Evidence for a membrane surface defect in erythrocytes in Huntington's disease

Electron spin resonance studies of erythrocyte membranes from patients with Huntington's disease and normal controls have been performed. Intact erythrocytes in each case were either untreated or subjected to proteolysis with the membrane impermeable enzymes, pronase, chymotrypsin, or trypsin. Membrane ghosts were prepared from untreated and protease-treated intact cells and spin labeled with protein- or lipid-specific spin probes. Comparison of the resulting electron spin resonance spectra confirmed our previous findings that in untreated samples the relevant parameter of the protein-specific spin label was increased in Huntington's disease (P < 0.02) suggesting an altered physical state of membrane proteins in this disorder, while no difference in erythrocyte lipid fluidity could be discerned. No significant difference in the physical state of membrane proteins in Huntington's disease and control as judged as spin labeling methods could be detemined in membrane ghosts prepared from protease-treated intact cells. These results, together with the known specificity of the proteases used in this study, suggest that a molecular defect in Huntington's disease erythrocytes is manifested in an exterior part of a membrane protein and supports our hypothesis that Huntington's disease is associated with a generalized cell membrane defect.     

Electron spin resonance investigations of membrane proteins in erythrocytes in muscle diseases. Duchenne and myotonic muscular dystrophy and congenital myotonia.

Comparison of electron spin resonance spectra of spin labeled erythrocyte membranes from patients with the dystrophic conditions Duchenne and myotonic muscular dystrophy with those of normal controls suggests that alterations in membrane protein conformation and/or organization are present in these disease states. These protein alterations are not apparent in the non-dystrophic disease congenital myotonia. The results suggest a correlation between changes in the physical state of proteins in membranes with the presence of dystrophy. In addition, the present results from erythrocytes lend support for the concept of a generalized membrane defect in these diseases.     

Electron spin resonance investigations of membrane proteins in erythrocytes in muscle diseases. Duchenne and myotonic muscular dystrophy and congenital myotonia

Comparison of electron spin resonance spectra of spin labeled erythrocyte membranes from patients with the dystrophic conditions Duchenne and myotonic muscular dystrophy with those of normal controls suggests that alterations in membrane protein conformation and/or organization are present in these disease states. These protein alterations are not apparent in the nondystrophic disease congenital myotonia. The results suggest a correlation between changes in the physical state of protein in membranes with the presence of dystrophy. In addition, the present results from erythrocytes lend support for the concept of a generalized membrane defect in these diseases.     

Electron spin resonance, hematological, and deformability studies of erythrocytes from patients with Huntington's disease.

Electron spin resonance, hematologic, and deformability studies of erythrocytes from patients with Huntington's disease have been performed A decreased deformability of Huntington's disease erythrocytes compared to normal controls was demonstrated. No difference in erythrocyte hematologic indices, osmotic fragility, reticulocyte counts, or intracellular Na+ concentration was found. Huntington's disease serum had no demonstrable effect on electron spin resonance parameters of a protein-specific spin label attached to membrane proteins in control erythrocytes compared to the effect of control serum. This finding suggests that under the conditions employed no serum component or circulating factor is responsible for the changes in the physical state of membrane proteins in Huntington's disease erythrocytes (Butterfield, D.A., Oeswein, J.Q. and Markesbery, W.R. (1977) Nature 267, 453--455). No alteration in lipid fluidity of Huntington's disease erythrocyte membranes could be discerned suggesting that the underlying molecular defect in Huntington's disease involves a membrane protein. The results of the present studies on erythrocytes strongly support the concept that Huntington's disease is associated with a generalized membrane abnormality.     

Progressive muscular dystrophy type Duchenne. I. Spin label studies on the physico-chemical state of erythrocyte membranes.

Electron spin resonance studies of erythrocyte membranes from patients with Duchenne muscular dystrophy exhibit changes in the physical state of lipids and proteins in membranes when compared to membranes from normal subjects. The results suggest that the alterations in membrane lipid-protein organization are present in this disease.     

Electron spin resonance studies of an animal model of human congenital myotonia: increased erythrocyte membrane fluidity in rats with 20,25-diazacholesterol-induced myotonia.

