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Caspase-cleaved arrestin-2 and BID cooperatively facilitate cytochrome C release and cell death.
Kook S, Zhan X, Cleghorn WM, Benovic JL, Gurevich VV, Gurevich EV
(2014) Cell Death Differ 21: 172-84
MeSH Terms: Animals, Apoptosis, Arrestins, BH3 Interacting Domain Death Agonist Protein, Caspase 3, Caspases, Cell Line, Cytochromes c, Etoposide, Mice, Mitochondria, Protein Binding, Protein Isoforms, Recombinant Proteins, Tumor Necrosis Factor-alpha
Show Abstract · Added February 12, 2015
Apoptosis is programmed cell death triggered by activation of death receptors or cellular stress. Activation of caspases is the hallmark of apoptosis. Arrestins are best known for their role in homologous desensitization of G protein-coupled receptors (GPCRs). Arrestins quench G protein activation by binding to activated phosphorylated GPCRs. Recently, arrestins have been shown to regulate multiple signalling pathways in G protein-independent manner via scaffolding signalling proteins. Here we demonstrate that arrestin-2 isoform is cleaved by caspases during apoptosis induced via death receptor activation or by DNA damage at evolutionarily conserved sites in the C-terminus. Caspase-generated arrestin-2-(1-380) fragment translocates to mitochondria increasing cytochrome C release, which is the key checkpoint in cell death. Cells lacking arrestin-2 are significantly more resistant to apoptosis. The expression of wild-type arrestin-2 or its cleavage product arrestin-2-(1-380), but not of its caspase-resistant mutant, restores cell sensitivity to apoptotic stimuli. Arrestin-2-(1-380) action depends on tBID: at physiological concentrations, arrestin-2-(1-380) directly binds tBID and doubles tBID-induced cytochrome C release from isolated mitochondria. Arrestin-2-(1-380) does not facilitate apoptosis in BID knockout cells, whereas its ability to increase caspase-3 activity and facilitate cytochrome C release is rescued when BID expression is restored. Thus, arrestin-2-(1-380) cooperates with another product of caspase activity, tBID, and their concerted action significantly contributes to cell death.
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15 MeSH Terms
Preconditioning mesenchymal stem cells with caspase inhibition and hyperoxia prior to hypoxia exposure increases cell proliferation.
Saini U, Gumina RJ, Wolfe B, Kuppusamy ML, Kuppusamy P, Boudoulas KD
(2013) J Cell Biochem 114: 2612-23
MeSH Terms: Amino Acid Chloromethyl Ketones, Animals, Caspase 1, Caspase 3, Caspase 6, Caspase 7, Caspase 9, Cell Hypoxia, Cell Proliferation, Cells, Cultured, Male, Mesenchymal Stem Cells, Rats
Show Abstract · Added February 21, 2015
Myocardial infarction is a leading cause of mortality and morbidity worldwide. Occlusion of a coronary artery produces ischemia and myocardial necrosis that leads to left ventricular (LV) remodeling, dysfunction, and heart failure. Stem cell therapy may decrease infarct size and improve LV function; the hypoxic environment, however, following a myocardial infarction may result in apoptosis, which in turn decreases survival of transplanted stem cells. Therefore, the effects of preconditioned mesenchymal stem cells (MSC) with hyperoxia (100% oxygen), Z-VAD-FMK pan-caspase inhibitor (CI), or both in a hypoxic environment in order to mimic conditions seen in cardiac tissue post-myocardial infarction were studied in vitro. MSCs preconditioned with hyperoxia or CI significantly decreased apoptosis as suggested by TUNEL assay and Annexin V analysis using fluorescence assisted cell sorting. These effects were more profound when both, hyperoxia and CI, were used. Additionally, gene and protein expression of caspases 1, 3, 6, 7, and 9 were down-regulated significantly in MSCs preconditioned with hyperoxia, CI, or both, while the survival markers Akt1, NF-κB, and Bcl-2 were significantly increased in preconditioned MSCs. These changes ultimately resulted in a significant increase in MSC proliferation in hypoxic environment as determined by BrdU assays compared to MSCs without preconditioning. These effects may prove to be of great clinical significance when transplanting stem cells into the hypoxic myocardium of post-myocardial infarction patients in order to attenuate LV remodeling and improve LV function.
