151
|
Zhu H, Gao W, Jiang H, Wu J, Shi YF, Zhang XJ. Calcineurin mediates acetylcholinesterase expression during calcium ionophore A23187-induced HeLa cell apoptosis. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2007; 1773:593-602. [PMID: 17320203 DOI: 10.1016/j.bbamcr.2007.01.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2006] [Revised: 01/15/2007] [Accepted: 01/17/2007] [Indexed: 11/18/2022]
Abstract
We previously reported that acetylcholinesterase plays a critical role in apoptosis and its expression is regulated by Ca(2+) mobilization. In the present study, we show that activated calpain, a cytosolic calcium-activated cysteine protease, and calcineurin, a calcium-dependent protein phosphatase, regulate acetylcholinesterase expression during A23187-induced apoptosis. The calpain inhibitor, calpeptin, and the calcineurin inhibitors, FK506 and cyclosporine A, inhibited acetylcholinesterase expression at both mRNA and protein levels and suppressed the activity of the human acetylcholinesterase promoter. In contrast, overexpression of constitutively active calcineurin significantly activated the acetylcholinesterase promoter. Furthermore, we identify a role for the transcription factor NFAT (nuclear factor of activated T cells), a calcineurin target, in regulating the acetylcholinesterase promoter during ionophore-induced apoptosis. Overexpression of human NFATc3 and NFATc4 greatly increased the acetylcholinesterase promoter activity in HeLa cells treated with A23187. Overexpression of constitutive nuclear NFATc4 activated the acetylcholinesterase promoter independent of A23187, whereas overexpression of dominant-negative NFAT blocked A23187-induced acetylcholinesterase promoter activation. These results indicate that calcineurin mediates acetylcholinesterase expression during apoptosis.
Collapse
Affiliation(s)
- Hui Zhu
- Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | | | | | | | | | | |
Collapse
|
152
|
Abstract
AMPA receptors (AMPARs) are the principal glutamate receptors mediating fast excitatory synaptic transmission in neurons. Aberrant extracellular glutamate has long been recognized as a hallmark phenomenon during neuronal excitotoxicity. Excessive glutamate triggers massive Ca(2+) influx through NMDA receptors (NMDARs), which in turn can activate Ca(2+)-dependent protease, calpain. In the present study, we found that prolonged NMDA treatment (100 microM, 10 min) caused a sustained and irreversible suppression of AMPAR-mediated currents in cortical pyramidal neurons, which was largely blocked by selective calpain inhibitors. Biochemical and immunocytochemical studies demonstrated that in cortical cultures, prolonged glutamate or NMDA treatment reduced the level of surface and total GluR1, but not GluR2, subunits in a calpain-dependent manner. Consistent with the in vitro data, in animals exposed to transient ischaemic insults, calpain was strongly activated, and the AMPAR current density and GluR1 expression level were substantially reduced. Moreover, calpain inhibitors blocked the ischaemia-induced depression of AMPAR currents, and the NMDAR-induced, calpain-mediated depression of AMPA responses was occluded in ischaemic animals. Taken together, our studies show that overstimulation of NMDARs reduces AMPAR functions in cortical pyramidal neurons through activation of endogenous calpain, and calpain mediates the ischaemia-induced synaptic depression. The down-regulation of AMPARs by calpain provides a negative feedback to dampen neuronal excitability in excitotoxic conditions like ischaemia and epilepsy.
Collapse
MESH Headings
- Animals
- Blotting, Western
- Calpain/physiology
- Cells, Cultured
- Cerebral Cortex/cytology
- Cerebral Cortex/drug effects
- Cerebral Cortex/physiology
- Electrophysiology
- Endocytosis/drug effects
- Gerbillinae
- Immunohistochemistry
- MAP Kinase Kinase 2/metabolism
- Male
- Neurons/drug effects
- Neurons/physiology
- Neuroprotective Agents/pharmacology
- Patch-Clamp Techniques
- Pyramidal Cells/drug effects
- Pyramidal Cells/physiology
- Rats
- Rats, Sprague-Dawley
- Receptors, AMPA/agonists
- Receptors, AMPA/antagonists & inhibitors
- Receptors, AMPA/metabolism
- Receptors, AMPA/physiology
- Receptors, Cell Surface/drug effects
- Receptors, Cell Surface/physiology
- Receptors, N-Methyl-D-Aspartate/agonists
- Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors
- Receptors, N-Methyl-D-Aspartate/physiology
- Stimulation, Chemical
- Synapses/drug effects
- Synapses/physiology
- Synaptic Transmission/drug effects
- Synaptic Transmission/physiology
Collapse
Affiliation(s)
- Eunice Y Yuen
- Department of Physiology and Biophysics, State University of New York at Buffalo, 124 Sherman Hall, Buffalo, NY 14214, USA
| | | | | |
Collapse
|
153
|
Lee JE, Kim H, Jang H, Cho EJ, Youn HD. Hydrogen peroxide triggers the proteolytic cleavage and the inactivation of calcineurin. J Neurochem 2007; 100:1703-12. [PMID: 17217415 DOI: 10.1111/j.1471-4159.2006.04340.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Increases in the levels of reactive oxygen species (ROS) are correlated with a decrease in calcineurin (CN) activity under oxidative or neuropathological conditions. However, the molecular mechanism underlying this ROS-mediated CN inactivation remains unclear. Here, we describe a mechanism for the inactivation of CN by hydrogen peroxide. The treatment of mouse primary cortical neuron cells with Abeta(1-42) peptide and hydrogen peroxide triggered the proteolytic cleavage of CN and decreased its enzymatic activity. In addition, hydrogen peroxide was found to cleave CN in different types of cells. Calcium influx was not involved in CN inactivation during hydrogen peroxide-mediated cleavage, but CN cleavage was partially blocked by chloroquine, indicating that an unidentified lysosomal protease is probably involved in its hydrogen peroxide-mediated cleavage. Treatment with hydrogen peroxide triggered CN cleavage at a specific sequence within its catalytic domain, and the cleaved form of CN had no enzymatic ability to dephosphorylate nuclear factor in activated T cells. Thus, our findings suggest a molecular mechanism by which hydrogen peroxide inactivates CN by proteolysis in ROS-related diseases.
Collapse
Affiliation(s)
- Ji-Eun Lee
- Department of Biochemistry and Molecular Biology, Cancer Research Institute, Interdisciplinary Program in Genetic Engineering, Seoul National University College of Medicine, Seoul, South Korea
| | | | | | | | | |
Collapse
|
154
|
Hallhuber M, Ritter O. New approach to prevent myocardial hypertrophy: the import blocking peptide. Future Cardiol 2007; 3:91-8. [PMID: 19804210 DOI: 10.2217/14796678.3.1.91] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Calcineurin, a serine/threonine phosphatase, plays a crucial role in the development of myocardial hypertrophy. Calcineurin is a cytosolic phosphatase that dephosphorylates the nuclear factor of activated T cells (NFAT), a transcription factor. Until now, it has been postulated that dephosphorylated NFAT is shuttled into the nucleus. Recent evidence demonstrates that not only NFAT, but also calcineurin, is localized in the nucleus. Once calcineurin and NFAT enter the nucleus of cardiomyocytes, transcription of genes that are characteristic for myocardial hypertrophy (e.g., brain natriuretic peptide and atrial natriuretic peptide) occurs. Although the exact nuclear function of calcineurin remains unclear, its co-existence with NFAT is important for the full transcriptional activity of the calcineurin/NFAT signaling cascade. The principal effect of nuclear calcineurin is likely the prolonged nuclear retention period of NFAT. Potential effects of nuclear calcineurin include an antagonistic function to glycogen synthase kinase 3beta, which phosphorylates NFAT for its export out of the nucleus, or direct antagonization of the export of NFAT, catalyzed by the chromosome region maintenance 1, which would leave NFAT nuclear. The nuclear localization sequence (NLS) region at the amino acid sequence from position 172 to 183 of calcineurin Abeta is essential for shuttling calcineurin into the nucleus by importinbeta(1). A synthetic import blocking peptide (IBP) that mimics the nuclear localization sequence of calcineurin was generated. The NLS analog on IBP saturates the calcineurin binding site of importinbeta(1). This prevents the binding of calcineurin to importin and inhibits the nuclear shuttling of calcineurin. Inhibition of the calcineurin/importinbeta(1) interaction by competing synthetic peptides represents a new approach to the inhibition of the development of myocardial hypertrophy.
