Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.22.62 (caspase-9)
 7,507 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The infantile neuronal ceroid lipofuscinosis (INCL), a rare (one in 100 000 births) but one of the most lethal inherited neurodegenerative storage disorders of childhood, is caused by inactivating mutations in the palmitoyl-protein thioesterase-1 (PPT1) gene. PPT1 cleaves thioester linkages in s-acylated (palmitoylated) proteins and facilitates their degradation and/or recycling. Thus, PPT1-deficiency leads to an abnormal intracellular accumulation of s-acylated proteins causing INCL pathogenesis. Although neuronal apoptosis is the suggested cause of neurodegeneration in this disease, the molecular mechanism(s) remains poorly understood. We recently reported that one of the major pathways of neuronal apoptosis in PPT1-knockout (PPT1-KO) mice that mimic INCL, is mediated by endoplasmic reticulum (ER) stress-induced caspase-12 activation. ER stress also increases the production of reactive oxygen species (ROS), disrupts Ca(2+) homeostasis and increases the potential for destabilizing mitochondrial membrane. Mitochondrial membrane destabilization activates caspase-9 present in this organelle, and can mediate apoptosis. We report here that the levels of superoxide dismutase (SOD), most likely induced by ROS, in human INCL as well as PPT1-KO mouse brain tissues are markedly elevated. Moreover, we demonstrate that activated caspase-3 and cleaved-PARP, indicative of apoptosis, are also increased in these tissues. Using cultured neurospheres from PPT1-KO and wild-type mouse fetuses, we further demonstrate that the levels of ROS, SOD-2, cleaved-caspase-9, activated caspase-3 and cleaved-PARP are elevated. We propose that: (i) ER stress due to PPT1-deficiency increases ROS and disrupts calcium homeostasis activating caspase-9 and (ii) caspase-9 activation mediates caspase-3 activation and apoptosis contributing to rapid neurodegeneration in INCL.
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PMID:Palmitoyl-protein thioesterase-1 deficiency leads to the activation of caspase-9 and contributes to rapid neurodegeneration in INCL. 1657

Apoptosis of retinal ganglion cells (RGCs) impairs vision in glaucoma patients. RGCs are also degenerated in multiple sclerosis (MS), resulting in loss of visual perception in MS patients. We examined the involvement of calpain and caspase cascades in apoptosis of the rat retinal ganglion cell line RGC-5 following 24 h of exposure to 250 nM ionomycin (IMN) or 300 units/ml interferon-gamma (IFN-gamma) and then evaluated functional neuroprotection with 2 microM calpeptin (CP, a calpain-specific inhibitor). Morphological and biochemical features of apoptosis were detected in RGC-5 cells following exposure to IMN or IFN-gamma. Fura-2 assay determined significant increases in intracellular free [Ca2+] following exposure to IMN or IFN-gamma. Pretreatment with CP for 1 h prevented Ca2+ influx, proteolytic activities, and apoptosis in RGC-5 cells. Western blot analyses showed an increase in activities of calpain and caspase-12, upregulation of Bax:Bcl-2 ratio, release of cytochrome c from mitochondria, and increase in caspase-9 and caspase-3 activities during apoptosis. Increased caspase-3 activity was also confirmed by a colorimetric assay. Activation of caspase-8 and cleavage of Bid to tBid in RGC-5 cells following exposure to IFN-gamma indicated co-operation between extrinsic and intrinsic pathways of apoptosis. Patch-clamp recordings showed that pretreatment with CP attenuated apoptosis and maintained normal whole-cell membrane potential, indicating functional neuroprotection. Taken together, our results demonstrated that Ca2+ overload could be responsible for activation of calpain and caspase cascades leading to apoptotic death of RGC-5 cells and CP provided functional neuroprotection.
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PMID:Calpeptin provides functional neuroprotection to rat retinal ganglion cells following Ca2+ influx. 1660 Jan 92

