[Show abstract][Hide abstract] ABSTRACT: Changes in isoform composition, secondary structure, and titin phosphorylation in Mongolian gerbil (Meriones unguiculatus) cardiac muscle were studied after 12-day-long space flight onboard the Russian spacecraft Foton-M3. The effect of titin on the actin-activated myosin ATPase activity at pCa 7.5 and 4.6 was also studied. Almost twofold increase in titin long N2BA isoform content relative to that of short N2B isoform was found on electrophoregrams of cardiac muscle left ventricle of the flight group gerbils. Differences in secondary structure of titin isolated from cardiac muscle of control and flight groups of gerbils were found. An increase in phosphorylation (1.30-1.35-fold) of titin of cardiac muscle of the flight group gerbils was found. A decrease in activating effect of titin of cardiac muscle of the flight group gerbils on actomyosin ATPase activity in vitro was also found. The observed changes are discussed in the context of M. unguiculatus cardiac muscle adaptation to conditions of weightlessness.
[Show abstract][Hide abstract] ABSTRACT: It has been revealed for the first time that sodium fullerenolate Na(4)[C(60)(OH)(∼30)] (NaFL), a water soluble polyhydroxylated fullerene derivative, destroys amyloid fibrils of the Aβ(1-42) peptide in the brain and prevents their formation in in vitro experiments. The cytotoxicity of NaFL was found to be negligibly low with respect to nine different culture cell lines. At the same time, NaFL showed a very low acute toxicity in vivo. The maximal tolerable dose (MTD) and LD50 for NaFL correspond to 1000 mg kg(-1) and 1800 mg kg(-1), respectively, as revealed by in vivo tests in mice using intraperitoneal drug injection. The observed pronounced anti-amyloid activity and low toxicity of NaFL make it a very promising lead drug for the development of potent fullerene-based therapeutic approaches for the treatment of amyloidoses, such as Alzheimer's disease and others.
[Show abstract][Hide abstract] ABSTRACT: It has been shown for the first time by transmission electron microscopy that the hydrated fullerene C60 inhibited the fibrillization of amyloid-beta25-35 peptide. The fullerene affected the amyloid-beta25-35 assembly, manifesting its anti-amyloidogenic capacity. Our in vivo investigations demonstrated also that a single intracerebroventricular injection of the C60 hydrated fullerene at a dose of 7.2 nmol/ventricle significantly improved the performance of the cognitive task in control rats. The intracerebroventricular injection of the C60 hydrated fullerene (3.6 nmol/ventricle) prevented the impairment of performance of the cognitive task induced by amyloid-beta25-35 (22.5 nmol/ventricle). The results obtained may be useful in the development of therapy of Alzheimer's disease.
Journal of Nanoscience and Nanotechnology 03/2007; 7(4-5):1479-85. · 1.15 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Amyloid oligomers, protofibrils, and fibrils of various amyloidogenic proteins are known to induce cell death. Tetracycline
prevents the formation of fibrils of Aβ peptide and other amyloidogenic proteins and decomposes mature fibrils. It was previously
shown that sarcomeric cytoskeletal proteins of the titin family (protein X, protein C, and protein H) in vitro form amyloid
fibrils and tetracycline decomposes them. In this work, the concentration and time dependence of the survival of polymorphonuclear
leukocytes in the presence of protein X amyloid fibrils is demonstrated. It is also shown that the survival rate increases
as fibrils are decomposed by tetracycline. The antibiotic itself is found to be nontoxic. The results obtained show that this
approach can be used to evaluate the efficiency of drugs that prevent or rectify amyloidoses.
[Show abstract][Hide abstract] ABSTRACT: The antiamyloidogenic effect of hydrated fullerence C60 HyFn was shown by electron microscopy. It was found that fullerene binds to growing fibrils formed by the [beta]-amyloid
peptide Aβ25–35 and thus prevents their further growth and interferes with the formation of new fibrils. Instead of long broad helically
twisted ‘ribbons’ formed by Aβ25–35 in the absence of fullerene, short narrow protofibrils form in its presence. These results suggest that fullerenes can be
useful in treatment for Alzheimer’s disease.
