scholarly journals An Update on CARD Only Proteins (COPs) and PYD Only Proteins (POPs) as Inflammasome Regulators

2020 ◽  
Vol 21 (18) ◽  
pp. 6901
Author(s):  
Savita Devi ◽  
Christian Stehlik ◽  
Andrea Dorfleutner
Keyword(s):  
Inflammatory Disease ◽  
Host Response ◽  
Inflammasome Activation ◽  
Control Mechanisms ◽  
Protein Protein Interaction ◽  
Single Domain Protein ◽  
Pyrin Domain ◽  
Nucleated Polymerization ◽  
Point Of No Return ◽  
Interaction Domains

Inflammasomes are protein scaffolds required for the activation of caspase-1 and the subsequent release of interleukin (IL)-1β, IL-18, and danger signals, as well as the induction of pyroptotic cell death to restore homeostasis following infection and sterile tissue damage. However, excessive inflammasome activation also causes detrimental inflammatory disease. Therefore, extensive control mechanisms are necessary to prevent improper inflammasome responses and inflammatory disease. Inflammasomes are assembled by sequential nucleated polymerization of Pyrin domain (PYD) and caspase recruitment domain (CARD)-containing inflammasome components. Once polymerization is nucleated, this process proceeds in a self-perpetuating manner and represents a point of no return. Therefore, regulation of this key step is crucial for a controlled inflammasome response. Here, we provide an update on two single domain protein families containing either a PYD or a CARD, the PYD-only proteins (POPs) and CARD-only proteins (COPs), respectively. Their structure allows them to occupy and block access to key protein–protein interaction domains necessary for inflammasome assembly, thereby regulating the threshold of these nucleated polymerization events, and consequently, the inflammatory host response.

scholarly journals Aggregated Tau-PHF6 (VQIVYK) Potentiates NLRP3 Inflammasome Expression and Autophagy in Human Microglial Cells

Cells ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1652
Author(s):  
Chinmaya Panda ◽  
Clara Voelz ◽  
Pardes Habib ◽  
Christian Mevissen ◽  
Thomas Pufe ◽  
...  
Keyword(s):  
Tau Protein ◽  
Nlrp3 Inflammasome ◽  
Time Dependent ◽  
Microglial Cells ◽  
Inflammasome Activation ◽  
Dependent Manner ◽  
Progressive Dementia ◽  
Microglial Polarization ◽  
Protein Levels ◽  
Pyrin Domain

Intra-neuronal misfolding of monomeric tau protein to toxic β-sheet rich neurofibrillary tangles is a hallmark of Alzheimer’s disease (AD). Tau pathology correlates not only with progressive dementia but also with microglia-mediated inflammation in AD. Amyloid-beta (Aβ), another pathogenic peptide involved in AD, has been shown to activate NLRP3 inflammasome (NOD-like receptor family, pyrin domain containing 3), triggering the secretion of proinflammatory interleukin-1β (IL1β) and interleukin-18 (IL18). However, the effect of tau protein on microglia concerning inflammasome activation, microglial polarization, and autophagy is poorly understood. In this study, human microglial cells (HMC3) were stimulated with the unaggregated and aggregated forms of the tau-derived PHF6 peptide (VQIVYK). Modulation of NLRP3 inflammasome was examined by qRT-PCR, immunocytochemistry, and Western blot. We demonstrate that fibrillar aggregates of VQIVYK upregulated the NLRP3 expression at both mRNA and protein levels in a dose- and time-dependent manner, leading to increased expression of IL1β and IL18 in HMC3 cells. Aggregated PHF6-peptide also activated other related inflammation and microglial polarization markers. Furthermore, we also report a time-dependent effect of the aggregated PHF6 on BECN1 (Beclin-1) expression and autophagy. Overall, the PHF6 model system-based study may help to better understand the complex interconnections between Alzheimer’s PHF6 peptide aggregation and microglial inflammation, polarization, and autophagy.

scholarly journals Mutations and Protein Interaction Landscape Reveal Key Cellular Events Perturbed in Upper Motor Neurons with HSP and PLS

