The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
Gail V.w. Johnson - One of the best experts on this subject based on the ideXlab platform.
-
Transglutaminase 2 facilitates or ameliorates HIF signaling and Ischemic Cell Death depending on its conformation and localization.
Biochimica et biophysica acta, 2012Co-Authors: Soner Gundemir, Gozde Colak, Julianne Feola, Richard Blouin, Gail V.w. JohnsonAbstract:Transglutaminase 2 (TG2) is a widely expressed and multifunctional protein that modulates Cell Death/survival processes. We have previously shown that TG2 binds to hypoxia inducible factor 1β (HIF1β) and decreases the upregulation of HIF responsive genes; however, the relationship between these observations was not investigated. In this study, we investigated whether endogenous TG2 is sufficient to suppress HIF activity and whether the interaction between TG2 and HIF1β is required for this suppression. shRNA-mediated silencing of TG2 significantly enhanced HIF activation in response to hypoxia. In addition, nuclear localization of TG2 is required for its suppressive effect on HIF activity, with TG2 being recruited to HIF responsive promoters in hypoxic conditions. These observations suggest that TG2 directly regulates hypoxic transcriptional machinery; however, its interaction with HIF1β was not required for this regulation. We also examined whether TG2's effect on Cell Death/survival processes in ischemia is due to its effects on HIF signaling. Our results indicate that TG2 mediated HIF suppression can be separated from TG2's effect on Cell survival in hypoxic/hypoglycemic conditions. Lastly, here we show that nuclear TG2 in the closed conformation and non-nuclear TG2 in the open conformation have opposing effects on hypoxic/hypoglycemic Cell Death, which could explain previous controversial results. Overall, our results further clarify the role of TG2 in mediating the Cellular response to ischemia and suggest that manipulating the conformation of TG2 might be of pharmacological interest as a therapeutic strategy for the treatment of ischemia-related pathologies.
-
Cytosolic guanine nucledotide binding deficient form of transglutaminase 2 (R580a) potentiates Cell Death in oxygen glucose deprivation.
PloS one, 2011Co-Authors: Gozde Colak, Jeffrey W. Keillor, Gail V.w. JohnsonAbstract:Transglutaminase 2 (TG2) is a hypoxia-responsive protein that is a calcium-activated transamidating enzyme, a GTPase and a scaffolding/linker protein. Upon activation TG2 undergoes a large conformational change, which likely affects not only its enzymatic activities but its non-catalytic functions as well. The focus of this study was on the role of transamidating activity, conformation and localization of TG2 in Ischemic Cell Death. Cells expressing a GTP binding deficient form of TG2 (TG2-R580A) with high basal transamidation activity and a more extended conformation showed significantly increased Cell Death in response to oxygen-glucose deprivation; however, targeting TG2-R580A to the nucleus abrogated its detrimental role in oxygen-glucose deprivation. Treatment of Cells expressing wild type TG2, TG2-C277S (a transamidating inactive mutant) and TG2-R580A with Cp4d, a reversible TG2 inhibitor, did not affect Cell Death in response to oxygen-glucose deprivation. These findings indicate that the pro-Cell Death effects of TG2 are dependent on its localization to the cytosol and independent of its transamidation activity. Further, the conformational state of TG2 is likely an important determinant in Cell survival and the prominent function of TG2 in Ischemic Cell Death is as a scaffold to modulate Cellular processes.
A Schurr - One of the best experts on this subject based on the ideXlab platform.
-
Neuroprotection against Ischemic/hypoxic brain damage: blockers of ionotropic glutamate receptor and voltage sensitive calcium channels.
Current drug targets, 2004Co-Authors: A SchurrAbstract:The growing number of Cellular and molecular pathways believed to be involved in mechanisms of Ischemic Cell Death in the brain has spurred a similar growth in the number of potential neuroprotective modalities, the majority of which are pharmacological in nature. Preventing or minimizing the first few steps in the cascade of events leading to Ischemic Cell Death would have a more profound effect on the postIschemic outcome than intervention at later steps in that cascade. This logic is, of course, at the heart of the urgency in providing the stroke or cardiac arrest patient with the earliest possible neuroprotective treatment. For the purpose of assessing potential neuroprotective modalities, the use of a well-established cerebral hypoxic/Ischemic model system is a prerequisite. In our studies, we have used two major approaches, in vitro and in vivo. We evaluated both agonists and antagonists of ionotropic glutamate receptor channels (IGRC) and their effects in exacerbating and attenuating, respectively, the posthypoxic/Ischemic outcome. Other drugs were tested for their ability to block the L-type voltage-sensitive calcium channels (VSCC), which are responsible for calcium influx and overload upon hypoxia/ischemia. These two membrane protein entities, the IGRC and the VSCC, are believed to be involved in the early stages of the Cellular cascade that leads to the demise of neurons posthypoxia/ischemia. Some of the drugs were also tested for possible interaction with each other searching for possible synergy. These and other published studies in the field are reviewed here.