© 2013 Wiley Periodicals, Inc.
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13 MeSH Terms
Metabolic regulation of CaMKII protein and caspases in Xenopus laevis egg extracts.
McCoy F, Darbandi R, Chen SI, Eckard L, Dodd K, Jones K, Baucum AJ, Gibbons JA, Lin SH, Colbran RJ, Nutt LK
(2013) J Biol Chem 288: 8838-48
MeSH Terms: Animals, Apoptosis, Calcium-Calmodulin-Dependent Protein Kinase Type 2, Caspase 2, Caspase 3, Caspase 7, Cell Death, Cell Proliferation, Gene Expression Regulation, Developmental, Gene Expression Regulation, Enzymologic, Mass Spectrometry, Oocytes, Oxygen, Peptides, Phosphorylation, Protein Phosphatase 1, Recombinant Proteins, Sepharose, Serine, Xenopus, Xenopus laevis
Show Abstract · Added June 21, 2013
The metabolism of the Xenopus laevis egg provides a cell survival signal. We found previously that increased carbon flux from glucose-6-phosphate (G6P) through the pentose phosphate pathway in egg extracts maintains NADPH levels and calcium/calmodulin regulated protein kinase II (CaMKII) activity to phosphorylate caspase 2 and suppress cell death pathways. Here we show that the addition of G6P to oocyte extracts inhibits the dephosphorylation/inactivation of CaMKII bound to caspase 2 by protein phosphatase 1. Thus, G6P sustains the phosphorylation of caspase 2 by CaMKII at Ser-135, preventing the induction of caspase 2-mediated apoptotic pathways. These findings expand our understanding of oocyte biology and clarify mechanisms underlying the metabolic regulation of CaMKII and apoptosis. Furthermore, these findings suggest novel approaches to disrupt the suppressive effects of the abnormal metabolism on cell death pathways.
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21 MeSH Terms
Age-related susceptibility to apoptosis in human retinal pigment epithelial cells is triggered by disruption of p53-Mdm2 association.
Bhattacharya S, Chaum E, Johnson DA, Johnson LR
(2012) Invest Ophthalmol Vis Sci 53: 8350-66
MeSH Terms: Acetylation, Adult, Aged, Aged, 80 and over, Aging, Apoptosis, Apoptosis Regulatory Proteins, Benzamides, Blotting, Western, Caspase 3, Cell Proliferation, Cells, Cultured, DNA Fragmentation, Disease Susceptibility, Enzyme-Linked Immunosorbent Assay, Fluorescent Antibody Technique, Indirect, Humans, Imidazoles, In Situ Nick-End Labeling, Middle Aged, Naphthols, Phosphorylation, Piperazines, Proto-Oncogene Proteins, Proto-Oncogene Proteins c-mdm2, RNA, Small Interfering, Retinal Pigment Epithelium, Sirtuin 1, Sirtuin 2, Tumor Suppressor Protein p53
Show Abstract · Added June 11, 2018
PURPOSE - Relatively little is known about the contribution of p53/Mdm2 pathway in apoptosis of retinal pigment epithelial (RPE) cells or its possible link to dysfunction of aging RPE or to related blinding disorders such as age-related macular degeneration (AMD).
METHODS - Age-associated changes in p53 activation were evaluated in primary RPE cultures from human donor eyes of various ages. Apoptosis was evaluated by activation of caspases and DNA fragmentation. Gene-specific small interfering RNA was used to knock down expression of p53.
