scholarly journals Establishing the role of ATP for the function of the RIG-I innate immune sensor

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
David C Rawling ◽  
Megan E Fitzgerald ◽  
Anna Marie Pyle
Keyword(s):  
Immune Response ◽  
Atp Hydrolysis ◽  
Innate Immune ◽  
Atp Binding ◽  
Rna Molecules ◽  
Proof Reading ◽  
Atp Binding And Hydrolysis ◽  
Signal Activation ◽  
Inducible Gene

Retinoic acid-inducible gene I (RIG-I) initiates a rapid innate immune response upon detection and binding to viral ribonucleic acid (RNA). This signal activation occurs only when pathogenic RNA is identified, despite the ability of RIG-I to bind endogenous RNA while surveying the cytoplasm. Here we show that ATP binding and hydrolysis by RIG-I play a key role in the identification of viral targets and the activation of signaling. Using biochemical and cell-based assays together with mutagenesis, we show that ATP binding, and not hydrolysis, is required for RIG-I signaling on viral RNA. However, we show that ATP hydrolysis does provide an important function by recycling RIG-I and promoting its dissociation from non-pathogenic RNA. This activity provides a valuable proof-reading mechanism that enhances specificity and prevents an antiviral response upon encounter with host RNA molecules.

scholarly journals In vivo FRET analyses reveal a role of ATP hydrolysis–associated conformational changes in human P-glycoprotein

2020 ◽  
Vol 295 (15) ◽  
pp. 5002-5011 ◽  
Author(s):  
Ryota Futamata ◽  
Fumihiko Ogasawara ◽  
Takafumi Ichikawa ◽  
Atsushi Kodan ◽  
Yasuhisa Kimura ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Drug Transport ◽  
Atp Hydrolysis ◽  
Hek293 Cells ◽  
Atp Binding ◽  
Binding Domains ◽  
P Glycoprotein ◽  
Atp Binding And Hydrolysis

P-glycoprotein (P-gp; also known as MDR1 or ABCB1) is an ATP-driven multidrug transporter that extrudes various hydrophobic toxic compounds to the extracellular space. P-gp consists of two transmembrane domains (TMDs) that form the substrate translocation pathway and two nucleotide-binding domains (NBDs) that bind and hydrolyze ATP. At least two P-gp states are required for transport. In the inward-facing (pre-drug transport) conformation, the two NBDs are separated, and the two TMDs are open to the intracellular side; in the outward-facing (post-drug transport) conformation, the NBDs are dimerized, and the TMDs are slightly open to the extracellular side. ATP binding and hydrolysis cause conformational changes between the inward-facing and the outward-facing conformations, and these changes help translocate substrates across the membrane. However, how ATP hydrolysis is coupled to these conformational changes remains unclear. In this study, we used a new FRET sensor that detects conformational changes in P-gp to investigate the role of ATP binding and hydrolysis during the conformational changes of human P-gp in living HEK293 cells. We show that ATP binding causes the conformational change to the outward-facing state and that ATP hydrolysis and subsequent release of γ-phosphate from both NBDs allow the outward-facing state to return to the original inward-facing state. The findings of our study underscore the utility of using FRET analysis in living cells to elucidate the function of membrane proteins such as multidrug transporters.

scholarly journals The role of hPNPase, an IFN‐inducible gene, in the hepatocellular innate immune response to HCV infection

2010 ◽  
Vol 24 (S1) ◽  
Author(s):  
Oscar Gonzalez ◽  
George K. Yeh ◽  
Carla M. Koehler ◽  
Michael A. Teitiell ◽  
Samuel W. French
Keyword(s):  
Immune Response ◽  
Innate Immune Response ◽  
Innate Immune ◽  
Hcv Infection ◽  
Inducible Gene

scholarly journals The role of ATP hydrolysis in conformational changes of human P-glycoprotein in living cells