Antrodia cinnamomea is well known in Taiwan as a traditional medicine for treating cancer and inflammation. The purpose of this study was to evaluate the apoptotic effects of ethylacetate extract from A. cinnamomea (EAC) fruiting bodies in Hep 3B, a liver cancer cell line. EAC decreased cell proliferation of Hep 3B cells by inducing apoptotic cell death. EAC treatment increased the level of calcium (Ca2+) in the cytoplasm and triggered the subsequent activation of calpain and caspase-12. EAC also initiated the mitochondrial apoptotic pathway through regulation of Bcl-2 family proteins expression, release of cytochrome c, and activation of caspase-9 in Hep 3B cells. Furthermore, the mitochondrial apoptotic pathway amplified the calpain pathway by Bid and Bax interaction and Ca2+ translocation. We have therefore concluded that the molecular mechanisms during EAC-mediated proliferation inhibition in Hep 3B cells were due to: (1) apoptosis induction, (2) triggering of Ca2+/calpain pathway, (3) disruption of mitochondrial function, and (4) apoptotic signaling being amplified by cross-talk between the calpain/Bid/Bax and Ca2+/mitochondrial apoptotic pathways.
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PMID:Apoptotic effects of Antrodia cinnamomea fruiting bodies extract are mediated through calcium and calpain-dependent pathways in Hep 3B cells. 1660 Apr 60

Following ischemia-reperfusion, there is a sustained increase of TNF-alpha both locally in the heart as well as in circulating levels in blood. While TNF-alpha has been implicated in cardiomyocyte apoptosis which occurs in several cardiomyopathies, the molecular pathways by which TNF-alpha induces apoptosis in these cells are not fully elucidated. We investigated the role of the two families of cysteine proteases, caspases and calpains, which are known to participate in apoptotic cell death. The effect of the highly specific calpain inhibitor, Z-LLY-fmk, and the caspase pathways involved in TNF-alpha-mediated apoptosis of the HL-1 cardiomyocyte cell line were examined. Activation of the downstream caspase-3, and the cleavage of poly ADP-ribose polymerase (PARP) were observed in a time-dependent manner upon treatment with TNF-alpha. Caspase-12, but not caspase-9, was activated in response to TNF-stimulation, indicating that an endoplasmic reticulum (ER)/calcium-dependent pathway may be involved. In HL-1 cardiomyocytes, TNF-alpha-induced apoptosis appears to be mediated by calpain as apoptotic changes were abrogated in the presence of the highly specific calpain inhibitor, Z-LLY-fmk. In conclusion, our results suggest that TNF-alpha-mediated apoptosis in HL-1 cardiomyocytes follows the caspase-12 apoptotic pathway that involves calpain.
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PMID:TNF-alpha-mediated cardiomyocyte apoptosis involves caspase-12 and calpain. 1672 70

Loss of trophic or activity-dependent survival signals is commonly recognized as a stimulus for neuronal apoptosis and may play a significant role in neurodegeneration. Recent data have also implicated endoplasmic reticulum (ER) stress as an important factor in some neurodegenerative conditions. However, whether shared or unique apoptotic cascades are activated by trophic factor withdrawal (TFW) versus ER stress in primary neurons has not previously been investigated. In primary cultures of rat cerebellar granule neurons (CGNs), the ER stressor brefeldin A activated a discrete pathway involving the following: (1) stimulation of the ER resident kinase PERK, (2) enhanced phosphorylation of the translation initiation factor eIF2alpha, and (3) increased expression and nuclear localization of the transcription factor Gadd153/CHOP. ER stress-induced CGN apoptosis was blocked by an antagonist of IP3 receptor-mediated Ca2+ release, 2-aminoethoxydiphenyl borate (2-APB), and by expression of ER-targeted Bcl-2. In contrast, CGN apoptosis elicited by TFW (i.e., removal of serum and depolarizing extracellular potassium) did not display any ER stress component nor was it blocked by either 2-APB or ER-Bcl-2. Despite these apparent differences, both brefeldin A and TFW induced dephosphorylation (activation) of glycogen synthase kinase-3beta (GSK-3beta). Moreover, inhibitors of GSK-3beta (IGF-I, lithium) and caspase-9 (LEHD-fmk) significantly protected CGNs from apoptosis induced by either ER stress or TFW. These data indicate that ER stress and TFW elicit distinct signals that activate GSK-3beta and intrinsic apoptosis in neurons.
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PMID:Endoplasmic reticulum stress and trophic factor withdrawal activate distinct signaling cascades that induce glycogen synthase kinase-3 beta and a caspase-9-dependent apoptosis in cerebellar granule neurons. 1676 55

