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)

The crypt and villus epithelium associated with Peyer's patches (PPs) is largely spared from methotrexate (MTX)-induced damage, compared with the non-patch (NP) epithelium. To assess the mechanism(s) preventing damage to the PP epithelium after MTX treatment, epithelial proliferation, apoptosis, and cell functions were studied in a rat-MTX model. Small intestinal segments containing PPs were excised after MTX treatment. Epithelial proliferation and apoptosis were assessed by detection of incorporated BrdU and cleaved caspase-3, respectively. Epithelial functions were determined by the expression of cell type-specific gene products at mRNA and protein level. Before and after MTX treatment, the number of BrdU-positive cells was higher in PP crypts than in NP crypts. BrdU incorporation was diminished in NP crypts, while in PP crypts incorporation was hardly affected. In PP and NP crypts, similar and increased levels of cleaved caspase-3-positive cells were observed after MTX. The enterocyte markers, sucrase-isomaltase, sodium-glucose co-transporter 1, glucose transporters 2 and 5, and intestinal and liver fatty acid binding protein, were down-regulated after MTX in NP epithelium but not in PP epithelium. In contrast, expression of the goblet cell markers, Muc2 and trefoil factor 3, and the Paneth cell marker, lysozyme, was maintained after MTX in both PP and NP epithelium. In conclusion, as MTX-induced apoptosis was similar in PP and NP crypts, the protection of the PP epithelium seems to be based on differences in the regulation of epithelial proliferation. Enterocyte function in the PP epithelium was unaffected by MTX treatment. Goblet and Paneth cell function was maintained in both NP and PP epithelium.
 ...
PMID:Protection of the Peyer's patch-associated crypt and villus epithelium against methotrexate-induced damage is based on its distinct regulation of proliferation. 1221 64

Free fatty acids (FFA) have been reported to reduce pancreatic beta-cell mitogenesis and to increase apoptosis. Here we show that the FFA, oleic acid, increased apoptosis 16-fold in the pancreatic beta-cell line, INS-1, over a 18-h period as assessed by Hoechst 33342/propidium iodide staining and caspase-3 and -9 activation, with negligible necrosis. A parallel analysis of the phosphorylation activation of protein kinase B (PKB) showed this was reduced in the presence of FFA that correlated with the incidence of apoptosis. At stimulatory 15 mm glucose and/or in the added presence of insulin-like growth factor 1, FFA-induced beta-cell apoptosis was lessened compared with that at a basal 5 mm glucose. However, most strikingly, adenoviral mediated expression of a constitutively active PKB, but not a "kinase-dead" PKB variant, essentially prevented FFA-induced beta-cell apoptosis under all glucose/insulin-like growth factor 1 conditions. Further analysis of pro-apoptotic downstream targets of PKB, implicated a role for PKB-mediated phosphorylation inhibition of glycogen synthase kinase-3alpha/beta and the forkhead transcription factor, FoxO1, in protection of FFA-induced beta-cell apoptosis. In addition, down-regulation of the pro-apoptotic tumor suppressor protein, p53, via PKB-mediated phosphorylation of MDM2 might also play a role in partially protecting beta-cells from FFA-induced apoptosis. Adenoviral mediated expression of wild type p53 potentiated FFA-induced beta-cell apoptosis, whereas expression of a dominant negative p53 partly inhibited beta-cell apoptosis by approximately 50%. Hence, these data demonstrate that PKB activation plays an important role in promoting pancreatic beta-cell survival in part via inhibition of the pro-apoptotic proteins glycogen synthase kinase-3alpha/beta, FoxO1, and p53. This, in turn, provides novel insight into the mechanisms involved in FFA-induced beta-cell apoptosis.
 ...
PMID:Protein kinase B/Akt prevents fatty acid-induced apoptosis in pancreatic beta-cells (INS-1). 1239 70