Collapse
Affiliation(s)
- Matthias Hallhuber
- University of Wuerzburg, Department of Medicine I, Department of Molecular Cardiology, Josef-Schneider-Str. 2, 97080 Wuerzburg, Germany.
| | | |
Collapse
|
155
|
Sribnick EA, Matzelle DD, Ray SK, Banik NL. Estrogen treatment of spinal cord injury attenuates calpain activation and apoptosis. J Neurosci Res 2006; 84:1064-75. [PMID: 16902996 DOI: 10.1002/jnr.21016] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Spinal cord injury (SCI) is a devastating neurologic injury, and currently, the only recommended pharmacotherapy is high-dose methylprednisolone, which has limited efficacy. Estrogen is a multi-active steroid with anti-oxidant and anti-apoptotic effects. Estrogen may modulate intracellular Ca2+ and prevent inflammation. For this study, male rats were divided into three groups. Sham-group animals received a laminectomy at T12. Injured rats received both laminectomy and 40 gram centimeter force SCI. Estrogen-group rats received 4 mg/kg 17beta-estradiol (estrogen) at 15 min and 24 hr post-injury, and vehicle-group rats received equal volumes of dimethyl sulfoxide. Animals were sacrificed at 48 hr post-injury, and 1-cm segments of the lesion, rostral penumbra, and caudal penumbra were excised. The degradation of 68 kD neurofilament protein (NFP) and estrogen receptors (ER) was examined by Western blot analysis. Protein levels of calpain and the activities of calpain and caspase-3 were also examined. Levels of cytochrome c were determined in both cytosolic and mitochondrial fractions. Cell death with DNA fragmentation was examined using the TUNEL assay. At the lesion, samples from both vehicle and estrogen treated animals showed increased levels of 68 kD NFP degradation, calpain content, calpain activity, cytochrome c release, and degradation of ERalpha and ERbeta, as compared to sham. In the caudal penumbra, estrogen treatment significantly attenuated 68 kD NFP degradation, calpain content, calpain activity, levels of cytosolic cytochrome c, and ERbeta degradation. At the lesion, vehicle-treated animals displayed more TUNEL+ cells, and estrogen treatment significantly attenuated this cell death marker. We conclude that estrogen may inhibit cell death in SCI through calpain inhibition.
Collapse
Affiliation(s)
- Eric Anthony Sribnick
- Department of Neurosciences, Division of Neurology, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
| | | | | | | |
Collapse
|
156
|
Akashiba H, Matsuki N, Nishiyama N. Calpain activation is required for glutamate-induced p27 down-regulation in cultured cortical neurons. J Neurochem 2006; 99:733-44. [PMID: 16824045 DOI: 10.1111/j.1471-4159.2006.04100.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Recent evidence suggests that cell cycle-related molecules play pivotal roles in multiple forms of cell death in post-mitotic neurons. Nevertheless, it remains unclear what molecular mechanisms are involved in the regulation of expression levels and activities of these molecules. We showed previously that treatment with extracellular glutamate decreases cyclin-dependent kinase inhibitor p27 before neuronal cell death. In this study, we demonstrate that reductions of both p27 and neuronal viability were dependent on activity of calpain, a Ca(2+)-dependent protease, but not on activity of caspase 3. Interestingly, the glutamate-induced reduction of p27 was not dependent on the ubiquitin-proteasome system. In fact, p27 was present only in the neuronal nucleus, whereas calpain 1, a ubiquitous calpain, was observed both in the neuronal nucleus and cytoplasm in control cultures. Glutamate treatment did not change the localization patterns of p27 and calpain 1. It reduced p27 expression level in the nucleus in a calpain-dependent manner. In vitro experiments using neuronal cell lysate and p27 recombinant protein revealed that p27 was degraded as a substrate of activated calpain 1. These results suggest that calpain(s), activated by glutamate treatment, degrade(s) p27 in the nucleus of neurons, which might promote aberrant cell cycle progression.
Collapse
Affiliation(s)
- Hiroki Akashiba
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | | | | |
Collapse
|
157
|
Shioda N, Moriguchi S, Shirasaki Y, Fukunaga K. Generation of constitutively active calcineurin by calpain contributes to delayed neuronal death following mouse brain ischemia. J Neurochem 2006; 98:310-20. [PMID: 16805817 DOI: 10.1111/j.1471-4159.2006.03874.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Calpain, a Ca(2+)-dependent cysteine protease, in vitro converts calcineurin (CaN) to constitutively active forms of 45 kDa and 48 kDa by cleaving the autoinhibitory domain of the 60 kDa subunit. In a mouse middle cerebral artery occlusion (MCAO) model, calpain converted the CaN A subunit to the constitutively active form with 48 kDa in vivo. We also confirmed increased Ca(2+)/CaM-independent CaN activity in brain extracts. The generation of constitutively active and Ca(2+)/CaM-independent activity of CaN peaked 2 h after reperfusion in brain extracts. Increased constitutively active CaN activity was associated with dephosphorylation of dopamine-regulated phosphoprotein-32 in the brain. Generation of constitutively active CaN was accompanied by translocation of nuclear factor of activated T-cells (NFAT) into nuclei of hippocampal CA1 pyramidal neurons. In addition, a novel calmodulin antagonist, DY-9760e, blocked the generation of constitutively active CaN by calpain, thereby inhibiting NFAT nuclear translocation. Together with previous studies indicating that NFAT plays a critical role in apoptosis, we propose that calpain-induced CaN activation in part mediates delayed neuronal death in brain ischemia.
Collapse
Affiliation(s)
- Norifumi Shioda
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
| | | | | | | |
Collapse
|
158
|
Yagisawa H, Okada M, Naito Y, Sasaki K, Yamaga M, Fujii M. Coordinated intracellular translocation of phosphoinositide-specific phospholipase C-δ with the cell cycle. Biochim Biophys Acta Mol Cell Biol Lipids 2006; 1761:522-34. [PMID: 16580873 DOI: 10.1016/j.bbalip.2006.02.016] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2005] [Accepted: 02/16/2006] [Indexed: 11/18/2022]
Abstract
The delta family phosphoinositide (PI)-specific phospholipase C (PLC) are most fundamental forms of eukaryotic PI-PLCs. Despite the presence of lipid targeting domains such as the PH domain and C2 domain, the isoforms are also found in the cytoplasm and nucleus as well as at the plasma membrane. The isoforms have sequences or regions that can serve as a nuclear localization signal (NLS) and a nuclear export signal (NES). Their intracellular localization differs from one isoform to another, presumably due to the difference in the transport equilibrium balanced by the strength of the two signals of each isoform. Even for a particular isoform, its intracellular localization seems to vary during the cell cycle. As an example, PLCdelta(1), which is generally found at the plasma membrane and in the cytoplasm of quiescent cells, localizes to discrete nuclear structures in the G(1)/S boundary of the cell cycle. This may be at least partly due to an increase in intracellular Ca(2+), since Ca(2+) facilitates the formation of a nuclear transport complex comprised of PLCdelta(1) and importin beta1, a carrier molecule for the nuclear import. PLCdelta(1) as well as PLCdelta(4) may play a pivotal role in controlling the initiation of DNA synthesis in S phase. Spatio-temporal changes in the levels of PtdIns(4,5)P(2) seem to be another major determinant for the localization and regulation of the delta isoforms. High nuclear PtdIns(4,5)P(2) levels are associated with the G(1)/S phases. After entering M phase, PtdIns(4,5)P(2) synthesis at sites of cell division occurs and PLCs seem to localize to the cleavage furrow during cytokinesis. Coordinated translocation of PLCs with the cell cycle or with stress responses may result in changes in intra-nuclear environments and local membrane architectures that modulate proliferation and differentiation. In this review, recent findings regarding the molecular machineries and mechanisms of the nucleocytoplasmic shuttling as well as roles in the cell cycle progression of the delta isoforms of PLC will be discussed.
