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Administration of an Acidic Sphingomyelinase (ASMase) Inhibitor, Imipramine, Reduces Hypoglycemia-Induced Hippocampal Neuronal Death. Cells 2022; 11:cells11040667. [PMID: 35203316 PMCID: PMC8869983 DOI: 10.3390/cells11040667] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 01/31/2022] [Accepted: 02/12/2022] [Indexed: 01/27/2023] Open
Abstract
Severe hypoglycemia (below 35 mg/dL) appears most often in diabetes patients who continuously inject insulin. To rapidly cease the hypoglycemic state in this study, glucose reperfusion was conducted, which can induce a secondary neuronal death cascade following hypoglycemia. Acid sphingomyelinase (ASMase) hydrolyzes sphingomyelin into ceramide and phosphorylcholine. ASMase activity can be influenced by cations, pH, redox, lipids, and other proteins in the cells, and there are many changes in these factors in hypoglycemia. Thus, we expect that ASMase is activated excessively after hypoglycemia. Ceramide is known to cause free radical production, excessive inflammation, calcium dysregulation, and lysosomal injury, resulting in apoptosis and the necrosis of neurons. Imipramine is mainly used in the treatment of depression and certain anxiety disorders, and it is particularly known as an ASMase inhibitor. We hypothesized that imipramine could decrease hippocampal neuronal death by reducing ceramide via the inhibition of ASMase after hypoglycemia. In the present study, we confirmed that the administration of imipramine significantly reduced hypoglycemia-induced neuronal death and improved cognitive function. Therefore, we suggest that imipramine may be a promising therapeutic tool for preventing hypoglycemia-induced neuronal death.
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2
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Intracellular Signaling. Stroke 2022. [DOI: 10.1016/b978-0-323-69424-7.00006-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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3
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Jiang Y, He X, Simonaro CM, Yi B, Schuchman EH. Acid Ceramidase Protects Against Hepatic Ischemia/Reperfusion Injury by Modulating Sphingolipid Metabolism and Reducing Inflammation and Oxidative Stress. Front Cell Dev Biol 2021; 9:633657. [PMID: 34026750 PMCID: PMC8134688 DOI: 10.3389/fcell.2021.633657] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 04/12/2021] [Indexed: 11/30/2022] Open
Abstract
Ceramide is a bioactive signaling lipid involved in the pathogenesis of numerous diseases. It also plays an important role in ischemia reperfusion (IR) injury via activation of inflammatory/oxidative stress-stimulated signaling pathways, resulting in tissue damage. Acid ceramidase is a lipid hydrolase that modulates the levels of ceramide, and as such has a potential therapeutic role in many human diseases where ceramide has been implicated. Here we investigated the therapeutic potential of recombinant acid ceramidase in a murine model of hepatic IR injury. Serum ALT, AST, and LDH activities, as well as oxidative stress (MDA) and inflammatory (MCP-1) markers, were increased in mice subjected to IR compared to a sham group. In contrast, these elevations were significantly lower in an IR group pretreated with a single injection of acid ceramidase. Histological examination by two different assessment criteria also revealed that acid ceramidase pretreatment alleviated IR-induced hepatocyte damage, including reduced evidence of cell death and necrosis. In addition, elevated ceramide and sphingosine levels were observed in the IR group compared to sham, and were markedly reduced when pretreated with acid ceramidase. In contrast, the levels of the protective signaling lipid, sphingosine-1-phosphate (S1P), were reduced following IR and elevated in response to acid ceramidase pretreatment. These changes in sphingolipid levels could be correlated with changes in the activities of several sphingolipid-metabolizing enzymes. Overall, these results indicated that sphingolipid changes were an important pathologic component of hepatic IR injury, and that acid ceramidase administration ameliorated these lipid changes and other downstream pathologic changes.
