Biomedical subjects

C C Cunningham

Publications and source records attributed to C C Cunningham.

At least 37 records · Page 2Linked to original sources

PubMed1999

Ethanol stimulates the production of reactive oxygen species at mitochondrial complexes I and III.

The aim of this study was to investigate the hepatocellular site of reactive oxygen species generation during acute ethanol metabolism. Reactive oxygen species production was detected using the 2',7'-dichlorofluorescein fluorescence assay and cell injury was determined by lactate dehydrogenase release. Incubation with 1 and 10 mM ethanol increased the production of reactive oxygen species by 72% and 151%, respectively, which was associated with mild decreases in cell viability. Antimycin, a mitochondrial complex III inhibitor, elicited a 17-fold increase in the levels of reactive oxygen species and markedly decreased hepatocyte viability and ATP levels. Ethanol increased reactive oxygen species production and the cytosolic NADH/NAD+ ratio in antimycin-treated cells. Rotenone, a mitochondrial complex I inhibitor that allows electron flow through the flavin mononucleotide (FMN), but prevents electron flow to complex III, significantly increased reactive oxygen species production in untreated cells, but decreased reactive oxygen species production in antimycin plus ethanol-treated cells. Diphenyliodonium, a mitochondrial complex I inhibitor that inhibits electron flow through FMN, attenuated reactive oxygen species generation in all groups. Fructose prevented cytotoxicity in all treatment groups. Though they do not eliminate the participation of other intracellular compartments, these results indicate that the NADH dehydrogenase complex, as well as complex III of mitochondria, are involved in ethanol-related production of reactive oxygen species.

Adenosine Triphosphate↗

PubMed1999

Actin filament organization is required for proper cAMP-dependent activation of CFTR.

Previous studies have indicated a role of the actin cytoskeleton in the regulation of the cystic fibrosis transmembrane conductance regulator (CFTR) ion channel. However, the exact molecular nature of this regulation is still largely unknown. In this report human epithelial CFTR was expressed in human melanoma cells genetically devoid of the filamin homologue actin-cross-linking protein ABP-280 [ABP(-)]. cAMP stimulation of ABP(-) cells or cells genetically rescued with ABP-280 cDNA [ABP(+)] was without effect on whole cell Cl(-) currents. In ABP(-) cells expressing CFTR, cAMP was also without effect on Cl(-) conductance. In contrast, cAMP induced a 10-fold increase in the diphenylamine-2-carboxylate (DPC)-sensitive whole cell Cl(-) currents of ABP(+)/CFTR(+) cells. Further, in cells expressing both CFTR and a truncated form of ABP-280 unable to cross-link actin filaments, cAMP was also without effect on CFTR activation. Dialysis of ABP-280 or filamin through the patch pipette, however, resulted in a DPC-inhibitable increase in the whole cell currents of ABP(-)/CFTR(+) cells. At the single-channel level, protein kinase A plus ATP activated single Cl(-) channels only in excised patches from ABP(+)/CFTR(+) cells. Furthermore, filamin alone also induced Cl(-) channel activity in excised patches of ABP(-)/CFTR(+) cells. The present data indicate that an organized actin cytoskeleton is required for cAMP-dependent activation of CFTR.

Actins↗

PubMed1999

Effect of dietary fat on chronic ethanol-induced oxidative stress in hepatocytes.

