bluuebunny/crossref_metadata_2025_split huggingface dataset:
ASPP2 inhibits APP‐BP1‐mediated NEDD8 conjugation to cullin‐1 and decreases APP‐BP1‐induced cell proliferation and neuronal apoptosis
Authors: Chen Yuzhi , Liu Wenyun , Naumovski Louie , Neve Rachael L. 
Published: July 2010

AbstractAPP‐BP1, first identified as a protein that interacts with the carboxyl (C) terminus of the amyloid precursor protein (APP), is one‐half of the bipartite activating enzyme for the ubiquitin‐like protein NEDD8. We report here that APP‐BP1 also specifically interacts with apoptosis stimulating protein of p53 ASPP2 in non‐transfected cells through the functional predominant N‐terminal domain ASPP2(332–483). ASPP2 inhibits the ability of APP‐BP1 to rescue the ts41 cell cycle mutation and inhibits APP‐BP1 induced apoptosis in primary neurons. ASPP2 reduces the ability of NEDD8 to conjugate to Cullin‐1, inhibits APP‐BP1‐dependent ts41 cell proliferation, and blocks the ability of APP‐BP1 to cause apoptosis and to cause DNA synthesis in neurons. We also show that ASPP2 activates nuclear factor‐κB (NF‐κB) transcriptional activity, which seems to be inhibited by the neddylation pathway since the dominant negative NEDD8 activating enzyme causes enhanced NF‐κB activity. Our data provide the first in vivo evidence that ASPP2 is a negative regulator of the neddylation pathway through specific interaction with APP‐BP1 and suggest that dysfunction of the APP–BP1 interaction with APP may be one cause of Alzheimer's disease.
Neuronal nitric oxide synthase proteolysis limits the involvement of nitric oxide in kainate‐induced neurotoxicity in hippocampal neurons
Authors: Araújo Inês M. , Ambrósio António F. , Leal Ermelindo C. , Santos Paulo F. , Carvalho Arsélio P. , Carvalho Caetana M. 
Published: July 2010

AbstractIn this work, we investigated the role of nitric oxide (NO) in neurotoxicity triggered by α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionate (AMPA) receptor activation in cultured hippocampal neurons. In the presence of cyclothiazide (CTZ), short‐term exposures to kainate (KA; 5 and 15 min, followed by 24‐h recovery) decreased cell viability. Both NBQX and d‐AP‐5 decreased the neurotoxicity caused by KA plus CTZ. Long‐term exposures to KA plus CTZ (24 h) resulted in increased toxicity. In short‐, but not in long‐term exposures, the presence of NO synthase (NOS) inhibitors (l‐NAME and 7‐NI) decreased the toxicity induced by KA plus CTZ. We also found that KA plus CTZ (15‐min exposure) significantly increased cGMP levels. Furthermore, short‐term exposures lead to decreased intracellular ATP levels, which was prevented by NBQX, d‐AP‐5 and NOS inhibitors. Immunoblot analysis revealed that KA induced neuronal NOS (nNOS) proteolysis, gradually lowering the levels of nNOS according to the time of exposure. Calpain, but not caspase‐3 inhibitors, prevented this effect. Overall, these results show that NO is involved in the neurotoxicity caused by activation of non‐desensitizing AMPA receptors, although to a limited extent, since AMPA receptor activation triggers mechanisms that lead to nNOS proteolysis by calpains, preventing a further contribution of NO to the neurotoxic process.
Bcl‐2 overexpression protects against neuron loss within the ischemic margin following experimental stroke and inhibits cytochrome c translocation and caspase‐3 activity
Authors: Zhao Heng , Yenari Midori A. , Cheng Danye , Sapolsky Robert M. , Steinberg Gary K. 
Published: July 2010

AbstractBcl‐2 protects against both apoptotic and necrotic death induced by several cerebral insults. We and others have previously demonstrated that defective herpes simplex virus vectors expressing Bcl‐2 protect against various insults in vitro and in vivo, including cerebral ischemia. Because the infarct margin may be a region that is most amenable to treatment, we first determined whether gene transfer to the infarct margin is possible using a focal ischemia model. Since ischemic injury with and without reperfusion may occur by different mechanisms, we also determined whether Bcl‐2 protects against focal cerebral ischemic injury either with or without reperfusion in rats. Bax expression, cytochrome c translocation and activated caspase‐3 expression were also assessed. Viral vectors overexpressing Bcl‐2 were delivered to the infarct margin. Reperfusion resulted in larger infarcts than permanent occlusion. Bcl‐2 overexpression significantly improved neuron survival in both ischemia models. Bcl‐2 overexpression did not alter overall Bax expression, but inhibited cytosolic accumulation of cytochrome c and caspase‐3 activation. Thus, we provide the first evidence that gene transfer to the infarct margin is feasible, that overexpression of Bcl‐2 protects against damage to the infarct margin induced by ischemia with and without reperfusion, and that Bcl‐2 overexpression using gene therapy attenuates apoptosis‐related proteins. This suggests a potential therapeutic strategy for stroke.
Potassium channel gene therapy can prevent neuron death resulting from necrotic and apoptotic insults
Authors: Lee Angela L. , Dumas Theodore C. , Tarapore Phiroz E. , Webster Brian R. , Ho Dora Y. , Kaufer Daniela , Sapolsky Robert M. 
Published: July 2010

