Electron Transport Complex II
Antimycin A
Electron Transport
Mitochondria
Succinate Dehydrogenase
Encyclopedias as Topic
Succinates
Citric Acid Cycle
Succinic Acid
Implication of mitochondria-derived reactive oxygen species, cytochrome C and caspase-3 in N-(4-hydroxyphenyl)retinamide-induced apoptosis in cervical carcinoma cells. (1/40)
N-(4-Hydroxyphenyl)retinamide (4HPR) is currently used in cancer prevention and therapy trials. It is thought that its effects result from induction of apoptosis. 4HPR-induced apoptosis in human cervical carcinoma C33A cells involves enhanced generation of reactive oxygen species (ROS). In this study we explored the mechanism by which 4HPR increases ROS and induces apoptosis in these cells. 4HPR induced cytochrome c release from mitochondria to cytoplasm, activated caspase-3, and caused a membrane permeability transition (MPT). All these 4HPR's effects, as well as the induction of apoptosis, were inhibited by antioxidants, which decrease ROS. Thenoyltrifluoroacetone, a mitochondrial respiratory chain (MRC) complex II inhibitor, and carbonylcyanide m-chlorophenyl hydrazone, which uncouples electron transfer and ATP synthesis and inhibits ROS generation by MRC, inhibited 4HPR-induced ROS generation very effectively. Rotenone, an MRC complex I inhibitor was less effective and azide, an MRC complex IV inhibitor, exhibited a marginal effect. In contrast, antimycin A, an MRC complex III inhibitor, enhanced 4HPR-induced ROS generation. These findings suggest that 4HPR enhances ROS generation by affecting a target between complex II and complex III, presumably coenzyme Q. This effect is followed by release of cytochrome c, increased caspase-3 activity, induction of MPT and eventual DNA fragmentation and cell death. (+info)Hypoxia-induced alterations in Ca(2+) mobilization in brain microvascular endothelial cells. (2/40)
To investigate the possible cellular mechanisms of the ischemia-induced impairments of cerebral microcirculation, we investigated the effects of hypoxia/reoxygenation on the intracellular Ca(2+) concentration ([Ca(2+)](i)) in bovine brain microvascular endothelial cells (BBEC). In the cells kept in normal air, ATP elicited Ca(2+) oscillations in a concentration-dependent manner. When the cells were exposed to hypoxia for 6 h and subsequent reoxygenation for 45 min, the basal level of [Ca(2+)](i) was increased from 32.4 to 63.3 nM, and ATP did not induce Ca(2+) oscillations. Hypoxia/reoxygenation also inhibited capacitative Ca(2+) entry (CCE), which was evoked by thapsigargin (Delta[Ca(2+)](i-CCE): control, 62.3 +/- 3.1 nM; hypoxia/reoxygenation, 17.0 +/- 1.8 nM). The impairments of Ca(2+) oscillations and CCE, but not basal [Ca(2+)](i), were restored by superoxide dismutase and the inhibitors of mitochondrial electron transport, rotenone and thenoyltrifluoroacetone (TTFA). By using a superoxide anion (O(2)(-))-sensitive luciferin derivative MCLA, we confirmed that the production of O(2)(-) was induced by hypoxia/reoxygenation and was prevented by rotenone and TTFA. These results indicate that hypoxia/reoxygenation generates O(2)(-) at mitochondria and impairs some Ca(2+) mobilizing properties in BBEC. (+info)Role of caspases and mitochondria in the steroid-induced programmed cell death of a motoneuron during metamorphosis. (3/40)
Accessory planta retractor (APR) motoneurons of the hawk moth, Manduca sexta, undergo a segment-specific pattern of programmed cell death (PCD) 24 to 48 h after pupal ecdysis (PE). Cell culture experiments show that the PCD of APRs in abdominal segment 6 [APR(6)s] is a cell-autonomous response to the steroid hormone 20-hydroxyecdysone (20E) and involves mitochondrial demise and cell shrinkage. Twenty-four hours before PE, at stage W3-noon, APR(6)s require further 20E exposure and protein synthesis (as tested with cycloheximide) to undergo PCD, and death can be blocked by a broad-spectrum caspase inhibitor. By PE, death is 20E- and protein synthesis-independent and the caspase inhibitor blocks cell shrinkage but not loss of mitochondrial function. Thus, the commitment to mitochondrial demise precedes the commitment