BACKGROUND: Although oxidative stress and deficits in hepatic energy metabolism have been implicated as important factors in the initiation of alcoholic liver disease, their relative contribution to ethanol-induced cell death is not known. The purpose of this study was to examine the effects of chronic ethanol administration on hepatocyte reactive oxygen species (ROS) generation, energy state, and viability, as well as the effect of dietary fat on these parameters. METHODS: Male Sprague-Dawley rats were fed liquid diets that provided 36% total calories as ethanol, with fat as either 12% (low fat) or 35% (high fat) of total calories. Pair-fed controls received liquid diets in which maltose-dextrin was substituted for ethanol calories. The fluorescent probe 2',7'-dichlorofluorescin diacetate was used to detect ROS, lactate dehydrogenase leakage was used to assess viability, and ATP levels were used as a measure of the energy state. The effect of chronic ethanol feeding on these parameters was determined by incubating hepatocytes under a 5% oxygen-containing atmosphere or an atmosphere < or = 1% oxygen for 60 min. RESULTS: In general, chronic ethanol feeding stimulated ROS production and decreased ATP concentrations, which were associated with decreased viability in hepatocytes isolated from rats fed either high- or low-fat, ethanol-containing diets, compared to the corresponding controls. Incubation under an atmosphere < or = 1% oxygen and/or ethanol (10 mM) augmented these effects in both high- and low-fat control and ethanol-fed hepatocytes. The addition of antimycin to the incubations increased ROS production, decreased ATP concentrations, and accelerated loss of hepatocyte viability. Viability loss under all conditions used in this study was correlated with decreases in cellular ATP. CONCLUSIONS: Comparisons of incubations performed under the two oxygenation conditions revealed that viability loss was inversely associated with ROS production, which indicates that ATP loss and not ROS production was a better predictor of loss in cell integrity. This study also demonstrates that the level of dietary fat has only minor effects on generation of ROS and the cellular energy state. In contrast, ethanol consumption had significant effects on generation of ROS, energy state, and hepatocyte viability.

Adenosine Triphosphate↗

PubMed1998

Effect of chronic ethanol consumption on respiratory and glycolytic activities of rat periportal and perivenous hepatocytes.

Previous studies (Ivester et al., Arch. Biochem. Biophys. 322, 14-21, 1995) have established that periportal and perivenous hepatocytes isolated from ethanol-fed rats demonstrate lower ATP concentrations than those in control preparations when the cells are maintained at very low oxygen tension. In the present investigation, experiments were implemented with periportal and perivenous hepatocytes to determine the effects of chronic ethanol consumption on cellular respiratory and glycolytic activities, since both contribute to maintenance of the energy state of the liver cell. Both periportal and perivenous hepatocytes from ethanol-fed rats demonstrated significantly increased, rather than decreased, respiratory activity when monitored with oxygen concentrations ranging from 16 to 140 microM. Whole liver hepatocytes from control and ethanol-fed animals demonstrated equivalent oxygen utilization, however. Glycolytic activity, monitored by lactate + pyruvate concentrations obtained after both anaerobic and aerobic incubation protocols, was decreased in both cell types from ethanol-fed animals. The glycogen concentrations in freshly isolated periportal and perivenous hepatocytes were also decreased eight- and sevenfold, respectively, as compared with control preparations. Incubation under anaerobic conditions resulted in almost complete depletion of glycogen in both cell types. These observations suggest the possibility that the decreased energy state observed in hepatocytes from ethanol-fed animals is related to a depression in anaerobic glycolysis due to depletion of the endogenous substrate, glycogen.

Adenosine Triphosphate↗

PubMed1998

Acute and chronic ethanol increases reactive oxygen species generation and decreases viability in fresh, isolated rat hepatocytes.

Although reactive oxygen species (ROS) have been implicated in the etiology of alcohol-induced liver disease, neither their relative contribution to cell death nor the cellular mechanisms mediating their formation are known. The purpose of this study was to test the hypothesis that acute and chronic ethanol exposure enhances the mitochondrial generation of ROS in fresh, isolated hepatocytes. Acute ethanol exposure stimulated ROS production, increased the cellular NADH/NAD+ ratio, and decreased hepatocyte viability slightly, which was prevented by pretreatment with 4-methylpyrazole (4-MP), an inhibitor of alcohol dehydrogenase. Similarly, xylitol, an NADH-generating compound, enhanced hepatocyte ROS production and decreased viability. Incubation with pyruvate, an NADH-oxidizing compound, and cyanamide, an inhibitor of aldehyde dehydrogenase, significantly decreased ROS levels in acute ethanol-treated hepatocytes. Chronic ethanol consumption produced a sixfold increase in hepatocyte ROS production compared with levels measured in controls. Hepatocytes from ethanol-fed rats were less viable compared with controls, e.g., viability was 68% +/- 2% (ethanol) versus 83% +/- 1% (control) after 60 minutes of incubation. Antimycin A increased ROS production and decreased cell viability; however, the toxic effect of antimycin A was more pronounced in ethanol-fed hepatocytes. These results suggest that acute and chronic ethanol exposure exacerbates mitochondrial ROS production, contributing to cell death.

