Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.22.36 (caspase-1)
 6,285 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Synthesis and release of pro-inflammatory cytokines, such as IL-1beta, play a crucial role in the intestinal inflammation that characterizes Crohn's disease. Mutations in the nucleotide oligomerization domain 2 (NOD2) gene are associated with an increased risk of Crohn's disease. Although it is known that NOD2 mediates cytokine responses to muramyl dipeptide (MDP), it is yet unclear whether NOD2 stimulation mediates only transcription of pro-IL-1beta mRNA, or whether NOD2 is also involved in the activation of caspase-1 and release of active IL-1beta. By investigating the response of MNC from Crohn's disease patients homozygous for the 3020insC NOD2 mutation, we were able to show that NOD2 signaling after stimulation with MDP has a dual effect by activating proIL-1beta mRNA transcription and inducing release of bioactive IL-1beta. Because NOD2 engagement amplifies TLR stimulation, we investigated whether activation of caspase-1 by MDP is involved in the NOD2/TLR synergism. The synergy in IL-1beta production between NOD2 and TLR is mediated at post-translational level in a caspase-1-dependent manner, which indirectly suggests that NOD2 also induces caspase-1 activation. In contrast, the synergy in TNF-alpha production after stimulation with MDP and LPS is induced at transcriptional level. This demonstrates that both caspase-1-dependent and -independent mechanisms are involved in the synergy between NOD2 and TLR.
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PMID:Engagement of NOD2 has a dual effect on proIL-1beta mRNA transcription and secretion of bioactive IL-1beta. 1815 16

Promyelocytic HL-60 cells differentiated to a neutrophilic phenotype by incubation with all-trans retinoic acid become constitutively apoptotic. Exposure to either LPS or IL-1beta inhibited the apoptosis of differentiated HL-60 cells. LPS induced the expression of pro-IL-1beta message, upregulated the activity of the interleukin-1beta converting enzyme (caspase-1), and increased the release of IL-1beta into the culture medium. Prevention of IL-1beta translation with an anti-sense oligonucleotide, or prevention of IL-1beta cellular binding with a blocking antibody, accelerated rates of spontaneous apoptosis, and abrogated the inhibitory effects of LPS. However inhibition of caspase-1 activity further inhibited constitutive apoptosis of mature HL-60 cells. These studies provide further evidence of a complex regulatory pathway that modulates the expression of granulocyte apoptosis during inflammation, and point to a specific role for IL-1beta as an autocrine survival factor.
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PMID:Interleukin-1beta mediates LPS-induced inhibition of apoptosis in retinoic acid-differentiated HL-60 cells. 1829 Oct 94

The IL-1 family member 7b (IL-1F7b) is a novel homolog of the IL-1 cytokine family discovered by computational cloning. We have reported that IL-1F7b shares critical amino acid residues with IL-18 and binds the IL-18-binding protein; in doing so, IL-1F7b augments the inhibition of IFN-gamma by the IL-18-binding protein. IL-1F7b also binds IL-18Ralpha but neither induces signal nor acts as a receptor antagonist. Hence, the function of IL-1F7b remains unknown. In the present study, we analyzed the intracellular expression pattern of IL-1F7b. Using two variants of GFP fusion constructs of human IL-1F7b stably expressed in RAW macrophages, only the postcleavage mature form of the IL-1F7b precursor-but not the N-terminal propiece-specifically translocates to the nucleus following LPS stimulation. IL-1F7b, like IL-1beta, IL-18, and IL-33, is processed by caspase-1 to generate the mature cytokines. Therefore, we tested whether caspase-1-mediated cleavage of the IL-1F7b precursor is required for mature IL-1F7b to translocate actively into the nucleus. Indeed, a specific caspase-1 inhibitor markedly reduced nuclear entry of IL-1F7b. In stable transfectants of human IL-1F7b in RAW macrophages stimulated with LPS, levels of TNF-alpha, IL-1alpha, IL-6, as well as the chemokine MIP-2, were substantially reduced (72-98%) compared with LPS-stimulated cells transfected with the empty plasmid. These results demonstrate that IL-1F7b translocates to the nucleus after caspase-1 processing and may act as a transcriptional modulator reducing the production of LPS-stimulated proinflammatory cytokines, consistent with IL-1F7b being an anti-inflammatory member of the IL-1 family.
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PMID:The IL-1 family member 7b translocates to the nucleus and down-regulates proinflammatory cytokines. 1839 Jul 30