to execution events. The phenotype of necrotic cell death induced by a mitochondrial electron transfer inhibitor differs unambiguously from 20E-induced PCD. By inducing PCD pharmacologically, the readiness of APR(6)s to execute PCD was found to increase during the final larval instar. These data suggest that the 20E-induced PCD of APR(6)s includes a premitochondrial phase which includes 20E-induced synthetic events and apical caspase activity, a mitochondrial phase which culminates in loss of mitochondrial function, and a postmitochondrial phase during which effector caspases are activated and APR(6) is destroyed. (+info)Leptin induces mitochondrial superoxide production and monocyte chemoattractant protein-1 expression in aortic endothelial cells by increasing fatty acid oxidation via protein kinase A. (4/40)
Leptin, a circulating hormone secreted mainly from adipose tissues, is involved in the control of body weight. The plasma concentrations are correlated with body mass index, and are reported to be high in patients with insulin resistance, which is one of the major risk factors for cardiovascular disease. However, the direct effect of leptin on vascular wall cells is not fully understood. In this study, we investigated the effects of leptin on reactive oxygen species (ROS) generation and expression of monocyte chemoattractant protein-1 (MCP-1) in bovine aortic endothelial cells (BAEC). We found that leptin increases ROS generation in BAEC in a dose-dependent manner and that its effects are additive with those of glucose. Rotenone, thenoyltrifluoroacetone (TTFA), carbonyl cyanide m-chlorophenylhydrazone (CCCP), Mn(III)tetrakis (4-benzoic acid) porphyrin (MnTBAP), uncoupling protein-1 (UCP1) HVJ-liposomes, or manganese superoxide dismutase (MnSOD) HVJ-liposomes completely prevented the effect of leptin, suggesting that ROS arise from mitochondrial electron transport. Leptin increased fatty acid oxidation by stimulating the activity of carnitine palmitoyltransferase-1 (CPT-1) and inhibiting that of acetyl-CoA carboxylase (ACC), pace-setting enzymes for fatty acid oxidation and synthesis, respectively. Leptin-induced ROS generation, CPT-1 activation, ACC inhibition, and MCP-1 overproduction were found to be completely prevented by either genistein, a tyrosine kinase inhibitor, H-89, a protein kinase A (PKA) inhibitor, or tetradecylglycidate, a CPT-1 inhibitor. Leptin activated PKA, and the effects of leptin were inhibited by the cAMP antagonist Rp-cAMPS. These results suggest that leptin induces ROS generation by increasing fatty acid oxidation via PKA activation, which may play an important role in the progression of atherosclerosis in insulin-resistant obese diabetic patients. (+info)Hyperglycemia potentiates collagen-induced platelet activation through mitochondrial superoxide overproduction. (5/40)
Alteration of platelet function contributes to microthrombus formation and may play an important role in the pathogenesis of diabetic micro- and macroangiopathies. However, the molecular mechanism for platelet dysfunction observed in patients with diabetes has not been fully elucidated. In this study, the direct effects of hyperglycemia on platelet function in vitro were investigated. Hyperglycemia increased reactive oxygen species generation in human platelets, and this effect was additive with that of collagen. Thenoyltrifluoroacetone (TTFA), an inhibitor of mitochondrial electron transport chain complex II, and carbonyl cyanide m-chlorophenylhydrazone (CCCP), an uncoupler of oxidative phosphorylation, completely prevented the effects of hyperglycemia, suggesting that reactive oxygen species arise from the mitochondrial electron transport chain. Hyperglycemia potentiated both platelet aggregation and the subsequent release of platelet-derived growth factor AB induced by a nonaggregating subthreshold concentration of collagen, which were also completely inhibited by TTFA or CCCP. Furthermore, hyperglycemia was found to inhibit protein tyrosine phosphatase (PTP) activity and increase phosphorylation of the tyrosine kinase Syk in platelets exposed to collagen. Hyperglycemia-induced PTP inhibition and Syk phosphorylation were found to be completely prevented by TTFA, CCCP, or Mn(III)tetrakis (4-benzoic acid) porphyrin, a stable cell-permeable superoxide dismutase mimetic. These results suggest that hyperglycemia-induced mitochondrial superoxide generation may play an important role in platelet dysfunction observed in patients with diabetes. (+info)Inhibition of photosystem II of spinach by the respiration inhibitors piericidin A and thenoyltrifluoroacetone. (6/40)