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Affiliation(s)
- Yuan Jiang
- Department of Clinical Laboratory, Xiangya Hospital, Central South University, Changsha, China.,Department of Clinical Laboratory, Hunan Cancer Hospital and The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, China
| | - Xingxuan He
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Calogera M Simonaro
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Bin Yi
- Department of Clinical Laboratory, Xiangya Hospital, Central South University, Changsha, China
| | - Edward H Schuchman
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States
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4
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Abstract
Ceramide, a bioactive membrane sphingolipid, functions as an important second messenger in apoptosis and cell signaling. In response to stresses, it may be generated by de novo synthesis, sphingomyelin hydrolysis, and/or recycling of complex sphingolipids. It is cleared from cells through the activity of ceramidases, phosphorylation to ceramide-1-phosphate, or resynthesis into more complex sphingolipids. Ischemia/reperfusion (IR) injury occurs when oxygen/nutrition is rapidly reintroduced into ischemic tissue, resulting in cell death and tissue damage, and is a major concern in diverse clinical settings, including organ resection and transplantation. Numerous reports show that ceramide levels are markedly elevated during IR. Mitochondria are major sites of reactive oxygen species (ROS) production and play a key role in IR-induced and ceramide-mediated cell death and tissue damage. During the development of IR injury, the initial response of ROS and TNF-alpha production activates two major ceramide generating pathways (sphingomyelin hydrolysis and de novo ceramide synthesis). The increased ceramide has broad effects depending on the IR phases, including both pro- and antiapoptotic effects. Therefore, strategies that reduce the levels of ceramide, for example, by modulation of ceramidase and/or sphingomyelinases activities, may represent novel and promising therapeutic approaches to prevent or treat IR injury in diverse clinical settings.
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5
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Adjustment of Dysregulated Ceramide Metabolism in a Murine Model of Sepsis-Induced Cardiac Dysfunction. Int J Mol Sci 2017; 18:ijms18040839. [PMID: 28420138 PMCID: PMC5412423 DOI: 10.3390/ijms18040839] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2017] [Revised: 04/02/2017] [Accepted: 04/10/2017] [Indexed: 12/24/2022] Open
Abstract
Cardiac dysfunction, in particular of the left ventricle, is a common and early event in sepsis, and is strongly associated with an increase in patients’ mortality. Acid sphingomyelinase (SMPD1)—the principal regulator for rapid and transient generation of the lipid mediator ceramide—is involved in both the regulation of host response in sepsis as well as in the pathogenesis of chronic heart failure. This study determined the degree and the potential role to which SMPD1 and its modulation affect sepsis-induced cardiomyopathy using both genetically deficient and pharmacologically-treated animals in a polymicrobial sepsis model. As surrogate parameters of sepsis-induced cardiomyopathy, cardiac function, markers of oxidative stress as well as troponin I levels were found to be improved in desipramine-treated animals, desipramine being an inhibitor of ceramide formation. Additionally, ceramide formation in cardiac tissue was dysregulated in SMPD1+/+ as well as SMPD1−/− animals, whereas desipramine pretreatment resulted in stable, but increased ceramide content during host response. This was a result of elevated de novo synthesis. Strikingly, desipramine treatment led to significantly improved levels of surrogate markers. Furthermore, similar results in desipramine-pretreated SMPD1−/− littermates suggest an SMPD1-independent pathway. Finally, a pattern of differentially expressed transcripts important for regulation of apoptosis as well as antioxidative and cytokine response supports the concept that desipramine modulates ceramide formation, resulting in beneficial myocardial effects. We describe a novel, protective role of desipramine during sepsis-induced cardiac dysfunction that controls ceramide content. In addition, it may be possible to modulate cardiac function during host response by pre-conditioning with the Food and Drug Administration (FDA)-approved drug desipramine.