Electron spin resonance experiments have been performed on erythrocyte membranes from rats with myotonia induced by treatment with 20,25-diazacholesterol. The results suggest that erythrocyte membranes in this animal model of human congenital myotonia possess a highly significantly increased surface membrane fluidity compared to that of controls. Alterations in the physical state of membrane proteins were not apparent. These findings, also present in human congenital myotonia [Butterfield, Chesnut, Roses & Appel, 1976, Nature (London) 263:159; Butterfield, 1977 (Submitted for publication)], strengthen the concepts that increased membrane fluidity is associated with the presence of myotonia and that congenital myotonia may be a diffuse membrane disease.     

Electron spin resonance studies of an animal model of human congenital myotonia: Increased erythrocyte membrane fluidity in rats with 20,25-diazacholesterol-induced myotonia

Summary Electron spin resonance experiments have been performed on erythrocyte membranes from rats with myotonia induced by treatment with 20,25-diazacholesterol. The results suggest that erythrocyte membranes in this animal model of human congenital myotonia possess a highly significantly increased surface membrane fluidity compared to that of controls. Alterations in the physical state of membrane proteins were not apparent. These findings, also present in human congenital myotonia [Butterfield, Chesnut, Roses & Appel, 1976,Nature (London)263:159; Butterfield, 1977 (Submitted for publication)], strengthen the concepts that increased membrane fluidity is associated with the presence of myotonia and that congenital myotonia may be a diffuse membrane disease.     

Alternations in lipid membrane fluidity and the physical state of cell-surface sialic acid in zinc-deficient rat erythrocyte ghosts

Erythrocyte ghosts, prepared from the blood of rats fed zinc-deficient diets, were evaluated for membrane fluidity and surface sialic acid properties using spin-labeled probes and electron spin resonance (ESR) spectroscopy. These physical parameters of the erythrocyte ghosts from the zinc-deficient group were compared to those for erythrocyte ghosts obtained from ad libitum and pair fed controls consuming zinc-adequate diets. As the animals became progressively zinc deficient, the erythrocyte ghost membranes became more fluid than those from the control groups. In addition, the apparent rotational correlation time of Tempamine spin probes on surface sialic acid residues was smaller for the zinc deficient group, indicative of an increased rotational mobility of the spin label. These results suggest that zinc deficiency can have pronounced effects on the physical state of membrane bilayer lipids and cell surface carbohydrates and supports the view that many of the pathological signs of zinc deficiency are due to a general membrane defect.     

Effects of intramembrane particle aggregation on erythrocyte membrane fluidity: an electron spin resonance study in normal and in dystrophic subjects

Mobilization and aggregation of intramembrane particles (IMPs) are physiological events observed in various cells. In erythrocyte membranes, aggregation of IMPs can be induced by the exposure of partially desprectrinized erythrocyte membranes to acidic pH. We investigated the association between IMPs aggregation, protein mobility, and membrane fluidity in erythrocyte membranes of healthy controls and Duchenne muscular dystrophy (DMD) patients by using electron spin resonance and specific spin labels for membrane proteins and lipids. In erythrocyte membranes of control subjects, the partial spectrin removal induced a decreased segmental motion of protein spin label indicating an increase of protein-protein interactions. Stearic acid spin labels 5- and 16-(N-oxyl-4,4'-dimethyloxazolidine) showed that the treatment induces an increase of membrane fluidity. In DMD patients, both treated and untreated erythrocyte membranes showed changes of membrane fluidity when compared to those of the controls. Our results suggest that defects in the interactions between skeletal proteins and/or between membrane and skeleton components may contribute to the alterations of erythrocyte membranes in DMD.     

Huntington disease and Tourette syndrome. I. Electron spin resonance of bed ghosts.

Abnormalities in the electron spin resonance (ESR) of nitroxide-labeled red blood cell membranes have been reported in Huntington disease (HD). Because of the importance of verifying a general membrane defect in this disease, we have examined 13 unmedicated HD patients of all grades of severity, with a duration of symptoms from 3 to 20 years and including juvenile and rigid cases. No significance differences in the ESR of controls, HD patients, and three Tourette syndrome patients were found.     

Quinolinic acid, an endogenous metabolite with neurotoxic properties, alters the physical state of membrane proteins in human erythrocytes

Quinolinic acid (2,3-pyridinedicarboxylic acid), an endogenous, tryptophan metabolite, is neurotoxic when injected into rat striatum (1). To begin to investigate the molecular interactions of quinolinic acid with membranes, electron spin resonance studies of the effects of this neurotoxin on the physical state of lipids, proteins, and cell-surface sialic acid in human erythrocyte ghosts have been performed. Quinolinic acid induced a highly significant alteration in the physical state of membrane proteins (P less than 0.01) while that of sialic acid and membrane lipids was unaffected. These results are similar to those induced by ibotenic acid, an exogenous neurotoxin, and are discussed with reference to possible molecular characteristics of the interaction of these neurotoxins with membrane proteins.     