The effects of several respiration inhibitors on photosystem II (PS II) were investigated. Among the agents tested, piericidin A and thenoyltrifluoroacetone (TTFA) inhibited the photosynthetic electron transport of spinach as measured from chlorophyll (Chl) fluorescence parameters (Fm'-F)/Fm' and Fv/Fm. Using specific donors and acceptors of electrons, we identified the sites of inhibition in and around the PS II complex; the site of inhibition by TTFA was between QA, primary quinone acceptor in PS II, and QB, secondary quinone acceptor, in the acceptor side of P680, the reaction center Chl of PS II, while inhibition by piericidin A of the acceptor side was downstream of Q(B), out of the PS II complex. Both agents also inhibited the donor side of P680, probably between tyrosine-161 of the reaction center protein of PS II and P680. (+info)Glucose regulates monocyte adhesion through endothelial production of interleukin-8. (7/40)
We have shown that glucose increases monocyte adhesion to human aortic endothelial cells (HAECs) in vitro.1 In the present study, we examined mechanisms by which glucose stimulates monocyte:endothelial interactions. HAECs cultured for 7 days in 25 mmol/L glucose had a 2-fold elevation in interleukin-8 (IL-8) secretion over control cells cultured in 5.5 mmol/L glucose (P<0.001). Use of a neutralizing antibody to IL-8 prevented glucose-mediated monocyte adhesion. Both glucose and IL-8 activated beta1 integrin on the HAEC surface, suggesting that both activate the alpha5beta1 integrin complex on the endothelial surface. The alpha5beta1 integrin complex is important for anchoring connecting segment-1 fibronectin on the HAEC surface for monocyte adhesion. Analysis of the human IL-8 promoter revealed binding sites for NF-kappaB and AP-1 as well as several aligned carbohydrate response elements (also known as E-boxes). Glucose dramatically stimulated IL-8 promoter activity. Using mutated IL-8 promoter constructs and EMSA, we found that the AP-1 element and the glucose-response element were responsible for much of the glucose-mediated activation of IL-8 transcription. Interestingly, inhibition of reactive oxygen species (ROS) production through use of pharmacological uncouplers of the mitochondrial electron transport chain significantly reduced glucose-mediated induction of IL-8 expression. These data indicate that glucose regulates monocyte:endothelial interactions through stimulation of IL-8 and ROS production and activation of the alpha5beta1 integrin complex on HAECs. (+info)Essential role of complex II of the respiratory chain in hypoxia-induced ROS generation in the pulmonary vasculature. (8/40)
In the pulmonary vasculature, the mechanisms responsible for oxygen sensing and the initiation of hypoxia-induced vasoconstriction and vascular remodeling are still unclear. Nitric oxide (NO) and reactive oxygen species (ROS) are discussed as early mediators of the hypoxic response. Here, we describe a quantitative analysis of NO- and ROS-producing cells within the vascular walls of murine lung sections cultured at normoxia or hypoxia. Whereas the number of NO-producing cells was not changed by hypoxia, the number of ROS-generating cells was significantly increased. Addition of specific inhibitors revealed that mitochondria were the source of ROS. The participation of the individual mitochondrial complexes differed in normoxic and hypoxic ROS generation. Whereas normoxic ROS production required complexes I and III, hypoxic ROS generation additionally demanded complex II. Histochemically demonstrable succinate dehydrogenase activity of complex II in the arterial wall decreased during