RESULTS - We observed that the basal rate of p53-dependent apoptosis increased in an age-dependent manner in human RPE. The age-dependent increase in apoptosis was linked to alterations in several aspects of the p53 pathway. p53 phosphorylation Ser15 was increased through the stimulation of ATM-Ser1981. p53 acetylation Lys379 was increased through the inhibition of SIRT1/2. These two posttranslational modifications of p53 blocked the sequestration of p53 by Mdm2, thus resulting in an increase in free p53 and of p53 stimulation of apoptosis through increased expression of PUMA (p53 upregulated modulator of apoptosis) and activation of caspase-3. Aged RPE also had reduced expression of antiapoptotic Bcl-2, which contributed to the increase in apoptosis. Of particular interest in these studies was that pharmacologic treatments to block p53 phosphorylation, acetylation, or expression were able to protect RPE cells from apoptosis.
CONCLUSIONS - Our studies suggest that aging in the RPE leads to alterations of specific checkpoints in the apoptotic pathway, which may represent important molecular targets for the treatment of RPE-related aging disorders such as AMD.
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MeSH Terms
Regulation of ERBB2 receptor by t-DARPP mediates trastuzumab resistance in human esophageal adenocarcinoma.
Hong J, Katsha A, Lu P, Shyr Y, Belkhiri A, El-Rifai W
(2012) Cancer Res 72: 4504-14
MeSH Terms: Adenocarcinoma, Animals, Antibodies, Monoclonal, Humanized, Antineoplastic Agents, Apoptosis, Caspase 3, Cell Line, Tumor, Cell Survival, Dopamine and cAMP-Regulated Phosphoprotein 32, Drug Resistance, Neoplasm, Enzyme Activation, Esophageal Neoplasms, Female, Gene Expression Regulation, Neoplastic, Gene Silencing, Humans, Mice, Mice, Nude, Protein Binding, Protein Stability, Receptor, ErbB-2, Signal Transduction, Trastuzumab, Tumor Burden, Xenograft Model Antitumor Assays
Show Abstract · Added September 3, 2013
Esophageal adenocarcinoma (EAC) is an aggressive malignancy with a poor outcome. Although targeting ERBB2 with trastuzumab has been evaluated in clinical trials, the molecular mechanisms of trastuzumab resistance remain uncharacterized in EAC. The dopamine and cyclic AMP-regulated phosphoprotein of MR 32000 (DARPP-32), also known as PPP1R1B, is located together with ERBB2 at the 17q12-q21 amplicon. We evaluated the expression of a transcript variant of DARPP-32 (t-DARPP) and ERBB2 in 141 primary tumors and investigated the role of t-DARPP in trastuzumab resistance using OE19 and OE33 EAC cell models. Overexpression of t-DARPP mRNA was detected in two-thirds of tumors with a correlation between ERBB2 and t-DARPP overexpression levels (r = 0.58, P = 0.003). Cell viability and clonogenic survival assays showed that t-DARPP increased survival by 40% in response to trastuzumab (P < 0.01). The Annexin-V staining and Western blot analysis indicated that t-DARPP effectively abrogated trastuzumab-induced apoptosis, inhibited cleavage of caspase-3, and blocked trastuzumab-induced dephosphorylation of ERBB2 and AKT proteins. The knockdown of endogenous t-DARPP reversed these effects and sensitized cells to trastuzumab (P < 0.01). The cycloheximide-based protein degradation analysis indicated that t-DARPP extended the half-life of ERBB2, explaining the increase in the basal levels of ERBB2, p-ERBB2(Y1248), and p-AKT(S473). Coimmunoprecipitation and Western blot analysis showed that t-DARPP associated with ERBB2 in a protein complex, and interfered with trastuzumab binding to the ERBB2 receptor. Using EAC-xenografted mouse model, t-DARPP enhanced tumor growth and rendered tumors unresponsive to trastuzumab. This study establishes t-DARPP as a mediator of trastuzumab resistance and underscores its potential importance in clinical trials of EAC.
©2012 AACR.
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25 MeSH Terms
Overexpression of angiopoietin-2 impairs myocardial angiogenesis and exacerbates cardiac fibrosis in the diabetic db/db mouse model.