Collapse
Affiliation(s)
- Hitoshi Yagisawa
- Graduate School of Life Science, University of Hyogo, Harima Science Garden City, Hyogo 678-1297, Japan.
| | | | | | | | | | | |
Collapse
|
159
|
Lopez-Picon FR, Kukko-Lukjanov TK, Holopainen IE. The calpain inhibitor MDL-28170 and the AMPA/KA receptor antagonist CNQX inhibit neurofilament degradation and enhance neuronal survival in kainic acid-treated hippocampal slice cultures. Eur J Neurosci 2006; 23:2686-94. [PMID: 16817871 DOI: 10.1111/j.1460-9568.2006.04793.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The cytoskeleton controls the architecture and survival of the central nervous system neurons by maintaining the stability of axons, dendrites and cellular architecture, and any disturbance in this genuine structure could compromise cell survival. The developmentally regulated intracellular intermediate filament protein neurofilament (NF), composed of the light (NF-L), medium (NF-M) and high (NF-H) molecular weight isoforms, is expressed abundantly in nerve cells but its significance in nerve cell survival in stress situations in the brain is unknown. We have used Western blotting, immunocytochemistry, and Fluoro-Jade B and thionine stainings to clarify the effect of kainic acid (KA) treatment on NF protein stability, and its importance for neuronal survival in hippocampal slice cultures. The contribution of N-methyl-D-aspartate (NMDA) and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/KA glutamate receptor subtypes, calpain proteases and L-type Ca2+-channels to these processes were also assessed. Our results indicated that KA-induced degradation of NF was a fast process, similarly affecting all three NF proteins. It was effectively inhibited by the AMPA/KA receptor antagonist CNQX and the calpain inhibitor MDL-28170, whereas the Ca2+-channel blocker nifedipine and the NMDA receptor antagonist MK-801 had no significant effect. Moreover, KA-induced neuronal damage was effectively decreased in cultures treated with CNQX and MDL-28170. Our results suggest that the stability of NF proteins is an important factor contributing to neuronal survival after excitotoxic injury, and that both AMPA/KA receptor antagonists and calpain inhibitors might serve as neuroprotectants against this type of insult in the immature hippocampus.
Collapse
Affiliation(s)
- Francisco R Lopez-Picon
- Department of Pharmacology, Drug Development and Therapeutics, University of Turku, Itäinen Pitkäkatu 4, FIN-20520 Turku, Finland
| | | | | |
Collapse
|
160
|
Pardo R, Colin E, Régulier E, Aebischer P, Déglon N, Humbert S, Saudou F. Inhibition of calcineurin by FK506 protects against polyglutamine-huntingtin toxicity through an increase of huntingtin phosphorylation at S421. J Neurosci 2006; 26:1635-45. [PMID: 16452687 PMCID: PMC6675484 DOI: 10.1523/jneurosci.3706-05.2006] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Huntington's disease (HD) is caused by an abnormal expanded polyglutamine (polyQ) repeat in the huntingtin protein. Insulin-like growth factor-1 acting through the prosurvival kinase Akt mediates the phosphorylation of huntingtin at S421 and inhibits the toxicity of polyQ-expanded huntingtin in cell culture, suggesting that compounds enhancing phosphorylation are of therapeutic interest. However, it is not clear whether phosphorylation of S421 is crucial in vivo. Using a rat model of HD based on lentiviral-mediated expression of a polyQ-huntingtin fragment in the striatum, we demonstrate here that phosphorylation of S421 is neuroprotective in vivo. We next demonstrate that calcineurin (CaN), a calcium/calmodulin-regulated Ser/Thr protein phosphatase, dephosphorylates S421 in vitro and in cells. Inhibition of calcineurin activity, either by overexpression of the dominant-interfering form of CaN or by treatment with the specific inhibitor FK506, favors the phosphorylation of S421, restores the alteration in huntingtin S421 phosphorylation in HD neuronal cells, and prevents polyQ-mediated cell death of striatal neurons. Finally, we show that administration of FK506 to mice increases huntingtin S421 phosphorylation in brain. Collectively, these data highlight the importance of CaN in the modulation of S421 phosphorylation and suggest the potential use of CaN inhibition as a therapeutic approach to treat HD.
Collapse
|
161
|
Hernández-Espinosa D, Morton AJ. Calcineurin inhibitors cause an acceleration of the neurological phenotype in a mouse transgenic for the human Huntington's disease mutation. Brain Res Bull 2006; 69:669-79. [PMID: 16716837 DOI: 10.1016/j.brainresbull.2006.03.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2006] [Accepted: 03/23/2006] [Indexed: 10/24/2022]
Abstract
Calcineurin (CaN) is a Ca(2+)- and calmodulin-dependent protein serine-threonine phosphatase that is thought to play an important role in the neuronal response to changes in the intracellular Ca(2+) concentration. CaN has been implicated in numerous physiological processes including learning and memory. Decreases in CaN expression are thought to be responsible for some of the pathological features seen in brain ischemia, Down's syndrome and Alzheimer's disease. In this study, we examined the possibility of CaN playing a role in the progressive neurological phenotype of the R6/2 mouse of Huntington's disease. We studied the effects of the CaN inhibitors cyclosporin A and FK506 on the progressive neurological phenotype in the R6/2 mouse. We found that an immunosuppressive dose of both drugs dramatically accelerated the main features of the neurological phenotype in R6/2 mice. This was unlikely to be due solely to the immunosuppressive action of these drugs, since treatment with cyclophosphamide, an immunosuppressant drug with a mechanism of action that is not mediated via CaN, did not have deleterious effects on the R6/2 mouse. If anything, cyclophosphamide improved the neurological symptoms in the R6/2 mice. Together, our data suggest a central role for CaN in the deleterious phenotype of the R6/2 mouse. Treatments aimed at preventing the loss of CaN or stimulating its function may be beneficial in the treatment of HD.
Collapse
Affiliation(s)
- David Hernández-Espinosa
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QJ, United Kingdom
| | | |
Collapse
|
162
|
Ahn DH, Singaravelu G, Lee S, Ahnn J, Shim YH. Functional and phenotypic relevance of differentially expressed proteins in calcineurin mutants ofCaenorhabditis elegans. Proteomics 2006; 6:1340-50. [PMID: 16402360 DOI: 10.1002/pmic.200500315] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Calcineurin is a heterodimeric serine/threonine protein phosphatase, important for many cellular processes such as T-cell regulation, cardiac hypertrophy and kidney development. We previously reported the characterization of Caenorhabditis elegans calcineurin mutants as providing a simple but excellent genetic model system for studying in vivo functions of calcineurin. Calcineurin loss-of-function mutants, cnb-1(lf), and gain-of-function mutants, tax-6(gf), show certain opposite phenotypes as well as some similar phenotypes. In order to explain the phenotypic similarity observed in both loss-of-function and gain-of-function mutants, we examined the proteins that followed similar trends in both mutants relative to wild-type worms by using 2-DE. Interestingly, VHA-13, HSP-6 and phosphoenolpyruvate carboxykinase are down-regulated in both mutants. A total of 96 differentially regulated proteins were identified by MALDI-TOF/MS. Among these, 42 proteins are up-regulated and 54 proteins are down-regulated in calcineurin mutants. Furthermore, knock-down of about 30% of the genes, which are down-regulated in calcineurin mutants, showed some of the phenotypes of calcineurin-null mutants. This analysis suggests the functional relevance of these proteins to calcineurin activity in C. elegans.
