T sub(H)17 responses through the activation of AP-1 transcription factor complexes and the histone deacetylase HDAC4. Thus, miR-22 is a critical regulator of both emphysema and T sub(H)17 responses.
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