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6
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Thompson JW, Dawson VL, Perez-Pinzon MA, Dawson TM. Intracellular Signaling. Stroke 2016. [DOI: 10.1016/b978-0-323-29544-4.00006-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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7
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Maarman G, Blackhurst D, Thienemann F, Blauwet L, Butrous G, Davies N, Sliwa K, Lecour S. Melatonin as a preventive and curative therapy against pulmonary hypertension. J Pineal Res 2015. [PMID: 26201290 DOI: 10.1111/jpi.12263] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Pulmonary hypertension (PH) is characterized by elevated pulmonary arterial pressure, which leads to right ventricular (RV) hypertrophy and failure. The pathophysiological mechanisms of PH remain unclear but oxidative stress is believed to contribute to RV dysfunction. Melatonin is a powerful antioxidant and is cardioprotective against ischemia-reperfusion injury and hypertension. Therefore, we hypothesized that a chronic treatment with melatonin, given as a curative or preventive therapy, may confer cardiovascular benefits in PH. PH was induced in Long Evans rats (n ≥ 6 per group), with a single subcutaneous injection of monocrotaline (MCT, 80 mg/kg). Melatonin was given daily in the drinking water, with the treatment starting either on the day of the injection of MCT (dose testing: melatonin 75 ng/L and 6 mg/kg), 14 days after the injection of MCT (curative treatment: 6 mg/kg), or 5 days before the injection (preventive treatment: 6 mg/kg). The development of PH was assessed by measuring RV hypertrophy, RV function, cardiac interstitial fibrosis, and plasma oxidative stress. Compared with controls, MCT-treated rats displayed RV hypertrophy and dysfunction, increased interstitial fibrosis, and elevated plasma oxidative stress. A chronic melatonin treatment (75 ng/L or 6 mg/kg) reduced RV hypertrophy, improved RV function and reduced plasma oxidative stress. Curative and preventive treatment improved RV functional and plasma oxidative stress parameters and reduced cardiac interstitial fibrosis. Our data demonstrate that melatonin confers cardioprotection in this model of PH. As melatonin is an inexpensive and safe drug, we propose that clinical investigation of the effects of melatonin on RV function in patients with PH should be considered.
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MESH Headings
- Animals
- Antioxidants/therapeutic use
- Hypertension, Pulmonary/chemically induced
- Hypertension, Pulmonary/drug therapy
- Hypertension, Pulmonary/prevention & control
- Hypertrophy, Right Ventricular/chemically induced
- Hypertrophy, Right Ventricular/drug therapy
- Hypertrophy, Right Ventricular/prevention & control
- Male
- Melatonin/therapeutic use
- Monocrotaline/toxicity
- Rats
- Rats, Long-Evans
- Ventricular Dysfunction, Right/chemically induced
- Ventricular Dysfunction, Right/drug therapy
- Ventricular Dysfunction, Right/prevention & control
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Affiliation(s)
- Gerald Maarman
- Hatter Institute for Cardiovascular Research in Africa and Inter University MRC Cape Heart Group, Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Dee Blackhurst
- Division of Chemical Pathology, Department of Clinical Laboratory Sciences, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Friedrich Thienemann
- Clinical Infectious Diseases Research Initiative, Institute of Infectious Diseases and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | | | | | - Neil Davies
- Cardiovascular Research Unit, Chris Barnard Division of Cardiothoracic Surgery, University of Cape Town, Faculty of Health Sciences, Cape Town, South Africa
| | - Karen Sliwa
- Hatter Institute for Cardiovascular Research in Africa and Inter University MRC Cape Heart Group, Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Sandrine Lecour
- Hatter Institute for Cardiovascular Research in Africa and Inter University MRC Cape Heart Group, Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
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8