Collapse
Affiliation(s)
- Do-Hwan Ahn
- Department of Biological Sciences, Bio/Molecular Informatics Center and Institute of Biomedical Science and Technology, Konkuk University, Seoul, Korea
| | | | | | | | | |
Collapse
|
163
|
Ubol S, Kasisith J, Pitidhammabhorn D, Tepsumethanol V. Screening of pro-apoptotic genes upregulated in an experimental street rabies virus-infected neonatal mouse brain. Microbiol Immunol 2005; 49:423-31. [PMID: 15905604 DOI: 10.1111/j.1348-0421.2005.tb03746.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Rabies virus (RABV) is able to induce apoptotic death of target cells. The molecular pathway of RABV-induced cell death is partially known. In the present study, cDNA array analysis was used as a tool to screen for pro-apoptotic genes that may be involved in RABV induction. RNA was extracted from the infected CNS and from mock-infected controls. When the mean gene expression was compared between the infected group and controls, 21 potential apoptotic genes were identified that exhibited more than 2.5-fold difference in their expression levels. These 21 genes can be grouped into two groups, those genes that participate in the commitment phase and those that play a role as executioners. Examples of genes in commitment phase were death receptors (Fas-L receptor, TNF-receptor), lysosomal proteases, calpain, caspase-1, signaling molecules (ERK, p38MAPK) and bcl-2 family members. Cytochrome c and caspase-3 were representatives of executioners. Based on types of genes activated during the commitment phase, two independent apoptotic mechanisms may be activated in response to the RV infection. The first is immune-mediated death which may operate through the receptor-ligand pathway activated by caspase-1 and the pro-inflammatory cytokine, IL-1beta. The other mechanism is a protease-mediated process which involves lysosomal proteases and calcium-dependent neutral proteases. These two stimulating pathways were followed by Bad, Bak, Bid activation and subsequently the upregulation of cytochrome c and caspase-3. In addition, mobilization of K+ ion and other accessory apoptotic genes such as annexins and clusterin were also upregulated.
Collapse
Affiliation(s)
- Sukathida Ubol
- Department of Microbiology, Faculty of Science, Mahidol University, Ratchatewee, Bangkok, Thailand.
| | | | | | | |
Collapse
|
164
|
Sribnick EA, Ray SK, Banik NL. Estrogen prevents glutamate-induced apoptosis in C6 glioma cells by a receptor-mediated mechanism. Neuroscience 2005; 137:197-209. [PMID: 16289585 DOI: 10.1016/j.neuroscience.2005.08.074] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2005] [Revised: 06/05/2005] [Accepted: 08/15/2005] [Indexed: 12/28/2022]
Abstract
Estrogen-mediated neuroprotection is well established; however, no single mechanism of action for this effect has yet been established. As glial cells are integral for both the intact and injured nervous system, we hypothesized that estrogen-mediated neuroprotection may partly be attributed to attenuation of glial cell apoptosis, allowing them to protect neurons following injury. To assess the protective effects of estrogen on glia, C6 rat glioma cells were treated for 24 h with 500 microM glutamate. Cell viability was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and apoptosis was confirmed by cell morphology and DNA fragmentation. Pretreatment with 10 nM 17beta-estradiol (estrogen) increased cell viability and attenuated apoptosis. Treatment with the stereoisomer 17alpha-estradiol, or estrogen plus estrogen receptor antagonist ICI 182,780, was significantly less effective, indicating that cytoprotection was receptor-mediated. Estrogen treatment upregulated expression of estrogen receptor alpha. Cell impermeable bovine serum albumin-conjugated estrogen was also protective, indicating activation of estrogen receptors on the cell membrane. Intracellular free [Ca2+] was increased after glutamate treatment. This increase was attenuated in cells pretreated with estrogen. Glutamate increased the activity of pro-apoptotic proteases, such as calpain and caspase-3, and these protease activities were significantly attenuated by estrogen. The mechanism by which estrogen decreased intracellular Ca2+ was examined by assaying cell viability after using inhibitors that either blocked extracellular Ca2+ influx or prevented the release of intracellular Ca2+ stores. While several inhibitors increased cell viability in glutamate-treated cells, none were as protective as estrogen, and estrogen co-treatment significantly increased cell viability. These findings indicate that estrogen-mediated cytoprotection may be related to effects on Ca2+ entry but that these effects are not limited to any one of these Ca2+ entry points alone.
Collapse
Affiliation(s)
- E A Sribnick
- Department of Neurology, Medical University of South Carolina, 96 Johnathan Lucas Street, Charleston, SC 29425, USA
| | | | | |
Collapse
|
165
|
Liu F, Grundke-Iqbal I, Iqbal K, Oda Y, Tomizawa K, Gong CX. Truncation and Activation of Calcineurin A by Calpain I in Alzheimer Disease Brain. J Biol Chem 2005; 280:37755-62. [PMID: 16150694 DOI: 10.1074/jbc.m507475200] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A disturbance of calcium homeostasis is believed to play an important role in the neurodegeneration of the brains of Alzheimer disease (AD) patients, but the molecular pathways by which it contributes to the disease are not well understood. Here we studied the activation of two major Ca(2+)-regulated brain proteins, calpain and calcineurin, in AD brain. We found that calpain I is activated, which in turn cleaves and activates calcineurin in AD brain. Mass spectrometric analysis indicated that the cleavage of calcineurin by calpain I is at lysine 501, a position C-terminal to the autoinhibitory domain, which produces a 57-kDa truncated form. The 57-kDa calcineurin maintains its Ca(2+)/calmodulin dependence of the phosphatase activity, but the phosphatase activity is remarkably activated upon truncation. The cleavage and activation of calcineurin correlate to the number of neurofibrillary tangles in human brains. These findings suggest that the overactivation of calpain I and calcineurin may mediate the role of calcium homeostatic disturbance in the neurodegeneration of AD.
Collapse
Affiliation(s)
- Fei Liu
- Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, 10314, USA.
| | | | | | | | | | | |
Collapse
|
166
|
Chiu K, Lam TT, Ying Li WW, Caprioli J, Kwong Kwong JM. Calpain and N-methyl-d-aspartate (NMDA)-induced excitotoxicity in rat retinas. Brain Res 2005; 1046:207-15. [PMID: 15878434 DOI: 10.1016/j.brainres.2005.04.016] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2005] [Revised: 03/29/2005] [Accepted: 04/01/2005] [Indexed: 11/21/2022]
Abstract
Calpain-mediated proteolysis has been implicated as a major process in neuronal cell death in both acute insults and the chronic neurodegenerative disorders in the central nerves system. However, activation of calpain also plays a protective function in the early phase of excitotoxic neuronal death. The exact role of calpains in neuronal death and recovery after exposure to N-methyl-D-aspartate (NMDA) is not clearly known. The purpose of present study was to examine the involvement of mu- and m-calpain in NMDA-induced excitotoxicity in the adult rat retina. Increased immunoreactivity of mu-calpain was noted in RGC layer cells and in the inner nuclear layer with maximal expression at 12 h after NMDA injection. This was further confirmed with Western blotting. TdT-mediated biotin-dUTP nick end labeling (TUNEL) positive cells in the inner retina co-localized with moderate or intense mu-calpain immunoreactivity. In contrast, there was no remarkable change in m-calpain immunoreactivity at any time point after NMDA injection. Simultaneous injection of 2 nmol of a calpain inhibitor (calpain inhibitor II) significantly reduced the number of TUNEL-positive cells in the inner retina at 18 h after NMDA injection and preserved RGC-like cells counted at 7 days after injection. The results of this study showed that mu-calpain may be involved in mediating NMDA-induced excitotoxicity in the rat retina and calpain inhibitors may play a therapeutic role in NMDA related disease.
