Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.22.56 (caspase-3)
 35,750 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Apoptosis has recently been extensively studied and multiple factors have been implicated in its regulation. It remains unclear how these factors are ordered in the cell death pathway. Here we investigate the relationship between the inhibitor of apoptosis, bcl-2, and the PARP protease, prlCE/CPP32, recently implicated in apoptosis. Using PARP proteolysis as an indicator of the activation of the PARP protease, we find that the chemotherapeutic agent, etoposide, induces apoptosis and PARP proteolysis in Molt4 cells as early as 4 h with cell death lagging behind this event. In contrast, Molt4 cells that over-express bcl-2 show no PARP proteolysis or cell death. In order to determine if bcl-2 inhibits the PARP protease or its activation, we developed a cell-free system. Using this system with extracts from etoposide-treated cells and purified bovine PARP, we demonstrate that extracts from bcl-2 over-expressing cells cause little or no PARP proteolysis. Whereas, extracts from control vector cells contain an active PARP protease. This protease is inhibited by the tetrapeptide ICE-like protease inhibitor, YVAD-chloromethylketone. Interestingly, this protease is not inhibited by the addition of purified bcl-2 protein. These results rule out that bcl-2 directly inhibits the active protease or that it has an effect downstream of prlCE/CPP32 such as preventing access to the PARP substrate. These results also demonstrate a role of bcl-2 in interfering with an upstream signal required to activate the PARP protease and allow us to begin to order the components in the apoptotic pathway.
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PMID:Bcl-2 acts upstream of the PARP protease and prevents its activation. 1646 7

Antithrombin, a serpin family protease inhibitor crucial to hemostasis, acquires antiangiogenic properties on undergoing conformational alterations induced by limited proteolysis or elevated temperature. To better understand the biochemical mechanisms underlying antithrombin antiangiogenic activity, we did genome-wide expression profiling, coupled with quantitative reverse transcription-PCR, Northern blot, and Western blot analyses, to characterize the gene expression patterns that are induced by antiangiogenic antithrombin in cultured primary human umbilical vein endothelial cells. Overall, 35 genes with significantly increased expression and 93 genes with significantly reduced expression (> or =2-fold changes) due to antiangiogenic antithrombin treatment were identified. More than half of the down-regulated genes have well-established proangiogenic functions in endothelial cells, including cell-surface and matrix proteoglycans (e.g., perlecan, biglycan, and syndecans 1 and 3) and mitogenesis-related signaling proteins (e.g., mitogen-activated protein kinase 3, signal transducers and activators of transcription 2, 3, and 6, and early growth response factor 1). In contrast, most up-regulated genes (e.g., caspase-3, p21, tissue inhibitor of metalloproteinases 1, 2, and 3, and adenomatosis polyposis coli) are known for their antiangiogenic functions which include the promotion of cell apoptosis and cell cycle arrest and the inhibition of tumor growth and metastasis. These results show that the antiangiogenic activity of antithrombin is mediated at least in part by a global genetic reprogramming of endothelial cells and strongly implicate an endothelial cell ligand-receptor signaling mechanism in this reprogramming.
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PMID:Antiangiogenic antithrombin induces global changes in the gene expression profile of endothelial cells. 1670 26

The mechanisms of CD4(+) T-cell depletion during human immunodeficiency virus type 1 (HIV-1) infection remain incompletely characterized. Of particular importance is how CD4(+) T cells are depleted within the lymphoid organs, including the lymph nodes and thymus. Herein we characterize the pathogenic mechanisms of an envelope from a rapid progressor (R3A Env) in the NL4-3 backbone (NL4-R3A) which is able to efficiently replicate and deplete CD4(+) thymocytes in the human fetal-thymus organ culture (HF-TOC). We demonstrate that uninterrupted replication is required for continual thymocyte depletion. During depletion, NL4-R3A induces an increase in thymocytes which uptake 7AAD, a marker of cell death, and which express active caspase-3, a marker of apoptosis. While 7AAD uptake is observed predominantly in uninfected thymocytes (p24(-)), active caspase-3 is expressed in both infected (p24(+)) and uninfected thymocytes (p24(-)). When added to HF-TOC with ongoing infection, the protease inhibitor saquinavir efficiently suppresses NL4-R3A replication. In contrast, the fusion inhibitors T20 and C34 allow for sustained HIV-1 production. Interestingly, T20 and C34 effectively prevent thymocyte depletion in spite of this sustained replication. Apoptosis of both p24(-) and p24(+) thymocytes appears to be envelope fusion dependent, as T20, but not saquinavir, is capable of reducing thymocyte apoptosis. Together, our data support a model whereby pathogenic envelope-dependent fusion contributes to thymocyte depletion in HIV-1-infected thymus, correlated with induction of apoptosis in both p24(+) and p24(-) thymocytes.
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PMID:Fusion-induced apoptosis contributes to thymocyte depletion by a pathogenic human immunodeficiency virus type 1 envelope in the human thymus. 1695 34