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Kelly-Laubscher RF, King JC, Hacking D, Somers S, Hastie S, Stewart T, Imamdin A, Maarman G, Pedretti S, Lecour S. Cardiac preconditioning with sphingosine-1-phosphate requires activation of signal transducer and activator of transcription-3. Cardiovasc J Afr 2015; 25:118-23. [PMID: 25000441 PMCID: PMC4120131 DOI: 10.5830/cvja-2014-016] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Accepted: 03/31/2014] [Indexed: 02/05/2023] Open
Abstract
Aims Sphingosine-1-phosphate (S1P) is a cardioprotective agent. Signal transducer and activator of transcription 3 (STAT-3) is a key mediator of many cardioprotective agents. We aimed to explore whether STAT-3 is a key mediator in S1P-induced preconditioning. Methods Langendorff-perfused hearts from Wistar rats and wild-type or cardiomyocyte-specific STAT-3 knockout mice were pre-treated with S1P (10 nmol/l), with or without the STAT-3 pathway inhibitor AG490, before an ischaemia–reperfusion insult. Triphenyltetrazolium chloride and Evans blue staining were used for the determination of infarct size. Western blot analysis was carried out on the S1P pre-treated hearts for detection of cytosolic, nuclear and mitochondrial phosphorylated and total STAT-3 proteins. Results Pre-treatment with S1P decreased the infarct size in isolated rat (5 ± 3% vs control 26 ± 8%, p < 0.01) and wild-type mouse hearts (13 ± 1% vs control 33 ± 3%, p < 0.05). This protective effect was abolished in the rat hearts pre-treated with AG490 (30 ± 10%, p = ns vs control) and in the hearts from STAT-3 knockout mice (35 ± 4% vs control 30 ± 3%, p = ns). Levels of phosphorylated STAT-3 were significantly increased in both the nuclear (p < 0.05 vs control) and mitochondrial (p < 0.05 vs control) fractions in the S1P pre-treated hearts, but remained unchanged in the cytosolic fraction (p = ns vs control). Conclusion These novel results demonstrate that pharmacological preconditioning with S1P in the isolated heart is mediated by activation of mitochondrial and nuclear STAT-3, therefore suggesting that S1P may be a novel therapeutic target to modulate mitochondrial and nuclear function in cardiovascular disease in order to protect the heart against ischaemia–reperfusion.
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Affiliation(s)
- Roisin F Kelly-Laubscher
- Hatter Institute for Cardiovascular Research in Africa, Chris Barnard Building, Medical School Campus, University of Cape Town, Cape Town, South Africa
| | - Jonathan C King
- Hatter Institute for Cardiovascular Research in Africa, Chris Barnard Building, Medical School Campus, University of Cape Town, Cape Town, South Africa
| | - Damian Hacking
- Hatter Institute for Cardiovascular Research in Africa, Chris Barnard Building, Medical School Campus, University of Cape Town, Cape Town, South Africa
| | - Sarin Somers
- Hatter Institute for Cardiovascular Research in Africa, Chris Barnard Building, Medical School Campus, University of Cape Town, Cape Town, South Africa
| | - Samantha Hastie
- Hatter Institute for Cardiovascular Research in Africa, Chris Barnard Building, Medical School Campus, University of Cape Town, Cape Town, South Africa
| | - Tessa Stewart
- Hatter Institute for Cardiovascular Research in Africa, Chris Barnard Building, Medical School Campus, University of Cape Town, Cape Town, South Africa
| | - Aqeela Imamdin
- Hatter Institute for Cardiovascular Research in Africa, Chris Barnard Building, Medical School Campus, University of Cape Town, Cape Town, South Africa
| | - Gerald Maarman
- Hatter Institute for Cardiovascular Research in Africa, Chris Barnard Building, Medical School Campus, University of Cape Town, Cape Town, South Africa
| | - Sarah Pedretti
- Hatter Institute for Cardiovascular Research in Africa, Chris Barnard Building, Medical School Campus, University of Cape Town, Cape Town, South Africa
| | - Sandrine Lecour
- Hatter Institute for Cardiovascular Research in Africa, Chris Barnard Building, Medical School Campus, University of Cape Town, Cape Town, South Africa
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Clapp C, Portt L, Khoury C, Sheibani S, Eid R, Greenwood M, Vali H, Mandato CA, Greenwood MT. Untangling the Roles of Anti-Apoptosis in Regulating Programmed Cell Death using Humanized Yeast Cells. Front Oncol 2012; 2:59. [PMID: 22708116 PMCID: PMC3374133 DOI: 10.3389/fonc.2012.00059] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Accepted: 05/24/2012] [Indexed: 11/13/2022] Open
