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Jawed Iqbal, Mairaj Ahmed Ansari, Binod Kumar, Dipanjan Dutta, Arunava Roy, Leela Chikoti, Gina Pisano, Sujoy Dutta, Shahrooz Vahedi, Mohanan Valiya Veettil, Bala Chandran
IFI16 (gamma-interferon-inducible protein 16), a predominantly nuclear protein involved in transcriptional regulation, also functions as an innate immune response DNA sensor and induces the IL-1β and antiviral type-1 interferon-β (IFN-β) cytokines. We have shown that IFI16, in association with BRCA1, functions as a sequence independent nuclear sensor of episomal dsDNA genomes of KSHV, EBV and HSV-1. Recognition of these herpesvirus genomes resulted in IFI16 acetylation, BRCA1-IFI16-ASC-procaspase-1 inflammasome formation, cytoplasmic translocation, and IL-1β generation...
October 2016: PLoS Pathogens
Stefanie Luecke, Søren R Paludan
Nucleic acids sensors of the innate immune system recognize various RNA and DNA structures during infection to induce transcription of interferon and pro-inflammatory cytokines and activation of inflammasomes. Cytosolic RNA is recognized by RIG-I and MDA5, while intracellular DNA is sensed among others by cGAS, AIM2, IFI16 and RNA polymerase III. The diversity of nucleic acid species produced during infection in the cytosol and nucleus and the limited chemical differences between self and non-self nucleic acids challenge the host's innate pattern recognition system to ensure reliable sensing while avoiding immune activation by self nucleic acids...
October 14, 2016: Cytokine
Shuting Xu, Aurélie Ducroux, Aparna Ponnurangam, Gabrielle Vieyres, Sergej Franz, Mathias Müsken, Thomas Zillinger, Angelina Malassa, Ellen Ewald, Veit Hornung, Winfried Barchet, Susanne Häussler, Thomas Pietschmann, Christine Goffinet
Upon sensing cytoplasmic retroviral DNA in infected cells, cyclic GMP-AMP (cGAMP) synthase (cGAS) produces the cyclic dinucleotide cGAMP, which activates STING to trigger a type I interferon (IFN) response. We find that membrane fusion-inducing contact between donor cells expressing the HIV envelope (Env) and primary macrophages endogenously expressing the HIV receptor CD4 and coreceptor enable intercellular transfer of cGAMP. This cGAMP exchange results in STING-dependent antiviral IFN responses in target macrophages and protection from HIV infection...
October 12, 2016: Cell Host & Microbe
Efficient N Ncube, Paul A Steenkamp, Ntakadzeni E Madala, Ian A Dubery
Centella asiatica is a perrenial herb that grows in tropical regions with numerous medicinal properties mostly attributed to the presence of pentacyclic triterpenoids. Interestingly, this plant also possess a significant amount of phenylpropanoid-derived chlorogenic acids (CGAs) that have recently been reported to confer neuroprotective properties. In a biotechnological attempt to increase the biosynthesis of CGA-derivatives in cultured Centella cells, acibenzolar-S-methyl was applied as a xenobiotic inducer in combination with quinic acid and shikimic acid as precursor molecules...
2016: Frontiers in Plant Science
Karin Kraehenbuehl, Nicole Page-Zoerkler, Olivier Mauroux, Karin Gartenmann, Imre Blank, Rachid Bel-Rhlid
Chlorogenic acid lactones have been identified as key contributors to coffee bitterness. These compounds are formed during roasting by dehydration and cyclization of their precursors, the chlorogenic acids (CGAs). In the present study, we investigated an approach to decompose these lactones in a selective way without affecting the positive coffee attributes developed during roasting. A model system composed of (3-caffeoylquinic acid lactone (3-CQAL), 4- caffeoyl quinic acid lactone (4-CQAL), and 4-feruloylquinic acid lactone (4-FQAL)) was used for the screening of enzymes before treatment of the coffee extracts...
March 1, 2017: Food Chemistry
Eileen E Parkes, Steven M Walker, Laura E Taggart, Nuala McCabe, Laura A Knight, Richard Wilkinson, Karen D McCloskey, Niamh E Buckley, Kienan I Savage, Manuel Salto-Tellez, Stephen McQuaid, Mary T Harte, Paul B Mullan, D Paul Harkin, Richard D Kennedy
BACKGROUND: Previously we identified a DNA damage response-deficient (DDRD) molecular subtype within breast cancer. A 44-gene assay identifying this subtype was validated as predicting benefit from DNA-damaging chemotherapy. This subtype was defined by interferon signaling. In this study, we address the mechanism of this immune response and its possible clinical significance. METHODS: We used immunohistochemistry (IHC) to characterize immune infiltration in 184 breast cancer samples, of which 65 were within the DDRD subtype...