2021 ◽  
Vol 11 (5) ◽  
pp. 578
Author(s):  
Oge Gozutok ◽  
Benjamin Ryan Helmold ◽  
P. Hande Ozdinler
Keyword(s):  
Motor Neurons ◽  
Protein Interaction ◽  
Protein Interactions ◽  
Cortical Neurons ◽  
Therapeutic Interventions ◽  
Functional Identification ◽  
Protein Protein Interaction ◽  
Cellular Events ◽  
Interaction Domains ◽  
Upper Motor Neurons

Hereditary spastic paraplegia (HSP) and primary lateral sclerosis (PLS) are rare motor neuron diseases, which affect mostly the upper motor neurons (UMNs) in patients. The UMNs display early vulnerability and progressive degeneration, while other cortical neurons mostly remain functional. Identification of numerous mutations either directly linked or associated with HSP and PLS begins to reveal the genetic component of UMN diseases. Since each of these mutations are identified on genes that code for a protein, and because cellular functions mostly depend on protein-protein interactions, we hypothesized that the mutations detected in patients and the alterations in protein interaction domains would hold the key to unravel the underlying causes of their vulnerability. In an effort to bring a mechanistic insight, we utilized computational analyses to identify interaction partners of proteins and developed the protein-protein interaction landscape with respect to HSP and PLS. Protein-protein interaction domains, upstream regulators and canonical pathways begin to highlight key cellular events. Here we report that proteins involved in maintaining lipid homeostasis and cytoarchitectural dynamics and their interactions are of great importance for UMN health and stability. Their perturbation may result in neuronal vulnerability, and thus maintaining their balance could offer therapeutic interventions.

scholarly journals LRR protein RNH1 inhibits inflammasome activation through proteasome-mediated degradation of Caspase-1 and is associated with adverse clinical outcomes in COVID-19 patients.

2021 ◽  
Author(s):  
Giuseppe Bombaci ◽  
Mayuresh A Sarangdhar ◽  
Nicola Andina ◽  
Aubry Tardivel ◽  
Eric Chi-Wang Yu ◽  
...  
Keyword(s):  
Inflammatory Diseases ◽  
Neutrophil Infiltration ◽  
Inflammasome Activation ◽  
Ribonuclease Inhibitor ◽  
Protein Levels ◽  
Caspase 1 ◽  
Pyrin Domain ◽  
Underlying Mechanisms ◽  
Lrr Protein ◽  
Receptor Family

Inflammasomes are cytosolic innate immune sensors that, upon activation, induce caspase-1 mediated inflammation. Although inflammation is protective, uncontrolled excessive inflammation can cause inflammatory diseases and is also detrimental in COVID-19 infection. However, the underlying mechanisms that control inflammasome activation are incompletely understood. Here we report that the leucine rich repeat (LRR) protein Ribonuclease inhibitor (RNH1), which shares homology with LRRs of NOD-like receptor family pyrin domain (PYD)-containing (NLRP) proteins, attenuates inflammasome activation. Mechanistically, RNH1 decreased pro-IL1b expression and induced proteasome-mediated caspase-1 degradation. Corroborating this, mouse models of monosodium urate (MSU)-induced peritonitis and LPS-induced endotoxemia, which are dependent on caspase-1, respectively showed increased neutrophil infiltration and lethality in Rnh1-/- mice compared to WT mice. Further, RNH1 protein levels were negatively correlated with inflammation and disease severity in hospitalized COVID-19 patients. We propose that RNH1 is a new inflammasome regulator with relevance to COVID-19 severity.

scholarly journals Activation of GSDME compensates for GSDMD deficiency in a mouse model of NLRP3 inflammasomopathy

2021 ◽  
Author(s):  
Chun Wang ◽  
Tong Yang ◽  
Jianqiu Xiao ◽  
Canxin Xu ◽  
Yael Alippe ◽  
...  
Keyword(s):  
Inflammatory Disease ◽  
Early Death ◽  
Organ Damage ◽  
Caspase 8 ◽  
Inflammasome Activation ◽  
Inflammatory Pathway ◽  
Disease Symptoms ◽  
Caspase 1 ◽  
Inflammatory Stimuli