Abstract
Genetically programmed cell death (PCD) mechanisms, including apoptosis, are important for the survival of metazoans since it allows, among things, the removal of damaged cells that interfere with normal function. Cell death due to PCD is observed in normal processes such as aging and in a number of pathophysiologies including hypoxia (common causes of heart attacks and strokes) and subsequent tissue reperfusion. Conversely, the loss of normal apoptotic responses is associated with the development of tumors. So far, limited success in preventing unwanted PCD has been reported with current therapeutic approaches despite the fact that inhibitors of key apoptotic inducers such as caspases have been developed. Alternative approaches have focused on mimicking anti-apoptotic processes observed in cells displaying increased resistance to apoptotic stimuli. Hormesis and pre-conditioning are commonly observed cellular strategies where sub-lethal levels of pro-apoptotic stimuli lead to increased resistance to higher or lethal levels of stress. Increased expression of anti-apoptotic sequences is a common mechanism mediating these protective effects. The relevance of the latter observation is exemplified by the observation that transgenic mice overexpressing anti-apoptotic genes show significant reductions in tissue damage following ischemia. Thus strategies aimed at increasing the levels of anti-apoptotic proteins, using gene therapy or cell penetrating recombinant proteins are being evaluated as novel therapeutics to decrease cell death following acute periods of cell death inducing stress. In spite of its functional and therapeutic importance, more is known regarding the processes involved in apoptosis than anti-apoptosis. The genetically tractable yeast Saccharomyces cerevisiae has emerged as an exceptional model to study multiple aspects of PCD including the mitochondrial mediated apoptosis observed in metazoans. To increase our knowledge of the process of anti-apoptosis, we screened a human heart cDNA expression library in yeast cells undergoing PCD due to the conditional expression of a mammalian pro-apoptotic Bax cDNA. Analysis of the multiple Bax suppressors identified revealed several previously known as well as a large number of clones representing potential novel anti-apoptotic sequences. The focus of this review is to report on recent achievements in the use of humanized yeast in genetic screens to identify novel stress-induced PCD suppressors, supporting the use of yeast as a unicellular model organism to elucidate anti-apoptotic and cell survival mechanisms.
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Affiliation(s)
- Caitlin Clapp
- Department of Chemistry and Chemical Engineering, Royal Military College Kingston, ON, Canada
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10
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Ke Y, Solaro RJ. Use of a decoy peptide to purify p21 activated kinase-1 in cardiac muscle and identification of ceramide-related activation. Biologics 2011; 2:903-9. [PMID: 19707468 PMCID: PMC2727905 DOI: 10.2147/btt.s3870] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The p21 activated kinase-1 (Pak1) is a serine-threonine protein kinase directly activated by Cdc42 and Rac1. In cardiac myocytes, Pak1 activation leads to dephosphorylation of cTnI and C-protein through upregulation of phosphatase-2A (PP2A). Pak1 activity is directly correlated with its autophosphorylation, which occurs upon binding to the small GTPases and to some small organic molecules as well. In this report, we describe a novel method for rapid purification of endogenous Pak1 from bovine ventricle muscle. The method is simple and easy to carry out. The purified Pak1 demonstrated autophosphorylation in vitro that was enhanced by D-erythro-sphingosine-1, N-acetyl-D-erythro-sphingosine (C2-ceramide), and N-hexanoyl-D-erythro-sphingosine (C6-ceramide). Dihydro-L-threo-sphingosine (saphingol) also had some effect on Pak1 autophosphorylation. The method we developed provides a useful tool to study Pak1 activity and regulation in the heart. Moreover, our results indicate a potential role of the sphingolipids as unique signaling molecules inducing a direct activation of Pak1 that may modulate different cardiac functions.