2019 ◽  
Author(s):  
Ryota Futamata ◽  
Fumihiko Ogasawara ◽  
Takafumi Ichikawa ◽  
Atsushi Kodan ◽  
Yasuhisa Kimura ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Drug Transport ◽  
Atp Hydrolysis ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Living Cells ◽  
Atp Binding ◽  
P Glycoprotein ◽  
Atp Binding And Hydrolysis

AbstractP-glycoprotein (P-gp; also known as MDR1 or ABCB1) is an ATP-driven multidrug transporter that extrudes various hydrophobic toxic compounds to the extracellular space. P-gp consists of two transmembrane domains (TMDs) that form the substrate translocation pathway and two nucleotide-binding domains (NBDs) that bind and hydrolyze ATP. P-gp takes at least two states during transport; the inward-facing (pre-drug transport) conformation, in which the two NBDs are separated and the two TMDs are open to the intracellular side, and the outward-facing (post-drug transport) conformation, in which the NBDs are dimerized and the TMDs are slightly open to the extracellular side. ATP binding and hydrolysis cause conformational changes between the inward-facing and the outward-facing conformations to translocate substrates across the membrane. However, it remains unclear how ATP is used during these conformational changes in living cells. In this study, we investigated the role of ATP binding and hydrolysis during the conformational changes of human P-gp in living cells by using fluorescence resonance energy transfer (FRET). We show that ATP binding causes the conformational change to the outward-facing state and that ATP hydrolysis and subsequent release of γ-phosphate from both NBDs allow the outward-facing state to return to the original inward-facing state.

scholarly journals Unified mechanisms for self-RNA recognition by RIG-I Singleton-Merten syndrome variants

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Charlotte Lässig ◽  
Katja Lammens ◽  
Jacob Lucián Gorenflos López ◽  
Sebastian Michalski ◽  
Olga Fettscher ◽  
...  
Keyword(s):  
Immune Response ◽  
Retinoic Acid ◽  
Rna Binding ◽  
Atp Hydrolysis ◽  
Innate Immune ◽  
Rna Recognition ◽  
Double Stranded Rna ◽  
Lower Affinity ◽  
Structural Conformation ◽  
Inducible Gene

The innate immune sensor retinoic acid-inducible gene I (RIG-I) detects cytosolic viral RNA and requires a conformational change caused by both ATP and RNA binding to induce an active signaling state and to trigger an immune response. Previously, we showed that ATP hydrolysis removes RIG-I from lower-affinity self-RNAs (<xref ref-type="bibr" rid="bib19">Lässig et al., 2015</xref>), revealing how ATP turnover helps RIG-I distinguish viral from self-RNA and explaining why a mutation in a motif that slows down ATP hydrolysis causes the autoimmune disease Singleton-Merten syndrome (SMS). Here we show that a different, mechanistically unexplained SMS variant, C268F, which is localized in the ATP-binding P-loop, can signal independently of ATP but is still dependent on RNA. The structure of RIG-I C268F in complex with double-stranded RNA reveals that C268F helps induce a structural conformation in RIG-I that is similar to that induced by ATP. Our results uncover an unexpected mechanism to explain how a mutation in a P-loop ATPase can induce a gain-of-function ATP state in the absence of ATP.

scholarly journals Bacterial Cyclic Dinucleotides and the cGAS–cGAMP–STING Pathway: A Role in Periodontitis?

Pathogens ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 675
Author(s):  
Samira Elmanfi ◽  
Mustafa Yilmaz ◽  
Wilson W. S. Ong ◽  
Kofi S. Yeboah ◽  
Herman O. Sintim ◽  
...  
Keyword(s):  
Immune Response ◽  
Periodontal Disease ◽  
Innate Immune ◽  
Host Cells ◽  
Type I Interferons ◽  
Type I ◽  
Vaccine Adjuvants ◽  
Cyclic Dinucleotides ◽  
Sting Pathway

