Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P42574 (caspase-3)
 45,978 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Renal tubular epithelial cell (RTC) apoptosis causes tubular atrophy, a hallmark of renal disease progression. Apoptosis is generally characterized by reduced cell volume and cytosolic pH, but epithelial cells are relatively resistant to shrinkage due to regulatory volume increase, which is mediated by Na(+)/H(+) exchanger (NHE) 1. We investigated whether RTC apoptosis requires caspase cleavage of NHE1. Staurosporine- and hypertonic NaCl-induced RTC apoptosis was associated with cell shrinkage and diminished cytosolic pH, and apoptosis was potentiated by amiloride analogs, suggesting NHE1 activity opposes apoptosis. NHE1-deficient fibroblasts demonstrated increased susceptibility to apoptosis, which was reversed by NHE1 reconstitution. NHE1 expression was markedly decreased in apoptotic RTC due to degradation, and preincubation with peptide caspase antagonists restored NHE1 expression, indicating that NHE1 is degraded by caspases. Recombinant caspase-3 cleaved the in vitro-translated NHE1 cytoplasmic domain into five distinct peptides, identical in molecular weight to NHE1 degradation products derived from staurosporine-stimulated RTC lysates. In vivo, NHE1 loss-of-function C57BL/6.SJL-swe/swe mice with adriamycin-induced nephropathy demonstrated increased RTC apoptosis compared with adriamycin-treated wild-type controls, thereby implicating NHE1 inactivation as a potential mechanism of tubular atrophy. We conclude that NHE1 activity is critical for RTC survival after injury and that caspase cleavage of RTC NHE1 may promote apoptosis and tubular atrophy by preventing compensatory intracellular volume and pH regulation.
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PMID:Renal tubular epithelial cell apoptosis is associated with caspase cleavage of the NHE1 Na+/H+ exchanger. 1245 72

Although increased Na(+)/H(+) exchanger type-1 (NHE-1) activity has been implicated in the pathogenesis of myocardial infarction, the role of NHE-1 in induction of apoptosis, and the potential mechanisms involved have not been fully characterized. This study tested the hypothesis that NHE-1 activity is involved in hypoxia (H)/re-oxygenation (Re)-induced cardiomyocyte apoptosis by increasing mitochondrial Ca(2+) ([Ca(2+)]m). Primary cultured neonatal rat cardiomyocytes were subjected to 4.5 h of H followed by 12 h of Re. Relative to H alone, the level of X-rhod-1 acetoxymethyl (AM)-labeled [Ca(2+)]m was increased, and the frequency of cell death (propidium iodide (PI) staining) and apoptotic cells (terminal deoxynucleotidyl transferase (TdT)-mediated-UTP nick end labeling [TUNEL]), confirmed by Annexin-V, were augmented at the end of Re, along with appearance of cytosolic cytochrome c, activation of caspase-3, and increased ratio of Bax and Bcl-2. Addition of cariporide (20 micromol/l), a well-known NHE-1 inhibitor, to cultured cells before H significantly reduced [Ca(2+)]m, the number of PI and TUNEL positive cells relative to the levels at end of Re, but did not completely eliminate these changes compared to Sham control. There was a strong trend for attenuation in increased levels of [Ca(2+)]m, and the number of PI and TUNEL positive cells when same dose of cariporide was added only at Re, but the difference in these variables did not reach significance. In contrast, the levels of [Ca(2+)]m and the number of PI and TUNEL positive cells were significantly reduced to a level comparable to Sham control when cariporide (20 micromol/l) was administered before H and during Re, respectively, associated with a reduction in cytosolic cytochrome c, caspase-3 activity and ratio of Bax and Bcl-2. In conclusion, these data suggest that NHE-1 is involved in induction of cardiomyocyte apoptosis during both H and Re through a [Ca(2+)]m-dependent manner, thereby resulting in activation of cytochrome c-caspase-3 signaling pathways.
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PMID:Involvement of Na+/H+ exchanger in hypoxia/re-oxygenation-induced neonatal rat cardiomyocyte apoptosis. 1497 1