Carriers of ataxia-telangiectasia gene display additional protein fraction and changes in the environment of SH groups in erythrocyte membrane

Additional protein fraction migrating slower than spectrin has been detected in erythrocyte membranes from an ataxia-telangiectasia (A-T) patient and from his mother (A-T heterozygote). In erythrocyte membranes labelled with maleimide spin label changes in signal of the weakly immobilized spin label as related to that of strongly immobilized one (w/s) were noted. In comparison to age-matched control groups the values of w/s were lower in A-T heterozygotes (ten persons) and higher in A-T homozygotes (four persons). In control persons the values of w/s increased with age, whereas in families with A-T no significant differences in this parameter were noted between children and parents. The presence of additional protein fraction in erythrocytes membranes of A-T patient and A-T heterozygote indicates that these phenotypes can be differentiated from the healthy control persons for the first time on the basis of changes detected in the erythrocytes. This change in erythrocyte membrane may explain the decrease in the w/s parameter of electron spin resonance in A-T heterozygotes. On the other hand increased values of w/s in A-T patients may be caused by disease process.     

Temperature-dependent abnormalities of the erythrocyte membrane in porcine malignant hyperthermia

The temperature dependence of ATPase activities and stearic acid spin label motion in red blood cells of normal and MH-susceptible pigs have been examined. Arrhenius plots of red blood cell ghost Ca-ATPase and calmodulin-stimulable Ca-ATPase activities were identical for both normal and MH erythrocyte ghosts. Arrhenius plots of Mg-ATPase activity exhibited a break (defined as a change in slope) at 24 degrees C in both MH and normal erythrocyte ghosts. However, below 24 degrees C the apparent activation energy for this activity was less in MH than normal ghosts. To determine whether breaks in ATPase Arrhenius plots could be correlated with changes in the physical state of the red blood cell membrane, the spin label 16-doxyl-stearate was introduced into the bilayer of both erythrocyte ghosts and red blood cells. With both ghosts and intact cells, at each temperature examined, the mobility of the probe in the lipid bilayer, as measured by electron paramagnetic resonance, was greater in normal than in MH membranes. While there were no breaks in Arrhenius plots for probe motion in the erythrocyte ghosts, the apparent activation energy for probe motion was significantly greater in normal than in MH ghost membranes. While there was no break in the Arrhenius plot of probe motion in normal intact red blood cell membranes, there were breaks in the Arrhenius plot of probe motion at both 24 and 33 degrees C in intact MH red blood cell membranes. Based on the altered temperature dependence of Mg-ATPase activity and spin probe motion in membranes derived from MH red blood cells, we conclude that there may be a generalized membrane defect in MH pigs which is reflected in the red blood cell as an altered membrane composition or organization.     

The mobility and reactivity of maleimide-binding proteins in the rat erythrocyte membrane. Effects of dietary zinc deficiency and incubation with zinc in vitro

Erythrocyte ghosts, prepared from rats fed zinc-deficient diets, were analyzed for the mobility of membrane proteins by electron spin resonance spectroscopy of the sulfhydryl-binding spin probe, 4-maleimido-2,2,6,6-tetramethylpiperidine-N-oxyl. Compared with erythrocyte membranes from rats fed zinc-adequate diets ad libitum or pair-fed, erythrocyte membranes from zinc-deficient rats had a significantly increased ratio of weakly immobilized to strongly immobilized probe-binding proteins. This suggests that dietary zinc deficiency causes a conformational change in erythrocyte membrane proteins. Dietary zinc deficiency did not significantly affect N-ethylmaleimide (NEM)-induced thermal sensitivity or NEM-induced mechanical fragility in rat erythrocytes; however, the addition of zinc in vitro to red cells significantly inhibits NEM-induced mechanical fragility.     

Structural alterations of the human erythrocyte membrane upon influenza virus attachment

Molecular events on the human erythrocyte membrane subsequent to influence virus binding were investigated by electron spin resonance (ESR) measurements after spin labeling of the cell membrane at different positions. Virus binding affected the glycocalyx structure as well as the physical state of the cytoskeleton at the inner leaflet, but not the lipid phase. A lateral reorganization of spin-labeled glycophorin was not indicated after virus attachment.     