AbstractNecrotic insults such as seizure are excitotoxic. Logically, membrane hyperpolarization by increasing outwardly conducting potassium channel currents should attenuate hyperexcitation and enhance neuron survival. Therefore, we overexpressed a small‐conductance calcium‐activated (SK2) or voltage‐gated (Kv1.1) channel via viral vectors in cultured hippocampal neurons. We found that SK2 or Kv1.1 protected not only against kainate or glutamate excitotoxicity but also increased survival after sodium cyanide or staurosporine.In vivooverexpression of either channel in dentate gyrus reduced kainate‐induced CA3 lesions. In hippocampal slices, the kainate‐induced increase in granule cell excitability was reduced by overexpression of either channel, suggesting that these channels exert their protective effects during hyperexcitation. It is also important to understand any functional disturbances created by transgene overexpression alone. In the absence of insult, overexpression of Kv1.1, but not SK2, reduced baseline excitability in dentate gyrus granule cells. Furthermore, while no behavioral disturbances during spatial acquisition in the Morris water maze were observed with overexpression of either channel, animals overexpressing SK2, but not Kv1.1, exhibited a memory deficit post‐training. This difference raises the possibility that the means by which these channel subtypes protect may differ. With further development, potassium channel vectors may be an effective pre‐emptive strategy against necrotic insults.
Lipopolysaccharide‐induced dopaminergic cell death in rat midbrain slice cultures: role of inducible nitric oxide synthase and protection by indomethacin
Authors: Shibata Haruki , Katsuki Hiroshi , Nishiwaki Mayumi , Kume Toshiaki , Kaneko Shuji , Akaike Akinori 
Published: July 2010

AbstractGlial cell activation associated with inflammatory reaction may contribute to pathogenic processes of neurodegenerative disorders, through production of several cytotoxic molecules. We investigated the consequences of glial activation by interferon‐γ (IFN‐γ)/lipopolysaccharide (LPS) in rat midbrain slice cultures. Application of IFN‐γ followed by LPS caused dopaminergic cell death and accompanying increases in nitrite production and lactate dehydrogenase release. Aminoguanidine, an inhibitor of inducible nitric oxide synthase (iNOS), or SB203580, an inhibitor of p38 mitogen‐activated protein kinase, prevented dopaminergic cell loss as well as nitrite production. SB203580 also suppressed expression of iNOS and cyclooxygenase‐2 (COX‐2) induced by IFN‐γ/LPS. A COX inhibitor indomethacin protected dopaminergic neurons from IFN‐γ/LPS‐induced injury, whereas selective COX‐2 inhibitors such as NS‐398 and nimesulide did not. Notably, indomethacin was able to attenuate neurotoxicity of a nitric oxide (NO) donor. Neutralizing antibodies against tumour necrosis factor‐α and interleukin‐1β did not inhibit dopaminergic cell death caused by IFN‐γ/LPS, although combined application of these antibodies blocked lactate dehydrogenase release and decrease in the number of non‐dopaminergic neurons. These results indicate that iNOS‐derived NO plays a crucial role in IFN‐γ/LPS‐induced dopaminergic cell death, and that indomethacin exerts protective effect by mechanisms probably related to NO neurotoxicity rather than through COX inhibition.
Expression of death‐associated protein kinase and recruitment to the tumor necrosis factor signaling pathway following brief seizures
Authors: Henshall David C. , Araki Tomohiro , Schindler Clara K. , Shinoda Sachiko , Lan Jing‐Quan , Simon Roger P. 
Published: July 2010