Cell shrinkage is a ubiquitous feature of programmed cell death (PCD), but whether it is an obligatory signalling event in PCD is unclear. Heat shock protein 70 (Hsp70) potently counteracts PCD in many cells, by mechanisms that are incompletely understood. In the present investigation, we found that severe hypertonic stress greatly diminished the viability of murine fibrosarcoma cells (WEHI-902) and immortalized murine embryonic fibroblasts (iMEFs). This effect was attenuated markedly by Hsp70 over-expression. To determine whether the protective effect of Hsp70 was mediated via an effect on volume regulatory ion transport, we compared regulatory volume decrease (RVD) and increase (RVI) in control WEHI-902 cells and after increasing Hsp70 levels by heat shock or over-expression (WEHI-912). Hsp70 levels affected neither RVD, RVI nor the relative contributions of the Na(+)/H(+)-exchanger (NHE1) and Na(+),K(+),2Cl(-)-cotransporter (NKCC1) to RVI. Hypertonic stress induced caspase-3 activity in WEHI cells and iMEFs, an effect potentiated by Hsp70 in WEHI cells but inhibited by Hsp70 in iMEFs. Osmotic shrinkage-induced PCD was associated with Hsp70-inhibitable cysteine cathepsin release in iMEFs and attenuated by caspase and cathepsin inhibitors in WEHI cells. Treatment with TNF-alpha or the NHE1 inhibitor 5'-(N-ethyl-N-isopropyl)amiloride (EIPA) reduced the viability of WEHI cells further under isotonic and mildly, but not severely, hypertonic conditions. Thus, it is concluded that shrinkage-induced PCD involves both caspase- and cathepsin-dependent death mechanisms and is potently counteracted by Hsp70.
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PMID:Heat shock protein 70 inhibits shrinkage-induced programmed cell death via mechanisms independent of effects on cell volume-regulatory membrane transport proteins. 1534 Aug 51

Sustained cell shrinkage is a major hallmark of apoptotic cell death. In apoptotic cells, whole cell volume reduction, called apoptotic volume decrease (AVD), proceeds until fragmentation of cells. Under non-apoptotic conditions, human epithelial HeLa cells exhibited a slow regulatory volume increase (RVI) after osmotic shrinkage induced by exposure to hypertonic solution. When AVD was induced by treatment with a Fas ligand, TNF-alpha or staurosporine, however, it was found that HeLa cells failed to undergo RVI. When RVI was inhibited by combined application of Na+/H+ exchanger (NHE) and anion exchanger blockers, hypertonic stress induced prolonged shrinkage followed by caspase-3 activation in HeLa cells. Hypertonicity also induced apoptosis in NHE1-deficient PS120 fibroblasts, which lack the RVI response. When RVI was restored by transfection of these cells with NHE1, hypertonicity-induced apoptosis was completely prevented. Thus, it is concluded that RVI dysfunction is indispensable for the persistence of AVD and induction of apoptosis.
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PMID:Dysfunction of regulatory volume increase is a key component of apoptosis. 1710 Nov 38

Activation of Na(+)/H(+) exchange (NHE) plays a major role in cell death following ischemia/hypoxia in many cell types, yet counteracts apoptotic cell death after other stimuli. To address the role of NHE activity in regulation of cell death/survival, we examined the causal relationship between NHE, p38 mitogen-activated protein kinase (MAPK), ERK1/2, p53, and Akt activity, and cell death, after chemical anoxia in NIH3T3 fibroblasts. The NHE1 inhibitor 5'-(N-ethyl-N-isopropyl) amiloride (EIPA) (5 muM), as well as removal of extracellular Na(+) [replaced by N-methyl-D: -glucamine (NMDG(+))], prevented recovery of intracellular pH (pH(i)) during chemical anoxia (10 mM NaN(3) +/- 10 mM glucose), indicating that activation of NHE was the dominating mechanism of pH(i) regulation under these conditions. NHE activation by chemical anoxia was unaffected by inhibitors of p38 MAPK (SB203580) and extracellular signal-regulated kinase (ERK) (PD98059). In contrast, chemical anoxia activated p38 MAPK in an NHE-dependent manner, while ERK1/2 activity was unaffected. Anoxia-induced cell death was caspase-3-independent, mildly attenuated by EIPA, potently exacerbated by SB203580, and unaffected by PD98059. Ser(15) phosphorylation of p53 was increased by anoxia in an NHE- and p38 MAPK-independent manner, while Akt activity was unaffected. It is suggested that after chemical anoxia in NIH3T3 fibroblasts, NHE activity is required for activation of p38 MAPK, which in turn protects the cells against anoxia-induced death. In spite of this, NHE inhibition slightly attenuates anoxia-induced cell death, likely due to the involvement of NHE in other anoxia-induced death pathways.
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PMID:Roles of Na+/H+ exchange in regulation of p38 mitogen-activated protein kinase activity and cell death after chemical anoxia in NIH3T3 fibroblasts. 1733 79