A constant remodeling of islet cell mass mediated by proliferative and apoptotic stimuli ensures a dynamic response to a changing demand for insulin. In this study, we investigated the effect of glucagon-like peptide-1 (GLP-1) in Zucker diabetic rats, an animal model in which the onset of diabetes occurs when the proliferative potential and the rate of beta-cell apoptosis no longer compensate for the increased demand for insulin. We subjected diabetic rats to a 2-d infusion of GLP-1 and tested their response to an ip glucose tolerance test. GLP-1 produced a significant increase of insulin secretion, which was paralleled by a decrease in plasma glucose levels (P < 0.001 and P < 0.01, respectively). Four days after the removal of the infusion pumps, rats were killed and the pancreas harvested to study the mechanism by which GLP-1 ameliorated glucose tolerance. Ex vivo immunostaining with the marker of cell proliferation, Ki-67, showed that the metabolic changes observed in rats treated with GLP-1 were associated with an increase in cell proliferation of the endocrine and exocrine component of the pancreas. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling staining, a marker of cellular apoptosis, indicated a reduction of apoptotic cells within the islet as well in the exocrine pancreas in GLP-1-treated rats. Double immunostaining for the apoptotic marker caspase-3 and for insulin showed a significant reduction of caspase-3 expression and an increase in insulin content in GLP-1-treated animals. Finally, staining of pancreatic sections with the nuclear dye 4,6-Diaminidino-2-phenyl-dihydrochloride demonstrated a marked reduction of fragmented nuclei in the islet cells of rats treated with GLP-1. Our findings provide evidence that the beneficial effects of GLP-1 in Zucker diabetic rats is mediated by an increase in islet cell proliferation and a decrease of cellular apoptosis.
 ...
PMID:Glucagon-like peptide-1 promotes islet cell growth and inhibits apoptosis in Zucker diabetic rats. 1239 37

The current study examines the association between glucose induction of reactive oxygen species (ROS), mitochondrial (Mt) depolarization, and programmed cell death in primary neurons. In primary dorsal root ganglion (DRG) neurons, 45 mM glucose rapidly induces a peak rise in ROS corresponding to a 50% increase in mean Mt size at 6 h (P<0.001). This is coupled with loss of regulation of the Mt membrane potential (Mt membrane hyperpolarization, followed by depolarization, MMD), partial depletion of ATP, and activation of caspase-3 and -9. Glucose-induced activation of ROS, MMD, and caspase-3 and -9 activation is inhibited by myxothiazole and thenoyltrifluoroacetone (P<0.001), which inhibit specific components of the Mt electron transfer chain. Similarly, MMD and caspase-3 activation are inhibited by 100 microM bongkrekic acid (an inhibitor of the adenosine nucleotide translocase ANT). These results indicate that mild increases in glucose induce ROS and Mt swelling that precedes neuronal apoptosis. Glucotoxicity is blocked by inhibiting ROS induction, MMD, or caspase cleavage by specific inhibitors of electron transfer, or by stabilizing the ANT.
 ...
PMID:High glucose-induced oxidative stress and mitochondrial dysfunction in neurons. 1240 16

Caspase-3 is a major cell death effector protease in the adult and neonatal nervous system. We found a greater number and higher density of cells in the cortex of caspase-3(-/-) adult mice, consistent with a defect in developmental cell death. Caspase-3(-/-) mice were also more resistant to ischemic stress both in vivo and in vitro. After 2 h of ischemia and 48 h of reperfusion, cortical infarct volume was reduced by 55%, and the density of terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling-positive cells was decreased by 36% compared with wild type. When subjected to oxygen-glucose deprivation (2 h), cortical neurons cultured from mice deficient in caspase-3 expression were also more resistant to cell death by 59%. Mutant brains showed caspase-specific poly(ADP-ribose) polymerase cleavage product (85-kDa fragment) in vivo and in vitro, suggesting redundant mechanisms and persistence of caspase-mediated cell death. In the present study, we found that caspase-8 mediated poly(ADP-ribose) polymerase cleavage in caspase-3(-/-) neurons in vivo and in vitro. In addition, mutant neurons showed no evidence of compensatory activation by caspase-6 or caspase-7 after ischemia. Taken together, these data extend the pharmacological evidence supporting an important role for caspase-3 and caspase-8 as cell death mediators in mammalian cortex and indicate the potential advantages of targeting more than a single caspase family member to treat ischemic cell injury.
 ...
PMID:Caspase activation and neuroprotection in caspase-3- deficient mice after in vivo cerebral ischemia and in vitro oxygen glucose deprivation. 1241 17

