Journal articles: 'Contractile Proteins'

1

Ruff, R. L., and J. Weissman. "Iodoacetate-induced contracture in rat skeletal muscle: possible role of ADP." American Journal of Physiology-Cell Physiology 261, no. 5 (November 1, 1991): C828—C836. http://dx.doi.org/10.1152/ajpcell.1991.261.5.c828.

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The effects of iodoacetic acid (IAA) and ischemic contraction were studied in rat extensor digitorum longus muscles. Ischemic contraction of IAA-treated muscles produced contracture. The onset of contracture was not associated with a change in sarcolemmal electrical properties or reduction in intracellular [ATP]; however, [creatine phosphate] was reduced by 75% and free [ADP] was increased by 665%. Continued stimulation of IAA-treated fibers resulted in depolarization, loss of membrane excitability, further depletion of creatine phosphate, and reduction in [ATP]. The effects seen in IAA-treated muscle did not appear to result from a direct action of IAA on the surface membrane, contractile proteins, or excitation-contraction coupling. The contractures in IAA-treated muscle may have resulted from increased Ca sensitivity of the contractile proteins, increased myoplasmic [Ca], or both. Both effects may have resulted from increased [ADP]. In addition, the reduced acidification during ischemic contraction of IAA-treated fibers compared with control fibers may have further increased the Ca sensitivity of IAA-treated fibers compared with controls.

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2

Gros, Francois, and Margaret Buckingham. "Polymorphism of contractile proteins." Biopolymers 26, S0 (1987): S177—S192. http://dx.doi.org/10.1002/bip.360260016.

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3

Syrový, I. "Isoforms of contractile proteins." Progress in Biophysics and Molecular Biology 49, no. 1 (January 1987): 1–27. http://dx.doi.org/10.1016/0079-6107(87)90007-1.

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4

Ordway, George A., P. Darrell Neufer, Eva R. Chin, and George N. DeMartino. "Chronic contractile activity upregulates the proteasome system in rabbit skeletal muscle." Journal of Applied Physiology 88, no. 3 (March 1, 2000): 1134–41. http://dx.doi.org/10.1152/jappl.2000.88.3.1134.

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Remodeling of skeletal muscle in response to altered patterns of contractile activity is achieved, in part, by the regulated degradation of cellular proteins. The ubiquitin-proteasome system is a dominant pathway for protein degradation in eukaryotic cells. To test the role of this pathway in contraction-induced remodeling of skeletal muscle, we used a well-established model of continuous motor nerve stimulation to activate tibialis anterior (TA) muscles of New Zealand White rabbits for periods up to 28 days. Western blot analysis revealed marked and coordinated increases in protein levels of the 20S proteasome and two of its regulatory proteins, PA700 and PA28. mRNA of a representative proteasome subunit also increased coordinately in contracting muscles. Chronic contractile activity of TA also increased total proteasome activity in extracts, as measured by the hydrolysis of a proteasome-specific peptide substrate, and the total capacity of the ubiquitin-proteasome pathway, as measured by the ATP-dependent hydrolysis of an exogenous protein substrate. These results support the potential role of the ubiquitin-proteasome pathway of protein degradation in the contraction-induced remodeling of skeletal muscle.

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5

Yamaguchi, Osamu, Yoshinari Sakagami, Takayuki Suzuki, Masato Kobayashi, and Yasuo Shiraiwa. "CONTRACTILE PROTEINS IN THE KIDENY." Japanese Journal of Urology 79, no. 2 (1988): 326–31. http://dx.doi.org/10.5980/jpnjurol1928.79.2_326.

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6

Sakagami, Yoshinari. "CONTRACTILE PROTEINS IN THE KIDNEY." Japanese Journal of Urology 79, no. 2 (1988): 332–38. http://dx.doi.org/10.5980/jpnjurol1928.79.2_332.

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7

KIEHART, D. P., A. KETCHUM, P. YOUNG, D. LUTZ, M. R. ALFENITO, X. j. CHANG, M. AWOBULUYI, et al. "Contractile Proteins in Drosophila Development." Annals of the New York Academy of Sciences 582, no. 1 Cytokinesis (April 1990): 233–51. http://dx.doi.org/10.1111/j.1749-6632.1990.tb21683.x.

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8

Mehta, D., M. F. Wu, and S. J. Gunst. "Role of contractile protein activation in the length-dependent modulation of tracheal smooth muscle force." American Journal of Physiology-Cell Physiology 270, no. 1 (January 1, 1996): C243—C252. http://dx.doi.org/10.1152/ajpcell.1996.270.1.c243.