Inhibition of stress-induced apoptosis by the molecular chaperone protein Hsp70 is a contributing factor in tumorigenesis and suppression of this ability could increase the effectiveness of anti-tumor therapy. Tumor cells exist in an acidic environment and acute acidification can sensitize tumor cells to heat-induced cell death. However, the ability of Hsp70 to prevent apoptosis under these conditions has not been examined. The effect of acute acidification on heat-induced apoptosis was examined in a human T-cell line with tetracycline-regulated Hsp70 expression. Apoptosis was inhibited in cells exposed to hyperthermia in acidic media when examined 6 h after the heat stress, but resumed if cells were returned to physiological pH during this recovery period. Long-term proliferation assays showed that acute acidification sensitized cells to heat-induced apoptosis. Hsp70 expressing cells were also sensitized and this was correlated with a reduced ability to suppress the activation of JNK (c-jun N-terminal kinase), Bax and caspase-3. Further sensitization could be achieved with the NHE1 (Na(+)/H(+) exchanger) inhibitor HMA (5-(N, N-hexamethylene) amiloride), which potentiated JNK activation in heat-shocked cells. These results demonstrate that the ability of Hsp70 to suppress apoptosis is compromised when cells are exposed to hyperthermia in an acidic environment, which is correlated with an impaired ability to inhibit JNK activation.
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PMID:Acute acidification or amiloride treatment suppresses the ability of Hsp70 to inhibit heat-induced apoptosis. 1743 90

OBJECTIVE To examine the participation of NHE1 in the regulation of the apoptotic response in neonatal obstruction, as the ubiquitously expressed NHE1 isoform is an important component of regulatory volume increase. MATERIALS AND METHODS Rats had a unilateral ureteric obstruction (UUO) or a sham operation, and the kidneys were harvested 5 and 14 days afterward. Cellular apoptosis in proximal tubules (PT) and collecting ducts (CD) was assessed using a standard assay, and NHE1 expression in the renal cortex assessed using reverse transcription-polymerase chain reaction and Western blots. Mitochondrial apoptosis was evaluated by Bax/BcL2 expression, and caspase-3 expression and activity. In addition, we evaluated the in vivo administration of increasing doses of 5-(N-ethyl-N-isopropyl)-amiloride (EIPA) on NHE1 inhibition associated with the induction of apoptosis. RESULTS After 14 days there were consistently more apoptotic cells in CD than in PT, associated with a lower expression of NHE1 at the mRNA and protein levels. There was increased expression of the Bax/BcL2 ratio, linked to decreased pro-caspase-3 protein levels and with increased caspase-3 activation. NHE1 inhibition by increasing doses of EIPA induced epithelial cell apoptosis and increased caspase-3 activity in a dose-dependent manner. After in vitro incubation with amiloride (100 mm) there was less NHE1 expression associated with reduced 32 kDa pro-caspase-3 protein levels. Kidneys obstructed for 5 days showed no changes in NHE1 expression or induction of apoptosis. CONCLUSION In neonatal obstruction, we suggest that the decreased NHE1 expression could be a signal-transduction event participating in the induction of epithelial tubular cell apoptosis, through the regulation of the BcL-2 gene family and activation of caspase-3.
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PMID:Apoptosis induction is associated with decreased NHE1 expression in neonatal unilateral ureteric obstruction. 1755 65