Host cells can recognize cytosolic double-stranded DNAs and endogenous second messengers as cyclic dinucleotides—including c-di-GMP, c-di-AMP, and cGAMP—of invading microbes via the critical and essential innate immune signaling adaptor molecule known as STING. This recognition activates the innate immune system and leads to the production of Type I interferons and proinflammatory cytokines. In this review, we (1) focus on the possible role of bacterial cyclic dinucleotides and the STING/TBK1/IRF3 pathway in the pathogenesis of periodontal disease and the regulation of periodontal immune response, and (2) review and discuss activators and inhibitors of the STING pathway as immune response regulators and their potential utility in the treatment of periodontitis. PubMed/Medline, Scopus, and Web of Science were searched with the terms “STING”, “TBK 1”, “IRF3”, and “cGAS”—alone, or together with “periodontitis”. Current studies produced evidence for using STING-pathway-targeting molecules as part of anticancer therapy, and as vaccine adjuvants against microbial infections; however, the role of the STING/TBK1/IRF3 pathway in periodontal disease pathogenesis is still undiscovered. Understanding the stimulation of the innate immune response by cyclic dinucleotides opens a new approach to host modulation therapies in periodontology.

Intestinal dysbiosis augments liver disease progression via NLRP3 in a murine model of primary sclerosing cholangitis

Gut ◽  
2019 ◽  
Vol 68 (8) ◽  
pp. 1477-1492 ◽  
Author(s):  
Lijun Liao ◽  
Kai Markus Schneider ◽  
Eric J C Galvez ◽  
Mick Frissen ◽  
Hanns-Ulrich Marschall ◽  
...  
Keyword(s):  
Immune Response ◽  
Liver Injury ◽  
Sclerosing Cholangitis ◽  
Functional Role ◽  
Innate Immune ◽  
Caspase 8 ◽  
Inflammasome Activation ◽  
Intestinal Dysbiosis ◽  
Nlrp3 Inflammasome Activation

ObjectiveThere is a striking association between human cholestatic liver disease (CLD) and inflammatory bowel disease. However, the functional implications for intestinal microbiota and inflammasome-mediated innate immune response in CLD remain elusive. Here we investigated the functional role of gut–liver crosstalk for CLD in the murine Mdr2 knockout (Mdr2−/−) model resembling human primary sclerosing cholangitis (PSC).DesignMale Mdr2−/−, Mdr2−/− crossed with hepatocyte-specific deletion of caspase-8 (Mdr2−/−/Casp8∆hepa) and wild-type (WT) control mice were housed for 8 or 52 weeks, respectively, to characterise the impact of Mdr2 deletion on liver and gut including bile acid and microbiota profiling. To block caspase activation, a pan-caspase inhibitor (IDN-7314) was administered. Finally, the functional role of Mdr2−/−-associated intestinal dysbiosis was studied by microbiota transfer experiments.ResultsMdr2−/− mice displayed an unfavourable intestinal microbiota signature and pronounced NLRP3 inflammasome activation within the gut–liver axis. Intestinal dysbiosis in Mdr2−/− mice prompted intestinal barrier dysfunction and increased bacterial translocation amplifying the hepatic NLRP3-mediated innate immune response. Transfer of Mdr2−/− microbiota into healthy WT control mice induced significant liver injury in recipient mice, highlighting the causal role of intestinal dysbiosis for disease progression. Strikingly, IDN-7314 dampened inflammasome activation, ameliorated liver injury, reversed serum bile acid profile and cholestasis-associated microbiota signature.ConclusionsMDR2-associated cholestasis triggers intestinal dysbiosis. In turn, translocation of endotoxin into the portal vein and subsequent NLRP3 inflammasome activation contribute to higher liver injury. This process does not essentially depend on caspase-8 in hepatocytes, but can be blocked by IDN-7314.

scholarly journals The role of beneficial bacteria wall elasticity in regulating innate immune response

2015 ◽  
Vol 6 (1) ◽  
Author(s):  
Viktoria V. Мokrozub ◽  
Liudmyla M. Lazarenko ◽  
Liubov M. Sichel ◽  
Lidia P. Babenko ◽  
Petro M. Lytvyn ◽  
...  
Keyword(s):  
Immune Response ◽  
Innate Immune Response ◽  
Innate Immune ◽  
Beneficial Bacteria
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