[Show abstract][Hide abstract] ABSTRACT: Changes of titin and myosin heavy chain isoform composition in skeletal muscles (m. soleus, m. gastrocnemius, m. tibialis anterior, m. psoas major) in Mongolian Gerbil (Meriones unguiculatus) were investigated after 12-day spaceflight on board of Russian space vehicle “Foton-M3.” In m. psoas and m. soleus in the gerbils from “Flight” group the expected increase in the content of fast myosin heavy chain isoforms (IIxd and IIa, respectively) were observed. No significant differences were found in the content of IIxd and IIa isoforms of myosin heavy chain in m. tibialis anterior in the gerbils from control group as compared to that in “Flight” group. An unexpected increase in the content of slow myosin heavy chain I isoform and a decrease in the content of fast IIx/d isoform in m. gastrocnemius of the gerbils from “Flight” group were observed. In skeletal muscles of the gerbils from “Flight” group the relative content of titin N2A-isoform was reduced (by 1.2–1.7 times), although the content of its NT-isoform, which was revealed in striated muscles of mammals in our experiments earlier, remained the same. When the content of titin N2A-isoform was decreased, no predictable abnormalities in sarcomeric structure and contractile ability of skeletal muscles in the gerbils from “Flight” group were found. An assumption on the leading role of titin NT-isoform in maintenance of structural and functional properties of striated muscles of mammals was made.
[Show abstract][Hide abstract] ABSTRACT: A comparative estimation of the ability of complexes of fullerene C60 with polyvinylpyrrolidone and fullerene C60 derivatives (the sodium salt of the polycarboxylic derivative of fullerene C60, sodium fullerenolate), has been carried out. The fullerenes destroyed amyloid fibrils of the Abeta(1-42) peptide of the brain and the muscle X-protein. A study of the effect of fullerenes on muscle actin showed that complexes of fullerene C60 with polyvinylpyrrolidone and sodium fullerenolate did not prevent the filament formation of actin, nor did they destroy its filaments in vitro. Conversely, sodium salt of the polycarboxylic derivative of fullerene C60 destroyed actin filaments and prevented their formation. It was concluded that sodium fullerenolate and complexes of fullerene C60 with polyvinylpyrrolidone are the most effective antiamyloid compounds among the fullerenes examined.
[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: The antiamyloidogenic capacity of water-soluble nitroderivatives of fullerene C60: methyl ester of L-N-[(2-nitroglyceryl) fullerenyl] proline, methyl ester of L-N-[(2,3-dinitroglyceryl) fullerenyl] proline,
and 2-nitroxyethyl ester of L-N-([2-(nitroxy) ethyl] fullerenyl) proline has been studied in vitro by high-resolution electron
microscopy. It was shown that these fullerene C60 nitroderivatives are able to prevent the formation of amyloid fibrils by the brain Aβ(1–42)-peptide and muscle X-protein
and to destroy mature fibrils. Electron microscopy is a promising method for selecting effective antiamyloidogenic drugs.
The antiamyloidogenic activity of nanodimensional fullerene C60 nitroderivatives offers strong possibilities for creating a new nanotechnology for the therapy of amyloidoses.
Key wordsamyloids-muscle X-protein-Aβ peptides-fullerenes-amyloidoses-Alzheimer’s disease
[Show abstract][Hide abstract] ABSTRACT: The inhibitory effect of hydrated fullerene C60 and the sodium salt of the fullerene polycarboxylic derivative C60Cl(C6H4CH2COONa)5 on the formation of amyloid fibrils by X-protein in vitro has been studied by electron microscopy. It is shown that these
compounds not only destroy mature amyloid fibrils but also prevent the formation of new fibrils. This property of fullerenes,
which are nanoparticles, can be used to develop a novel medical nanotechnology in the therapy for amyloidoses.
[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. DOI:10.1166/jnn.2007.330 · 1.34 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: Atrial light chain 1 (ALC-1) is expressed in embryonic and hypertrophied human ventricles but not in normal adult human ventricles. We investigated the effects of recombinant human atrial light chains (hALC-1) on the structure and enzymatic activity of synthetic filaments of ventricular myosin. The endogenous ventricular myosin light chain 1 (VLC-1) was partially replaced by recombinant hALC-1 yielding hALC-1 levels of 12%, 24% and 42%. This reconstitution of ventricular myosin with hALC-1 did not change the length of synthetic myosin filaments but led to more rounded myosin heads in comparison with those of control filaments. Actin-activated ATPase activity of myosin, a parameter of functional activity of molecular motor, amounted to 79.5 nmol P(i)/mg per min in control myosin filaments. Reconstitution with hALC-1 caused a profound increase of the actin-activated myosin ATPase activity in a dose dependent manner, for example, synthetic myosin filaments formed with 12%, 24% and 42% hALC-1 reconstituted myosin revealed the actin-activated ATPase activity increased by 18%, 26% and 36%, respectively, as compared to control. These results strongly suggest that in vivo expression of ALC-1 enhances ventricular myosin function, thereby contributing to cardiac compensation.
[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: 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: 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: 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.