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Affiliation(s)
- Yunbo Ke
- Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois at Chicago, Chicago, IL, USA
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11
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Balková P, Hlaváčková M, Milerová M, Neckář J, Kolář F, Novák F, Nováková O. N-acetylcysteine treatment prevents the up-regulation of MnSOD in chronically hypoxic rat hearts. Physiol Res 2011; 60:467-74. [PMID: 21401304 DOI: 10.33549/physiolres.932042] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Chronic intermittent hypoxia (CIH) is associated with increased production of reactive oxygen species that contributes to the adaptive mechanism underlying the improved myocardial ischemic tolerance. The aim was to find out whether the antioxidative enzyme manganese superoxide dismutase (MnSOD) can play a role in CIH-induced cardioprotection. Adult male Wistar rats were exposed to intermittent hypobaric hypoxia (7000 m, 8 h/day, 25 exposures) (n=14) or kept at normoxia (n=14). Half of the animals from each group received N-acetylcysteine (NAC, 100 mg/kg) daily before the hypoxic exposure. The activity and expression of MnSOD were increased by 66 % and 23 %, respectively, in the mitochondrial fraction of CIH hearts as compared with the normoxic group; these effects were suppressed by NAC treatment. The negative correlation between MnSOD activity and myocardial infarct size suggests that MnSOD can contribute to the improved ischemic tolerance of CIH hearts.
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Affiliation(s)
- P Balková
- Department of Cell Biology, Charles University, Faculty of Science, Prague, Czech Republic
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12
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Lacerda L, McCarthy J, Mungly SFK, Lynn EG, Sack MN, Opie LH, Lecour S. TNFα protects cardiac mitochondria independently of its cell surface receptors. Basic Res Cardiol 2010; 105:751-62. [PMID: 20680307 PMCID: PMC3414057 DOI: 10.1007/s00395-010-0113-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2009] [Revised: 07/12/2010] [Accepted: 07/13/2010] [Indexed: 10/19/2022]
Abstract
Our novel proposal is that TNFα exerts a direct effect on mitochondrial respiratory function in the heart, independently of its cell surface receptors. TNFα-induced cardioprotection is known to involve reactive oxygen species (ROS) and sphingolipids. We therefore further propose that this direct mitochondrial effect is mediated via ROS and sphingolipids. The protective concentration of TNFα (0.5 ng/ml) was added to isolated heart mitochondria from black 6 × 129 mice (WT) and double TNF receptor knockout mice (TNFR1&2(-/-)). Respiratory parameters and inner mitochondrial membrane potential were analyzed in the presence/absence of two antioxidants, N-acetyl-L: -cysteine or N-tert-butyl-α-(2-sulfophenyl)nitrone or two antagonists of the sphingolipid pathway, N-oleoylethanolamine (NOE) or imipramine. In WT, TNFα reduced State 3 respiration from 279.3 ± 3 to 119.3 ± 2 (nmol O₂/mg protein/min), increased proton leak from 15.7 ± 0.6% (control) to 36.6 ± 4.4%, and decreased membrane potential by 20.5 ± 3.1% compared to control groups. In TNFR1&2(-/-) mice, TNFα reduced State 3 respiration from 205.2 ± 4 to 75.7 ± 1 (p < 0.05 vs. respective control). In WT mice, both antioxidants added with TNFα restored State 3 respiration to 269.2 ± 2 and 257.6 ± 2, respectively. Imipramine and NOE also restored State 3 respiration to 248.4 ± 2 and 249.0 ± 2, respectively (p < 0.01 vs. TNFα alone). Similarly, both antioxidant and inhibitors of the sphingolipid pathway restored the proton leak to pre-TNF values. TNFα-treated mitochondria or isolated cardiac muscle fibers showed an increase in respiration after anoxia-reoxygenation, but this effect was lost in the presence of an antioxidant or NOE. Similar data were obtained in TNFR1&2(-/-) mice. TNFα exerts a protective effect on respiratory function in isolated mitochondria subjected to an anoxia-reoxygenation insult. This effect appears to be independent of its cell surface receptors, but is likely to be mediated by ROS and sphingolipids.