Reactive oxygen species are recognized as important mediators of biological responses. Hyperglycemia promotes the intracellular generation of superoxide anion and hydrogen peroxide. In several cell lines, oxidant stress has been linked to the activation of death programs. Here, we report for the first time that high ambient glucose concentration induces apoptosis in murine and human mesangial cells by an oxidant-dependent mechanism. The signaling cascade activated by glucose-induced oxidant stress included the heterodimeric redox-sensitive transcription factor NF-kappaB, which exhibited an upregulation in p65/c-Rel binding activity and suppressed binding activity of the p50 dimer. Recruitment of NF-kappaB and mesangial cell apoptosis were both inhibited by antioxidants, implicating oxidant-induced activation of NF-kappaB in the transmission of the death signal. The genetic program for glucose-induced mesangial cell apoptosis was characterized by an upregulation of the Bax/Bcl-2 ratio. In addition, phosphorylation of the proapoptotic protein Bad was attenuated in mesangial cells maintained at high-glucose concentration, favoring progression of the apoptotic process. These perturbations in the expression and phosphorylation of the Bcl-2 family were coupled with the release of cytochrome c from mitochondria and caspase activation. Our findings indicate that in mesangial cells exposed to high ambient glucose concentration, oxidant stress is a proximate event in the activation of the death program, which culminates in mitochondrial dysfunction and caspase-3 activation, as the terminal event.
 ...
PMID:High glucose promotes mesangial cell apoptosis by oxidant-dependent mechanism. 1241 73

We investigated the effect of altered extracellular pH, mitochondrial function, and ATP content on development of apoptosis in human pulmonary artery endothelial cells after treatment with staurosporine (STS). STS produced a concentration- and time-dependent increase in caspase-3 activity in pH 7.4 medium that reached a peak at 6 h. The increase in caspase activity was associated with significant DNA fragmentation. Fluorescent imaging of treated monolayers in pH 7.4 medium with Hoechst-33342-propidium iodide demonstrated a large percentage of apoptotic cells ( approximately 40%) with no evidence of necrosis. Caspase activity, DNA fragmentation, and percentage of apoptotic cells were reduced after STS treatment in acidic media (pH 7.0 and 6.6). The Ca2+ chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-AM inhibited STS-induced apoptosis, whereas the rise in intracellular Ca2+concentration in STS-treated cells in pH 7.4 medium was reduced in pH 7.0 medium. These results suggest that one mechanism for inhibitory effects of acidosis may be a pH-induced alteration in Ca2+ signaling. Treatment with STS in the presence of oligomycin (10 microM), an inhibitor of the mitochondrial F(0)F(1)-ATPase, in glucose-free media abolished caspase activation and DNA fragmentation in association with severe ATP depletion ( approximately 2% of control cells). Imaging demonstrated a change in the mode of cell death from apoptosis to necrosis under these conditions. This change was linked to the level of ATP depletion, because STS treatment in the absence of glucose or the presence of oligomycin in media with glucose still leads to apoptosis in the presence of only moderate ATP depletion. These results demonstrate that pH, mitochondrial function, and ATP supply are important variables that regulate STS-induced apoptosis in human pulmonary artery endothelial cells.
 ...
PMID:Inhibition of apoptosis in pulmonary endothelial cells by altered pH, mitochondrial function, and ATP supply. 1242 47