The proinflammatory IL-1 cytokines IL-1alpha, IL-1beta, and IL-18 are key mediators of the acute immune response to injury and infection. Mechanisms underlying their cellular release remain unclear. Activation of purinergic P2X(7) receptors (P2X(7)R) by extracellular ATP is a key physiological inducer of rapid IL-1beta release from LPS-primed macrophage. We investigated patterns of ATP-mediated release of IL-1 cytokines from three macrophage types in attempts to provide direct evidence for or against distinct release mechanisms. We used peritoneal macrophage from P2X(7)R(-/-) mice and found that release of IL-1alpha, IL-18, as well as IL-1beta, by ATP resulted exclusively from activation of P2X(7)R, release of all these IL-1 cytokines involved pannexin-1 (panx1), and that there was both a panx1-dependent and -independent component to IL-1beta release. We compared IL-1-release patterns from LPS-primed peritoneal macrophage, RAW264.7 macrophage, and J774A.1 macrophage. We found RAW264.7 macrophage readily release pro-IL-1beta independently of panx1 but do not release mature IL-1beta because they do not express apoptotic speck-like protein with a caspase-activating recruiting domain and so have no caspase-1 inflammasome activity. We delineated two distinct release pathways: the well-known caspase-1 cascade mediating release of processed IL-1beta that was selectively blocked by inhibition of caspase-1 or panx1, and a calcium-independent, caspase-1/panx1-independent release of pro-IL-1beta that was selectively blocked by glycine. None of these release responses were associated with cell damage or cytolytic effects. This provides the first direct demonstration of a distinct signaling mechanism responsible for ATP-induced release of pro-IL-1beta.
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PMID:P2X7 receptor differentially couples to distinct release pathways for IL-1beta in mouse macrophage. 1849 Jul 13

The P2X7 receptor (P2X7R), an ATP-gated ion channel, plays essential roles in the release and maturation of IL-1beta in microglial cells in the brain. Previously, we found that lysophosphatidylcholine (LPC) potentiated P2X7R-mediated intracellular signals in microglial cells. In this study, we determined whether the lysophospholipids, i.e., LPC and sphingosylphosphorylcholine (SPC), modulate the ATP-induced release and processing of IL-1beta mediated by P2X7R in mouse MG6 microglial cells. LPC or SPC alone induced the release of precursor (pro-IL-1beta) and mature IL-1beta (mIL-1beta) from LPS-primed MG6 cells, possibly due to lytic functions. However, these lysophospholipids inhibited ATP-induced caspase-1 activation that is usually followed by the release of mIL-1beta. Conversely, ATP inhibited the release of pro-IL-1beta and mIL-1beta induced by LPC/SPC. This suggests that lysophospholipids and ATP mutually suppressed each function to release IL-1beta. P2X7R activation resulted in microtubule reorganization in the MG6 cells that was blocked in the presence of LPC and SPC. LPC/SPC reduced the amount of activated RhoA after stimulation with ATP, implying that these lysophospholipids block ATP-induced microtubule reorganization by interfering with RhoA activation. In addition, the microtubule inhibitor colchicine inhibited ATP-induced release of mIL-1beta similar to that of LPC and SPC. This suggests that the impairment of the microtubule reassembly may be associated with the inhibitory effects of LPC/SPC on ATP-induced mIL-1beta release. Mutual suppression by ATP and LPC/SPC on the maturation of IL-1beta was observed in LPS-primed primary microglia. Collectively, these data suggest opposing functions by lysophospholipids, either proinflammatory or anti-inflammatory, in regard to the maturation and release of IL-1beta from microglial cells.
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PMID:Lysophospholipids and ATP mutually suppress maturation and release of IL-1 beta in mouse microglial cells using a Rho-dependent pathway. 1852 46

Aluminum hydroxide (alum) is the most widely used adjuvant in human vaccines, but the immune mechanisms that are activated by alum remain poorly understood. Alum has recently been shown to promote caspase-1 activation and IL-1beta secretion, but the cellular pathways involved remain elusive. Here we report that the release of IL-1beta triggered by alum is abrogated in macrophages deficient in the NLR family, pyrin domain containing 3 (Nlrp3) protein and the apoptosis-associated speck-like protein containing a caspase recruitment domain (Asc) but not the NLR family, CARD domain containing 4 (Nlrc4) protein. The requirement of the Nlrp3 inflammasome was specific for IL-1beta in that secretion of TNF-alpha was independent of Nlrp3 or Asc. Consistently, processing of pro-caspase-1 induced by alum was abolished in macrophages lacking Nlrp3 or Asc. Unlike caspase-1 processing and IL-1beta secretion triggered by LPS, alum-mediated activation of the inflammasome did not require exogenous ATP. Importantly, induction of IgG production against human serum albumin by alum was unimpaired in mice deficient in Nlrp3. These results indicate that alum induces IL-1beta via the Nlrp3 inflammasome but this activity is dispensable for alum-mediated adjuvant activity.
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PMID:The Nlrp3 inflammasome is critical for aluminium hydroxide-mediated IL-1beta secretion but dispensable for adjuvant activity. 1865 1