January 2017: Journal of the National Cancer Institute
Jianli Tao, Xiang Zhou, Zhengfan Jiang
Innate immunity is the first line of host defense against invading pathogens. The detection of aberrant nucleic acids which represent some conserved PAMPs triggers robust type I IFN-mediated innate immune responses. Host- or pathogen-derived cytosolic DNA binds and activates the DNA sensor cGAS, which synthesizes the second messenger 2'3'-cGAMP and triggers STING-dependent downstream signaling. Here, we highlight recent progress in cGAS-cGAMP-STING, the Three Musketeers of cytosolic DNA sensing and signaling, and their essential roles in infection, autoimmune diseases, and cancer...
October 5, 2016: IUBMB Life
Di Xiao, Weihuang Huang, Meiling Ou, Congcong Guo, Xingguang Ye, Yang Liu, Man Wang, Baohuan Zhang, Na Zhang, Shiqi Huang, Jiankun Zang, Zixing Zhou, Zihao Wen, Chengli Zeng, Chenfei Wu, Chuican Huang, Xiangcai Wei, Guang Yang, Chunxia Jing
Human papillomavirus (HPV) infection is a definite risk factor for cervical cancer. Nevertheless, only some infected individuals actually develop cervical cancer. The cGAS-STING pathway in innate immunity plays an important role in protecting against HPV infection. Chen et al. described that the rs2516448 SNP in the MHC locus may affect susceptibility to cervical cancer, a finding that we attempted to replicate in a Chinese population. To investigate the effects of cGAS, STING and MHC polymorphisms on susceptibility to cervical precancerous lesions, 9 SNPs were analyzed in 164 cervical precancerous lesion cases and 428 controls...
October 1, 2016: Oncotarget
Jolien Vermeire, Ferdinand Roesch, Daniel Sauter, Réjane Rua, Dominik Hotter, Anouk Van Nuffel, Hanne Vanderstraeten, Evelien Naessens, Veronica Iannucci, Alessia Landi, Wojciech Witkowski, Ann Baeyens, Frank Kirchhoff, Bruno Verhasselt
Several pattern-recognition receptors sense HIV-1 replication products and induce type I interferon (IFN-I) production under specific experimental conditions. However, it is thought that viral sensing and IFN induction are virtually absent in the main target cells of HIV-1 in vivo. Here, we show that activated CD4(+) T cells sense HIV-1 infection through the cytosolic DNA sensor cGAS and mount a bioactive IFN-I response. Efficient induction of IFN-I by HIV-1 infection requires proviral integration and is regulated by newly expressed viral accessory proteins: Vpr potentiates, while Vpu suppresses cGAS-dependent IFN-I induction...
October 4, 2016: Cell Reports
Pengyan Xia, Shuo Wang, Pu Gao, Guangxia Gao, Zusen Fan
The host takes use of pattern recognition receptors (PRRs) to defend against pathogen invasion or cellular damage. Among microorganism-associated molecular patterns detected by host PRRs, nucleic acids derived from bacteria or viruses are tightly supervised, providing a fundamental mechanism of host defense. Pathogenic DNAs are supposed to be detected by DNA sensors that induce the activation of NFκB or TBK1-IRF3 pathway. DNA sensor cGAS is widely expressed in innate immune cells and is a key sensor of invading DNAs in several cell types...
September 30, 2016: Protein & Cell
Geneviève Pépin, Charlotte Nejad, Belinda J Thomas, Jonathan Ferrand, Kate McArthur, Philip G Bardin, Bryan R G Williams, Michael P Gantier
Acridine dyes, including proflavine and acriflavine, were commonly used as antiseptics before the advent of penicillins in the mid-1940s. While their mode of action on pathogens was originally attributed to their DNA intercalating activity, work in the early 1970s suggested involvement of the host immune responses, characterized by induction of interferon (IFN)-like activities through an unknown mechanism. We demonstrate here that sub-toxic concentrations of a mixture of acriflavine and proflavine instigate a cyclic-GMP-AMP (cGAMP) synthase (cGAS)-dependent type-I IFN antiviral response...
September 29, 2016: Nucleic Acids Research
Tianli Xia, Hiroyasu Konno, Glen N Barber
The innate immune regulator STING stimulates cytokine production in response to the presence of cytosolic DNA, which can arise following DNA damage. Extrinsic STING signaling is also needed for antigen-presenting cells (APC) to stimulate antitumor T cell immunity. Here we show that STING signaling is recurrently suppressed in melanoma cells, where this event may enable immune escape after DNA damage. Mechanistically STING signaling was suppressed most frequently by epigenetic silencing of either STING or the cyclic GMP-AMP synthase (cGAS), which generates STING-activating cyclic dinucleotides (CDNs) after binding cytosolic DNA species...
September 28, 2016: Cancer Research
Meixin Chen, Qingcai Meng, Yunfei Qin, Puping Liang, Peng Tan, Lian He, Yubin Zhou, Yongjun Chen, Junjiu Huang, Rong-Fu Wang, Jun Cui
Cyclic GMP-AMP synthase (cGAS) is an essential DNA virus sensor that triggers type I interferon (IFN) signaling by producing cGAMP to initiate antiviral immunity. However, post-translational regulation of cGAS remains largely unknown. We report that K48-linked ubiquitination of cGAS is a recognition signal for p62-depdendent selective autophagic degradation. The induction of TRIM14 by type I IFN accelerates cGAS stabilization by recruiting USP14 to cleave the ubiquitin chains of cGAS at lysine (K) 414. Knockout of TRIM14 impairs herpes simplex virus type 1 (HSV-1)-triggered antiviral responses in a cGAS-dependent manner...