Nasal NK/T-cell lymphoma is a rare disease entity with a poor outcome. Expression of antiapoptotic proteins has not been extensively investigated in this entity. Forty-eight patients with nasal T/NK-cell lymphoma who received first-line polychemotherapy (n = 44) or chemoradiotherapy (n = 4) were analyzed for expression of active caspase-3 (aC3), granzyme B protease inhibitor 9 (PI9), and Bcl-2 proteins. Lymphomas were CD3+/CD5-/granzyme B+ and EBV-associated. Median age was 46 years. Stage I/II disease was present in 75% of the cases and an International Prognostic Index (IPI) score less than 1 in 65%. With a median follow-up of 6.3 years, 5-year event-free survival (EFS) and overall survival (OS) rates were 39% and 49%, respectively. Apoptotic index was scored as high in 32% of cases and PI9 expression as positive in 68%, whereas 35% disclosed a high number of aC3+ tumor cells. Univariate analysis showed that absence of PI9 and low apoptotic index were associated with poor outcome, but not aC3 expression nor IPI score. By multivariate analysis, both parameters affected independently EFS (P = .02 and .08, respectively) and OS (P = .009 and .04). In view of its constitutive expression by normal NK cells, it is suggested that loss of PI9 expression in tumor cells may reflect some mechanism associated with progression.
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PMID:Expression of the granzyme B inhibitor PI9 predicts outcome in nasal NK/T-cell lymphoma: results of a Western series of 48 patients treated with first-line polychemotherapy within the Groupe d'Etude des Lymphomes de l'Adulte (GELA) trials. 1707 22

Numerous reports now indicate that HIV patients administered long-term antiretroviral therapy (ART) are at a greater risk for developing cardiovascular diseases. Endothelial dysfunction is an initiating event in atherogenesis and may contribute to HIV-associated atherosclerosis. We previously reported that ART induces direct endothelial dysfunction in rodents. In vitro treatment of human umbilical vein endothelial cells (HUVEC) with ART indicated endothelial mitochondrial dysfunction and a significant increase in the production of reactive oxygen species (ROS). In this study, we determined whether ART-induced endothelial dysfunction is mediated via mitochondria-derived ROS and whether this mitochondrial injury culminates in endothelial cell apoptosis. Two major components of ART combination therapy, a nucleoside reverse transcriptase inhibitor and a protease inhibitor, were tested, using AZT and indinavir as representatives for each. Microscopy utilizing fluorescent indicators of ROS and mitochondria demonstrated the mitochondrial localization of ART-induced ROS. MnTBAP, a cell-permeable metalloporphyrin antioxidant, abolished ART-induced ROS production. As a final step in confirming the mitochondrial origin of the ART-induced ROS, HUVEC were transduced with a cytosolic- compared to a mitochondria-targeted catalase. Transduction with the mitochondria-targeted catalase was more effective than cytoplasmic catalase in inhibiting the ROS and 8-isoprostane (8-iso-PGF2alpha) produced after treatment with either AZT or indinavir. However, both mitochondrial and cytoplasmic catalase attenuated ROS and 8-iso-PGF2alpha production induced by the combination treatment, suggesting that in this case, the formation of cytoplasmic ROS may also occur, and thus, that the mechanism of toxicity in the combination treatment group may be different compared to treatment with AZT or indinavir alone. Finally, to determine whether ART-induced mitochondrial dysfunction and ROS production culminate in apoptosis, we performed the terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling (TUNEL), annexin V and 4',6-diamidino-2-phenylindole (DAPI) staining, and caspase-3 activity assays. However, none of these assays showed appreciable levels of ART-induced apoptosis. Our studies thus suggest that in endothelial cells, ART induces mitochondrial dysfunction with a concomitant increase in mitochondria-derived ROS. This compromised mitochondrial function may be one important factor culminating in endothelial dysfunction, without inducing an increase in apoptosis.
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PMID:HIV antiretroviral drug combination induces endothelial mitochondrial dysfunction and reactive oxygen species production, but not apoptosis. 1766 53