-
neuroprotection against Ischemic hypoxic brain damage blockers of ionotropic glutamate receptor and voltage sensitive calcium channels
Current Drug Targets, 2004Co-Authors: A SchurrAbstract:The growing number of Cellular and molecular pathways believed to be involved in mechanisms of Ischemic Cell Death in the brain has spurred a similar growth in the number of potential neuroprotective modalities, the majority of which are pharmacological in nature. Preventing or minimizing the first few steps in the cascade of events leading to Ischemic Cell Death would have a more profound effect on the postIschemic outcome than intervention at later steps in that cascade. This logic is, of course, at the heart of the urgency in providing the stroke or cardiac arrest patient with the earliest possible neuroprotective treatment. For the purpose of assessing potential neuroprotective modalities, the use of a well-established cerebral hypoxic/Ischemic model system is a prerequisite. In our studies, we have used two major approaches, in vitro and in vivo. We evaluated both agonists and antagonists of ionotropic glutamate receptor channels (IGRC) and their effects in exacerbating and attenuating, respectively, the posthypoxic/Ischemic outcome. Other drugs were tested for their ability to block the L-type voltage-sensitive calcium channels (VSCC), which are responsible for calcium influx and overload upon hypoxia/ischemia. These two membrane protein entities, the IGRC and the VSCC, are believed to be involved in the early stages of the Cellular cascade that leads to the demise of neurons posthypoxia/ischemia. Some of the drugs were also tested for possible interaction with each other searching for possible synergy. These and other published studies in the field are reviewed here.
Helena Cimarosti - One of the best experts on this subject based on the ideXlab platform.
-
In Vitro Oxygen-Glucose Deprivation to Study Ischemic Cell Death
Methods in molecular biology (Clifton N.J.), 2014Co-Authors: Carla I. Tasca, Tharine Dal-cim, Helena CimarostiAbstract:Oxygen-glucose deprivation (OGD ) is widely used as an in vitro model for stroke, showing similarities with the in vivo models of brain ischemia. In order to perform OGD, Cell or tissue cultures, such as primary neurons or organotypic slices, and acutely prepared tissue slices are usually incubated in a glucose-free medium under a deoxygenated atmosphere, for example in a hypoxic chamber. Here, we describe the step-by-step procedure to expose cultures and acute slices to OGD, focusing on the most suitable methods for assessing Cellular Death and/or viability. OGD is a simple yet highly useful technique, not only for the elucidation of the role of key Cellular and molecular mechanisms underlying brain ischemia, but also for the development of novel neuroprotective strategies.
-
Investigating the Mechanisms Underlying Neuronal Death in Ischemia Using In Vitro Oxygen-Glucose Deprivation: Potential Involvement of Protein SUMOylation:
The Neuroscientist : a review journal bringing neurobiology neurology and psychiatry, 2008Co-Authors: Helena Cimarosti, Jeremy M. HenleyAbstract:It is well established that brain ischemia can cause neuronal Death via different signaling cascades. The relative importance and interrelationships between these pathways, however, remain poorly understood. Here is presented an overview of studies using oxygen-glucose deprivation of organotypic hippocampal slice cultures to investigate the molecular mechanisms involved in ischemia. The culturing techniques, setup of the oxygen-glucose deprivation model, and analytical tools are reviewed. The authors focus on SUMOylation, a posttranslational protein modification that has recently been implicated in ischemia from whole animal studies as an example of how these powerful tools can be applied and could be of interest to investigate the molecular pathways underlying Ischemic Cell Death.
Eunhee Kim - One of the best experts on this subject based on the ideXlab platform.
-
Design and synthesis of fluorescent and biotin tagged probes for the study of molecular actions of FAF1 inhibitor.
Bioorganic & medicinal chemistry letters, 2016Co-Authors: Sung-eun Yoo, Eunhee Kim, Seohee Jung, Nam Sook KangAbstract:To study the molecular action of Ischemic Fas-mediated Cell Death inhibitor, we prepared fluorescent-tagged and biotin-tagged probes of the potent inhibitor, KR-33494, of Ischemic Cell Death. We used the molecular modeling technique to find the proper position for attaching those probes with minimum interference in the binding process of probes with Fas-mediated Cell Death target, FAF1.
-
Daxx is a key downstream component of receptor interacting protein kinase 3 mediating retinal Ischemic Cell Death.