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MESH Headings
- Adenosine Triphosphate/metabolism
- Animals
- Antioxidants/pharmacology
- Cell Hypoxia
- Cell Respiration
- Enzyme Inhibitors/pharmacology
- Male
- Membrane Potential, Mitochondrial
- Mice
- Mice, 129 Strain
- Mice, Knockout
- Mitochondria, Heart/drug effects
- Mitochondria, Heart/metabolism
- Mitochondrial Membrane Transport Proteins/metabolism
- Mitochondrial Permeability Transition Pore
- Myocytes, Cardiac/metabolism
- Reactive Oxygen Species/metabolism
- Receptors, Tumor Necrosis Factor, Type I/deficiency
- Receptors, Tumor Necrosis Factor, Type I/genetics
- Receptors, Tumor Necrosis Factor, Type I/metabolism
- Receptors, Tumor Necrosis Factor, Type II/deficiency
- Receptors, Tumor Necrosis Factor, Type II/genetics
- Receptors, Tumor Necrosis Factor, Type II/metabolism
- Sphingolipids/metabolism
- Tumor Necrosis Factor-alpha/metabolism
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Affiliation(s)
- Lydia Lacerda
- Cardioprotection Group, Hatter Cardiovascular Research Institute, Department of Medicine, Faculty of Health Sciences, University of Cape Town, Anzio Road, Observatory 7925, Cape Town, South Africa.
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13
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Lowes DA, Webster NR, Galley HF. Dehydroascorbic acid as pre-conditioner: protection from lipopolysaccharide induced mitochondrial damage. Free Radic Res 2010; 44:283-92. [PMID: 20166893 DOI: 10.3109/10715760903468766] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Oxidative stress-induced mitochondrial dysfunction is a common consequence of severe sepsis. However, oxidative stress also activates signalling cascades which enable protection of cells against subsequent oxidative damage. This study hypothesized that cellular uptake of vitamin C as dehydroascorbic acid rather than ascorbic acid would up-regulate antioxidant enzyme systems and impart a protective effect to mitochondria in cells subsequently exposed to lipopolysaccharide (LPS) in an iron free environment. Treatment of monocytes with dehydroascorbic acid, but not ascorbic acid, caused oxidative stress (p< 0.001). Dehydroascorbic acid exposure also resulted in increased manganese superoxide dismutase (p= 0.018) and catalase (p= 0.003) expression. Pre-treatment of monocytes with dehydroascorbic acid followed by LPS resulted in higher mitochondrial membrane potentials than cells without pre-treatment (p< 0.0001). Lower cytochrome c in cytosol (p< 0.05) and higher mitochondrial expression of the anti-apoptotic Bcl-2 protein (p= 0.029) was also found in monocytes pre-treated before subsequent LPS exposure, compared to cells without pre-treatment. In conclusion, acute exposure of monocytes to dehydroascorbic acid in an iron free environment induces cytoprotective antioxidant enzymes and protected mitochondria from the harmful effects of oxidative stress prior to a septic insult, which was abrogated when cells were pre-incubated with the DHA uptake inhibitor cytocholasin B.