October 6, 2016: Molecular Cell
Qi Chen, Lijun Sun, Zhijian J Chen
The recognition of microbial nucleic acids is a major mechanism by which the immune system detects pathogens. Cyclic GMP-AMP (cGAMP) synthase (cGAS) is a cytosolic DNA sensor that activates innate immune responses through production of the second messenger cGAMP, which activates the adaptor STING. The cGAS-STING pathway not only mediates protective immune defense against infection by a large variety of DNA-containing pathogens but also detects tumor-derived DNA and generates intrinsic antitumor immunity. However, aberrant activation of the cGAS pathway by self DNA can also lead to autoimmune and inflammatory disease...
September 20, 2016: Nature Immunology
Ming-Ming Hu, Qing Yang, Xue-Qin Xie, Chen-Yang Liao, Heng Lin, Tian-Tian Liu, Lei Yin, Hong-Bing Shu
During viral infection, sensing of cytosolic DNA by the cyclic GMP-AMP synthase (cGAS) activates the adaptor protein STING and triggers an antiviral response. Little is known about the mechanisms that determine the kinetics of activation and deactivation of the cGAS-STING pathway, ensuring effective but controlled innate antiviral responses. Here we found that the ubiquitin ligase Trim38 targets cGas for sumoylation in uninfected cells and during the early phase of viral infection. Sumoylation of cGas prevented its polyubiquitination and degradation...
September 20, 2016: Immunity
Daniela Moura de Oliveira, Geni Rodrigues Sampaio, Carolina Bonin Pinto, Rodrigo Ramos Catharino, Deborah H Markowicz Bastos
PURPOSE: Yerba maté is widely consumed in South America as different beverages, such as maté tea (roasted leaves) and chimarrão (green dried leaves), and linked to health benefits, mainly attributed to chlorogenic acids (CGAs). Health effects of CGAs depend on their bioavailability, but such data are scarce. The aim of this study was to investigate the distribution of CGAs and metabolites in tissues, hepatic and plasmatic kinetic profile and urinary excretion after ingestion of maté tea or 5-caffeoylquinic acid (5-CQA)...
August 17, 2016: European Journal of Nutrition
David A Jacques, William A McEwan, Laura Hilditch, Amanda J Price, Greg J Towers, Leo C James
During the early stages of infection, the HIV-1 capsid protects viral components from cytosolic sensors and nucleases such as cGAS and TREX, respectively, while allowing access to nucleotides for efficient reverse transcription. Here we show that each capsid hexamer has a size-selective pore bound by a ring of six arginine residues and a 'molecular iris' formed by the amino-terminal β-hairpin. The arginine ring creates a strongly positively charged channel that recruits the four nucleotides with on-rates that approach diffusion limits...
August 18, 2016: Nature
Kirsten E Wiens, Joel D Ernst
Type I interferons (including IFNαβ) are innate cytokines that may contribute to pathogenesis during Mycobacterium tuberculosis (Mtb) infection. To induce IFNβ, Mtb must gain access to the host cytosol and trigger stimulator of interferon genes (STING) signaling. A recently proposed model suggests that Mtb triggers STING signaling through bacterial DNA binding cyclic GMP-AMP synthase (cGAS) in the cytosol. The aim of this study was to test the generalizability of this model using phylogenetically distinct strains of the Mtb complex (MTBC)...
August 2016: PLoS Pathogens
M Ritt, K H Rádi, C Schwarz, L C Bollheimer, C C Sieber, K G Gaßmann
OBJECTIVE: To compare the ability of different frailty indexes based on a standardized comprehensive geriatric assessment (FI-CGAs) for predicting adverse outcomes. DESIGN AND SETTING: Prospective cohort study. Geriatric wards of a general hospital. PARTICIPANTS: 307 hospitalized patients ≥ 65 years. MEASUREMENTS: The FI-CGA-10D (potential health deficits in ten functional domains), the FI-CGA-10D+CM (aforementioned potential health deficits and co-morbidity burden) and the FI-CGA-MIHD (multiple, individual potential health deficits, including functional deficits, co-morbid diseases, amongst others) were assessed at baseline during the patients` hospital stay...
2016: Journal of Nutrition, Health & Aging
Jonathan Maelfait, Anne Bridgeman, Adel Benlahrech, Chiara Cursi, Jan Rehwinkel
SAMHD1 is a restriction factor for HIV-1 infection. SAMHD1 mutations cause the autoinflammatory Aicardi-Goutières syndrome that is characterized by chronic type I interferon (IFN) secretion. We show that the spontaneous IFN response in SAMHD1-deficient cells and mice requires the cGAS/STING cytosolic DNA-sensing pathway. We provide genetic evidence that cell-autonomous control of lentivirus infection in myeloid cells by SAMHD1 limits virus-induced production of IFNs and the induction of co-stimulatory markers...
August 9, 2016: Cell Reports
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