Alcohol Dehydrogenase↗

PubMed1998

Trypanosoma cruzi: effect of protein kinase inhibitors and cytoskeletal protein organization and expression on host cell invasion by amastigotes and metacyclic trypomastigotes.

Although trypomastigotes are regarded as the classic infective forms of T. cruzi, amastigotes generated extracellularly or released from infected cells during lysis may circulate and infect other cells. We have compared the infectivity of metacyclic trypomastigotes and extracellular amastigotes toward HeLa and Vero cells and observed that amastigotes were capable of invading both HeLa and Vero cells to a much higher degree than the corresponding metacyclic forms. Second, cell microfilament or microtubule disruption inhibited amastigote but not trypomastigote entry. Third, cells with altered expression in cytoskeletal components (ABP or gelsolin) internalize amastigotes and trypomastigotes with highly contrasting fashion. Fourth, protein kinase inhibitors such as genistein and staurosporine affect the internalization of amastigotes and trypomastigotes in a host-cell-dependent manner. Our results suggest that extracellular amastigotes and metacyclic trypomastigotes utilize mechanisms to invade host cells with particular features for each T. cruzi form and for each host cell. When internalized, both forms associate to lysosomes of HeLa cells.

Actin Cytoskeleton↗

PubMed1998

Gelsolin, a protein that caps the barbed ends and severs actin filaments, enhances the actin-based motility of Listeria monocytogenes in host cells.

The actin-based motility of Listeria monocytogenes requires the addition of actin monomers to the barbed or plus ends of actin filaments. Immunofluorescence micrographs have demonstrated that gelsolin, a protein that both caps barbed ends and severs actin filaments, is concentrated directly behind motile bacteria at the junction between the actin filament rocket tail and the bacterium. In contrast, CapG, a protein that strictly caps actin filaments, fails to localize near intracellular Listeria. To explore the effect of increasing concentrations of gelsolin on bacterial motility, NIH 3T3 fibroblasts stably transfected with gelsolin cDNA were infected with Listeria. The C5 cell line containing 2.25 times control levels of gelsolin supported significantly higher velocities of bacterial movement than did control fibroblasts (mean +/- standard error of the mean, 0.09 +/- 0.003 micro(m)/s [n = 176] versus 0.05 +/- 0.003 micro(m)/s [n = 65]). The rate of disassembly of the Listeria-induced actin filament rocket tail was found to be independent of gelsolin content. Therefore, if increases in gelsolin content result in increases in Listeria-induced rocket tail assembly rates, a positive correlation between gelsolin content and tail length would be expected. BODIPY-phalloidin staining of four different stably transfected NIH 3T3 fibroblast cell lines confirmed this expectation (r = 0.92). Rocket tails were significantly longer in cells with a high gelsolin content. Microinjection of gelsolin 1/2 (consisting of the amino-terminal half of native gelsolin) also increased bacterial velocity by more than 2.2 times. Microinjection of CapG had no effect on bacterial movement. Cultured skin fibroblasts derived from gelsolin-null mice were capable of supporting intracellular Listeria motility at velocities comparable to those supported by wild-type skin fibroblasts. These experiments demonstrated that the surface of Listeria contains a polymerization zone that can block the barbed-end-capping activity of both gelsolin and CapG. The ability of Listeria to uncap actin filaments combined with the severing activity of gelsolin can accelerate actin-based motility. However, gelsolin is not absolutely required for the actin-based intracellular movement of Listeria because its function can be replaced by other actin regulatory proteins in gelsolin-null cells, demonstrating the functional redundancy of the actin system.