AbstractThe D301N NLRP3 mutation in mice (D303N in humans) causes severe multi-organ damage and early death driven by the constitutively activated NLRP3 (NLRP3ca) inflammasome. Triggered inflammasomes activate caspase-1 to process IL-1 family cytokines and gasdermin D (GSDMD), generating N-terminal fragments, which oligomerize within the plasma membrane to form pores, which cause inflammatory cell death (pyroptosis) and through which IL-1β and IL-18 are secreted. GSDMD activation is central to disease symptoms since spontaneous inflammation in Nlrp3ca;Gsdmd-/- mice is negligible. Unexpectedly, when Nlrp3ca;Gsdmd-/- mice were challenged with LPS or TNF-α, they secreted high amounts of IL-1β and IL-18, suggesting an alternative GSDMD-independent inflammatory pathway. Here we show that GSDMD deficient macrophages subjected to inflammatory stimuli activate caspase-8, -3 and GSDME-dependent cytokine release and pyroptosis. Caspase-8, -3 and GSDME also activated pyroptosis when NLRP3 was stimulated in caspase-1 deficient macrophages. Thus, a salvage caspase-8, -3-GSDME inflammatory pathway is activated following NLRP3 activation when the canonical NLRP3-caspase-1-GSDMD is blocked. Surprisingly, the active metabolite of the GSDMD-inhibitor disulfiram, inhibited not only GSDMD but also GSDME-mediated inflammation in vitro and suppressed severe inflammatory disease symptoms in Nlrp3ca mice, a model for severe neonatal multisystem inflammatory disease. Although disulfiram did not directly inhibit GSDME, it suppressed inflammasome activation in GSDMD-deficient cells. Thus, the combination of inflammatory signals and NLRP3ca overwhelmed the protection provided by GSDMD deficiency, rewiring signaling cascades through caspase-8, -3 and GSDME to propagate inflammation. This functional redundancy suggests that concomitant inhibition of GSDMD and GSDME may be necessary to suppress disease in inflammasomopathy patients.

scholarly journals ASC filament formation serves as a signal amplification mechanism for inflammasomes

2016 ◽  
Vol 7 (1) ◽  
Author(s):  
Mathias S. Dick ◽  
Lorenzo Sborgi ◽  
Sebastian Rühl ◽  
Sebastian Hiller ◽  
Petr Broz
Keyword(s):  
Signal Amplification ◽  
Cytokine Production ◽  
Adaptor Protein ◽  
Site Directed Mutagenesis ◽  
Cross Linking ◽  
Directed Mutagenesis ◽  
Inflammasome Activation ◽  
Pyrin Domain ◽  
Efficient Processing ◽  
Amplification Mechanism

Abstract A hallmark of inflammasome activation is the ASC speck, a micrometre-sized structure formed by the inflammasome adaptor protein ASC (apoptosis-associated speck-like protein containing a CARD), which consists of a pyrin domain (PYD) and a caspase recruitment domain (CARD). Here we show that assembly of the ASC speck involves oligomerization of ASCPYD into filaments and cross-linking of these filaments by ASCCARD. ASC mutants with a non-functional CARD only assemble filaments but not specks, and moreover disrupt endogenous specks in primary macrophages. Systematic site-directed mutagenesis of ASCPYD is used to identify oligomerization-deficient ASC mutants and demonstrate that ASC speck formation is required for efficient processing of IL-1β, but dispensable for gasdermin-D cleavage and pyroptosis induction. Our results suggest that the oligomerization of ASC creates a multitude of potential caspase-1 activation sites, thus serving as a signal amplification mechanism for inflammasome-mediated cytokine production.

scholarly journals Dynamics of in vivo ASC speck formation

2017 ◽  
Vol 216 (9) ◽  
pp. 2891-2909 ◽  
Author(s):  
Paola Kuri ◽  
Nicole L. Schieber ◽  
Thomas Thumberger ◽  
Joachim Wittbrodt ◽  
Yannick Schwab ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Cell Death ◽  
Light And Electron Microscopy ◽  
Three Dimensional ◽  
Inflammasome Activation ◽  
Caspase Activation ◽  
Endogenous Gene ◽  
Pyrin Domain ◽  
Effector Caspase