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The active isometric force developed by a muscle decreases at muscle lengths below an optimal length (Lo). However, when the length of an actively contracting muscle is abruptly decreased, a lower level of isometric force is reached during force redevelopment than when the contraction is initiated at the shorter length. This has been attributed to a deactivation of contractile proteins caused by shortening. In this study, intracellular Ca2+ and myosin light chain (MLC) phosphorylation were measured to assess the mechanisms for the modulation of isometric force caused by changing smooth muscle length before or during isometric contraction. The decline in isometric force between Lo and 0.5Lo was associated with decreases in MLC phosphorylation and intracellular Ca2+ during contractions elicited by acetylcholine or 60 mM KCl. Quick release of the muscle during contraction depressed force redevelopment at the shorter length but not MLC phosphorylation. We conclude that decreases in Ca(2+)-calmodulin-dependent MLC phosphorylation contribute significantly to the decline in isometric force at lengths below Lo, but the depression of contractility associated with the quick release of actively contracted smooth muscle is not caused by a shortening-induced deactivation of contractile proteins.

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9

Dou, Ying, Per Arlock, and Anders Arner. "Blebbistatin specifically inhibits actin-myosin interaction in mouse cardiac muscle." American Journal of Physiology-Cell Physiology 293, no. 3 (September 2007): C1148—C1153. http://dx.doi.org/10.1152/ajpcell.00551.2006.

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Blebbistatin is a powerful inhibitor of actin-myosin interaction in isolated contractile proteins. To examine whether blebbistatin acts in a similar manner in the organized contractile system of striated muscle, the effects of blebbistatin on contraction of cardiac tissue from mouse were studied. The contraction of paced intact papillary muscle preparations and shortening of isolated cardiomyocytes were inhibited by blebbistatin with inhibitory constants in the micromolar range (1.3–2.8 μM). The inhibition constants are similar to those previously reported for isolated cardiac myosin subfragments showing that blebbistatin action is similar in filamentous myosin of the cardiac contractile apparatus and isolated proteins. The inhibition was not associated with alterations in action potential duration or decreased influx through L-type Ca2+ channels. Experiments on permeabilized cardiac muscle preparations showed that the inhibition was not due to alterations in Ca2+ sensitivity of the contractile filaments. The maximal shortening velocity was not affected by 1 μM blebbistatin. In conclusion, we show that blebbistatin is an inhibitor of the actin-myosin interaction in the organized contractile system of cardiac muscle and that its action is not due to effects on the Ca2+ influx and activation systems.

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10

Pavalko, F. M., L. P. Adam, M. F. Wu, T. L. Walker, and S. J. Gunst. "Phosphorylation of dense-plaque proteins talin and paxillin during tracheal smooth muscle contraction." American Journal of Physiology-Cell Physiology 268, no. 3 (March 1, 1995): C563—C571. http://dx.doi.org/10.1152/ajpcell.1995.268.3.c563.

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Reorganization of cytoskeletal-membrane interactions during contractile stimulation may contribute to the regulation of airway smooth muscle contraction. We investigated the effect of contractile stimulation on the phosphorylation of the actin-membrane attachment proteins talin, vinculin, and paxillin. Stimulation of 32P-labeled canine tracheal smooth muscle strips with acetylcholine (ACh; 10(-3) M) resulted in a rapid 2.6-fold increase in phosphorylation of serine and/or threonine residues, compared with resting levels of 0.22 mol PO4(3-)/mol talin. After stimulation with ACh, phosphorylation of tyrosine residues on paxillin increased approximately threefold. Two-dimensional phosphopeptide mapping of in vivo labeled talin and paxillin indicated phosphorylation on a limited number of sites. Vinculin phosphorylation was undetectable in either resting or ACh-stimulated muscle. We conclude that phosphorylation of talin and paxillin occurs during ACh-stimulated contraction of tracheal smooth muscle and that distinct signaling pathways activate a serine/threonine kinase that phosphorylates talin and a tyrosine kinase that phosphorylates paxillin. The pharmacological activation of airway smooth muscle cells might involve the anchoring of contractile filaments to the membrane.

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11

Gerthoffer, W. T. "Regulation of the contractile element of airway smooth muscle." American Journal of Physiology-Lung Cellular and Molecular Physiology 261, no. 2 (August 1, 1991): L15—L28. http://dx.doi.org/10.1152/ajplung.1991.261.2.l15.

