12 results on '"Orlov, Sergei N."'
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2. Rebuttal from Sergei N. Orlov, Michael M. Model and Ryszard Grygorczyk.
- Author
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Orlov SN, Model MA, and Grygorczyk R
- Subjects
- Animals, Humans, Apoptosis, Cell Size, Ion Transport
- Published
- 2013
- Full Text
- View/download PDF
3. Cell volume and monovalent ion transporters: their role in cell death machinery triggering and progression.
- Author
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Orlov SN, Platonova AA, Hamet P, and Grygorczyk R
- Subjects
- Animals, Cardiac Glycosides pharmacology, Cytoprotection, Humans, Ion Transport, Kidney drug effects, Kidney metabolism, Kidney pathology, Kinetics, Membrane Transport Proteins drug effects, Muscle, Smooth, Vascular drug effects, Muscle, Smooth, Vascular metabolism, Muscle, Smooth, Vascular pathology, Necrosis, Signal Transduction, Sodium-Potassium-Exchanging ATPase antagonists & inhibitors, Sodium-Potassium-Exchanging ATPase metabolism, Thermodynamics, Water-Electrolyte Balance, Apoptosis drug effects, Cell Size drug effects, Membrane Transport Proteins metabolism
- Abstract
Cell death is accompanied by the dissipation of electrochemical gradients of monovalent ions across the plasma membrane that, in turn, affects cell volume via modulation of intracellular osmolyte content. In numerous cell types, apoptotic and necrotic stimuli caused cell shrinkage and swelling, respectively. Thermodynamics predicts a cell type-specific rather than an ubiquitous impact of monovalent ion transporters on volume perturbations in dying cells, suggesting their diverse roles in the cell death machinery. Indeed, recent data showed that apoptotic collapse may occur in the absence of cell volume changes and even follow cell swelling rather than shrinkage. Moreover, side-by-side with cell volume adjustment, monovalent ion transporters contribute to cell death machinery engagement independently of volume regulation via cell type-specific signaling pathways. Thus, inhibition of Na(+)-K(+)-ATPase by cardiotonic steroids (CTS) rescues rat vascular smooth muscle cells from apoptosis via a novel Na(+)i-K(+)i-mediated, Ca(2+)i-independent mechanism of excitation-transcription coupling. In contrast, CTS kill renal epithelial cells independently of Na(+)-K(+)-ATPase inhibition and increased [Na(+)]i/[K(+)]i ratio. The molecular origin of [Na(+)]i/[K(+)]i sensors involved in the inhibition of apoptosis as well as upstream intermediates of Na(+)i/K(+)i-independent death signaling triggered by CTS remain unknown.
- Published
- 2013
- Full Text
- View/download PDF
4. Swelling rather than shrinkage precedes apoptosis in serum-deprived vascular smooth muscle cells.
- Author
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Platonova A, Koltsova SV, Hamet P, Grygorczyk R, and Orlov SN
- Subjects
- Animals, Caspase 3 metabolism, Cells, Cultured, Chromatin metabolism, Colforsin pharmacology, Culture Media, Serum-Free, DNA Cleavage, Myocytes, Smooth Muscle drug effects, Osmotic Pressure, Ouabain pharmacology, Rats, Single-Cell Analysis, Staurosporine pharmacology, Time-Lapse Imaging, Apoptosis drug effects, Cell Size, Muscle, Smooth, Vascular cytology, Myocytes, Smooth Muscle physiology
- Abstract
Contrasting cell volume behaviours (swelling vs. shrinkage) are considered as criteria to distinguish necrosis from apoptosis. In this study, we employed a time-lapse, dual-image surface reconstruction technique to assess the volume of single vascular smooth muscle cells transfected with E1A-adenoviral protein (E1A-VSMC) and undergoing rapid apoptosis in the absence of growth factors or in the presence of staurosporine. After 30- to 60-min lag-phase, serum-deprived E1A-VSMC volume was increased by ~40%, which preceded maximal increments of caspase-3 activity and chromatin cleavage. Swollen cells underwent rapid apoptotic collapse, documented by plasma membrane budding, and terminated in 10-15 min by the formation of numerous apoptotic bodies. Suppression of apoptosis by inhibition of Na(+),K(+)-ATPase and activation of cAMP signalling with ouabain and forskolin, respectively, completely abolished the swelling of serum-deprived E1A-VSMC. In contrast to serum deprivation, apoptotic collapse of staurosporine-treated E1A-VSMC preceded attenuation of their volume by ~30%. Neither transient hyposmotic swelling nor isosmtotic shrinkage triggered apoptosis. Our results show that cell shrinkage can not be considered as ubiquitous hallmark of apoptosis. The involvement of stimulus-specific cell volume perturbations in initiation and progression of apoptosis in vascular smooth muscle cells should be examined further.