AbstractDeath‐associated protein (DAP) kinase is calcium‐regulated and known to function downstream of death receptors, prompting us to examine its role in the mechanism of seizure‐induced neuronal death. Brief seizures were focally evoked in rats, eliciting neuronal death within the CA3 subfield of the hippocampus, and to a lesser extent, cortex. Western blotting confirmed expression of DAP kinase within hippocampus and cortex at the predicted weight of ∼160 kDa. Immunohistochemistry revealed seizures triggered a significant increase in numbers of DAP kinase‐expressing cells within CA3 and cortex, without affecting cell counts within seizure‐resistant CA2 or the dentate gyrus. Numbers of DAP kinase‐expressing cells were increased in relation to specific patterns of injury‐causing seizure activity, electrographically defined. Seizures caused an early increase in DAP kinase binding to actin, and association with calmodulin. Co‐immunoprecipitation studies also revealed seizures triggered binding of DAP kinase to the tumor necrosis factor receptor 1 and the Fas‐associated death domain protein, commensurate with caspase‐8 proteolysis. In contrast, within surviving fields of the hippocampus, DAP kinase interacted with the molecular chaperone 14–3−3. These data suggest DAP kinase is involved in the molecular pathways activated during seizure‐induced neuronal death.
Identification of members of the Bex gene family as olfactory marker protein (OMP) binding partners
Authors: Behrens Maik , Margolis Joyce W. , Margolis Frank L. 
Published: July 2010

AbstractOlfactory marker protein (OMP) expression is a hallmark of mature vertebrate olfactory receptor neurons (ORNs). Evidence for OMP function derives from altered behavioral and electrophysiological activities of OMP‐KO mice. The molecular basis for the altered phenotype following the deletion of OMP is still unclear. Recent structural studies predict the involvement of OMP in protein–protein interaction. Here we report the identification of an OMP partner, Bex2, by phage‐display screening of an olfactory mucosal cDNA‐library. In situ hybridization demonstrates cellular co‐localization of OMP mRNA with mRNAs for Bex1, Bex2, and Bex3 in ORNs of olfactory tissue of the mouse. The OMP/Bex interaction has been confirmed by demonstrating the chemical cross‐linking of recombinant rat OMP with a synthetic peptide derived from the Bex amino acid sequence. The subcellular localization of Bex and OMP proteins was evaluated in transfected HEK293 cells. Bex is visualized in the nucleus and cytoplasm. Following co‐transfection we observed the unexpected presence of some OMP in the nucleus along with Bex. Together, these data argue convincingly that we have identified Bex as an OMP partner whose further characterization will provide insight to the role of OMP and to the mechanism of theOMP/Bex interaction in ORN differentiation and function.
Dysfunction of mitochondrial complex I and the proteasome: interactions between two biochemical deficits in a cellular model of Parkinson's disease
Authors: Höglinger Günter U. , Carrard Géraldine , Michel Patrick P. , Medja Fadia , Lombès Anne , Ruberg Merle , Friguet Bertrand , Hirsch Etienne C. 
Published: July 2010

AbstractTwo biochemical deficits have been described in the substantia nigra in Parkinson's disease, decreased activity of mitochondrial complex I and reduced proteasomal activity. We analysed interactions between these deficits in primary mesencephalic cultures. Proteasome inhibitors (epoxomicin, MG132) exacerbated the toxicity of complex I inhibitors [rotenone, 1‐methyl‐4‐phenylpyridinium (MPP+)] and of the toxic dopamine analogue 6‐hydroxydopamine, but not of inhibitors of mitochondrial complex II–V or excitotoxins [N‐methyl‐d‐aspartate (NMDA), kainate]. Rotenone and MPP+ increased free radicals and reduced proteasomal activity via adenosine triphosphate (ATP) depletion. 6‐hydroxydopamine also increased free radicals, but did not affect ATP levels and increased proteasomal activity, presumably in response to oxidative damage. Proteasome inhibition potentiated the toxicity of rotenone, MPP+ and 6‐hydroxydopamine at concentrations at which they increased free radical levels ≥ 40% above baseline, exceeding the cellular capacity to detoxify oxidized proteins reduced by proteasome inhibition, and also exacerbated ATP depletion caused by complex I inhibition. Consistently, both free radical scavenging and stimulation of ATP production by glucose supplementation protected against the synergistic toxicity. In summary, proteasome inhibition increases neuronal vulnerability to normally subtoxic levels of free radicals and amplifies energy depletion following complex I inhibition.
Ebselen inhibits NO‐induced apoptosis of differentiated PC12 cells via inhibition of ASK1‐p38 MAPK‐p53 and JNK signaling and activation of p44/42 MAPK and Bcl‐2
Authors: Sarker Krishna P. , Biswas Kamal K. , Rosales Jesusa L. , Yamaji Kazuyo , Hashiguchi Teruto , Lee Ki‐Young , Maruyama Ikuro 
Published: July 2010