Electron spin resonance studies of the effects of naturally-occurring excitotoxic amino acid analogues on the physical state of membrane proteins in human erythrocytes

The interaction of the neurotoxic natural products, kainic and ibotenic acids, both of which are also excitatory neurotransmitters and amino acid analogues of glutamic acid, along with the latter compound, with human erythrocyte membranes has been investigated by electron spin resonance methods. Only ibotenic acid caused a statistically significant alteration in the physical state of membrane proteins (P = 0.01) while none of these excitotoxins measurably affected motion of membrane lipids. In order to further investigate some of the molecular characteristics of ibotenic acid that may have contributed to its effect on the conformation of membrane proteins, similar spin labeling studies were performed employing the decarboxylation product and parent ring compound of this excitotoxin, muscimol and isoxazole, respectively. No effect of either of these latter compounds was observed suggesting that the carboxylic acid group of ibotenic acid is essential for its interaction with membrane proteins. These results are discussed in relation to the known different neurotoxic and physiological effects of kainic and ibotenic acids and muscimol.     

Selective labeling of membrane protein sulfhydryl groups with methanethiosulfonate spin label

Electron paramagnetic resonance was used to characterize the first use of a thiol-specific spin label in membranes. Procedures for use of the spin-label, 1-oxyl-2,2,5,5-tetramethyl-Δ³-pyrroline-3-methyl (methanethiosulfonate MTS) covalently attached to membrane proteins in human erythrocyte membranes are reported. The major findings are: (1) MTS was found to be thiol-specific in membranes as it is for soluble proteins; (2) MTS labels ghost proteins in as few as 30 min at room temperature, providing a distinct advantage when sensitive or fragile membranes are to be used; (3) the distribution of the spin label suggests that the major cytoskeletal protein, spectrin, and the major transmembrane protein (Band 3) incorporate the highest percentage of spin label. This procedure expands the tools with which the researcher can investigate the physical state of membrane proteins and its alteration upon interaction of membrane perturbants or in pathological conditions.     

Membrane-altering effects of velnacrine and N-methylacridinium: relevance to tacrine and Alzheimer's disease.

The interaction of pharmacological agents potentially useful in Alzheimer's disease, 9-amino-1,2,3,4-tetrahydroacridine (THA or tacrine) and its major metabolite velnacrine (or HP-029), along with related compounds with cytoskeletal proteins in human erythrocyte membrane was investigated using electron paramagnetic resonance spin labeling techniques. The results suggest that: (1) the position of the positive charge of tacrine may be important in the mechanism of its interaction with the membrane cytoskeleton; (2) like tacrine, velnacrine also strengthens cytoskeletal protein-protein interactions in erythrocyte membranes, but appears to be only about half as potent as tacrine. These results are discussed with relevance to therapeutic use of these agents in Alzheimer's disease.     

Lipid composition and fluidity of liver plasma membranes from rats with chronic dietary iron overload

Liver plasma membranes isolated from rats with chronic dietary iron overload showed a large modification of their phospholipid fatty acid composition. Specifically, a significant decrease in polyunsaturated fatty acids and a parallel increase in saturated fatty acids was observed. This pattern was consistent with thein vivo occurrence of lipoperoxidative reactions in the liver plasma membranes. However, neither change in the cholesterol/phospholipid molar ratio nor in the lipid/protein ratio was detected. Direct measurement of the plasma membrane fluidity state by electron spin resonance spectrometry did not reveal any difference between control and iron-treated rats. These findings indicate that chronic dietary iron overload can induce lipid peroxidation of rat liver plasma membranes, but this event does not bring about modification in the physical state of the membrane.     

Alteration of membrane conductivity and fluidity in human erythrocyte membranes and erythrocyte ghosts following gamma-irradiation

Alterations of electrical properties of human erythrocyte membranes induced by gamma irradiation have been studied by means of conductivity measurements in the frequency range from 10 KHz to 100 MHz. The results clearly demonstrate the role played by haemoglobin in the structural modification of the membrane produced by gamma irradiation. Further support for this point of view has been derived from electron spin resonance measurements carried out on the same samples, labelled with different spin labels which probe the outer half layer of membrane at different penetration levels.