- Published
- 2012
- Full Text
- View/download PDF
5. Apoptosis vs. oncosis: role of cell volume and intracellular monovalent cations.
- Author
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Orlov SN and Hamet P
- Subjects
- Animals, Caspase 3 metabolism, Dogs, Gene Expression Regulation drug effects, Humans, Intracellular Space drug effects, Jurkat Cells, Mannitol pharmacology, Membrane Transport Proteins metabolism, Models, Biological, Muscle, Smooth, Vascular cytology, Myocytes, Smooth Muscle cytology, Myocytes, Smooth Muscle drug effects, Myocytes, Smooth Muscle enzymology, Myocytes, Smooth Muscle metabolism, Osmosis drug effects, Ouabain pharmacology, Rats, Sodium-Potassium-Exchanging ATPase metabolism, Transcription, Genetic drug effects, Apoptosis drug effects, Cations, Monovalent metabolism, Cell Size drug effects, Intracellular Space metabolism
- Abstract
Several research teams have proposed that shrinkage and swelling in cells undergoing apoptosis and oncosis are not only the earliest morphological markers of the two modes of cell death but are also obligatory steps in the development of the death machinery. We examined this hypothesis as well as the role of monovalent cations as major intracellular osmolytes using vascular smooth muscle cells (VSMC) from the rat aorta and C7-MDCK cells derived from the Madin-Darby canine kidney. 48-hr inhibition of the Na(+)-K+ pump with ouabain did not affect VSMC survival and delayed serum deprivation-induced apoptosis at a step upstream of caspase-3 via elevation of the [Na+]i/[K+]i ratio and the expression of Na+ i-sensitive antiapoptotic genes including mortalin. Transient and modest (15-20%) shrinkage observed in serum-deprived VSMC did not contribute to triggering of the apoptotic machinery. In contrast to VSMC, ouabain led to oncosis of C7-MDCK cells, indicated by swelling and resistance to the pan-caspase inhibitor z-VAD.fmk. In these cells, the death signal was mediated by interaction of ouabain with the Na(+)-K(+)-ATPase alpha-subunit but was independent of the inhibition of Na(+)-K+ pump-mediated ion fluxes and elevation of the [Na+]i/[K+]i ratio.
- Published
- 2004
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- View/download PDF
6. Proteome analysis and functional expression identify mortalin as an antiapoptotic gene induced by elevation of [Na+]i/[K+]i ratio in cultured vascular smooth muscle cells.
- Author
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Taurin S, Seyrantepe V, Orlov SN, Tremblay TL, Thibault P, Bennett MR, Hamet P, and Pshezhetsky AV
- Subjects
- Animals, Blotting, Northern, Cells, Cultured, Electrophoresis, Gel, Two-Dimensional, Gene Expression Regulation physiology, HSP70 Heat-Shock Proteins genetics, HSP70 Heat-Shock Proteins metabolism, Male, Mass Spectrometry, Membrane Proteins genetics, Membrane Proteins metabolism, Muscle, Smooth, Vascular cytology, Muscle, Smooth, Vascular drug effects, Ouabain pharmacology, Proteome chemistry, RNA, Messenger metabolism, Rats, Rats, Inbred BN, Signal Transduction drug effects, Signal Transduction physiology, Sodium-Potassium-Exchanging ATPase antagonists & inhibitors, Transfection, Tumor Suppressor Protein p53 antagonists & inhibitors, Tumor Suppressor Protein p53 metabolism, Apoptosis genetics, HSP70 Heat-Shock Proteins biosynthesis, Muscle, Smooth, Vascular metabolism, Potassium metabolism, Proteome metabolism, Sodium metabolism
- Abstract
Apoptosis of vascular smooth muscle cells (VSMCs) plays an important role in remodeling of vessel walls, one of the major determinants of long-term blood pressure elevation and an independent risk factor for cardiovascular morbidity and mortality. Recently, we have found that apoptosis in cultured VSMCs can be inhibited by inversion of the intracellular [Na+]/[K+] ratio after the sustained blockage of the Na+,K+-ATPase by ouabain. To understand the mechanism of ouabain action, we analyzed subsets of hydrophilic and hydrophobic VSMC proteins from control and ouabain-treated cells by 2-dimensional electrophoresis. Ouabain treatment led to overexpression of numerous soluble and hydrophobic cellular proteins. Among proteins that showed the highest level of ouabain-induced expression, we identified mortalin (also known as GRP75 or PBP-74), a member of the heat shock protein 70 (HSP70) superfamily and a marker for cellular mortal and immortal phenotypes. Northern and Western blotting and immunocytochemistry all have confirmed that treatment of VSMCs with ouabain results in potent induction of mortalin expression. Transient transfection of cells with mortalin cDNA led to at least a 6-hour delay in the development of apoptosis after serum deprivation. The expression of tumor suppressor gene, p53, in mortalin-transfected cells was delayed to the same extent, and the expressed protein showed abnormal perinuclear distribution, suggesting that p53 is retained and inactivated by mortalin. Our studies therefore define a new [Na+]i/[K+]i-responsive signaling pathway that may play an important role in the regulation of programmed cell death in VSMCs.