AbstractEbselen, a selenium‐containing heterocyclic compound, prevents ischemia‐induced cell death. However, the molecular mechanism through which ebselen exerts its cytoprotective effect remains to be elucidated. Using sodium nitroprusside (SNP) as a nitric oxide (NO) donor, we show here that ebselen potently inhibits NO‐induced apoptosis of differentiated PC12 cells. This was associated with inhibition of NO‐induced phosphatidyl Serine exposure, cytochrome c release, and caspase‐3 activation by ebselen. Analysis of key apoptotic regulators during NO‐induced apoptosis of differentiated PC12 cells showed that ebselen blocks the activation of the apoptosis signaling‐regulating kinase 1 (ASK1), and inhibits phosphorylation of p38 mitogen‐activated protein kinase (MAPK) and c‐jun N‐terminal protein kinase (JNK). Moreover, ebselen inhibits NO‐induced p53 phosphorylation at Ser15 and c‐Jun phosphorylation at Ser63 and Ser73. It appears that inhibition of p38 MAPK and p53 phosphorylation by ebselen occurs via a thiol‐redox‐dependent mechanism. Interestingly, ebselen also activates p44/42 MAPK, and inhibits the downregulation of the antiapoptotic protein Bcl‐2 in SNP‐treated PC12 cells. Together, these findings suggest that ebselen protects neuronal cells from NO cytotoxicity by reciprocally regulating the apoptotic and antiapoptotic signaling cascades.
Lactate and glucose as energy substrates during, and after, oxygen deprivation in rat hippocampal acute and cultured slices
Authors: Cater Heather L. , Chandratheva Arvind , Benham Christopher D. , Morrison Barclay , Sundstrom Lars E. 
Published: July 2010

AbstractThe effects of raised brain lactate levels on neuronal survival following hypoxia or ischemia is still a source of controversy among basic and clinical scientists. We have sought to address this controversy by studying the effects of glucose and lactate on neuronal survival in acute and cultured hippocampal slices. Following a 1‐h hypoxic episode, neuronal survival in cultured hippocampal slices was significantly higher if glucose was present in the medium compared with lactate. However, when the energy substrate during the hypoxic period was glucose and then switched to lactate during the normoxic recovery period, the level of cell damage in the CA1 region of organotypic cultures was significantly improved from 64.3 ± 2.1 to 74.6 ± 2.1% compared with cultures receiving glucose during and after hypoxia. Extracellular field potentials recorded from the CA1 region of acute slices were abolished during oxygen deprivation for 20 min, but recovered almost fully to baseline levels with either glucose (82.6 ± 10.0%) or lactate present in the reperfusion medium (108.1 ± 8.3%). These results suggest that lactate alone cannot support neuronal survival during oxygen deprivation, but a combination of glucose followed by lactate provides for better neuroprotection than either substrate alone.
Pharmacologic suppression of neuronal oxidative damage and dendritic degeneration following direct activation of glial innate immunity in mouse cerebrum
Authors: Milatovic Dejan , Zaja‐Milatovic Snjeanna , Montine Kathleen S. , Horner Philip J. , Montine Thomas J. 
Published: July 2010

AbstractActivation of glial innate immunity is widely proposed to contribute to a number of degenerative and destructive diseases of brain. However, the precise role of activated innate immunity has been difficult to define in vivo because of multiple simultaneous pathogenic processes and responses to injury that confound interpretation of results from complex models of disease. Here, we used the model of intracerebroventricular (ICV) injection of lipopolysaccharide (LPS) to test the hypothesis that directly activated glial innate immunity leads to neurodegeneration in cerebrum and to establish the molecular determinants of and neuroprotectants from such innate immunity‐mediated neuronal damage. Our results showed that ICV LPS induced delayed, reversible oxidative damage to cerebral neuronal membranes as measured by F4‐neuroprostanes that was coincident with degeneration of the hippocampal pyramidal neuron dendritic system, but not neuron death, in adult mice. Both neuronal oxidative damage and dendritic degeneration were NF‐κB and iNOS dependent and were completely suppressed by ibuprofen and α‐tocopherol, but not naproxen or γ‐tocopherol. These results prove that activation of glial innate immunity can lead to neurodegeneration independent of other pathologic processes, closely associate oxidative damage to neuronal membranes with degeneration of the dendritic system, and provide a possible explanation for the varying efficacy of neuroprotectants that have been suggested in observational studies of dementia.
Glycogen in the brain of Drosophila melanogaster: diurnal rhythm and the effect of rest deprivation
Authors: Zimmerman John E. , Mackiewicz Miroslaw , Galante Raymond J. , Zhang Lin , Cater Jacqueline , Zoh Christine , Rizzo Wendy , Pack Allan I. 
Published: July 2010

