The activation of the nucleotide oligomerization domain (NOD)‐like receptor (NLR) family, pyrin domain‐containing protein 3 (NLRP3) inflammasome is related to the pathogenesis of a wide range of ...inflammatory diseases, but drugs targeting the NLRP3 inflammasome are still scarce. In the present study, we demonstrated that Licochalcone B (LicoB), a main component of the traditional medicinal herb licorice, is a specific inhibitor of the NLRP3 inflammasome. LicoB inhibits the activation of the NLRP3 inflammasome in macrophages but has no effect on the activation of AIM2 or NLRC4 inflammasome. Mechanistically, LicoB directly binds to NEK7 and inhibits the interaction between NLRP3 and NEK7, thus suppressing NLRP3 inflammasome activation. Furthermore, LicoB exhibits protective effects in mouse models of NLRP3 inflammasome‐mediated diseases, including lipopolysaccharide (LPS)‐induced septic shock, MSU‐induced peritonitis and non‐alcoholic steatohepatitis (NASH). Our findings indicate that LicoB is a specific NLRP3 inhibitor and a promising candidate for treating NLRP3 inflammasome‐related diseases.
Synopsis
Licochalcone B, a main component of the medicinal herb licorice, specifically inhibits the NLRP3 inflammasome by disrupting NEK7‐NLRP3 interaction and exhibits protective effects in mouse models of NLRP3 inflammasome‐mediated diseases.
Licochalcone B specifically inhibits both canonical and non‐canonical NLRP3 inflammasome activation.
Licochalcone B blocks NLRP3‐dependent ASC oligomerization.
Licochalcone B binds to NEK7 and disrupts the NEK7‐NLRP3 interaction.
Licochalcone B effectively protects against NLRP3‐mediated diseases.
Licochalcone B, a main component of the medicinal herb licorice, specifically inhibits the NLRP3 inflammasome by disrupting NEK7‐NLRP3 interaction and exhibits protective effects in mouse models of NLRP3 inflammasome‐mediated diseases.
The kinetochore is a supramolecular complex that facilitates faithful chromosome segregation by bridging the centromere and spindle microtubules. Recent functional and structural studies on the inner ...kinetochore subcomplex, constitutive centromere-associated network (CCAN) have updated our understanding of kinetochore architecture. While the CCAN core establishes a stable interface with centromeric chromatin, CCAN organization is dynamically altered and coupled with cell cycle progression. Furthermore, the CCAN components, centromere protein (CENP)-C and CENP-T, mediate higher-order assembly of multiple kinetochore units on the regional centromeres of vertebrates. This review highlights new insights into kinetochore rigidity, plasticity, and clustering, which are key to understanding temporal and spatial regulatory mechanisms of chromosome segregation.
A full understanding of Parkinson's Disease etiopathogenesis and of the causes of the preferential vulnerability of nigrostriatal dopaminergic neurons is still an unsolved puzzle. A multiple-hit ...hypothesis has been proposed, which may explain the convergence of familial, environmental and idiopathic forms of the disease. Among the various determinants of the degeneration of the neurons in Substantia Nigra pars compacta, in this review we will focus on the endotoxicity associated to dopamine dyshomeostasis. In particular, we will discuss the relevance of the reactive dopamine metabolite 3,4-dihydroxyphenylacetaldehyde (DOPAL) in the catechol-induced neurotoxicity. Indeed, the synergy between the catechol and the aldehyde moieties of DOPAL exacerbates its reactivity, resulting in modification of functional protein residues, protein aggregation, oxidative stress and cell death. Interestingly, αSynuclein, whose altered proteostasis is a recurrent element in Parkinson's Disease pathology, is considered a preferential target of DOPAL modification. DOPAL triggers αSynuclein oligomerization leading to synapse physiology impairment. Several factors can be responsible for DOPAL accumulation at the pre-synaptic terminals, i.e. dopamine leakage from synaptic vesicles, increased rate of dopamine conversion to DOPAL by upregulated monoamine oxidase and decreased DOPAL degradation by aldehyde dehydrogenases. Various studies report the decreased expression and activity of aldehyde dehydrogenases in parkinsonian brains, as well as genetic variants associated to increased risk in developing the pathology. Thus, we discuss how the deregulation of these enzymes might be considered a contributing element in the pathogenesis of Parkinson's Disease or a down-stream effect. Finally, we propose that a better understanding of the impaired dopamine metabolism in Parkinson's Disease would allow a more refined patients stratification and the design of more targeted and successful therapeutic strategies.