3T3 Cells↗

PubMed1997

Cytoskeletal protein ABP-280 directs the intracellular trafficking of furin and modulates proprotein processing in the endocytic pathway.

Furin catalyzes the proteolytic maturation of many proproteins within the trans-Golgi network (TGN)/endosomal system. Furin's cytosolic domain (cd) directs both the compartmentalization to and transit between its manifold processing compartments (i.e., TGN/biosynthetic pathway, cell surface, and endosomes). Here we report the identification of the first furin cd sorting protein, ABP-280 (nonmuscle filamin), an actin gelation protein. The furin cd was used as bait in a yeast two-hybrid screen to identify ABP-280 as a furin-binding protein. Binding analyses in vitro and coimmunoprecipitation studies in vivo showed that furin and ABP-280 interact directly and that ABP-280 tethers furin molecules to the cell surface. Quantitative analysis of both ABP-280-deficient and genetically replete cells showed that ABP-280 modulates the rate of internalization of furin but not of the transferrin receptor, a cycling receptor. However, although ABP-280 directs the rate of furin internalization, the efficiency of sorting of the endoprotease from the cell surface to early endosomes is independent of expression of ABP-280. By contrast, efficient sorting of furin from early endosomes to the TGN requires expression of ABP-280. In addition, ABP-280 is also required for the correct localization of late endosomes (dextran bead uptake) and lysosomes (LAMP-1 staining), demonstrating a pleiotropic role for this actin binding protein in the organization of cellular compartments and directing protein traffic. Finally, and consistent with the trafficking studies on furin, we showed that ABP-280 modulates the processing of furin substrates in the endocytic but not the biosynthetic pathways. The novel roles of ABP-280 and the cytoskeleton in the sorting of furin in the TGN/ endosomal system and the formation of proprotein processing compartments are discussed.

Amino Acid Sequence↗

PubMed1997

Microtubule-associated protein 2c reorganizes both microtubules and microfilaments into distinct cytological structures in an actin-binding protein-280-deficient melanoma cell line.

The emergence of processes from cells often involves interactions between microtubules and microfilaments. Interactions between these two cytoskeletal systems are particularly apparent in neuronal growth cones. The juvenile isoform of the neuronal microtubule-associated protein 2 (MAP2c) is present in growth cones, where we hypothesize it mediates interactions between microfilaments and microtubules. To approach this problem in vivo, we used the human melanoma cell, M2, which lacks actin-binding protein-280 (ABP-280) and forms membrane blebs, which are not seen in wild-type or ABP-transfected cells. The microinjection of tau or mature MAP2 rescued the blebbing phenotype; MAP2c not only caused cessation of blebbing but also induced the formation of two distinct cellular structures. These were actin-rich lamellae, which often included membrane ruffles, and microtubule-bearing processes. The lamellae collapsed after treatment with cytochalasin D, and the processes retracted after treatment with colchicine. MAP2c was immunocytochemically visualized in zones of the cell that were devoid of tubulin, such as regions within the lamellae and in association with membrane ruffles. In vitro rheometry confirmed that MAP2c is an efficient actin gelation protein capable of organizing actin filaments into an isotropic array at very low concentrations; tau and mature MAP2 do not share this rheologic property. These results suggest that MAP2c engages in functionally specific interactions not only with microtubules but also with microfilaments.

Actin Cytoskeleton↗

PubMed1997

Identification of the region in actin-binding protein that binds to the cytoplasmic domain of glycoprotein IBalpha.