hypoxia. Inhibition of the reversed enzymatic reaction, i.e., fumarate reductase, by application of succinate, specifically abolished hypoxic, but not normoxic, ROS generation. Thus complex II plays an essential role in hypoxic ROS production. Presumably, its catalytic activity switches from succinate dehydrogenase to fumarate reductase at reduced oxygen tension, thereby modulating the directionality of the electron flow. (+info)Thenoyltrifluoroacetone (TTA) is not typically considered a medical compound, but rather a chemical compound with potential uses in various fields including chemistry, biology, and materials science. However, I can provide a general definition:
Thenoyltrifluoroacetone is an organofluorine compound with the formula C6H3F3O2S. It is a colorless liquid that is used as a fluorinated ligand in coordination chemistry and as a reagent in organic synthesis. Its unique chemical properties, such as its ability to act as a metal chelator and its volatility, have led to its use in various applications. Please consult relevant technical or scientific literature for more specific information regarding its uses and properties.
Electron Transport Complex II, also known as succinate-Q oxidoreductase, is a key component of the electron transport chain in the inner mitochondrial membrane. It plays a crucial role in the process of cellular respiration, where it facilitates the transfer of electrons from succinate to ubiquinone (Q), thereby generating a proton gradient across the membrane. This gradient drives the synthesis of ATP, which is the primary source of energy for the cell.
The complex is composed of four core subunits: flavoprotein (Fp), iron-sulfur protein (Ip), cytochrome b (Cyb), and ubiquinone-binding protein (Qp). Electrons from succinate are accepted by FAD in the Fp subunit, and then transferred to the Ip subunit containing iron-sulfur clusters. From there, the electrons are moved to heme groups in the Cyb subunit, and finally passed on to ubiquinone at the Qp subunit.
In addition to its role in the electron transport chain, Complex II has been implicated in various cellular processes such as regulation of reactive oxygen species (ROS) production and modulation of apoptosis. Mutations in genes encoding Complex II subunits have been associated with several human diseases, including neurodegenerative disorders and cancer.
Antimycin A is an antibiotic substance produced by various species of Streptomyces bacteria. It is known to inhibit the electron transport chain in mitochondria, which can lead to cellular dysfunction and death. Antimycin A has been used in research to study the mechanisms of cellular respiration and oxidative phosphorylation.
In a medical context, antimycin A is not used as a therapeutic agent due to its toxicity to mammalian cells. However, it may be used in laboratory settings to investigate various biological processes or to develop new therapies for diseases related to mitochondrial dysfunction.
Rotenone is not strictly a medical term, but it is a pesticide that is used in some medical situations. According to the National Pesticide Information Center, rotenone is a pesticide derived from the roots and stems of several plants, including Derris Eliptica, Lonchocarpus utilis, and Tephrosia vogelii. It is used as a pesticide to control insects, mites, and fish in both agricultural and residential settings.
In medical contexts, rotenone has been studied for its potential effects on human health, particularly in relation to Parkinson's disease. Some research suggests that exposure to rotenone may increase the risk of developing Parkinson's disease, although more studies are needed to confirm this link. Rotenone works by inhibiting the mitochondria in cells, which can lead to cell death and neurodegeneration.
It is important to note that rotenone is highly toxic and should be handled with care. It can cause skin and eye irritation, respiratory problems, and gastrointestinal symptoms if ingested or inhaled. Therefore, it is recommended to use personal protective equipment when handling rotenone and to follow all label instructions carefully.