[Show abstract][Hide abstract] ABSTRACT: It is known that amyloid oligomers, protofibrils, and fibrils induce cell death, and antibiotic tetracycline inhibits the fibrillization of beta amyloid peptides and other amyloidogenic proteins and disassembles their pre-formed fibrils. Earlier we have demonstrated that sarcomeric cytoskeletal proteins of the titin family (X-, C-, and H-proteins) are capable to form in vitro amyloid fibrils, and tetracycline effectively destroys these fibrils. Here we show that the viability of polymorphonuclear leukocytes in the presence of X-protein amyloids depends on the concentration of amyloid fibrils of X-protein and the time of incubation. In addition to the disaggregation of X-protein fibrils, tetracycline eliminated the cytotoxic effect of the protein. The antibiotic itself did not show a toxic effect, and the cell viability in its presence even increased. Our results evidence the potential of this approach for evaluating the effectiveness of drugs preventing or treating amyloidoses.
[Show abstract][Hide abstract] ABSTRACT: Using the system of F-actin paracrystals, we have obtained electron microscopic evidence that projectin from synchronous flight muscles of Locusta migratoria binds to actin filaments in the same fashion as skeletal titin. Control actin paracrystals formed in the presence of Mg(2+) ions have great width and length and blunted ends. The addition of either projectin or titin results in disruption of compact ordered packing of F-actin in paracrystals and leads to the formation of loose filament bundles with smaller diameters and tapered ends. It is also accompanied with the appearance of individual actin filaments in considerable amounts. The effect becomes more pronounced with the increase in concentrations of added projectin or titin. Possible physiological implications of projectin-actin interactions are discussed.
[Show abstract][Hide abstract] ABSTRACT: To elucidate the functional importance of the appearance of atrial myosin light chains (ALC) in ventricles in some cardiomyopathies, a partial (75%) substitution of myosin light chains 1 and 2 of the left ventricle for ALC-1 and ALC-2 was carried out in vitro. It is shown that this substitution does not lead to changes in shapes and sizes of the filaments formed by hybrid myosin but causes changes in the shape of myosin heads. The replacement of the light chains increases the actin-activated ATPase activity of hybrid myosin by 63%. The results obtained are evidence that the substitution of ventricle myosin light chains with atrial ones is of physiological importance for the improvement of myosin functional properties and thereby for the compensation of the insufficiency of myocardium in dilated cardiomyopathy. These data and the data on dynamics of ALC-1 in diseased ventricles are important for creating the prognostic test of dilated cardiomyopathy development based on the registration of changes in the isoform composition of cardiac myosin light chains.
[Show abstract][Hide abstract] ABSTRACT: To elucidate the role of titin in the onset and development of dilated cardiomyopathy, the structure and functional properties of this protein from pathological myocardium (human left ventricle) were studied. By the use of SDS gel electrophoresis, a decrease in molecular weight of titin in dilated cardiomyopathy compared with norm (pig left ventricle) was revealed. The decrease correlated with the stage of the disease. A decrease in the length of molecules of pathological forms of titin was also found by electron microscopy, which confirms the results of electrophoresis tests. It was shown that, unlike titin from healthy muscle, pathological forms of titin do not activate but inhibit the main functional properties of control myosin: the actin-activated ATPase activity and its Ca2+ sensitivity. The direction of the changes in structure and functional properties of titin allows one to conclude about its contribution to the development of the pathology studied.