Actin-binding protein (ABP-280) is a component of the submembranous cytoskeleton and interacts with the glycoprotein (GP) Ibalpha subunit of the GP Ib-IX complex in platelets. In the present studies, we have identified the binding site for GP Ibalpha in ABP-280. A melanoma cell line lacking ABP-280 was stably transfected with the cDNAs coding for GP Ib-IX, then transiently transfected with cDNA coding for various carboxyl-truncates of ABP-280. Immunocapture assays and co-immunoprecipitation experiments from detergent-lysed cells showed that deletion of the carboxyl-terminal repeats 20-24 of ABP-280 had no effect on GP Ib-IX binding, but deletion of residues 2099 through 2136 within repeat 19 abolished binding. In the yeast two-hybrid system, an ABP-280 fragment comprising repeats 17-19 bound GP Ibalpha. Deletion from either end abolished binding. Individual or multiple repeats of ABP-280 were expressed as fusion protein in bacteria and purified; structural folding was evaluated, and binding to GP Ib-IX was assessed. Binding depended on the presence of repeats 17-19. None of the individual repeats were able to bind to GP Ib-IX. These findings demonstrate that residues 1850-2136 comprising repeats 17-19 contain the binding site for GP Ib-IX.

Binding Sites↗

PubMed1997

The structure of divalent cation-induced aggregates of PIP2 and their alteration by gelsolin and tau.

Phosphatidylinositol bisphosphate (PIP2) serves as a precursor for diacylglycerol and inositol trisphosphate in signal transduction cascades and regulates the activities of several actin binding proteins that influence the organization of the actin cytoskeleton. Molecules of PIP2 form 6-nm diameter micelles in water, but aggregate into larger, multilamellar structures in physiological concentrations of divalent cations. Electron microscopic analysis of these aggregates reveals that they are clusters of striated filaments, suggesting that PIP2 aggregates form stacks of discoid micelles rather than multilamellar vesicles or inverted hexagonal arrays as previously inferred from indirect observations. The distance between striations within the filaments varies from 4.2 to 5.4 nm and the diameter of the filaments depends on the dehydrated ionic radius of the divalent cation, with average diameters of 19, 12, and 10 nm for filaments formed by Mg2+, Ca2+, and Ba2+, respectively. The structure of the divalent cation-induced aggregates can be altered by PIP2 binding proteins. Gelsolin and the microtubule associated protein tau both affect the formation of aggregates, indicating that tau acts as a PIP2 binding protein in a manner similar to gelsolin. In contrast, another PIP2 binding protein, profilin, does not modify the aggregates.

Barium↗

PubMed1996

Renal epithelial protein (Apx) is an actin cytoskeleton-regulated Na+ channel.

Apx, the amphibian protein associated with renal amiloride-sensitive Na+ channel activity and with properties consistent with the pore-forming 150-kDa subunit of an epithelial Na+ channel complex initially purified by Benos et al. (Benos, D. J., Saccomani, G., and Sariban-Sohraby, S.(1987) J. Biol. Chem. 262, 10613-10618), has previously failed to generate amiloride-sensitive Na+ currents (Staub, O., Verrey, F., Kleyman, T. R., Benos, D. J., Rossier, B. C., and Kraehenbuhl, J.-P.(1992) J. Cell Biol. 119, 1497-1506). Renal epithelial Na+ channel activity is tonically inhibited by endogenous actin filaments (Cantiello, H. F., Stow, J., Prat, A. G., and Ausiello, D. A.(1991) Am. J. Physiol. 261, C882-C888). Thus, Apx was expressed and its function examined in human melanoma cells with a defective actin-based cytoskeleton. Apx-transfection was associated with a 60-900% increase in amiloride-sensitive (Ki = 3 microM) Na+ currents. Single channel Na+ currents had a similar functional fingerprint to the vasopressin-sensitive, and actin-regulated epithelial Na+ channel of A6 cells, including a 6-7 pS single channel conductance and a perm-selectivity of Na+:K+ of 4:1. Na+ channel activity was either spontaneous, or induced by addition of actin or protein kinase A plus ATP to the bathing solution of excised inside-out patches. Therefore, Apx may be responsible for the ionic conductance involved in the vasopressin-activated Na+ reabsorption in the amphibian kidney.

Actins↗

PubMed1996

Differential effects of chronic ethanol consumption on hepatic mitochondrial and cytoplasmic ribosomes.