The Electron Transport Chain (ETC) is a series of complexes in the inner mitochondrial membrane that are involved in the process of cellular respiration. It is the final pathway for electrons derived from the oxidation of nutrients such as glucose, fatty acids, and amino acids to be transferred to molecular oxygen. This transfer of electrons drives the generation of a proton gradient across the inner mitochondrial membrane, which is then used by ATP synthase to produce ATP, the main energy currency of the cell.
The electron transport chain consists of four complexes (I-IV) and two mobile electron carriers (ubiquinone and cytochrome c). Electrons from NADH and FADH2 are transferred to Complex I and Complex II respectively, which then pass them along to ubiquinone. Ubiquinone then transfers the electrons to Complex III, which passes them on to cytochrome c. Finally, cytochrome c transfers the electrons to Complex IV, where they combine with oxygen and protons to form water.
The transfer of electrons through the ETC is accompanied by the pumping of protons from the mitochondrial matrix to the intermembrane space, creating a proton gradient. The flow of protons back across the inner membrane through ATP synthase drives the synthesis of ATP from ADP and inorganic phosphate.
Overall, the electron transport chain is a crucial process for generating energy in the form of ATP in the cell, and it plays a key role in many metabolic pathways.
Mitochondria are specialized structures located inside cells that convert the energy from food into ATP (adenosine triphosphate), which is the primary form of energy used by cells. They are often referred to as the "powerhouses" of the cell because they generate most of the cell's supply of chemical energy. Mitochondria are also involved in various other cellular processes, such as signaling, differentiation, and apoptosis (programmed cell death).
Mitochondria have their own DNA, known as mitochondrial DNA (mtDNA), which is inherited maternally. This means that mtDNA is passed down from the mother to her offspring through the egg cells. Mitochondrial dysfunction has been linked to a variety of diseases and conditions, including neurodegenerative disorders, diabetes, and aging.
Succinate dehydrogenase (SDH) is an enzyme complex that plays a crucial role in the process of cellular respiration, specifically in the citric acid cycle (also known as the Krebs cycle) and the electron transport chain. It is located in the inner mitochondrial membrane of eukaryotic cells.
SDH catalyzes the oxidation of succinate to fumarate, converting it into a molecule of fadaquate in the process. During this reaction, two electrons are transferred from succinate to the FAD cofactor within the SDH enzyme complex, reducing it to FADH2. These electrons are then passed on to ubiquinone (CoQ), which is a mobile electron carrier in the electron transport chain, leading to the generation of ATP, the main energy currency of the cell.
SDH is also known as mitochondrial complex II because it is the second complex in the electron transport chain. Mutations in the genes encoding SDH subunits or associated proteins have been linked to various human diseases, including hereditary paragangliomas, pheochromocytomas, gastrointestinal stromal tumors (GISTs), and some forms of neurodegenerative disorders.
An encyclopedia is a comprehensive reference work containing articles on various topics, usually arranged in alphabetical order. In the context of medicine, a medical encyclopedia is a collection of articles that provide information about a wide range of medical topics, including diseases and conditions, treatments, tests, procedures, and anatomy and physiology. Medical encyclopedias may be published in print or electronic formats and are often used as a starting point for researching medical topics. They can provide reliable and accurate information on medical subjects, making them useful resources for healthcare professionals, students, and patients alike. Some well-known examples of medical encyclopedias include the Merck Manual and the Stedman's Medical Dictionary.
Succinates, in a medical context, most commonly refer to the salts or esters of succinic acid. Succinic acid is a dicarboxylic acid that is involved in the Krebs cycle, which is a key metabolic pathway in cells that generates energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins.
Succinates can also be used as a buffer in medical solutions and as a pharmaceutical intermediate in the synthesis of various drugs. In some cases, succinate may be used as a nutritional supplement or as a component of parenteral nutrition formulations to provide energy and help maintain acid-base balance in patients who are unable to eat normally.