Collapse
Affiliation(s)
- Kin Chiu
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong
| | | | | | | | | |
Collapse
|
167
|
Huang W, Fileta JB, Dobberfuhl A, Filippopolous T, Guo Y, Kwon G, Grosskreutz CL. Calcineurin cleavage is triggered by elevated intraocular pressure, and calcineurin inhibition blocks retinal ganglion cell death in experimental glaucoma. Proc Natl Acad Sci U S A 2005; 102:12242-7. [PMID: 16103353 PMCID: PMC1186026 DOI: 10.1073/pnas.0505138102] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2005] [Indexed: 11/18/2022] Open
Abstract
Increased intraocular pressure (IOP) leads, by an unknown mechanism, to apoptotic retinal ganglion cell (RGC) death in glaucoma. We now report cleavage of the autoinhibitory domain of the protein phosphatase calcineurin (CaN) in two rodent models of increased IOP. Cleaved CaN was not detected in rat or mouse eyes with normal IOP. In in vitro systems, this constitutively active cleaved form of CaN has been reported to lead to apoptosis via dephosphorylation of the proapoptotic Bcl-2 family member, Bad. In a rat model of glaucoma, we similarly detect increased Bad dephosphorylation, increased cytoplasmic cytochrome c (cyt c), and RGC death. Oral treatment of rats with increased IOP with the CaN inhibitor FK506 led to a reduction in Bad dephosphorylation and cyt c release. In accord with these biochemical results, we observed a marked increase in both RGC survival and optic nerve preservation. These data are consistent with a CaN-mediated mechanism of increased IOP toxicity. CaN cleavage was not observed at any time after optic nerve crush, suggesting that axon damage alone is insufficient to trigger cleavage. These findings implicate this mechanism of CaN activation in a chronic neurodegenerative disease. These data demonstrate that increased IOP leads to the initiation of a CaN-mediated mitochondrial apoptotic pathway in glaucoma and support neuroprotective strategies for this blinding disease.
Collapse
Affiliation(s)
- Wei Huang
- Howe Laboratory of Ophthalmology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA 02114, USA
| | | | | | | | | | | | | |
Collapse
|
168
|
Okada M, Ishimoto T, Naito Y, Hirata H, Yagisawa H. Phospholipase Cδ1associates with importin β1 and translocates into the nucleus in a Ca2+-dependent manner. FEBS Lett 2005; 579:4949-54. [PMID: 16115628 DOI: 10.1016/j.febslet.2005.07.082] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2005] [Accepted: 07/29/2005] [Indexed: 11/23/2022]
Abstract
Phospholipase C (PLC)delta1 shuttles between the nucleus and the cytoplasm. Here, we demonstrate that treatment of MDCK cells and PC12 cells with ionomycin causes nuclear accumulation of ectopically expressed and endogenous PLCdelta1, respectively, suggesting that signals that increase [Ca2+]i trigger nuclear translocation. To clarify the molecular mechanisms involved in this translocation, we have examined whether PLCdelta1 binds with importins. PLCdelta1 interacted with importin beta1 in a Ca2+-dependent manner in vitro even in the absence of importin alpha. A PLCdelta1 mutant E341A, which lacks Ca2+-binding to the catalytic core, did not show this interaction at any physiological Ca2+ concentration and did not translocate into the nucleus after ionomycin treatment when expressed in MDCK cells. These results suggested that the nuclear import of PLCdelta1 is mediated by its Ca2+-dependent interaction with importin beta1.
Collapse
Affiliation(s)
- Masashi Okada
- Graduate School of Life Science, University of Hyogo, Harima Science Garden City, Hyogo 678-1297, Japan.
| | | | | | | | | |
Collapse
|
169
|
Waxman EA, Lynch DR. N-methyl-D-aspartate receptor subtypes: multiple roles in excitotoxicity and neurological disease. Neuroscientist 2005; 11:37-49. [PMID: 15632277 DOI: 10.1177/1073858404269012] [Citation(s) in RCA: 255] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
N-methyl-D-aspartate (NMDA) receptors are the major mediator of excitotoxicity. Although physiological activation of the NMDA receptor is necessary for cell survival, overactivation is a signal for cell death. Several pathways are activated through NMDA receptor stimulation, most of which can contribute to excitotoxicity. These include events leading to mitochondrial dysfunction, activation of calcium-dependent enzymes, and activation of mitogen-activated protein kinase pathways. Understanding the role of these mechanisms is important in developing agents that block excitotoxicity without inhibiting functions necessary for survival. NMDA receptor subtypes may be responsible for mediating separate pathways, and subtype-specific inhibition has shown promising results in some neurological models. This review examines the roles of NMDA receptor subtypes in excitotoxicity and neurological disorders.
Collapse
Affiliation(s)
- Elisa A Waxman
- Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, USA
| | | |
Collapse
|
170
|
Kurz JE, Parsons JT, Rana A, Gibson CJ, Hamm RJ, Churn SB. A Significant Increase in Both Basal and Maximal Calcineurin Activity following Fluid Percussion Injury in the Rat. J Neurotrauma 2005; 22:476-90. [PMID: 15853464 DOI: 10.1089/neu.2005.22.476] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Calcineurin, a neuronally enriched, calcium-stimulated phosphatase, is an important modulator of many neuronal processes, including several that are physiologically related to the pathology of traumatic brain injury. This study examined the effects of moderate, central fluid percussion injury on the activity of this important neuronal enzyme. Animals were sacrificed at several time-points postinjury and cortical, hippocampal, and cerebellar homogenates were assayed for calcineurin activity by dephosphorylation of p-nitrophenol phosphate. A significant brain injury-dependent increase was observed in both hippocampal and cortical homogenates under both basal and maximally-stimulated reaction conditions. This increase persisted 2-3 weeks post-injury. Brain injury did not alter substrate affinity, but did induce a significant increase in the apparent maximal dephosphorylation rate. Unlike the other brain regions, no change in calcineurin activity was observed in the cerebellum following brain injury. No brain region tested displayed a significant change in calcineurin enzyme levels as determined by Western blot, demonstrating that increased enzyme synthesis was not responsible for the observed increase in activity. The data support the conclusion that fluid percussion injury results in increased calcineurin activity in the rat forebrain. This increased activity has broad physiological implications, possibly resulting in altered cellular excitability or a greater likelihood of neuronal cell death.