Osmotic stress modulates mitogen activated protein kinase (MAPK) activities, leading to altered gene transcription and cell death/survival balance, however, the mechanisms involved are incompletely elucidated. Here, we show, using a combination of biochemical and molecular biology approaches, that three MAPKs exhibit unique interrelationships with the Na(+)/H(+) exchanger, NHE1, after osmotic cell shrinkage: Extracellular Signal Regulated Kinase (ERK1/2) is inhibited in an NHE1-dependent, pH(i)-independent manner, c-Jun N-terminal kinase (JNK1/2) is stimulated, in part through NHE1-mediated intracellular alkalinization, and p38 MAPK is activated in an NHE1-independent manner, and contributes to NHE1 activation and ERK inhibition. Shrinkage-induced ERK1/2 inhibition was attenuated in Ehrlich Lettre Ascites cells by NHE1 inhibitors (EIPA, cariporide) or removal of extracellular Na(+), and mimicked by human (h) NHE1 expression in cells lacking endogenous NHE1 activity. The effect of NHE1 on ERK1/2 was pH(i)-independent and upstream of MEK1/2. Shrinkage-activation of JNK1/2 was attenuated by EIPA, augmented by hNHE1 expression, and abolished in the presence of HCO(3)(-). Basal JNK activity was augmented at alkaline pH(i). Shrinkage-activation of p38 MAPK was NHE1-independent, and p38 MAPK inhibition (SB203580) attenuated NHE1 activation and ERK1/2 inhibition. Long-term shrinkage elicited caspase-3 activation and a loss of cell viability, which was augmented by ERK1/2 or JNK1/2 inhibition, and attenuated by p38 MAPK inhibition.
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PMID:The Na+/H+ exchanger, NHE1, differentially regulates mitogen-activated protein kinase subfamilies after osmotic shrinkage in Ehrlich Lettre Ascites cells. 1798 56

Na(+)/H(+) exchanger-1 (NHE-1) overexpression is associated with carcinogenesis and is an attractive target for intervention. We report that the chemopreventive agent resveratrol (RSV) downregulates NHE-1 in a caspase-dependent manner without inducing cell death. Resveratrol triggered early activation of caspase 3 and late activation of caspase 6, which were not inter-dependent. Whereas, caspase 3 activation appeared to be a direct effect of resveratrol, caspase 6 activation was mediated via intracellular hydrogen peroxide production and iron. Moreover, downregulation of NHE-1 expression was a function of resveratrol-induced repression of NHE-1 gene promoter activity. RNAi-mediated silencing of caspase 3 or 6 blocked the effect of resveratrol on NHE-1 expression, however the effect on NHE-1 promoter was observed at different phases of promoter repression with caspase 3 controlling the early phase (4-12 h) and caspase 6 regulating the late phase (12-24 h). Scavenging hydrogen peroxide or iron only reversed the late phase of resveratrol-induced NHE-1 promoter repression. Finally, an AP2 binding region within NHE-1 gene promoter was identified as the target of resveratrol. Collectively, these data could explain the anti-cancer activity of resveratrol in the light of the association of increased NHE-1 expression with carcinogenesis.
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PMID:Resveratrol regulates the expression of NHE-1 by repressing its promoter activity: critical involvement of intracellular H2O2 and caspases 3 and 6 in the absence of cell death. 1895 95

We investigated the effects of a novel Na(+)/H(+) exchanger-1 (NHE-1) inhibitor KR-33028 on glutamate excitotoxicity in cultured neuron cells in vitro and cerebral infarct in vivo by comparing its potency with that of zoniporide, a well-known, highly potent NHE-1 inhibitor. KR-33028 inhibited NHE-1 activation in a concentration-dependent manner (IC(50)=2.2 nM), with 18-fold greater potency than that of zoniporide (IC(50)=40.7 nM). KR-33028 significantly attenuated glutamate-induced LDH release with approximately 100 times lower EC(25) than that of zoniporide in cortical neurons in vitro (EC(25) of 0.007 and 0.81 microM, respectively), suggesting its 100-fold greater potency than zoniporide in producing anti-necrotic effect. In addition, the EC(50) of KR-33028 for anti-apoptotic effect was 100 times lower than that of zoniporide shown by TUNEL positivity (0.005 and 0.62 microM, respectively) and caspase-3 activity (0.01 and 2.64 microM, respectively). Furthermore, the EC(50) value of KR-33028 against glutamate-induced intracellular Ca(2+) overload was also 100 times lower than that of zoniporide (EC(50) of 0.004 and 0.65 microM, respectively). In the in vivo cerebral infarct model (60 min middle cerebral artery occlusion followed by 24 h reperfusion), KR-33028 reduced infarct size in a dose-dependent manner. Its ED(25) value, however, was quite similar to that of zoniporide (ED(25) of 0.072 and 0.097 mg/kg, respectively). Hence these results suggest that the novel NHE-1 inhibitor, KR-33028, could be an efficient therapeutic tool to protect neuronal cells against ischemic injury.
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PMID:Effects of KR-33028, a novel Na+/H+ exchanger-1 inhibitor, on glutamate-induced neuronal cell death and ischemia-induced cerebral infarct. 1902 30


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