Activated danger or pathogen sensors trigger assembly of the inflammasome adaptor ASC into specks, large signaling platforms considered hallmarks of inflammasome activation. Because a lack of in vivo tools has prevented the study of endogenous ASC dynamics, we generated a live ASC reporter through CRISPR/Cas9 tagging of the endogenous gene in zebrafish. We see strong ASC expression in the skin and other epithelia that act as barriers to insult. A toxic stimulus triggered speck formation and rapid pyroptosis in keratinocytes in vivo. Macrophages engulfed and digested that speck-containing, pyroptotic debris. A three-dimensional, ultrastructural reconstruction, based on correlative light and electron microscopy of the in vivo assembled specks revealed a compact network of highly intercrossed filaments, whereas pyrin domain (PYD) or caspase activation and recruitment domain alone formed filamentous aggregates. The effector caspase is recruited through PYD, whose overexpression induced pyroptosis but only after substantial delay. Therefore, formation of a single, compact speck and rapid cell-death induction in vivo requires a full-length ASC.

scholarly journals Coincidental loss of DOCK8 function in NLRP10-deficient and C3H/HeJ mice results in defective dendritic cell migration

2015 ◽  
Vol 112 (10) ◽  
pp. 3056-3061 ◽  
Author(s):  
Jayendra Kumar Krishnaswamy ◽  
Arpita Singh ◽  
Uthaman Gowthaman ◽  
Renee Wu ◽  
Pavane Gorrepati ◽  
...  
Keyword(s):  
T Cells ◽  
Lymph Nodes ◽  
Knockout Mice ◽  
T Cell Response ◽  
Inflammasome Activation ◽  
Nucleotide Exchange ◽  
Loss Of Function ◽  
Pyrin Domain ◽  
Proteomic Approach ◽  
Dendritic Cell Migration

Dendritic cells (DCs) are the primary leukocytes responsible for priming T cells. To find and activate naïve T cells, DCs must migrate to lymph nodes, yet the cellular programs responsible for this key step remain unclear. DC migration to lymph nodes and the subsequent T-cell response are disrupted in a mouse we recently described lacking the NOD-like receptor NLRP10 (NLR family, pyrin domain containing 10); however, the mechanism by which this pattern recognition receptor governs DC migration remained unknown. Using a proteomic approach, we discovered that DCs from Nlrp10 knockout mice lack the guanine nucleotide exchange factor DOCK8 (dedicator of cytokinesis 8), which regulates cytoskeleton dynamics in multiple leukocyte populations; in humans, loss-of-function mutations in Dock8 result in severe immunodeficiency. Surprisingly, Nlrp10 knockout mice crossed to other backgrounds had normal DOCK8 expression. This suggested that the original Nlrp10 knockout strain harbored an unexpected mutation in Dock8, which was confirmed using whole-exome sequencing. Consistent with our original report, NLRP3 inflammasome activation remained unaltered in NLRP10-deficient DCs even after restoring DOCK8 function; however, these DCs recovered the ability to migrate. Isolated loss of DOCK8 via targeted deletion confirmed its absolute requirement for DC migration. Because mutations in Dock genes have been discovered in other mouse lines, we analyzed the diversity of Dock8 across different murine strains and found that C3H/HeJ mice also harbor a Dock8 mutation that partially impairs DC migration. We conclude that DOCK8 is an important regulator of DC migration during an immune response and is prone to mutations that disrupt its crucial function.

scholarly journals Growth differentiation factor 11 ameliorates experimental colitis by inhibiting NLRP3 inflammasome activation

2018 ◽  
Vol 315 (6) ◽  
pp. G909-G920 ◽  
Author(s):  
Lanju Wang ◽  
Yaohui Wang ◽  
Zhenfeng Wang ◽  
Yu Qi ◽  
Beibei Zong ◽  
...  
Keyword(s):  
Ulcerative Colitis ◽  
Nlrp3 Inflammasome ◽  
Intestinal Inflammation ◽  
Experimental Colitis ◽  
Inflammasome Activation ◽  
Acute Colitis ◽  
Pyrin Domain ◽  
Differentiation Factor ◽  
Nlrp3 Inflammasome Activation ◽  
Receptor Family