Collapse
Affiliation(s)
- Jonathan E Kurz
- Department of Neurology, Medical College of Virginia/Virginia Commonwealth University, Richmond, VA 23298, USA
| | | | | | | | | | | |
Collapse
|
171
|
Spalding KL, Dharmarajan AM, Harvey AR. Caspase-independent retinal ganglion cell death after target ablation in the neonatal rat. Eur J Neurosci 2005; 21:33-45. [PMID: 15654841 DOI: 10.1111/j.1460-9568.2004.03826.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In neonatal rats, superior colliculus (SC) ablation results in a massive and rapid increase in retinal ganglion cell (RGC) death that peaks about 24 h post-lesion (PL). Naturally occurring cell death during normal development, and RGC death after axonal injury in neonatal and adult rats, has primarily been ascribed to apoptosis. Given that normal developmental cell death is reported to involve caspase 3 activation, and blocking caspase activity in adults reduces axotomy-induced death, we examined whether blocking caspases in vivo reduces RGC death after neonatal SC lesions. Neither general nor specific caspase inhibitors increased neonatal RGC survival 6 and 24 h PL. These inhibitors were, however, effective in blocking caspases in another well-defined in vitro apoptosis model, the corpus luteum. Caspase 3 protein and mRNA levels in retinas from normal and SC-lesioned neonatal rats were assessed 3, 6 and 24 h after SC removal using immunohistochemistry, western and northern blots and quantitative real-time polymerase chain reaction. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL) was used to independently monitor retinal cell death. The polymerase chain reaction data showed a small but insignificant increase in caspase 3 mRNA in retinas 24 h PL. Western blot analysis did not reveal a significant shift to cleaved (activated) caspase 3 protein. There was a small increase in the number of cleaved caspase 3 immunolabelled cells in the ganglion cell layer 24 h PL but this represented only a fraction of the death revealed by TUNEL. Together, these data indicate that, unlike the situation in adults, most lesion-induced RGC death in neonatal rats occurs independently of caspase activation.
Collapse
Affiliation(s)
- Kirsty L Spalding
- School of Anatomy and Human Biology, The University of Western Australia, Crawley, WA, Australia.
| | | | | |
Collapse
|
172
|
Wu HY, Yuen EY, Lu YF, Matsushita M, Matsui H, Yan Z, Tomizawa K. Regulation of N-methyl-D-aspartate receptors by calpain in cortical neurons. J Biol Chem 2005; 280:21588-93. [PMID: 15790561 DOI: 10.1074/jbc.m501603200] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The N-methyl-D-aspartate (NMDA) receptor is a cation channel highly permeable to calcium and plays critical roles in governing normal and pathologic functions in neurons. Calcium entry through NMDA receptors (NMDARs) can lead to the activation of the Ca2+-dependent protease, calpain. Here we investigated the involvement of calpain in regulation of NMDAR channel function. After prolonged (5-min) treatment with NMDA or glutamate, the whole-cell NMDAR-mediated current was significantly reduced in both acutely dissociated and cultured cortical pyramidal neurons. The down-regulation of NMDAR current was blocked by bath application of selective calpain inhibitors. Intracellular injection of a specific calpain inhibitory peptide also eliminated the down-regulation of NMDAR current induced by prolonged NMDA treatment. In contrast, dynamin inhibitory peptide had no effect on the depression of NMDAR current, suggesting the lack of involvement of dynamin/clathrin-mediated NMDAR internalization in this process. Immunoblotting analysis showed that the NR2A and NR2B subunits of NMDARs were markedly degraded in cultured cortical neurons treated with glutamate, and the degradation of NR2 subunits was prevented by calpain inhibitors. Taken together, our results suggest that prolonged activation of NMDARs in neurons activates calpain, and activated calpain in turn down-regulates the function of NMDARs, which provides a neuroprotective mechanism against NMDAR overstimulation accompanying ischemia and stroke.
Collapse
Affiliation(s)
- Hai-Yan Wu
- Department of Physiology, Okayama University Graduate School of Medicine and Dentistry, Okayama 700-8558, Japan
| | | | | | | | | | | | | |
Collapse
|
173
|
Abstract
Background—
Calcineurin (CnA) is important in the regulation of myocardial hypertrophy. We demonstrated that targeted proteolysis of the CnA autoinhibitory domain under pathological myocardial workload leads to increased CnA activity in human myocardium. Here, we investigated the proteolytic mechanism leading to activation of CnA.
Methods and Results—
In patients with diseased myocardium, we found strong nuclear translocation of CnA. In contrast, in normal human myocardium, there was a cytosolic distribution of CnA. Stimulation of rat cardiomyocytes with angiotensin (Ang) II increased calpain activity significantly (433±11%;
P
<0.01; n=6) and caused proteolysis of the autoinhibitory domain of CnA. Inhibition of calpain by a membrane-permeable calpain inhibitor prevented proteolysis. We identified the cleavage site of calpain in the human CnA sequence at amino acid 424. CnA activity was increased after Ang II stimulation (310±29%;
P
<0.01; n=6) and remained high after removal of Ang II (214±17%;
P
<0.01; n=6). Addition of a calpain inhibitor to the medium decreased CnA activity (110±19%;
P
=NS; n=6) after removal of Ang II. Ang II stimulation of cardiomyocytes also translocated CnA into the nucleus as demonstrated by immunohistochemical staining and transfection assays with GFP-tagged CnA. Calpain inhibition and therefore suppression of calpain-mediated proteolysis of CnA enabled CnA exit from the nucleus.
Conclusions—
Ang II stimulation of cardiomyocytes increased calpain activity, leading to proteolysis of the autoinhibitory domain of CnA. This causes an increase in CnA activity and results in nuclear translocation of CnA. Loss of the autoinhibitory domain renders CnA constitutively nuclear and active, even after removal of the hypertrophic stimulus.
Collapse
Affiliation(s)
- Natalie Burkard
- Department of Medicine, University of Wuerzburg, Wuerzburg, Germany
| | | | | | | | | | | |
Collapse
|
174
|
Yang HJ, Lee SH, Jin Y, Choi JH, Han DU, Chae C, Lee MH, Han CH. Toxicological effects of acrylamide on rat testicular gene expression profile. Reprod Toxicol 2005; 19:527-34. [PMID: 15749267 DOI: 10.1016/j.reprotox.2004.10.006] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2004] [Revised: 10/02/2004] [Accepted: 10/08/2004] [Indexed: 11/23/2022]
Abstract
Toxicological effects of acrylamide on differential gene expression profile of rat testis were evaluated. Acrylamide induced morphological sperm defects, and decreased sperm concentration in cauda epididymis. Serum testosterone level and Leydig cell viability were also decreased dose-dependently, which resulted in decreased spermatogenesis. Acrylamide-induced histopathological lesions, such as formation of multinucleated giant cells and vacuolation, and numerous apoptotic cells were observed in seminiferous tubules. cDNA microarray analysis revealed that genes related to testicular-functions, apoptosis, cellular redox, cell growth, cell cycle, and nucleic acid-binding were up/down-regulated in testes isolated from acrylamide-treated group (60 mg/kg/day). Acrylamide toxicity appears to increase Leydig cell death and perturb gene expression levels, contributing to sperm defects and various abnormal histopathological lesions including apoptosis in rat testis.
Collapse
Affiliation(s)
- Hye-Jin Yang
- Department of Biochemistry, College of Veterinary Medicine, Seoul National University, 151-742 Seoul, Republic of Korea
| | | | | | | | | | | | | | | |
Collapse
|
175
|
Polster BM, Basañez G, Etxebarria A, Hardwick JM, Nicholls DG. Calpain I induces cleavage and release of apoptosis-inducing factor from isolated mitochondria. J Biol Chem 2005; 280:6447-54. [PMID: 15590628 DOI: 10.1074/jbc.m413269200] [Citation(s) in RCA: 309] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The translocation of apoptosis-inducing factor (AIF) from mitochondria to the nucleus has been implicated in the mechanism of glutamate excitotoxicity in cortical neurons and has been observed in vivo following acute rodent brain injuries. However, the mechanism and time course of AIF redistribution to the nucleus is highly controversial. Because elevated intracellular calcium is one of the most ubiquitous features of neuronal cell death, this study tested the hypothesis that cleavage of AIF by the calcium-activated protease calpain mediates its release from mitochondria. Both precursor and mature forms of recombinant AIF were cleaved near the amino terminus by calpain I in vitro. Mitochondrial outer membrane permeabilization by truncated Bid induced cytochrome c release from isolated liver or brain mitochondria but only induced AIF release in the presence of active calpain. Enzymatic inhibition of calpain by calpeptin precluded AIF release, demonstrating that proteolytic activity was required for release. Calpeptin and the mitochondrial permeability transition pore antagonist cyclosporin A also inhibited calcium-induced AIF release from mouse liver mitochondria, implicating the involvement of an endogenous mitochondrial calpain in release of AIF during permeability transition. Cleavage of AIF directly decreased its association with pure lipid vesicles of mitochondrial inner membrane composition. Taken together, these results define a novel mechanism of AIF release involving calpain processing and identify a potential molecular checkpoint for cytoprotective interventions.