Chen JX, Zeng H, Reese J, Aschner JL, Meyrick B
(2012) Am J Physiol Heart Circ Physiol 302: H1003-12
MeSH Terms: Angiopoietin-2, Animals, Apoptosis, Caspase 3, Cells, Cultured, Coronary Vessels, Diabetes Mellitus, Disease Models, Animal, Endothelium, Vascular, Fibrosis, Intercellular Adhesion Molecule-1, Male, Mice, Mice, Mutant Strains, Myocardium, Neovascularization, Pathologic, Proto-Oncogene Proteins, Receptor, TIE-2, Up-Regulation, Vascular Cell Adhesion Molecule-1, Vascular Endothelial Growth Factor A, Wnt Proteins
Show Abstract · Added May 26, 2015
The angiopoietins/Tie-2 system is essential for the maintenance of vascular integrity and angiogenesis. The functional role of angiopoietin-2 (Ang-2) in the regulation of angiogenesis is dependent on other growth factors such as VEGF and a given physiopathological conditions. This study investigates the potential role of Ang-2 in myocardial angiogenesis and fibrosis formation in the diabetic db/db mouse. Diabetic db/db mice received intramyocardial administration of either adenovirus Ang-2 (Ad-CMV-Ang-2) or Ad-β-gal. The levels of Tie-2, VEGF, caspase-3, Wnt7b, fibroblast-specific protein-1 (FSP-1), and adhesion molecules (ICAM-1 and VCAM-1) expression were measured. Apoptosis, capillary density, and cardiac fibrosis were also analyzed in the db/db mouse hearts. Overexpression of Ang-2 suppressed Tie-2 and VEGF expression in db/db mouse hearts together with significant upregulation of Wnt7b expression. Overexpression of Ang-2 also sensitizes ICAM-1 and VCAM-1 expression in db/db mouse hearts. Immunohistochemical analysis revealed that overexpression of Ang-2 resulted in a gradual apoptosis as well as interstitial fibrosis formation, these leading to a significant loss of capillary density. Data from these studies were confirmed in cultured mouse heart microvascular endothelial cells (MHMEC) exposed to excessive Ang-2. Exposure of MHMEC to Ang-2 resulted in increased caspase-3 activity and endothelial apoptosis. Knockdown of Ang-2 attenuated high glucose-induced endothelial cell apoptosis. Further, counterbalance of Ang-2 by overexpression of Ang-1 reversed loss of capillary density and fibrosis formation in db/db mouse hearts. Our data demonstrate that Ang-2 increases endothelial apoptosis, sensitizes myocardial microvascular inflammation, and promotes cardiac fibrosis and thus contributes to loss of capillary density in diabetic diseases.
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Co-treatment with ginsenoside Rh2 and betulinic acid synergistically induces apoptosis in human cancer cells in association with enhanced capsase-8 activation, bax translocation, and cytochrome c release.
Li Q, Li Y, Wang X, Fang X, He K, Guo X, Zhan Z, Sun C, Jin YH
(2011) Mol Carcinog 50: 760-9
MeSH Terms: Antineoplastic Agents, Phytogenic, Apoptosis, BH3 Interacting Domain Death Agonist Protein, Blotting, Western, Caspase 3, Caspase 8, Caspase 9, Cell Line, Tumor, Cell Survival, Cytochromes c, Dose-Response Relationship, Drug, Drug Synergism, Enzyme Activation, Flow Cytometry, Ginsenosides, HeLa Cells, Hep G2 Cells, Humans, Molecular Structure, Neoplasms, Poly(ADP-ribose) Polymerases, Protein Transport, RNA Interference, Triterpenes, bcl-2-Associated X Protein
Show Abstract · Added July 28, 2015
We provide evidence for the first time, that two natural compounds ginsenoside Rh2 (G-Rh2) and betulinic acid (Bet A) synergistically induce apoptosis in human cervical adenocarcinoma (HeLa), human lung cancer A549, and human hepatoma HepG2 cells. G-Rh2 and Bet A cooperated to induce Bax traslocation to mitochondria and cytochrome c release. Co-treatment of G-Rh2 and Bet A resulted in enhanced cleavage of caspase-8 and Bid. Moreover, specific inhibition of caspase-8 by siRNA technology effectively reduced caspase-9 processing, poly (ADP-ribose) polymerase (PARP) cleavage, caspase-3 activation, and apoptosis in co-treated cells, which indicated that the caspase-8 feedback amplification pathway may have been involved in the apoptosis process. A previous study has shown that G-Rh2 induces cancer cell apoptosis via a Bcl-2 and/or Bcl-xL-independent mechanism, and Bet A induces apoptosis mainly through a mitochondrial pathway with tumor specificity. Since the antiapoptotic Bcl-2 and Bcl-xL are frequently overexpressed in human cancer cells, combined treatment with G-Rh2 and Bet A may be a novel strategy to enhance efficacy of anticancer therapy. © 2011 Wiley-Liss, Inc.