The effects of chronic ethanol consumption on the properties of mitochondrial and cytoplasmic ribosomes were investigated in rat liver. Sedimentation properties of purified mitochondrial (55S) and cytoplasmic (80S) ribosomes were determined by analyses on sucrose density gradients. Mitochondrial ribosomes from control animals moved further in the gradients than did those isolated from ethanol-fed rats, which suggests that ethanol ribosomes have a lower molecular weight. In addition, mitochondrial from ethanol-fed animals contained a lower percentage of ribosomes present as the intact monosome, suggesting that ethanol may have an effect on the stability of the functional mitochondrial ribosomes. This was confirmed by the presence of the larger 39S subunit in preparations from ethanol-fed animals. No such ethanol-related alterations were seen with cytoplasmic ribosomes. The protein composition of mitochondrial cytoplasmic ribosomes was investigated using two-dimensional gel electrophoresis, followed by two-dimensional densitometry. As indicated by differences in protein staining intensity, ethanol consumption seemed to alter the concentration of seven mitochondrial ribosomal proteins. In contrast, no such changes were observed in the protein pattern from cytoplasmic ribosomes. Observations in this study provide for the possibility that alterations in the amounts of selected proteins in the mitochondrial ribosome lead to impaired assembly of the ribosome. These ethanol-related structural changes may be responsible for the decreased activity of mitochondrial ribosomes that results in impaired hepatic mitochondrial protein synthesis (W.B. Coleman and C.C. Cunningham, Biochim. Biophys, Acta 1058:178-186, 1991). Furthermore, this study reemphasizes the increased susceptibility of the hepatic mitochondrial translation system, compared with the cytoplasmic system to chronic ethanol consumption.

Animals↗

PubMed1995

Isolation and characterization of rat liver mitochondrial ribosomes.

A procedure has been developed that allows characterization of mitochondrial ribosomes and quantitative analysis of the relative composition of constitutive ribosomal proteins. Purified mitochondrial ribosomes were isolated from two rat livers and shown to be active in catalyzing the polymerization of phenylalanine. They differ in sedimentation and spectral properties from cytoplasmic ribosomes isolated from the same livers. The number and relative composition of proteins present in active rat liver mitochondrial ribosomes were investigated using two-dimensional nonequilibrium pH gradient electrophoresis. There were 86 proteins found associated with mitochondrial ribosomes in contrast to 70 proteins found associated with cytoplasmic ribosomes. Comparison of electrophoretic patterns revealed that cytoplasmic ribosomal proteins were considerably more basic than their mitochondrial counterparts. Densitometry demonstrated that the relative changes in the concentrations of these proteins can be measured quantitatively. These procedures, developed for use with two rat livers, allow the rat to be used as an efficient model for further studies into disease states of mitochondrial translation.

Animals↗

PubMed1995

Effect of chronic ethanol consumption on the energy state and structural stability of periportal and perivenous hepatocytes.

This study was implemented to evaluate whether perivenous cells experience functional alterations due to a deficit in oxygen tension resulting from ethanol oxidation in the periportal regions of the lobule. Periportal and perivenous hepatocytes were prepared from ethanol-fed and control animals (Lieber-DeCarli diet, 31 days). These cells were either incubated at various oxygen tensions by varying the composition of the gases utilized to equilibrate the incubation buffers (0, 5, 25, and 95% oxygen) or they were unincubated. They were analyzed for adenine nucleotide and inorganic phosphate concentrations and from these data phosphorylation potentials and energy charge values were determined. Under highly aerobic conditions no differences were observed in the energy states of the cells irrespective of their source (control vs ethanol-fed; periportal vs perivenous). The ATP concentrations, phosphorylation potentials, and energy charge values indicated that the energy states of cells from both ethanol-fed and control rats were maintained at relatively high levels in incubations with 5 and 25% oxygen. However, unincubated cells and those incubated at 0% oxygen demonstrated lowered energy states and the decreases were most striking in hepatocytes from ethanol-fed animals. Measurements of LDH loss and trypan blue exclusion indicate that cell leakage and viability loss occur when cells are incubated under anoxic and hypoxic conditions. At low oxygen tensions perivenous cells from ethanol-fed rats demonstrated much greater loss of structural stability than did the other cell preparations. These observations indicate that decreased energy state is one factor which contributes to cell damage in hepatocytes from ethanol-fed animals. Moreover, perivenous cells from ethanol-fed animals seem to be particularly vulnerable to damage under hypoxic conditions.