[Show abstract][Hide abstract] ABSTRACT: Changes in the molecular weight and functional properties of the C and X proteins from skeletal muscles and the C protein from the cardiac muscle of hibernating ground squirrels Citellus undulatus at different stages of the hibernation were studied. A decrease in the molecular weight of the C protein from fast fibers of skeletal muscles of hibernating ground squirrels compared with awakening and active animals was revealed. The appearance of shorter molecules of the C protein upon hibernation was accompanied by a lowering of its capacity to enhance the actin-activated ATPase activity of control myosin and by the inhibition of its Ca(2+)-sensitivity. No similar changes were observed for the skeletal X protein and the cardiac C protein. The influence of the skeletal C protein on the main functional properties of myosin allows one to draw a conclusion about its contribution to the inhibition of contractile activity of skeletal muscles upon hibernation. The physiological significance of the changes in the C protein upon hibernation is discussed in connection with similar changes in some cardiomyopathies.
[Show abstract][Hide abstract] ABSTRACT: The ability of hibernating and arousing ground squirrels' myosins to bind the key enzyme of glycolysis was found to be significantly lower than that of active animals. The findings suggest considerable changes in the myosin heavy and light chain composition occurring during hibernation, as well as a major contribution of the myosin in inhibiting the contractile ability of the skeletal muscles during hibernation.
Rossiĭskii fiziologicheskiĭ zhurnal imeni I.M. Sechenova / Rossiĭskaia akademiia nauk 01/1997; 83(11-12):143-50.
[Show abstract][Hide abstract] ABSTRACT: It has been previously shown by us that phosphofructokinase (F-protein) binds to rabbit skeletal muscle F-actin and reconstituted thin filaments forming ordered bundles. Upon low molar ratios of phosphofructokinase to actin in the complex bundles the enzyme molecules are arranged between actin filaments regularly in the form of crossbridges. The increase of phosphofructokinase: actin ratio up to equimolar one and more leads to the filling of the space between actin filaments with phosphofructokinase-molecules. In these bundles the inclined cross striation with axial repeat of about 7.0 nm is clearly seen. Optical diffraction analysis of the micrographs revealed new features in the structure of such complexes in comparison with F-actin and reconstituted thin filaments. Optical diffraction patterns from F-actin and reconstituted thin filaments exhibit the first (35.5 nm) and sixth (5.9 nm) layer lines typical of F-actin helix structure. On the optical diffraction patterns from the complex bundles the meridional reflection of about 7.2nm is present, that is not observed on the optical diffraction patterns from F-actin alone. This reflection is characteristic of optical diffraction- and X-ray patterns of myosin filaments and is the sixth order of axial period of their structure (42.9 nm/6). The structural changes occurring upon binding is supposed to be important for the mutual regulation of functional activity of enzymes and actin-containing filaments in muscle.
[Show abstract][Hide abstract] ABSTRACT: The ultrastructure of sarcomeres of glycerinated rabbit psoas muscle was studied using freeze-fracture-etching, freeze-drying and optical diffraction techniques in comparison with the investigation of this muscle by plastic sections and negative staining methods. In frozen and dried myofibrils isolated from the above muscle the stripes of minor proteins location in A- and I-disks were clearly seen. The pivot structure in thick filaments was revealed in longitudinal fractures of the muscle. The ordered arrangement of myosin heads (crossbridges) associated with actin filaments was preserved in frozen longitudinal fractures as evidenced by optical diffraction. Freeze etching technique allowed to revealed some details of Z-line structure: alpha-actinin bridges connecting the ends of actin filaments of neighbouring sarcomeres and to preserve the lateral struts between actin filaments in I-disks.
[Show abstract][Hide abstract] ABSTRACT: Cardiac myofibrils were isolated from rabbit ventricular muscle by a method that preserves well the integrity of the A-band structure. For the first time electron microscopic observations using the negative staining method revealed, in cardiac A-bands, a full complement of pronounced transverse stripes which indicate the locations of minor proteins in skeletal muscles. The manifestation of some transverse stripes in the cardiac A-band was shown to depend on the duration of muscle incubation in a Ca2(+)-depleting and ATP-free solution before its homogenization into myofibrils. The clear visibility of fine structural details in electron micrographs allowed us to resolve morphological features specific for cardiac muscle at both the central and end parts of the A-bands. The myofibrils demonstrated here are expected to be useful for elucidating the fine structure of cardiac thick filaments and in particular the locations of minor proteins.