Recent reports suggest numerous roles for cysteine proteases in the progression of skeletal muscle atrophy due to disuse or disease. Nonetheless, a specific requirement for these proteases in the progression of skeletal muscle atrophy has not been demonstrated. Therefore, this investigation determined whether calpains or caspase-3 is required for oxidant-induced C2C12 myotube atrophy. We demonstrate that exposure to hydrogen peroxide (25 microM H2O2) induces myotube oxidative damage and atrophy, with no evidence of cell death. Twenty-four hours of exposure to H2O2 significantly reduced both myotube diameter and the abundance of numerous proteins, including myosin (-81%), alpha-actinin (-40%), desmin (-79%), talin (-37%), and troponin I (-80%). Myotube atrophy was also characterized by increased cleavage of the cysteine protease substrate alphaII-spectrin following 4 h and 24 h of H2O2 treatment. This degradation was blocked by administration of the protease inhibitor leupeptin (10 microM). Using small interfering RNA transfection of mature myotubes against the specific proteases calpain-1, calpain-2, and caspase-3, we demonstrated that calpain-1 is required for H2O2-induced myotube atrophy. Collectively, our data provide the first evidence for an absolute requirement for calpain-1 in the development of skeletal muscle myotube atrophy in response to oxidant-induced cellular stress.
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PMID:Calpain-1 is required for hydrogen peroxide-induced myotube atrophy. 1910 22

Plasminogen activator inhibitor-1 (PAI-1), a member of the serpin gene family, is the primary inhibitor of urokinase-type and tissue-type PAs. PAI-1 plays an important role in the process of peripheral tissue remodeling and fibrinolysis through the regulation of PA activity. This serpin is also produced in brain tissues and may regulate the neural protease sequence in the central nervous system (CNS), as it does in peripheral tissues. In fact, PAI-1 mRNA is up-regulated in mouse brain after stroke. The serpin activity of PAI-1 helps to prevent tissue-type PA-induced neuron death. However, we have previously found that PAI-1 has a novel biological function in the CNS: the contribution to survival of neurites on neurons. In neuronally differentiated rat pheochromocytoma (PC-12) cells, a deficiency of PAI-1 in vitro caused a significant reduction in Bcl-2 and Bcl-X(L) mRNAs and an increase in Bcl-X(S) and Bax mRNAs. The change in the balance between mRNA expressions of the anti- and pro-apoptotic Bcl-2 family proteins promoted the apoptotic sequence: caspase-3 activation, cytochrome c release from mitochondria and DNA fragmentation. Our results indicate that PAI-1 has an anti-apoptotic role in neurons. PAI-1 prevented the disintegration of the formed neuronal networks by maintaining or promoting neuroprotective signaling through the MAPK/ERK pathway, suggesting that the neuroprotective effect of PAI-1 is independent of its action as a protease inhibitor. This review discusses the neuroprotective effects of PAI-1 in vitro, together with the relevant data from other laboratories. Special emphasis is placed on its action on PC-12 cells.
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PMID:Anti-apoptotic roles of plasminogen activator inhibitor-1 as a neurotrophic factor in the central nervous system. 1913 24