Apoptosis of retinal endothelial cells and pericytes is postulated to contribute to the development of retinopathy in diabetes. The goal of this study is to investigate diabetes-induced activation of retinal caspase-3, an apoptosis executer enzyme, in retina, and examine the effects of antioxidants on the activation. Caspase-3 activation was determined in the retina of alloxan diabetic rats (2-14 months duration) and in the isolated retinal capillary cells (endothelial cells and pericytes) by measuring cleavage of caspase-3 specific fluorescent substrate, and cleavage of caspase-3 holoenzyme and poly (ADP ribosyl) polymerase. Effect of antioxidants on the activation of caspase-3 was determined by feeding a group of diabetic rats diet supplemented with a comprehensive mixture of antioxidants, including Trolox, alpha-tocopherol, N-acetyl cysteine, ascorbic acid, beta-carotene and selenium for 2-14 months, and also under in vitro conditions by incubating isolated retinal capillary cells with antioxidants with wide range of actions. Caspase-3 was activated in the rat retina at 14 months of diabetes (P < 0.05 vs. normal), but not at 2 months of diabetes, and administration of antioxidants for the entire duration inhibited this activation. In the isolated retinal capillary cells incubated in 25 mM glucose medium, caspase-3 activity was increased by 50% compared to the cells incubated in 5 mM glucose (P < 0.02), and antioxidants or caspase-3 inhibitor inhibited this increase. Our results suggest that increased oxidative stress in diabetes is involved in the activation of retinal caspase-3 and apoptosis of endothelial cells and pericytes. Antioxidants might be inhibiting the development of diabetic retinopathy by inhibiting microvascular apoptosis.
 ...
PMID:Diabetes-induced activation of caspase-3 in retina: effect of antioxidant therapy. 1244 25

Chronic hyperglycemia and cytokines such as tumor necrosis factor alpha (TNF-alpha) cause oxidative stress leading to dysregulated cell growth or apoptosis that contributes to the development of inflammation and secondary complications of diabetes. However, the mechanisms regulating hyperglycemic or cytokine injury are not well understood. Herein we report that inhibition of the polyol pathway enzyme aldose reductase (AR) by two structurally unrelated inhibitors--sorbinil and tolrestat--prevents, in the human lens epithelial cell line B-3, the apoptosis and activation of caspase-3 caused by exposure to high glucose levels or TNF-alpha. Inhibition of AR attenuated TNF-alpha and hyperglycemia-induced activation of protein kinase C (PKC), phosphorylation of the inhibitory subunit of nuclear factor-kappaB (NF-kappaB), and stimulation of NF-kappaB, but it did not prevent the activation of NF-kappaB and PKC by phorbol ester. Inhibition of AR also attenuated the increase in p38 mitogen-activated protein kinase and c-Jun N-terminal kinase phosphorylation. These signaling pathways were also inhibited in cells in which the expression of AR was reduced by antisense ablation. Collectively, these results identify a new participant in apoptotic signaling and suggest that AR is an obligatory mediator of the apoptotic events upstream of PKC. These observations could provide new insights into the pathophysiology of diabetes and the role of aberrant glucose metabolism in apoptotic cell death.
 ...
PMID:Aldose reductase mediates cytotoxic signals of hyperglycemia and TNF-alpha in human lens epithelial cells. 1249 May 36

Photodynamic therapy (PDT) may trigger apoptosis or necrosis in cancer cells. Several steps in the induction and execution of apoptosis require high amounts of adenosine-5'-triphosphate (ATP). Because the mitochondrial membrane potential (delta psi) decreases early in apoptosis, we raised the question about the mechanisms of maintaining a sufficiently high ATP level. We therefore monitored delta psi and the intracellular ATP level of apoptotic human epidermoid carcinoma cells (A431) after photodynamic treatment with aluminum (III) phthalocyanine tetrasulfonate. A maximum of caspase-3-like activity and nuclear fragmentation was found at fluences of about 4 J cm(-2). Under these conditions apoptotic cells reduced delta psi rapidly, while the ATP level remained high for 4-6 h after treatment for cells supplied with glucose. To analyze the contribution of glycolysis to the energy supply during apoptosis, experiments were carried out with cells deprived of glucose. These cells showed a rapid drop of ATP content and neither caspase activation nor nuclear fragmentation could be detected. We conclude that the use of glucose as a source of ATP is obligatory for the execution of PDT-induced apoptosis.
 ...
PMID:Glucose is required to maintain high ATP-levels for the energy-utilizing steps during PDT-induced apoptosis. 1251 Oct 53


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>