Adenosine Diphosphate↗

PubMed1995

Actin polymerization and intracellular solvent flow in cell surface blebbing.

The cortical actin gel of eukaryotic cells is postulated to control cell surface activity. One type of protrusion that may offer clues to this regulation are the spherical aneurysms of the surface membrane known as blebs. Blebs occur normally in cells during spreading and alternate with other protrusions, such as ruffles, suggesting similar protrusive machinery is involved. We recently reported that human melanoma cell lines deficient in the actin filament cross-linking protein, ABP-280, show prolonged blebbing, thus allowing close study of blebs and their dynamics. Blebs expand at different rates of volume increase that directly predict the final size achieved by each bleb. These rates decrease as the F-actin concentration of the cells increase over time after plating on a surface, but do so at lower concentrations in ABP-280 expressing cells. Fluorescently labeled actin and phalloidin injections of blebbing cells indicate that a polymerized actin structure is not present initially, but appears later and is responsible for stopping further bleb expansion. Therefore, it is postulated that blebs occur when the fluid-driven expansion of the cell membrane is sufficiently rapid to initially outpace the local rate of actin polymerization. In this model, the rate of intracellular solvent flow driving this expansion decreases as cortical gelation is achieved, whether by factors such as ABP-280, or by concentrated actin polymers alone, thereby leading to decreased size and occurrence of blebs. Since the forces driving bleb extension would always be present in a cell, this process may influence other cell protrusions as well.

Actins↗

PubMed1994

Differential effects of ethanol consumption on synthesis of cytoplasmic and mitochondrial encoded subunits of the ATP synthase.

The relative concentrations of several subunits of the mitochondrial F0.F1-ATP synthase were determined in mitochondria and submitochondrial particles prepared from the livers of ethanol-fed and control rats. The polypeptides were separated by sodium dodecylsulfate-polyacrylamide gel electrophoresis and the stained gels were analyzed by densitometry for the relative concentrations of the ATP synthase subunits. A significant decrease in the relative concentration of the mitochondrial gene product, ATPase subunit 8, was observed in mitochondria and submitochondrial particles from ethanol-fed animals. The relative concentration of the other mitochondrial encoded ATPase subunit, ATPase 6, was also depressed, as confirmed in submitochondrial particles. In contrast, there were no significant ethanol-related depressions in subunits alpha, beta, and OSCP of the F0.F1 or the adenine nucleotide carrier in intact mitochondria. These results demonstrate that ethanol consumption causes a decrease in the content of mitochondrial synthesized subunits 6 and 8 whereas no effect is exerted on the concentrations of nuclear gene products of the ATP synthase complex. Likewise, the adenine nucleotide transporter, also a nuclear gene product, is unaffected by ethanol consumption.

Alcohol Drinking↗

PubMed1994

Alcoholism and myocardial energy metabolism.

A review of the effects of chronic ethanol consumption on myocardial energy metabolism in animal models reveals that alterations in cardiac function are not accompanied by changes in the levels of the high-energy metabolites, ATP, and creatine phosphate. There are minor alterations in mitochondrial ultrastructure and function that appear to be accentuated by lowered nutrient intake. Observations to date indicate that, in animal models, there is an interaction between chronic ethanol consumption and caloric deprivation in eliciting alterations in myocardial energy metabolism. Furthermore, ethanol-related ultrastructural changes and depressed mitochondrial function are much more demonstrable in liver than in heart, suggesting strongly that the myocardium is less susceptible to the deleterious effects of alcohol than is the liver.

Alcoholism↗