Growth differentiation factor 11 (GDF11) has an anti-inflammatory effect in the mouse model of atherosclerosis and Alzheimer's disease, but how GDF11 regulates intestinal inflammation during ulcerative colitis (UC) is poorly defined. The Nod-like receptor family pyrin domain-1 containing 3 (NLRP3) inflammasome is closely associated with intestinal inflammation because of its ability to increase IL-1β secretion. Our aim is to determine whether GDF11 has an effect on attenuating experimental colitis in mice. In this study, using a dextran sodium sulfate (DSS)-induced acute colitis mouse model, we reported that GDF11 treatment attenuated loss of body weight, the severity of the disease activity index, shortening of the colon, and histological changes in the colon. GDF11 remarkably suppressed IL-1β secretion and NLRP3 inflammasome activation in colon samples and RAW 264.7 cells, such as the levels of NLRP3 and activated caspase-1. Furthermore, we found that GDF11 inhibited NLRP3 inflammasome activation by downregulating the Toll-like receptor 4/NF-κB p65 pathway and reactive oxygen species production via the typical Smad2/3 pathway. Thus, our research shows that GDF11 alleviates DSS-induced colitis by inhibiting NLRP3 inflammasome activation, providing some basis for its potential use in the treatment of UC. NEW & NOTEWORTHY Here, we identify a new role for growth differentiation factor 11 (GDF11), which ameliorates dextran sodium sulfate-induced acute colitis. Meanwhile, we discover a new phenomenon of GDF11 inhibiting IL-1β secretion and Nod-like receptor family pyrin domain-1 containing 3 (NLRP3) inflammasome activation. These findings reveal that GDF11 is a new potential candidate for the treatment of ulcerative colitis patients with a hyperactive NLRP3 inflammasome.

scholarly journals NLR Family Pyrin Domain‐Containing 3 Inflammasome Activation in Hepatic Stellate Cells Induces Liver Fibrosis in Mice

Hepatology ◽  
2019 ◽  
Vol 69 (2) ◽  
pp. 845-859 ◽  
Author(s):  
Maria Eugenia Inzaugarat ◽  
Casey D. Johnson ◽  
Theresa Maria Holtmann ◽  
Matthew D. McGeough ◽  
Christian Trautwein ◽  
...  
Keyword(s):  
Liver Fibrosis ◽  
Hepatic Stellate Cells ◽  
Stellate Cells ◽  
Inflammasome Activation ◽  
Pyrin Domain

Role of the Inflammasome in Liver Disease

2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Marcelle de Carvalho Ribeiro ◽  
Gyongyi Szabo
Keyword(s):  
Liver Disease ◽  
Liver Diseases ◽  
Annual Review ◽  
Publication Date ◽  
Inflammasome Activation ◽  
Proinflammatory Response ◽  
Nonalcoholic Fatty Liver ◽  
Pyrin Domain ◽  
Different Types

The involvement of inflammasomes in the proinflammatory response observed in chronic liver diseases, such as alcohol-associated liver disease (ALD) and nonalcoholic fatty liver disease (NAFLD), is widely recognized. Although there are different types of inflammasomes, most studies to date have given attention to NLRP3 (nucleotide-binding oligomerization domain-like receptor family, pyrin domain containing 3) in the pathogenesis of ALD, NAFLD/nonalcoholic steatohepatitis, and fibrosis. Canonical inflammasomes are intracellular multiprotein complexes that are assembled after the sensing of danger signals and activate caspase-1, which matures interleukin (IL)-1β, IL-18, and IL-37 and also induces a form of cell death called pyroptosis. Noncanonical inflammasomes activate caspase-11 to induce pyroptosis. We discuss the different types of inflammasomes involved in liver diseases with a focus on ( a) signals and mechanisms of inflammasome activation, ( b) the role of different types of inflammasomes and their products in the pathogenesis of liver diseases, and ( c) potential therapeutic strategies targeting components of the inflammasomes or cytokines produced upon inflammasome activation. Expected final online publication date for the Annual Review of Pathology: Mechanisms of Disease, Volume 17 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Sign in / Sign up

Export Citation Format

Share Document