FEBS letters, 2012Co-Authors: Yun-suk Lee, Sung-eun Yoo, Yogesh Dayma, Min-young Park, Kyung Il Kim, Eunhee KimAbstract:Abstract Receptor-interacting protein 3 (RIP3) has been implicated in Ischemic necrosis of retinal Cells. An in silico analysis followed by experimental validation identified Death associated protein (Daxx) as a novel substrate of RIP3. In vitro binding studies revealed that RIP3 binds to the serine/proline/threonine-rich domain (amino acid 625–740) of Daxx. Upon Ischemic insult, RIP3 phosphorylated Daxx at Ser-668 in the retinal ganglion Cells, triggering nuclear export of Daxx. Depletion of RIP3 significantly inhibited nuclear export of Daxx and attenuated Cell Death to a great extent. Collectively, the findings of this study demonstrate that phosphorylation of Daxx by RIP3 comprises an important part of Ischemic necrosis in rat retinal ganglion Cells. Structured summary of protein interactions Daxx binds to Rip3 by pull down (View Interaction: 1 , 2 ) Rip3 and Daxx colocalize by fluorescence microscopy ( View interaction ) Rip3 physically interacts with Daxx by anti bait coimmunoprecipitation ( View interaction ) Daxx binds to Rip1 by pull down ( View interaction )
-
Synthesis and biological evaluation of 3-substituted-benzofuran-2-carboxylic esters as a novel class of Ischemic Cell Death inhibitors.
Bioorganic & medicinal chemistry letters, 2010Co-Authors: Jeehee Suh, Eunhee Kim, Yun-suk Lee, Eul Kgun Yum, Sung-eun YooAbstract:A series of 3-substituted-benzofuran-2-carboxylic esters was synthesized and evaluated for biological activity as Ischemic Cell Death inhibitors in H9c2 Cells and rat primary cardiac myocytes under conditions of oxygen and glucose deprivation. The introduction of a sulfur atom at the three-position substituent of the benzofuran ring markedly improved Ischemic Cell Death inhibitory potency. In particular, 3-[2-(4-nitro-phenylsulfanyl)-acetylamino]-benzofuran-2-carboxylic acid ester (10) (EC(50)=0.532 μM, Cell Death=6.18%) and 4-chloro-3-[3-(pyridin-2-ylsulfanyl)-propionylamino]-benzofuran-2-carboxylic ester (18) (EC(50)=0.557 μM, Cell Death=7.02%) were shown to be the most potent in this series of benzofuran analogs.
-
Physical interactions and functional coupling between Daxx and sodium hydrogen exchanger 1 in Ischemic Cell Death.
Journal of Biological Chemistry, 2008Co-Authors: Yong-sam Jung, Hyeyoung Kim, Juno Kim, Min-goo Lee, Jacques Pouysségur, Eunhee KimAbstract:Daxx, a Death domain-associated protein, is implicated in Ischemic Cell Death. To clarify the mechanism of Cell Death mediated by Daxx, a yeast two-hybrid assay was performed. Sodium hydrogen exchanger isoform 1 (NHE1) was identified as a Daxx-interacting protein. During Ischemic stress, Daxx translocates from the nucleus to the cytoplasm, where it colocalizes with NHE1. Daxx binds to the ezrin/radixin/moesin-interacting domain of NHE1, in competition with ezrin. Consistent with this finding, transfection of the constitutively cytoplasmic mutant, Daxx(W621A), inhibited ezrin-mediated Akt-1 activation. Moreover, transfection of Daxx(W621A), but not the Daxx(S667A) mutant that is confined to the nucleus, accelerated pH(i) recovery from an acid load, indicating that the cytoplasmic protein activates NHE1. Based on the results, we propose that Ischemic insult triggers the nucleocytoplasmic translocation of Daxx, following which cytoplasmic Daxx stimulates the NHE1 transporter activity and suppresses activation of the NHE1-ezrin-Akt-1 pathway. Our data support a novel molecular function of Daxx as an upstream regulator of NHE1 in Ischemic Cell Death.
-
SubCellular localization of Daxx determines its opposing functions in Ischemic Cell Death.
FEBS letters, 2007Co-Authors: Yong-sam Jung, Hyeyoung Kim, Yong J. Lee, Eunhee KimAbstract:This study examined the role of Daxx in Ischemic stress. Upon Ischemic stress, nuclear export of Daxx to the cytoplasm was observed in primary myocytes as well as in various Cell lines. Daxx silencing using siRNAs was detrimental in tethering PML-nuclear body (PML-NB) constituents together. Overexpression of Daxx (W621A) caused nuclear export of p53 independently of PML and promoted Ischemic Cell Death via activation of JNK. Conversely, overexpression of Daxx (S667A) prevented dissociation of PML-NB constituents and protected Cells from Ischemic Death. Collectively, our results demonstrate that the subCellular localization of Daxx determines its role in Ischemic Cell Death.
Dirk D. Sauer - One of the best experts on this subject based on the ideXlab platform.
-
Chronic infusion of nerve growth factor does not rescue pyramidal Cells after transient forebrain ischemia in the rat
Neuroscience letters, 1992Co-Authors: Thomas Beck, Andreas Wree, Dirk D. SauerAbstract:Male Wistar rats received chronic intracerebroventricular infusions of nerve growth factor (NGF) starting immediately before induction of a transient forebrain ischemia and continuing until 7 days after the infarct. Ischemia was induced by carotid occlusion and simultaneous hypotension. Seven days after the infarct the brains were examined histologically and the number of necrotic Cells in the hippocampus were counted. The results did not reveal any difference in treated vs. untreated animals. The data suggest that application of exogenous NGF does not prevent Ischemic Cell Death in the hippocampus.