Glioblastoma is the most malignant and prevalent brain tumor that still remains incurable. Recent studies reported anti-cancer effect of the broccoli-derived compound sulforaphane. We explored the mechanisms of sulforaphane-mediated apoptosis in human glioblastoma T98G and U87MG cells. Wright staining and ApopTag assay confirmed apoptosis in glioblastoma cells treated with sulforaphane. Increase in intracellular free Ca2+ was detected by fura-2 assay, suggesting activation of Ca2+-dependent pathways for apoptosis. Western blotting was used to detect changes in expression of Bax and Bcl-2 proteins resulting in increased Bax:Bcl-2 ratio that indicated a commitment of glioblastoma cells to apoptosis. Upregulation of calpain, a Ca2+-dependent cysteine protease, activated caspase-12 that in turn caused activation of caspase-9. With the increased Bax:Bcl-2 ratio, cytochrome c was released from mitochondria to cytosol for sequential activation of caspase-9 and caspase-3. Increased calpain and caspase-3 activities generated 145 kD spectrin breakdown product and 120 kD spectrin breakdown product, respectively. Activation of caspase-3 also cleaved the inhibitor-of-caspase-activated-DNase. Accumulation of apoptosis-inducing-factor in cytosol suggested caspase-independent pathway of apoptosis as well. Two of the inhibitor-of-apoptosis proteins were downregulated because of an increase in 'second mitochondrial activator of caspases/Direct inhibitor-of-apoptosis protein binding protein with low pI.' Decrease in nuclear factor kappa B and increase in inhibitor of nuclear factor kappa B alpha expression favored the process of apoptosis. Collectively, our results indicated activation of multiple molecular mechanisms for apoptosis in glioblastoma cells following treatment with sulforaphane.
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PMID:Activation of multiple molecular mechanisms for apoptosis in human malignant glioblastoma T98G and U87MG cells treated with sulforaphane. 1676 23

The present study tests the hypothesis that cerebral hypoxia results in increased ratio of Bax/Bcl-2, activation of caspase-9, lipid peroxidation, and DNA fragmentation in mitochondria of the cerebral cortex of newborn piglets and that the inhibition of nitric oxide synthase by N-nitro-L-arginine during hypoxia will prevent the events leading to mitochondrial DNA fragmentation. To test this hypothesis, six piglets, 3-5 days old, were divided into three groups: normoxic (n=5), hypoxic (n=5), and hypoxic-nitric oxide synthase (n=4). Hypoxic animals were exposed to a FiO2 of 0.6 for 60 min. Nitric oxide synthase (40 mg/kg) was infused over 60 min prior to hypoxia. Tissue hypoxia was confirmed by measuring levels of ATP and phosphocreatine. Cerebral cortical tissue mitochondria were isolated and purified using a discontinuous ficoll gradient. Mitochondrial Bax and Bcl-2 proteins were determined by Western blot. Caspase-9 activity in mitochondria was determined spectro-fluorometrically using fluorogenic substrate for caspase-9. Fluorescent compounds, an index of mitochondrial membrane lipid peroxidation, were determined spectrofluorometrically. Mitochondrial DNA was isolated and separated by electrophoresis on 1% agarose gel and stained with ethidium bromide. ATP levels (micromol/g brain) were 4.52+/-0.34 in normoxic, 1.18+/-0.29 in hypoxic (P<0.05) and 1.00+/-0.26 in hypoxic-nitric oxide synthase animals (P<0.05 vs. normoxic). Phosphocreatine levels (micromol/g brain) were 3.61+/-0.33 in normoxic, 0.70+/-0.20 in hypoxic (P<0.05 vs. normoxic) and 0.57+/-0.14 in hypoxic-nitric oxide synthase animals (P<0.05 vs. normoxic, P=NS vs. hypoxic). Bax density in mitochondrial membranes was 160+/-28 in normoxic and 324+/-65 in hypoxic (P<0.001 vs. normoxic). Bcl-2 density mitochondria was 96+/-18 in normoxic and 98+/-20 in hypoxic (P=NS vs. normoxic). Mitochondrial caspase-9 activity (nmol/mg protein/h) was 1.32+/-0.23 in normoxic and 2.25+/-0.24 in hypoxic (P<0.01 vs. normoxic). Levels of fluorescent compounds (microg of quinine sulfate/g protein) were 12.48+/-4.13 in normoxic and 37.92+/-7.62 in hypoxic (P=0.003 vs. normoxic). Densities (ODxmm2) of low molecular weight DNA fragments were 143+/-38 in normoxic, 365+/-152 in hypoxic, (P<0.05 vs. normoxic) and 163+/-25 in hypoxic-nitric oxide synthase animals (P<0.05 vs. hypoxic, P=NS vs. normoxic). The data demonstrate that hypoxia results in increased mitochondrial proapoptotic protein Bax, increased mitochondrial caspase-9 activity, increased mitochondrial lipid peroxidation, and increased fragmentation of DNA in mitochondria of the cerebral cortex of newborn piglets. The administration of a nitric oxide synthase inhibitor, nitric oxide synthase, prior to hypoxia prevented fragmentation of mitochondrial DNA, indicating that the hypoxia-induced mitochondrial DNA fragmentation is NO-mediated. We propose that NO free radicals generated during hypoxia lead to NO-mediated altered expression of Bax leading to increased ratio of pro-apoptotic/anti-apoptotic protein resulting in modification of mitochondrial membrane, and subsequently Ca2+-influx and fragmentation of mitochondrial DNA.
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PMID:Hypoxia-induced Bax and Bcl-2 protein expression, caspase-9 activation, DNA fragmentation, and lipid peroxidation in mitochondria of the cerebral cortex of newborn piglets: the role of nitric oxide. 1677 44