- Published
- 2002
- Full Text
- View/download PDF
7. Genetics of programmed cell death and proliferation.
- Author
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Orlov SN, Tremblay J, Deblois D, and Hamet P
- Subjects
- Animals, Apoptosis physiology, Cell Cycle genetics, Cell Cycle physiology, Cell Division genetics, Cellular Senescence, Hyperplasia physiopathology, Hypertension physiopathology, Hypertrophy physiopathology, Kidney cytology, Models, Animal, Muscle, Smooth, Vascular cytology, Phenotype, Apoptosis genetics, Hypertension genetics
- Abstract
Vascular remodeling and hypertrophy-hyperplasia of the heart and kidney are the hallmarks of hypertensions, being involved in the long-term maintenance of elevated blood pressure and the development of cardiovascular and renal hypertension. Both augmented proliferation and unscheduled programmed cell death (apoptosis) contribute to this phenomenon. In the present article, we summarize the results of these studies with an emphasis on the relative impact of genetic determinants and the environment., (Copyright 2002, Elsevier Science (USA). All rights reserved.)
- Published
- 2002
- Full Text
- View/download PDF
8. Na+/K+ pump and endothelial cell survival: [Na+]i/[K+]i-independent necrosis triggered by ouabain, and protection against apoptosis mediated by elevation of [Na+]i
- Author
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Orlov, Sergei N., Thorin-Trescases, Nathalie, Pchejetski, Dimitri, Taurin, Sebastien, Farhat, Nada, Tremblay, Johanne, Thorin, Eric, and Hamet, Pavel
- Published
- 2004
- Full Text
- View/download PDF
9. Apoptosis in Cardiovascular Remodeling—Effect of Medication
- Author
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deBlois, Denis, Orlov, Sergei N., and Hamet, Pavel
- Published
- 2001
- Full Text
- View/download PDF
10. Na+/K+ pump and endothelial cell survival: [Na+]i/[K+]i-independent necrosis triggered by ouabain, and protection against apoptosis mediated by elevation of [Na+]i.
- Author
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Orlov, Sergei N., Thorin-Trescases, Nathalie, Pchejetski, Dimitri, Taurin, Sebastien, Farhat, Nada, Tremblay, Johanne, Thorin, Eric, and Hamet, Pavel
- Subjects
- *
APOPTOSIS , *NECROSIS , *ENDOTHELINS , *VASCULAR endothelium , *CONGESTIVE heart failure , *GENETIC mutation - Abstract
Recent studies have demonstrated the tissue-specific effect of Na+/K+ pump inhibition by ouabain and other cardiac glycosides on cell viability. The vascular endothelium is an initial target of cardiac glycosides employed for the management of congestive heart failure as well as circulating endogenous ouabain-like substances (EOLS), the production of which is augmented in volume-expanded hypertension. This study examined the role of the Na+/K+ pump in the survival of cultured porcine aortic endothelial cells (PAEC). Complete Na+/K+ pump inhibition with ouabain led to PAEC death, indicated by cell detachment and decreased staining with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). Based on cell swelling and resistance to benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (z-VAD.fmk) a pan-caspase inhibitor, this type of cell death was classified as necrosis. In contrast to ouabain, Na+/K+ pump inhibition in K+-free medium did not affect PAEC viability and sharply attenuated apoptosis triggered by 3H decay-induced DNA damage. Necrosis evoked by ouabain was preserved after dissipation of the transmembrane gradient of K+ and Na+, whereas dissipation of the Na+ gradient abolished the antiapoptotic action of K+-free medium. Comparative analysis of these results and modulation of intracellular Na+ and K+ content by the above-listed stimuli showed that interaction of ouabain with Na+/K+-ATPase triggered necrosis independently of inhibition of Na+/K+ pump-mediated ion fluxes and inversion of the [Na+]i/[K+]i ratio, whereas protection against apoptosis under Na+/K+ pump inhibition in K+-depleted medium was mediated by [Na+]i elevation. The role of Na+/K+ pump-mediated regulation of endothelial cell survival and vascular remodelling seen in hypertension should be investigated further in context of EOLS and chronic treatment with digitalis. [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
11. Na+/K+ pump and endothelial cell survival: [Na+]i/[K+]i-independent necrosis triggered by ouabain, and protection against apoptosis mediated by elevation of [Na+]i.