Inclusion of HIV protease inhibitors (PIs) in the treatment of people living with HIV+ has markedly decreased mortality but also increased the incidence of metabolic abnormalities, causes of which are not well understood. Here, we report that insulinopenia is exacerbated when Zucker fa/fa rats are exposed to a PI for 7 wk, suggesting that chronic PI exposure adversely affects pancreatic islet beta-cell function. In support of this possibility, we find increased apoptosis, as reflected by TUNEL fluorescence analyses, and reduced insulin-secretory capacity in insulinoma cells and human pancreatic islet cells after in vitro exposures (48-96 h) to clinically relevant PIs (ritonavir, lopinavir, atazanavir, or tipranavir). Furthermore, pancreatic islets isolated from rats administered an HIV-PI for 3 wk exhibit greater cell death than islets isolated from vehicle-administered rats. The higher incidence of HIV-PI-induced cell death was associated with cleavage and, hence, activation of caspase-3 and poly(ADP)-ribose polymerase but not with activation of phospho-pancreatic endoplasmic reticulum (ER) kinase or induction of ER stress apoptotic factor C/EBP homologous protein. Exposure to the HIV-PIs, however, led to activation of mitochondria-associated caspase-9, caused a loss in mitochondrial membrane potential, and promoted the release of cytochrome c, suggesting that HIV-PIs currently in clinically use can induce beta-cell apoptosis by activating the mitochondrial apoptotic pathway. These findings therefore highlight the importance of considering beta-cell viability and function when assessing loss of glycemic control and the course of development of diabetes in HIV+ subjects receiving a protease inhibitor.
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PMID:Protease inhibitors used in the treatment of HIV+ induce beta-cell apoptosis via the mitochondrial pathway and compromise insulin secretion. 1920 56

We developed novel substrates for protease activity evaluation by fluorescence correlation spectroscopy (FCS). Substrates were labeled in a position-specific manner with a fluorophore near the N terminus and included a C-terminal, 30 kDa, highly soluble protein (elongation factor Ts [EF-Ts]). The C-terminal protein enhanced the substrate peptide solubility and increased the molecular weight, enabling sensitive detection by FCS. Using the labeled substrates, caspase-3 and matrix metalloproteinase-9 (MMP-9) activities were confirmed by FCS. To demonstrate the suitability of this FCS-based assay for high-throughput screening, we screened various chemical compounds for MMP-9 inhibitors. The screening results confirmed the inhibitory activity of one compound and also revealed another potential MMP-9 inhibitor. Thus, this combination of position-specific labeled protein substrates and FCS may serve as a useful tool for evaluating activities of various proteases and for protease inhibitor screening.
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PMID:A protease inhibitor discovery method using fluorescence correlation spectroscopy with position-specific labeled protein substrates. 1939 4

Diabetic heart disease contributes to the high mortality in diabetics, although effective clinical management is lacking. The protease inhibitor 5-[5-(2-nitrophenyl) furfuryliodine]-1,3-diphenyl-2-thiobarbituric acid (UCF-101) was reported to protect the hearts against ischemic injury. This study examined the role of UCF-101 on streptozotocin (STZ)-induced diabetic heart defect. Vehicle or UCF-101 was administrated to STZ diabetic mice, and cardiomyocyte mechanical properties were analyzed. UCF-101 reduced STZ-induced hyperglycemia and alleviated STZ-induced aberration in cardiomyocyte contractile mechanics. Diabetes dramatically decreased AMPK phosphorylation at Thr(172) of catalytic alpha-subunit, which was restored by UCF-101. Neither diabetes nor UCF-101 affected the expression of HtrA2/Omi and XIAP or caspase-3 activity. The AMPK activator resveratrol mimicked the UCF-101-induced beneficial effect against diabetic cardiac dysfunction. Mechanical properties in cardiomyocytes from the AMPK-kinase-dead (KD) mice displayed markedly impaired contractile function reminiscent of diabetes. STZ injection in AMPK-KD mice failed to elicit any additional cardiomyocyte contractile defect. UCF-101 significantly downregulated the AMPK-degrading enzymes PP2A and PP2C, the effect of which was mimicked by resveratrol. Taken together, these results indicate that UCF-101 protects against STZ-induced cardiac dysfunction, possibly through AMPK signaling.
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PMID:UCF-101 mitigates streptozotocin-induced cardiomyocyte dysfunction: role of AMPK. 1969 68


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