Journal of Molecular Biology 01/1990; 210(3):655-8. · 3.91 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To determine the location of F-protein binding sites on myosin, the interaction of F-protein with myosin and its proteolytic fragments in 0.1 M KCl, 10 mM potassium phosphate, pH 6.5, has been investigated using sedimentation, electron microscopy and optical diffraction methods. Sedimentation experiments show that F-protein can bind to myosin and myosin rod rather than to light meromyosin or subfragment-1. The F-protein binding to myosin and rod is of a similar character. The calculated values of the constants of F-protein binding to myosin and rod are 2.6 X 10(5) M-1 and 2.1 X 10(5) M-1, respectively. The binding sites are probably located on the subfragment-2 portion of the myosin molecule. The number of the F-protein binding sites calculated per chain weight of 80,000 is 5 +/- 1. Electron microscopic observations confirm the sedimentation results. F-protein does not bind to light meromyosin paracrystals, but decorates myosin and rod filaments with the interval of 14.3 nm regardless of whether F-protein is added prior to or after filamentogenesis. The comparison of optical diffraction patterns obtained from myosin and rod filaments with those from decorated ones reveals the marked enhancement of meridional reflection at (14.3 nm)-1 in the latter case. Neither the increase in ionic strength from 0.1 to 0.15 and pH from 6.5 to 7.3 nor substitution of potassium phosphate buffer by imidazole-HCl buffer, or Tris-HCl influences F-protein binding to myosin and rod filaments as visualized by electron microscopy. The possible significance of F-protein location in the thick filament structure is discussed.
Journal of Muscle Research and Cell Motility 01/1987; 7(6):481-90. · 1.36 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To determine the localization of F-protein binding sites on myosin, the interaction of F-protein with myosin and its proteolytic fragments in 0.1 M KCl, 10 mM K-phosphate pH 6.5 was studied, using sedimentation, electron microscopic and optical diffraction methods. Sedimentation experiments showed that F-protein binds to myosin and myosin rod rather than to light meromyosin or S-1. The F-protein binding to myosin and rod is of a similar character. The calculated values of the constants of F-protein binding to myosin and rod are 2.6 X 10(5) M-1 and 2.1 X 10(5) M-1, respectively. The binding sites are probably located on the subfragment-2 portion of the myosin molecule. The number of F-protein binding sites on myosin calculated per chain weight of 80 000 is 5 +/- 1. The sedimentation results were confirmed by electron microscopic data. F-protein does not bind to light meromyosin paracrystals, but decorates myosin and rod filaments with the interval of 14.3 nm regardless of whether F-protein is added before or after filamentogenesis. A comparison of optical diffraction patterns obtained from myosin and rod filaments with those from decorated ones revealed a marked enhancement of meridional reflection at (14.3 nm)-1 in the latter case.
[Show abstract][Hide abstract] ABSTRACT: It was shown for the first time that skeletal muscle sarcomeric proteins of the titin family (X-, C- and H-proteins) are able to form in vitro amyloid aggregates of different types: granular aggregates, protofibrils, helically twisted ribbons, linear fibrils, and bundles of linear fibrils. Their amyloid nature was confirmed by electron, polarization, and fluorescence microscopy and by spectral methods. As opposed to other amyloidogenic proteins, X-, C-, and H-proteins easily form amyloids under mild conditions close to physiological ones (pH, ionic strength, temperature). Like amyloid fibrils of Abeta-peptide and tau protein in Alzheimer's disease, amyloid aggregates formed by X-, C-, and H-proteins are destroyed by the antibiotic tetracycline. Thus, new proteins-precursors of amyloids and possible participants of amyloidoses in muscles were discovered. Further study of in vitro amyloidogenesis of these proteins would help to find approaches to controlling this process in organs and tissues.