Collapse
Affiliation(s)
- Brian M Polster
- The Buck Institute for Age Research, Novato, California 94945, USA.
| | | | | | | | | |
Collapse
|
176
|
Minami SB, Yamashita D, Schacht J, Miller JM. Calcineurin activation contributes to noise-induced hearing loss. J Neurosci Res 2005; 78:383-92. [PMID: 15389832 DOI: 10.1002/jnr.20267] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Acoustic overstimulation increases Ca(2+) concentration in auditory hair cells. Because calcineurin is known to activate cell death pathways and is controlled by Ca(2+) and calmodulin, this study assessed the role of calcineurin in auditory hair cell death in guinea pigs after intense noise exposure. Immediately after noise exposure (4-kHz octave band, 120 dB, for 5 hr), a population of hair cells exhibited calcineurin immunoreactivity at the cuticular plate, with a decreasing number of positive-stained cells on Days 1-3. By Day 7, the levels of calcineurin immunoreactivity had diminished to near control, non-noise exposed values, concomitant with an increasing loss of hair cells. Staining of hair cell nuclei with propidium iodide (PI), restricted to calcineurin-immunopositive cells, indicated breakdown of cell membranes symptomatic of incipient cell death. The local application of the calcineurin inhibitors, FK506 and cyclosporin A, reduced the level of noise-induced auditory brain stem response threshold shift and hair cell death, indicating that calcineurin is a factor in noise-induced hearing loss. The results suggest that calcineurin inhibitors are of potential therapeutic value for long-term protection of the morphologic integrity and function of the organ of Corti against noise trauma.
Collapse
Affiliation(s)
- Shujiro B Minami
- Kresge Hearing Research Institute, University of Michigan, 1301 E. Ann Street, Ann Arbor, MI 48109-0506, USA.
| | | | | | | |
Collapse
|
177
|
Kumashiro S, Lu YF, Tomizawa K, Matsushita M, Wei FY, Matsui H. Regulation of synaptic vesicle recycling by calcineurin in different vesicle pools. Neurosci Res 2005; 51:435-43. [PMID: 15740806 DOI: 10.1016/j.neures.2004.12.018] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2004] [Revised: 12/21/2004] [Accepted: 12/21/2004] [Indexed: 11/19/2022]
Abstract
The synaptic vesicles keep recycling by the processes of endocytosis and exocytosis to maintain the normal synaptic transmission. The synaptic vesicles are classified as the readily releasable pool (RRP) and the reserve pool (RP). In the endocytosis process, calcineurin (CaN), a Ca2+/calmodulin-dependent protein phosphatase, has been shown to play important roles. However, it is unclear about its roles in different vesicle pools. Here, we investigated the role of CaN in the regulation of vesicle recycling in the RRP and RP. Vesicle recycling was monitored by using fluorescent dyes FM1-43 and FM4-64 in the primary cultures of hippocampal neurons. Inhibition of CaN by FK506 and cyclosporin A suppressed the endocytosis in the RP, but not in the RRP. Inhibition of CaN also restrained the exocytic process triggered by 10 Hz stimulation, but had no effect on 3-5 Hz stimulation-induced exocytosis. FK506 also reduced the total vesicle pool size in the synaptic terminals. A synthesized CaN inhibitory peptide showed the similar effects as FK506 and cyclosporin A. These results revealed a novel mechanism that CaN plays critical roles in the distinct vesicle recycling processes.
Collapse
Affiliation(s)
- Susumu Kumashiro
- Department of Physiology, Okayama University Graduate School of Medicine and Dentistry, Okayama 700-8558, Japan
| | | | | | | | | | | |
Collapse
|
178
|
Araújo IM, Verdasca MJ, Leal EC, Bahr BA, Ambrósio AF, Carvalho AP, Carvalho CM. Early calpain-mediated proteolysis following AMPA receptor activation compromises neuronal survival in cultured hippocampal neurons. J Neurochem 2005; 91:1322-31. [PMID: 15584909 DOI: 10.1111/j.1471-4159.2004.02811.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this work, we investigated the involvement of calpains in the neurotoxicity induced by short-term exposure to kainate (KA) in non-desensitizing conditions of AMPA receptor activation (cyclothiazide present, CTZ), in cultured rat hippocampal neurons. The calpain inhibitor MDL28170 had a protective effect in cultures treated with KA plus CTZ (p < 0.01), preventing the decrease in MTT reduction caused by exposure to KA (p < 0.001). Caspase inhibition by ZVAD-fmk was not neuroprotective against the toxic effect of KA. At 1 h after treatment, we could already observe significantly increased calpain activity, which was prevented by MDL 28170 and NBQX. Western blot analysis of calpain substrates, GluR1, neuronal nitric oxide synthase (nNOS) and nonerythroid spectrin (fodrin), showed a time-dependent and MDL 28170-sensitive proteolysis of these proteins. This effect was due to calpains, but not caspases, since ZVAD-fmk was ineffective in preventing proteolytic events. Breakdown products of fodrin (BDPs) were detected as early as 15 min after exposure to KA. Overall, these results show early activation of calpains following activation of AMPA receptors as well as compromise of neuronal survival, likely due to proteolytic events that affect proteins involved in neuronal signaling.
Collapse
Affiliation(s)
- Inês M Araújo
- Center for Neuroscience and Cell Biology, Department of Zoology, University of Coimbra, Coimbra, Portugal
| | | | | | | | | | | | | |
Collapse
|
179
|
Michiue H, Tomizawa K, Wei FY, Matsushita M, Lu YF, Ichikawa T, Tamiya T, Date I, Matsui H. The NH2 terminus of influenza virus hemagglutinin-2 subunit peptides enhances the antitumor potency of polyarginine-mediated p53 protein transduction. J Biol Chem 2004; 280:8285-9. [PMID: 15611109 DOI: 10.1074/jbc.m412430200] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein transduction therapy is a newly developing method that allows proteins, peptides, and biologically active compounds to penetrate across the plasma membrane by being fused with cell-penetrating peptides such as polyarginine. Polyarginine-fused p53 protein penetrates across the plasma membrane of cancer cells and inhibits the growth of the cells. However, the protein is often entrapped inside macropinosomes in the cytoplasm. Therefore, high dose concentrations of the protein are needed for it to function effectively. To overcome this problem, in the present study, polyarginine-fused p53 was linked with the NH(2)-terminal domain of influenza virus hemagglutinin-2 subunit (HA2), which is a pH-dependent fusogenic peptide that induces the lysis of membranes at low pH levels. The protein was capable of efficiently translocating into the nucleus of glioma cells and induced p21(WAF1) transcriptional activity more effectively than did polyarginine-fused p53 protein. Moreover, low concentrations of the protein significantly inhibited the growth of cancer cells. These results suggest that protein transduction therapy using polyarginine and HA2 may be useful as a method for cancer therapy.