It is unclear how the mitochondrial fusion protein Optic atrophy 1 (OPA1), which inhibits cristae remodeling, protects from mitochondrial dysfunction. Here we identify the mitochondrial F
F
-ATP ...synthase as the effector of OPA1 in mitochondrial protection. In OPA1 overexpressing cells, the loss of proton electrochemical gradient caused by respiratory chain complex III inhibition is blunted and this protection is abolished by the ATP synthase inhibitor oligomycin. Mechanistically, OPA1 and ATP synthase can interact, but recombinant OPA1 fails to promote oligomerization of purified ATP synthase reconstituted in liposomes, suggesting that OPA1 favors ATP synthase oligomerization and reversal activity by modulating cristae shape. When ATP synthase oligomers are genetically destabilized by silencing the key dimerization subunit e, OPA1 is no longer able to preserve mitochondrial function and cell viability upon complex III inhibition. Thus, OPA1 protects mitochondria from respiratory chain inhibition by stabilizing cristae shape and favoring ATP synthase oligomerization.
Accurate counting of single molecules at nanoscale resolution is essential for the study of molecular interactions and distribution in subcellular fractions. By using small-sized carbon dots (CDs), ...we have now developed a quantitative single-molecule localization microscopy technique (qSMLM) based on spontaneous blinking to count single molecules with a localization precision of 10 nm, which can be accomplished on conventional microscopes without sophisticated laser control. We explore and adapt the blinking of CDs with diverse structures and demonstrate a counting accuracy of >97% at a molecular density of 500 per μm2. When applied to G-protein coupled receptors on a cell membrane, we discriminated receptor oligomerization and clustering and revealed ligand-regulated receptor distribution patterns. This is the first example of adapting nanoparticle self-blinking for molecular counting, and this demonstrates the power of CDs as SMLM probes to reliably decipher sub-diffraction structures that mediate crucial biological functions.
Non-cytolytic cure of HBV-infected hepatocytes by cytokines, including type I interferons (IFNs), is of importance for resolving acute and chronic infection. However, as IFNs stimulate hundreds of ...genes, those most relevant for HBV suppression remain largely unknown. Amongst them are the large myxovirus resistance (Mx) GTPases. Human MX1 (or MxA) is active against many RNA viruses, while MX2 (or MxB) was recently found to restrict HIV-1, HCV, and herpesviruses. Herein, we investigated the anti-HBV activity of MX2.
The potential anti-HBV activity of MX2 and functional variants were assessed in transfected and HBV-infected hepatoma cells and primary human hepatocytes, employing multiple assays to analyze the synthesis and decay of HBV nucleic acids. The specific roles of MX2 in IFN-α-driven inhibition of HBV transcription and replication were assessed by MX2-specific shRNA interference (RNAi).
Both MX2 alone and IFN-α substantially inhibited HBV replication, due to significant deceleration of the synthesis and slight acceleration of the turnover of viral RNA. RNAi knockdown of MX2 significantly reduced the inhibitory effects of IFN-α. Strikingly, MX2 inhibited HBV infection by reducing covalently closed circular DNA (cccDNA), most likely by indirectly impairing the conversion of relaxed circular DNA to cccDNA rather than by destabilizing existing cccDNA. Various mutations affecting the GTPase activity and oligomerization status reduced MX2's anti-HBV activity.
MX2 is an important IFN-α inducible effector that decreases HBV RNA levels but can also potently inhibit HBV infection by indirectly impairing cccDNA formation. MX2 likely has the potential for therapeutic applications aimed at curing HBV infection by eliminating cccDNA.
This study shows that the protein MX2, which is induced by interferon-α, has important anti-hepatitis B virus (HBV) effector functions. MX2 can reduce the amount of covalently closed circular DNA, which is the form of DNA that HBV uses to maintain viral persistence within hepatocytes. MX2 also reduces HBV RNA levels by downregulating synthesis of viral RNA. MX2 likely represents a novel intrinsic HBV inhibitor that could have therapeutic potential, as well as being useful for improving our understanding of the complex biology of HBV and the antiviral mechanisms of interferon-α.
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•IFN-α inducible MX2 potently inhibited HBV replication driven by episomal templates.•MX2 reduced HBV RNA by significantly decreasing HBV RNA transcription and slightly accelerating its decay.•MX2 contributes substantially to the anti-HBV activity of IFN-α.•MX2 but not the homologous MX1 efficiently inhibited HBV infection of HepG2-NTCP cells and primary human hepatocytes.•Multiple MX2 determinants including GTPase activity and oligomerization status were required for anti-HBV activity.