Copyright © 2011 Wiley-Liss, Inc.
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25 MeSH Terms
The DNA damage mark pH2AX differentiates the cytotoxic effects of small molecule HDAC inhibitors in ovarian cancer cells.
Wilson AJ, Holson E, Wagner F, Zhang YL, Fass DM, Haggarty SJ, Bhaskara S, Hiebert SW, Schreiber SL, Khabele D
(2011) Cancer Biol Ther 12: 484-93
MeSH Terms: Antineoplastic Agents, Apoptosis, Caspase 3, Cell Line, Tumor, Cell Nucleus, Cell Survival, Cisplatin, DNA Damage, Drug Resistance, Neoplasm, Drug Screening Assays, Antitumor, Drug Synergism, Female, Histone Deacetylase Inhibitors, Histones, Humans, Microscopy, Fluorescence, Ovarian Neoplasms, Phosphorylation, Poly (ADP-Ribose) Polymerase-1, Poly(ADP-ribose) Polymerases
Show Abstract · Added March 5, 2014
High grade epithelial ovarian cancers are relatively sensitive to DNA damaging platinum-based chemotherapy, suggesting that the dependencies of ovarian tumors on DNA damage response pathways can be harnessed for therapeutic purposes. Our goal was to determine if the DNA damage mark gamma-H2AX phosphorylation (pH2AX) could be used to identify suitable cytotoxic histone deacetylase inhibitors (HDACi) for ovarian cancer treatment. Nineteen chemically diverse HDACi compounds were tested in 7 ovarian cancer cell lines. Fluorescent, biochemical and cell-based assays were performed to assess DNA damage by induction of pH2AX and to measure cell viability and apoptosis. The relationships between pH2AX and the cellular effects of cell viability and apoptosis were calculated. Selected HDACi were tested in combination with cisplatin and other DNA damaging agents to determine if the HDACi improved upon the effects of the DNA damaging agents. The HDACi compounds induced differing levels of pH2AX expression. High levels of pH2AX in HDACi-treated ovarian cancer cells were tightly associated with decreased cell viability and increased apoptosis. Consequently, a ketone-based HDACi was chosen and found to enhance the effects of cisplatin, even in ovarian cancer cells with extreme resistance to DNA damaging drugs. In conclusion, a fluorescent-based assay for pH2AX can be used to determine cellular responses to HDACi in vitro and may be a useful tool to identify potentially more effective HDACi for the treatment of ovarian cancer. In addition, these results lend support to the inclusion of ketone-derived HDACi compounds for future development.
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20 MeSH Terms
Induction of podocyte-derived VEGF ameliorates podocyte injury and subsequent abnormal glomerular development caused by puromycin aminonucleoside.