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Affiliation(s)
- Damon A Lowes
- Division of Applied Medicine, School of Medicine & Dentistry, University of Aberdeen, UK
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14
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Ke Y, Lei M, Solaro RJ. Regulation of cardiac excitation and contraction by p21 activated kinase-1. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2009; 98:238-50. [PMID: 19351515 DOI: 10.1016/j.pbiomolbio.2009.01.007] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Cardiac excitation and contraction are regulated by a variety of signaling molecules. Central to the regulatory scheme are protein kinases and phosphatases that carry out reversible phosphorylation of different effectors. The process of beta-adrenergic stimulation mediated by cAMP dependent protein kinase (PKA) forms a well-known pathway considered as the most significant control mechanism in excitation and contraction as well as many other regulatory mechanisms in cardiac function. However, although dephosphorylation pathways are critical to these regulatory processes, signaling to phosphatases is relatively poorly understood. Emerging evidence indicates that regulation of phosphatases, which dampen the effect of beta-adrenergic stimulation, is also important. We review here functional studies of p21 activated kinase-1 (Pak1) and its potential role as an upstream signal for protein phosphatase PP2A in the heart. Pak1 is a serine/threonine protein kinase directly activated by the small GTPases Cdc42 and Rac1. Pak1 is highly expressed in different regions of the heart and modulates the activities of ion channels, sarcomeric proteins, and other phosphoproteins through up-regulation of PP2A activity. Coordination of Pak1 and PP2A activities is not only potentially involved in regulation of normal cardiac function, but is likely to be important in patho-physiological conditions.
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Affiliation(s)
- Yunbo Ke
- The Department of Physiology and Biophysics and Center for Cardiovascular Research, University of Illinois at Chicago, College of Medicine, Room 202, COMRB, 835 South Wolcott Avenue, Chicago, IL 60612, USA
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Prasad VVTS, Nithipatikom K, Harder DR. Ceramide elevates 12-hydroxyeicosatetraenoic acid levels and upregulates 12-lipoxygenase in rat primary hippocampal cell cultures containing predominantly astrocytes. Neurochem Int 2008; 53:220-9. [PMID: 18680775 DOI: 10.1016/j.neuint.2008.07.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2008] [Revised: 06/01/2008] [Accepted: 07/01/2008] [Indexed: 10/21/2022]
Abstract
We report, exogenous addition of ceramide significantly increases 12-hydroxyeicosatetraenoic acid [12-(S)-HETE] levels, in a dose-dependent manner. 12-(S)-HETE levels, in 20, 30 and 40microM ceramide exposed rat primary hippocampal cell cultures containing predominantly astrocytes and few neurons and other glial cells (the cultured hippocampal cells were predominantly astrocytes amounting to over 99% of total cells with few neurons and other glial cells) amounted to 207, 260 and 408% of the controls, respectively. However, dihydroceramide, an inactive analog of ceramide did not alter the levels of 12-(S)-HETE. Ceramide also increased the mRNA and protein expression, and activity of 12-lipoxygease (12-LOX) needed for the synthesis of 12(S)-HETE. These results indicate a possible link between ceramide and 12-LOX pathway. However, ceramide did not alter expression of 5-lipoxygenase (5-LOX), another member of the lipoxygenase family. However, ceramide upregulated expression of cytosolic phospholipase-A(2) (cPLA(2)) and cyclooxygenase-2 (COX-2). Further, ceramide caused a significant increase in the levels of reactive oxygen species (ROS). Ceramide-mediated generation of ROS was inhibited by baicalien but not by indomethacin. In addition, ceramide treated cells exhibited increased mRNA expression of DNA damage induced transcript3 (Ddit3). This report which demonstrate induction of pro-carcinogenic 12-LOX pathway by an anticancer ceramide, may be relevant to cancer biologists studying drug resistant tumors and devising potent anticancer therapeutic strategies to treat drug resistant tumors. These results indicate possibility of 12-LOX involvement in ceramide-mediated generation of ROS and cellular oxidative stress. Induction of 12-LOX pathway by ceramide may have implications in understanding pathophysiology of neurodegenerative diseases involving ROS generation and inflammation.
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