- Author
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Orlov, Sergei N., Thorin-Trescases, Nathalie, Pchejetski, Dimitri, Taurin, Sebastien, Farhat, Nada, Tremblay, Johanne, Thorin, Eric, and Hamet, Pavel
- Subjects
APOPTOSIS ,NECROSIS ,ENDOTHELINS ,VASCULAR endothelium ,CONGESTIVE heart failure ,GENETIC mutation - Abstract
Recent studies have demonstrated the tissue-specific effect of Na
+ /K+ pump inhibition by ouabain and other cardiac glycosides on cell viability. The vascular endothelium is an initial target of cardiac glycosides employed for the management of congestive heart failure as well as circulating endogenous ouabain-like substances (EOLS), the production of which is augmented in volume-expanded hypertension. This study examined the role of the Na+ /K+ pump in the survival of cultured porcine aortic endothelial cells (PAEC). Complete Na+ /K+ pump inhibition with ouabain led to PAEC death, indicated by cell detachment and decreased staining with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). Based on cell swelling and resistance to benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (z-VAD.fmk) a pan-caspase inhibitor, this type of cell death was classified as necrosis. In contrast to ouabain, Na+ /K+ pump inhibition in K+ -free medium did not affect PAEC viability and sharply attenuated apoptosis triggered by3 H decay-induced DNA damage. Necrosis evoked by ouabain was preserved after dissipation of the transmembrane gradient of K+ and Na+ , whereas dissipation of the Na+ gradient abolished the antiapoptotic action of K+ -free medium. Comparative analysis of these results and modulation of intracellular Na+ and K+ content by the above-listed stimuli showed that interaction of ouabain with Na+ /K+ -ATPase triggered necrosis independently of inhibition of Na+ /K+ pump-mediated ion fluxes and inversion of the [Na+ ]i /[K+ ]i ratio, whereas protection against apoptosis under Na+ /K+ pump inhibition in K+ -depleted medium was mediated by [Na+ ]i elevation. The role of Na+ /K+ pump-mediated regulation of endothelial cell survival and vascular remodelling seen in hypertension should be investigated further in context of EOLS and chronic treatment with digitalis. [ABSTRACT FROM AUTHOR]- Published
- 2004
- Full Text
- View/download PDF
12. Activation of cAMP signaling transiently inhibits apoptosis in vascular smooth muscle cells in a site upstream of caspase-3.
- Author
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Orlov, Sergei N, Thorin-Trescases, Nathalie, Dulin, Nickolai O, Dam, Than-Vinh, Fortuno, Maria A, Tremblay, Johanne, and Hamet, Pavel
- Subjects
- *
CYCLIC adenylic acid , *SMOOTH muscle , *APOPTOSIS - Abstract
Intracellular signaling pathways that are involved in protection of vascular smooth muscle cells (VSMC) from apoptosis remain poorly understood. This study examines the effect of activators of cAMP/cGMP signaling on apoptosis in nontransfected VSMC and in VSMC transfected with c-myc (VSMC-MYC) or with its functional analogue, E1A-adenoviral protein (VSMC-E1A). Serum-deprived VSMC-E1A exhibited the highest apoptosis measured as the content of chromatin and low molecular weight DNA fragments, phosphatidylserine content in the outer surface of plasma membrane and caspase-3 activity (ten-, five-, four- and tenfold increase after 6 h of serum withdrawal, respectively). In VSMC-E1A, the addition of an activator of adenylate cyclase, forskolin, abolished chromatin cleavage, DNA laddering, caspase-3 activation and the appearance of morphologically-defined apoptotic cells triggered by 6 h of serum deprivation. In nontransfected VSMC and in VSMC-MYC, 6 h serum deprivation led to ∼ six- and threefold activation of chromatin cleavage, respectively, that was also blocked by forskolin. In VSMC-E1A, inhibition of apoptosis was observed with other activators of cAMP signaling (cholera toxin, isoproterenol, adenosine, 8Br-cAMP), whereas 6 h incubation with modulators of cGMP signaling (8-Br-cGMP, nitroprusside, atrial natriuretic peptide, L-NAME) did not affect the development of apoptotic machinery. The antiapoptotic effect of forskolin was abolished in 24 h of serum deprivation that was accompanied by normalization of intracellular cAMP content and protein kinase A (PKA) activity. Protection of VSMC-E1A from apoptosis by forskolin was blunted by PKA inhibitors (H-89 and KT5720), whereas transfection of cells with PKA catalytic subunit attenuated apoptosis triggered by serum withdrawal. The protection of VSMC-E1A by forskolin from apoptosis was insensitive to modulators of cytoskeleton assembly (cytochalasin B, colchicine). Neither acute (30 min) nor chronic (24 h)... [ABSTRACT FROM AUTHOR]
- Published
- 1999
- Full Text
- View/download PDF
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