Ma J, Matsusaka T, Yang HC, Zhong J, Takagi N, Fogo AB, Kon V, Ichikawa I
(2011) Pediatr Res 70: 83-9
MeSH Terms: Actinin, Animals, Animals, Newborn, Apoptosis, Autocrine Communication, Caspase 3, Cells, Cultured, Desmin, Disease Models, Animal, Doxycycline, Glomerulonephritis, Humans, Intracellular Signaling Peptides and Proteins, Kidney Glomerulus, Membrane Proteins, Mice, Mice, Inbred C57BL, Mice, Transgenic, Microfilament Proteins, Podocytes, Puromycin Aminonucleoside, Response Elements, Vascular Endothelial Growth Factor A, bcl-2-Associated X Protein, bcl-X Protein
Show Abstract · Added January 25, 2012
Our previous studies using puromycin aminonucleoside (PAN) established that podocyte damage leads to glomerular growth arrest during development and glomerulosclerosis later in life. This study examined the potential benefit of maintaining podocyte-derived VEGF in podocyte defense and survival after PAN injury using conditional transgenic podocytes and mice, in which human VEGF-A (hVEGF) transgene expression is controlled by tetracycline responsive element (TRE) promoter and reverse tetracycline transactivator (rtTA) in podocytes. In vitro experiments used primary cultured podocytes harvested from mice carrying podocin-rtTA and TRE-hVEGF transgenes, in which hVEGF can be induced selectively. Induction of VEGF in PAN-exposed podocytes resulted in preservation of intrinsic VEGF, α-actinin-4 and synaptopodin, antiapoptotic marker Bcl-xL/Bax, as well as attenuation in apoptotic marker cleaved/total caspase-3. In vivo, compared with genotype controls, PAN-sensitive neonatal mice with physiologically relevant levels of podocyte-derived VEGF showed significantly larger glomeruli. Furthermore, PAN-induced up-regulation of desmin, down-regulation of synaptopodin and nephrin, and disruption of glomerular morphology were significantly attenuated in VEGF-induced transgenic mice. Our data indicate that podocyte-derived VEGF provides self-preservation functions, which can rescue the cell after injury and preempt subsequent deterioration of the glomerulus in developing mice.
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25 MeSH Terms
Inhibition of Mdm2 sensitizes human retinal pigment epithelial cells to apoptosis.
Bhattacharya S, Ray RM, Chaum E, Johnson DA, Johnson LR
(2011) Invest Ophthalmol Vis Sci 52: 3368-80
MeSH Terms: Adult, Apoptosis, Blotting, Western, Caspase 3, Caspase 9, Cell Line, Cell Proliferation, DNA Fragmentation, Humans, Imidazoles, Piperazines, Protein Binding, Proto-Oncogene Proteins c-bcl-2, Proto-Oncogene Proteins c-mdm2, RNA, Small Interfering, Retinal Pigment Epithelium, Transfection, Tumor Suppressor Protein p53, bcl-X Protein
Show Abstract · Added June 11, 2018
PURPOSE - Because recent studies indicate that blocking the interaction between p53 and Mdm2 results in the nongenotoxic activation of p53, the authors sought to investigate whether the inhibition of p53-Mdm2 binding activates p53 and sensitizes human retinal epithelial cells to apoptosis.
METHODS - Apoptosis was evaluated by the activation of caspases and DNA fragmentation assays. The Mdm2 antagonist Nutlin-3 was used to dissociate p53 from Mdm2 and, thus, to increase p53 activity. Knockdown of p53 expression was accomplished by using p53 siRNA.
RESULTS - ARPE-19 and primary RPE cells expressed high levels of the antiapoptotic proteins Bcl-2 and Bcl-xL. Exposure of these cells to camptothecin (CPT) or TNF-α/ cycloheximide (CHX) failed to induce apoptosis. In contrast, treatment with the Mdm2 antagonist Nutlin-3 in the absence of CPT or TNF-α/CHX increased apoptosis. Activation of p53 in response to Nutlin-3 also increased levels of Noxa, p53-upregulated modulator of apoptosis (PUMA), and Siva-1, decreased expression of Bcl-2 and Bcl-xL, and simultaneously increased caspases-9 and -3 activities and DNA fragmentation. Knockdown of p53 decreased the basal expression of p21Cip1 and Bcl-2, inhibited the Nutlin-3-induced upregulation of Siva-1 and PUMA expression, and consequently inhibited caspase-3 activation.
CONCLUSIONS - These results indicate that the normally available pool of intracellular p53 is predominantly engaged in the regulation of cell cycle checkpoints by p21Cip1 and does not trigger apoptosis in response to DNA-damaging agents. However, the blockage of p53 binding to Mdm2 frees a pool of p53 that is sufficient, even in the absence of DNA-damaging agents, to increase the expression of proapoptotic targets and to override the resistance of RPE cells to apoptosis.
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