It's worth noting that there is also a condition called "succinic semialdehyde dehydrogenase deficiency" which is a genetic disorder that affects the metabolism of the amino acid gamma-aminobutyric acid (GABA). This condition can lead to an accumulation of succinic semialdehyde and other metabolic byproducts, which can cause neurological symptoms such as developmental delay, hypotonia, and seizures.
The Citric Acid Cycle, also known as the Krebs cycle or tricarboxylic acid (TCA) cycle, is a crucial metabolic pathway in the cell's powerhouse, the mitochondria. It plays a central role in the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins, into carbon dioxide and high-energy electrons. This process generates energy in the form of ATP (adenosine triphosphate), reducing equivalents (NADH and FADH2), and water.
The cycle begins with the condensation of acetyl-CoA with oxaloacetate, forming citrate. Through a series of enzyme-catalyzed reactions, citrate is converted back to oxaloacetate, releasing two molecules of carbon dioxide, one GTP (guanosine triphosphate), three NADH, one FADH2, and regenerating oxaloacetate to continue the cycle. The reduced coenzymes (NADH and FADH2) then donate their electrons to the electron transport chain, driving ATP synthesis through chemiosmosis. Overall, the Citric Acid Cycle is a vital part of cellular respiration, connecting various catabolic pathways and generating energy for the cell's metabolic needs.
Succinic acid, also known as butanedioic acid, is an organic compound with the chemical formula HOOC(CH2)2COOH. It is a white crystalline powder that is soluble in water and has a slightly acerbic taste. In medicine, succinic acid is not used as a treatment for any specific condition. However, it is a naturally occurring substance found in the body and plays a role in the citric acid cycle, which is a key process in energy production within cells. It can also be found in some foods and is used in the manufacturing of various products such as pharmaceuticals, resins, and perfumes.
Ubiquinone, also known as coenzyme Q10 (CoQ10), is a lipid-soluble benzoquinone that plays a crucial role in the mitochondrial electron transport chain as an essential component of Complexes I, II, and III. It functions as an electron carrier, assisting in the transfer of electrons from reduced nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FADH2) to molecular oxygen during oxidative phosphorylation, thereby contributing to the generation of adenosine triphosphate (ATP), the primary energy currency of the cell.
Additionally, ubiquinone acts as a potent antioxidant in both membranes and lipoproteins, protecting against lipid peroxidation and oxidative damage to proteins and DNA. Its antioxidant properties stem from its ability to donate electrons and regenerate other antioxidants like vitamin E. Ubiquinone is synthesized endogenously in all human cells, with the highest concentrations found in tissues with high energy demands, such as the heart, liver, kidneys, and skeletal muscles.
Deficiency in ubiquinone can result from genetic disorders, aging, or certain medications (such as statins), leading to impaired mitochondrial function and increased oxidative stress. Supplementation with ubiquinone has been explored as a potential therapeutic strategy for various conditions associated with mitochondrial dysfunction and oxidative stress, including cardiovascular diseases, neurodegenerative disorders, and cancer.
TTFA3
- Compounds tested were a) rotenone, b) thenoyltrifluoroacetone (TTFA), c) antimycin A, d) sodium azide and e) betaine. (cyprotex.com)
- Treatment of the cells with antioxidants SeMet, SOD mimetic MnTBAP and mitochondrial inhibitor thenoyltrifluoroacetone (TTFA) efficiently blocked these results induced by Age groups. (globaltechbiz.com)
- Cell lines carrying these mutations were characterized on the bases of CII activity and exposed to Qp site inhibitors MitoVES, thenoyltrifluoroacetone (TTFA) and Atpenin A5. (mitophysiology.org)
Chemical1
- Thenoyltrifluoroacetone, C8H5F3O2S, is a chemical compound used pharmacologically as a chelating agent. (wikipedia.org)