The Cover Feature illustrates auto‐regulated protein assembly in which a supramolecular ligand prompts tetramer formation and subsequent disassembly to a ligand‐coated monomer. Highly atypical ...isothermal titration calorimetry thermograms were obtained for the interactions of anionic sulfonato‐calix8arene and cationic cytochrome c. A modelling approach with Bayesian fitting provides new tools to understand such intricate assembly processes. More information can be found in the Article by M. L. Rennie and P. B. Crowley on page 1011 in Issue 8, 2019 (DOI: 10.1002/cphc.201900153).
Gasdermin-D (GSDMD), the executioner of pyroptotic cell death when it is cleaved by inflammatory caspases, plays a crucial role in host defense and the response to danger signals. So far, there are ...no known mechanisms, other than cleavage, for regulating GSDMD. Here, we show that tripartite motif protein TRIM21 acts as a positive regulator of GSDMD-dependent pyroptosis. TRIM21 interacted with GSDMD via its PRY-SPRY domain, maintaining GSDMD stable expression in resting cells yet inducing the N-terminus of GSDMD (GSDMD-N) aggregation during pyroptosis. TRIM21-deficient cells displayed a reduced cell death in response to NLRP3 or NLRC4 inflammasome activation. Genetic ablation of TRIM21 in mice conferred protection from LPS-induced inflammation and dextran sulfate sodium-induced colitis. Therefore, TRIM21 plays an essential role in GSDMD-mediated pyroptosis and may be a viable target for controlling and treating inflammation-associated diseases.
Abstract
The necroptosis pathway is a lytic, pro-inflammatory mode of cell death that is widely implicated in human disease, including renal, pulmonary, gut and skin inflammatory pathologies. The ...precise mechanism of the terminal steps in the pathway, where the RIPK3 kinase phosphorylates and triggers a conformation change and oligomerization of the terminal pathway effector, MLKL, are only emerging. Here, we structurally identify RIPK3-mediated phosphorylation of the human MLKL activation loop as a cue for MLKL pseudokinase domain dimerization. MLKL pseudokinase domain dimerization subsequently drives formation of elongated homotetramers. Negative stain electron microscopy and modelling support nucleation of the MLKL tetramer assembly by a central coiled coil formed by the extended, ~80 Å brace helix that connects the pseudokinase and executioner four-helix bundle domains. Mutational data assert MLKL tetramerization as an essential prerequisite step to enable the release and reorganization of four-helix bundle domains for membrane permeabilization and cell death.
In situ Raman spectroscopy was used for the first time to study the reaction intermediates/products of the oxidative polymerization of aniline to polyaniline (PANI) with peroxydisulfate in aqueous ...solutions of different initial acidity. Raman spectra were recorded for the drops of reaction mixture taken at various reaction times. Five reaction systems with different pH of the monomer solution (pHmon), leading to 1-D nanostructured PANIs (pHmon =5.8, 4.6 and 4.5) and granular PANIs (pHmon= 3.4 and 1.0) were explored. Spectral characteristics of different reaction phases - athermal, exothermic and post-propagation were identified and correlated with the proposed mechanisms of aniline polymerization and nanostructures formation. For the nanostructured PANIs, the athermal phase was characterized by pronounced strengthening of the δ(N−H)/ν(CN)Q band at 1510–1520 cm−1, while the characteristic of the second exothermic phase was the strengthening of the ν(C∼C)B/ν(C∼C)Phz band at c.a. 1636 cm−1 which becomes stronger than the ν(CC)Q/ν(C∼C)SQ band at c.a. 1590 cm–1. For granular PANIs, the band at 1590 cm–1 was stronger than that at 1630 cm–1 for all reaction phases. For all reaction systems, characteristic feature of the post-propagation phase was strengthening of the ν(C∼N+•) band at 1330–1340 cm−1 due to delocalized polarons. For granular PANIs, the band associated with phenazine-like units at c.a. 1415 cm−1 disappeared after the exothermic phase, while for nanostructured PANIs it was seen until the end of the reaction. The obtained results are expected to be useful in further investigations of the intermediates/products and mechanisms of polymerizations of other aromatic amines.
•The oxidative polymerization of aniline in media of different initial acidity leading to 1-D nanostructured and granular polyanilines (PANIs) was studied by in situ Raman spectroscopy.•Spectral characteristics of the individual reaction phases athermal, exothermic and post-propagation, were identified.•For nanostructured PANIs the bands at c.a. 1510 cm−1 and 1636 cm−1 showed pronounced strengthening during the athermal and second exothermic phases, respectively.•For nanostructured PANIs the band at c.a. 1636 cm−1 becomes stronger than that at c.a. 1590 cm–1 during the second exothermic phase while inverse intensity ratio characterizes the other phases.•For granular PANIs the band at c.a. 1590 cm–1 is stronger than the band c.a. 1636 cm−1 for all reaction phases.
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