A number of pro-apoptotic stimuli induce the activation of caspase-9, an initiator protease that activates executioner caspases, such as caspase-3, leading to the development of programmed cell death. Here we demonstrate that cell (platelets and pancreatic acinar cells) stimulation with agonists induces a bimodal activation of caspase-3. The early caspase-3 activation occurs within 1 min of stimulation and is independent on caspase-9 or mitochondrial cytochrome c release suggesting that is a non-apoptotic event. The ability of agonists to induce early activation of caspase-3 is similar to that observed for other physiological processes. Activation of caspase-3 by physiological concentrations of cellular agonists, including thrombin or CCK-8, is independent of rises in cytosolic calcium concentration but requires PKC activation, and is necessary for agonist-induced activation of the tyrosine kinases Btk and pp60src and for several cellular functions, including store-operated calcium entry, platelet aggregation, or pancreatic secretion. Thus, early activation of caspase-3 seems to be a non-apoptotic event required for cellular function.
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PMID:Early caspase-3 activation independent of apoptosis is required for cellular function. 1679 42

The calcium-sensing receptor (CaR) is a seven-transmembrane G-protein coupled receptor, which activates intracellular effectors, for example, it causes inositol phosphate (IP) accumulation to increase the release of intracellular calcium. Although intracellular calcium overload has been implicated in the cardiac ischemia/reperfusion (I/R)-induced apoptosis, the role of CaR in the induction of apoptosis has not been fully understood. This study tested the hypothesis that CaR is involved in I/R cardiomyocyte apoptosis by increasing [Ca2+]i. The isolated rat hearts were subjected to 40-min ischemia followed by 2 h of reperfusion, meanwhile GdCl3 was added to reperfusion solution. The expression of CaR increased at the exposure to GdCl3 during I/R. By laser confocal microscopy, it was observed that the intracellular calcium was significantly increased and exhibited a Deltapsim, as monitored by 5,5',6,6'-tetrachloro-1,1',3,3'- tetraethylbenzimidazolcarbocyanine iodide (JC-1) during reperfusion with GdCl3. Furthermore, the number of apoptotic cells was significantly increased as shown by TUNEL assay. Typical apoptotic cells were observed with transmission electron microscopy in I/R with GdCl3 but not in the control group. The expression of cytosolic cytochrome c and activated caspase-9 and caspase-3 was significantly increased whereas the expression of mitochondrial cytochrome c significantly decreased in I/R with GdCl3 in comparison to the control. In conclusion, these results suggest that CaR is involved in the induction of cardiomyocyte apoptosis during ischemia/reperfusion through activation of cytochrome c-caspase-3 signaling pathway.
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PMID:Involvement of calcium-sensing receptor in ischemia/reperfusion-induced apoptosis in rat cardiomyocytes. 1685 39

Asiatic acid (AA), a triterpene, is known to be cytotoxic to several tumor cell lines. AA induces dose- and time-dependent cell death in U-87 MG human glioblastoma. This cell death occurs via both apoptosis and necrosis. The effect of AA may be cell type-specific as AA-induced cell death was mainly apoptotic in colon cancer RKO cells. AA-induced glioblastoma cell death is associated with decreased mitochondrial membrane potential, activation of caspase-9 and -3, and increased intracellular free Ca2+. Although treatment of glioblastoma cells with the caspase inhibitor zVAD-fmk completely abolished AA-induced caspase activation, it did not significantly block AA-induced cell death. AA-induced cell death was significantly prevented by an intracellular Ca2+ inhibitor, BAPTA/AM. Taken together, these results indicate that AA induces cell death by both apoptosis and necrosis, with Ca2+-mediated necrotic cell death predominating.
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PMID:Glioblastoma cell death induced by asiatic acid. 1689 40


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