AbstractOne function of sleep is thought to be the restoration of energy stores in the brain depleted during wakefulness. One such energy store found in mammalian brains is glycogen. Many of the genes involved in glycogen regulation in mammals have also been found in Drosophila melanogaster and rest behavior in Drosophila has recently been shown to have the characteristics of sleep. We therefore examined, in the fly, variation in the glycogen contents of the brain, the whole head and the body throughout the rest/activity cycle and after rest deprivation. Glycogen in the brain varies significantly throughout the day (p = 0.001) and is highest during rest and lowest while flies are active. Glycogen levels in the whole head and body do not show diurnal variation. Brain glycogen drops significantly when flies are rest deprived for 3 h (p = 0.034) but no significant differences are observed after 6 h of rest deprivation. In contrast, glycogen is significantly depleted in the body after both 3 and 6 h of rest deprivation (p < 0.0001 and p < 0.0001, respectively). Glycogen in the fly brain changes in relationship to rest and activity and demonstrates a biphasic response to rest deprivation similar to that observed in mammalian astrocytes in culture.
Small peptides patterned after the N‐terminus domain of SNAP25 inhibit SNARE complex assembly and regulated exocytosis
Authors: Blanes‐Mira Clara , Merino Jaime M. , Valera Elvira , Fernández‐Ballester Gregorio , Gutiérrez Luis M. , Viniegra Salvador , Pérez‐Payá Enrique , Ferrer‐Montiel Antonio 
Published: July 2010

AbstractSynthetic peptides patterned after the C‐terminus of synaptosomal associated protein of 25 kDa (SNAP25) efficiently abrogate regulated exocytosis. In contrast, the use of SNAP25 N‐terminal‐derived peptides to modulate SNAP receptors (SNARE) complex assembly and neurosecretion has not been explored. Here, we show that the N‐terminus of SNAP25, specially the segment that encompasses 22Ala‐44Ile, is essential for the formation of the SNARE complex. Peptides patterned after this protein domain are potent inhibitors of SNARE complex formation. The inhibitory activity correlated with their propensity to adopt an α‐helical secondary structure. These peptides abrogated SNARE complex formation only when added previous to the onset of aggregate assembly. Analysis of the mechanism of action revealed that these peptides disrupted the binary complex formed by SNAP25 and syntaxin. The identified peptides inhibited Ca2+‐dependent exocytosis from detergent‐permeabilized excitable cells. Noteworthy, these amino acid sequences markedly protected intact hippocampal neurones against hypoglycaemia‐induced, glutamate‐mediated excitotoxicity with a potency that rivaled that displayed by botulinum neurotoxins. Our findings indicate that peptides patterned after the N‐terminus of SNAP25 are potent inhibitors of SNARE complex formation and neuronal exocytosis. Because of their activity in intact neurones, these cell permeable peptides may be hits for antispasmodic and analgesic drug development.
The mechanism of membrane‐translocation of regulator of G‐protein signaling (RGS) 8 induced by Gα expression
Authors: Masuho Ikuo , Itoh Masayuki , Itoh Hiroshi , Saitoh Osamu 
Published: July 2010

AbstractRGS (regulators of G‐protein signaling) proteins comprise a large family that modulates heterotrimeric G‐protein signaling. This protein family has a common RGS domain and functions as GTPase‐activating proteins for the α‐subunits of heterotrimeric G‐proteins located at the plasma membrane. RGS8 was identified as a neuron‐specific RGS protein, which belongs to the B/R4 subfamily. We previously showed that RGS8 protein was translocated to the plasma membrane from the nucleus on coexpression of GTPase‐deficient Gαo (GαoQL). Here, we first examined which subtypes of Gα can induce the translocation of RGS8. When the Gαi family was expressed, the translocation of RGS8 did occur. To investigate the mechanism of this translocation, we generated a mutant RGS8 with reduced affinity to Gαo and an RGS‐insensitive (RGS‐i) mutant of GαoQL. Co‐expression experiments with both mutants revealed that disruption of the Gα–RGS8 interaction abolished the membrane‐translocation of RGS8 despite the apparent membrane localization of RGS‐i GαoQL. These results demonstrated that RGS8 is recruited to the plasma membrane where G‐proteins are activated mainly by direct association with Gα.