Collapse
Affiliation(s)
- Hiroyuki Michiue
- Department of Physiology, Okayama University Graduate School of Medicine and Dentistry, 2-5-1 Shikata-cho, Okayama 700-8558, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|
180
|
Wen Z, Guirland C, Ming GL, Zheng JQ. A CaMKII/calcineurin switch controls the direction of Ca(2+)-dependent growth cone guidance. Neuron 2004; 43:835-46. [PMID: 15363394 DOI: 10.1016/j.neuron.2004.08.037] [Citation(s) in RCA: 159] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2004] [Revised: 07/26/2004] [Accepted: 08/24/2004] [Indexed: 11/30/2022]
Abstract
Axon pathfinding depends on attractive and repulsive turning of growth cones to extracellular cues. Localized cytosolic Ca2+ signals are known to mediate the bidirectional responses, but downstream mechanisms remain elusive. Here, we report that calcium-calmodulin-dependent protein kinase II (CaMKII) and calcineurin (CaN) phosphatase provide a switch-like mechanism to control the direction of Ca(2+)-dependent growth cone turning. A relatively large local Ca2+ elevation preferentially activates CaMKII to induce attraction, while a modest local Ca2+ signal predominantly acts through CaN and phosphatase-1 (PP1) to produce repulsion. The resting level of intracellular Ca2+ concentrations also affects CaMKII/CaN operation: a normal baseline allows distinct turning responses to different local Ca2+ signals, while a low baseline favors CaN-PP1 activation for repulsion. Moreover, the cAMP pathway negatively regulates CaN-PP1 signaling to inhibit repulsion. Finally, CaMKII/CaN-PP1 also mediates netrin-1 guidance. Together, these findings establish a complex Ca2+ mechanism that targets the balance of CaMKII/CaN-PP1 activation to control distinct growth cone responses.
Collapse
Affiliation(s)
- Zhexing Wen
- Department of Neuroscience and Cell Biology, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA
| | | | | | | |
Collapse
|
181
|
Kumar R, Musiyenko A, Oldenburg A, Adams B, Barik S. Post-translational generation of constitutively active cores from larger phosphatases in the malaria parasite, Plasmodium falciparum: implications for proteomics. BMC Mol Biol 2004; 5:6. [PMID: 15230980 PMCID: PMC459218 DOI: 10.1186/1471-2199-5-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2004] [Accepted: 07/01/2004] [Indexed: 11/16/2022] Open
Abstract
Background Although the complete genome sequences of a large number of organisms have been determined, the exact proteomes need to be characterized. More specifically, the extent to which post-translational processes such as proteolysis affect the synthesized proteins has remained unappreciated. We examined this issue in selected protein phosphatases of the protease-rich malaria parasite, Plasmodium falciparum. Results P. falciparum encodes a number of Ser/Thr protein phosphatases (PP) whose catalytic subunits are composed of a catalytic core and accessory domains essential for regulation of the catalytic activity. Two examples of such regulatory domains are found in the Ca+2-regulated phosphatases, PP7 and PP2B (calcineurin). The EF-hand domains of PP7 and the calmodulin-binding domain of PP2B are essential for stimulation of the phosphatase activity by Ca+2. We present biochemical evidence that P. falciparum generates these full-length phosphatases as well as their catalytic cores, most likely as intermediates of a proteolytic degradation pathway. While the full-length phosphatases are activated by Ca+2, the processed cores are constitutively active and either less responsive or unresponsive to Ca+2. The processing is extremely rapid, specific, and occurs in vivo. Conclusions Post-translational cleavage efficiently degrades complex full-length phosphatases in P. falciparum. In the course of such degradation, enzymatically active catalytic cores are produced as relatively stable intermediates. The universality of such proteolysis in other phosphatases or other multi-domain proteins and its potential impact on the overall proteome of a cell merits further investigation.
Collapse
Affiliation(s)
- Rajinder Kumar
- Department of Biochemistry and Molecular Biology, University of South Alabama, College of Medicine, 307 University Blvd., Mobile, Alabama, USA 36688-0002
| | - Alla Musiyenko
- Department of Biochemistry and Molecular Biology, University of South Alabama, College of Medicine, 307 University Blvd., Mobile, Alabama, USA 36688-0002
| | - Anja Oldenburg
- Department of Biochemistry and Molecular Biology, University of South Alabama, College of Medicine, 307 University Blvd., Mobile, Alabama, USA 36688-0002
| | - Brian Adams
- Department of Biochemistry and Molecular Biology, University of South Alabama, College of Medicine, 307 University Blvd., Mobile, Alabama, USA 36688-0002
| | - Sailen Barik
- Department of Biochemistry and Molecular Biology, University of South Alabama, College of Medicine, 307 University Blvd., Mobile, Alabama, USA 36688-0002
| |
Collapse
|
182
|
Kolchinskaya LI, Malysheva MK. Activity of calpain in subcellular fractions of the rat brain. NEUROPHYSIOLOGY+ 2004. [DOI: 10.1007/s11062-005-0013-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
183
|
Hashiguchi A, Yano S, Morioka M, Hamada J, Shirasaki Y, Kochi M, Fukunaga K. The Post-ischemic Administration of 3-[2-[4-(3-Chloro-2-methylphenyl)-1-piperazinyl]ethyl]-5,6-dimethoxy-1-(4-imidazolylmethyl)-1H-indazole Dihydrochloride 3.5 Hydrate (DY-9760e), a Novel Calmodulin Antagonist, Prevents Delayed Neuronal Death in Gerbil Hippocampus. J Pharmacol Sci 2004; 96:65-72. [PMID: 15359085 DOI: 10.1254/jphs.fp0040348] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
The novel calmodulin (CaM) antagonist DY-9760e (3-[2-[4-(3-chloro-2-methylphenyl)-1-piperazinyl]ethyl]-5,6-dimethoxy-1-(4-imidazolylmethyl)-1H-indazole dihydrochloride 3.5 hydrate) with an apparent neuroprotective effect in vivo preferentially inhibits neuronal nitric oxide synthase (nNOS), Ca2+/CaM-dependent protein kinase IIalpha (CaMKIIalpha), and calcineurin in vitro. In the present study, we investigated the molecular mechanism underlying its neuroprotective effect with the gerbil transient forebrain ischemia model, by focusing on its inhibition of these Ca2+/CaM-dependent enzymes. Post-ischemic DY-9760e treatment (5 mg/kg, i.p.) immediately after 5-min ischemia significantly reduced the delayed neuronal death in the hippocampal CA1 region. CaMKIIalpha was transiently autophosphorylated immediately after reperfusion with concomitant sustained decrease in its total amounts in the Triton X-100-soluble fractions. Calcineurin activity, accessed by the phosphorylation state of dopamine- and cAMP-regulated phosphoprotein of Mr 32,000 (DARPP-32) at Thr34, was elevated at 6 h after reperfusion. Post-treatment of DY-9760e had no effects on both CaMKIIalpha and DARPP-32 phosphorylation at 6 h after reperfusion. However, DY-9760e significantly inhibited nitrotyrosine formation, as a biomarker of NO, and in turn, peroxynitrite (ONOO-) production. These results suggest that DY-9760e primarily inhibits Ca2+/CaM-dependent neuronal NOS, without any effects on CaMKII and calcineurin, and the inhibition of NO production possibly accounts for its neuroprotective action in brain ischemic injury.
Collapse
Affiliation(s)
- Akihito Hashiguchi
- Department of Neurosurgery, Kumamoto University School of Medicine, Kumamoto-city, Japan
| | | | | | | | | | | | | |
Collapse
|