The cytokine interleukin (IL)-1beta is a key mediator of the inflammatory response and has been implicated in the pathophysiology of acute and chronic inflammation. IL-1beta is synthesized in response to many stimuli as an inactive pro-IL-1beta precursor protein that is further processed by caspase-1 into mature IL-1beta, which is the secreted biologically active form of the cytokine. Although stimulation of membrane-bound Toll-like receptors (TLRs) up-regulates pro-IL-1beta expression, activation of caspase-1 is believed to be mainly initiated by cytosolic Nod-like receptors. In this study, we show that polyinosinic:polycytidylic acid (poly[I:C]) and lipopolysaccharide stimulation of macrophages induces pro-IL-1beta processing via a Toll/IL-1R domain-containing adaptor-inducing interferon-beta-dependent signaling pathway that is initiated by TLR3 and TLR4, respectively. Ribonucleic acid interference (RNAi)-mediated knockdown of the intracellular receptors NALP3 or MDA5 did not affect poly(I:C)-induced pro-IL-1beta processing. Surprisingly, poly(I:C)- and LPS-induced pro-IL-1beta processing still occurred in caspase-1-deficient cells. In contrast, pro-IL-1beta processing was inhibited by caspase-8 peptide inhibitors, CrmA or vFLIP expression, and caspase-8 knockdown via RNAi, indicating an essential role for caspase-8. Moreover, recombinant caspase-8 was able to cleave pro-IL-1beta in vitro at exactly the same site as caspase-1. These results implicate a novel role for caspase-8 in the production of biologically active IL-1beta in response to TLR3 and TLR4 stimulation.
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PMID:Stimulation of Toll-like receptor 3 and 4 induces interleukin-1beta maturation by caspase-8. 1872 21

In the inflammosome complex, NALP3 or NALP1 binds to ASC and activates caspase-1 which induces IL-1beta. In murine LPS-induced ocular inflammation, the production of IL-1beta is increased. We suggest that NALP3- or NALP1-inflammasome complex can be participating in the LPS-induced ocular inflammation. In this work, eye, brain, testis, heart, spleen, and lung were obtained from C3H/HeN mice treated with LPS for 3 to 48 hours, and the expression of NALP1b, NALP3, ASC, caspase-1, IL-1beta, and IL-18 was determined. Infiltrated leukocytes producing IL-1beta in the anterior chamber were found at 12-hour posttreatment. A high upregulated expression of NALP3, ASC, caspase-1, IL-1beta, and IL-18 was found at the same time when infiltrated leukocytes were observed. NALP1b was not detected in the eye of treated mice. NALP3 was also overexpressed in heart and lung. These results suggest that NALP3-, but not NALP1-inflammosome complex, is participating in the murine LPS-induced ocular inflammation.
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PMID:The NALP3/Cryopyrin-inflammasome complex is expressed in LPS-induced ocular inflammation. 1876 97

In the present study, we examined the roles of natural killer T (NKT) cells in host defence against Legionella pneumophila in a mouse model. The survival rate of NKT cell-deficient Jalpha281 knock-out (KO) mice was significantly higher than that of wild-type mice. There was no bacterial overgrowth in the lungs, but Jalpha281 KO mice showed enhanced pulmonary clearance at a later stage of infection, compared with their wild-type counterparts. The severity of lung injury in L. pneumophila-infected Jalpha281 KO mice was less, as indicated by lung permeability measurements, such as lung weight and bronchoalveolar lavage fluid albumin concentration. Recruitment of inflammatory cells in the lungs was approximately twofold greater in Jalpha281 KO mice on day 3. Interestingly, higher values of interleukin (IL)-1beta and IL-18, and increased caspase-1 activity were noted in the lungs of Jalpha281 KO mice from an early time point (6 h). Exogenous alpha-galactosylceramide, a ligand of NKT cells, induced IL-12 and gamma interferon at 6 h, but suppressed IL-1beta at later time points in wild-type, whereas no effects were evident in Jalpha281 KO mice, as expected. Systemic administration of heat-killed L. pneumophila, but not Escherichia coli LPS, reproduced exaggerated production of IL-1beta in the lungs of Jalpha281 KO mice. These results demonstrate that NKT cells play a role in host defence against L. pneumophila, which is characterized by enhanced lung injury and decreased accumulation of inflammatory cells in the lungs. The regulation of IL-1beta, IL-18 and caspase-1 may be associated with the modulating effect of host responses by NKT cells.
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PMID:Paradoxically high resistance of natural killer T (NKT) cell-deficient mice to Legionella pneumophila: another aspect of NKT cells for modulation of host responses. 1892 10

Caspase-1 is an inflammatory caspase that controls the activation and secretion of the inflammatory cytokines, IL-1beta and IL-18. We observed that cellular levels of retinoic acid-inducible gene-I (RIG-I) were enhanced when the pan-caspase inhibitor Z-VAD-fmk or caspase-1-specific inhibitor Z-WEHD-fmk blocked caspase activity. Overexpression of caspase-1 reduced cellular levels of RIG-I and inhibited RIG-I-mediated signaling activity. Enzymatic activity of caspase-1 was necessary to control RIG-I, although it was not a substrate of proteolytic cleavage by caspase-1. Caspase-1 physically interacted with full length RIG-I, but not with mutant forms lacking either the amino- or carboxyl-terminal domains. RIG-I was present in the supernatant of cells transfected with active caspase-1 but not with caspase-4. Stimulating cells with LPS and ATP also induced secretion of endogenous RIG-I in macrophages. Our data suggest a novel mechanism that negatively regulates RIG-I-mediated signaling activity via caspase-1-dependent secretion of RIG-I protein.
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PMID:Active caspase-1-mediated secretion of retinoic acid inducible gene-I. 1898 Nov 55


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