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Smooth muscle of the mammalian airways controls airway diameter and resistance to airflow. Smooth muscle tone is in turn controlled by a variety of external signals that are transduced to useful work by contractile proteins. The protein components of the contractile element of airway smooth muscle are similar to those found in other smooth muscles and include actin, myosin, tropomyosin, caldesmon, and calponin. There has been significant recent progress in studies of contractile system regulation of airway smooth muscle. Regulation of myosin light chain kinase, identification of the sites phosphorylated on the regulatory myosin light chains, and the effect of myosin phosphorylation on stress development and crossbridge cycling rates have all been studied in some detail. We infer from these studies that besides myosin phosphorylation there is an important role for a thin filament Ca(2+)-dependent regulatory mechanism. The potentially important thin filament proteins caldesmon and calponin are present in tracheal smooth muscle and may be phosphorylated during contraction. The use of intracellular Ca2+ indicators to estimate changes in intracellular Ca2+ ([Ca2+]i) and the development of several skinned fiber preparations have broadened the scope of physiological studies with airway smooth muscle and have suggested that the contractile element sensitivity to Ca2+ is not fixed but might be modulated by undefined messengers or excitation-contraction pathways. This adds an additional challenge to the continuing effort to define the messengers and regulatory proteins that couple activation of membrane receptors to the contractile element in airway smooth muscle.

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12

Hernandez, Olga M., Philippe R. Housmans, and James D. Potter. "Invited Review: Pathophysiology of cardiac muscle contraction and relaxation as a result of alterations in thin filament regulation." Journal of Applied Physiology 90, no. 3 (March 1, 2001): 1125–36. http://dx.doi.org/10.1152/jappl.2001.90.3.1125.

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Cardiac muscle contraction depends on the tightly regulated interactions of thin and thick filament proteins of the contractile apparatus. Mutations of thin filament proteins (actin, tropomyosin, and troponin), causing familial hypertrophic cardiomyopathy (FHC), occur predominantly in evolutionarily conserved regions and induce various functional defects that impair the normal contractile mechanism. Dysfunctional properties observed with the FHC mutants include altered Ca2+ sensitivity, changes in ATPase activity, changes in the force and velocity of contraction, and destabilization of the contractile complex. One apparent tendency observed in these thin filament mutations is an increase in the Ca2+ sensitivity of force development. This trend in Ca2+ sensitivity is probably induced by altering the cross-bridge kinetics and the Ca2+ affinity of troponin C. These in vitro defects lead to a wide variety of in vivo cardiac abnormalities and phenotypes, some more severe than others and some resulting in sudden cardiac death.

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13

Knoblauch, Michael, Gundula A. Noll, Torsten Müller, Dirk Prüfer, Ingrid Schneider-Hüther, Dörte Scharner, Aart J. E. van Bel, and Winfried S. Peters. "ATP-independent contractile proteins from plants." Nature Materials 2, no. 9 (August 24, 2003): 600–603. http://dx.doi.org/10.1038/nmat960.

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14

Cavaillé, F., A. Kacémi, F. Mondon, T. Fournier, and F. Ferré. "Contractile proteins isoforms in placental vessels." Placenta 14, no. 4 (July 1993): A9. http://dx.doi.org/10.1016/s0143-4004(05)80484-9.

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15

WIEGAND, V., S. SCHULER, H. FIGULLA, H. WARNECKE, and H. KREUZER. "Contractile proteins in human dilatative cardiomyopathy." Journal of Molecular and Cellular Cardiology 18 (1986): 25. http://dx.doi.org/10.1016/s0022-2828(86)80374-1.

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16

Cavailleé, Françoise, Abdelkrim Kacémi, Françoise Mondon, Thérèse Fournier, and Françoise Ferré. "Contractile proteins in human fetoplacental vessels." American Journal of Obstetrics and Gynecology 173, no. 6 (December 1995): 1793–99. http://dx.doi.org/10.1016/0002-9378(95)90429-8.

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17

Izumi, Tohru, Haruo Hanawa, Makihiko Saeki, and Makoto Kodama. "Cardiac contractile proteins and autoimmune myocarditis." Molecular and Cellular Biochemistry 119, no. 1-2 (1993): 67–71. http://dx.doi.org/10.1007/bf00926855.

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18

Leinwand, Leslie A., Regina Sohn, Stewart A. Frankel, Elizabeth B. Goodwin, and Elizabeth M. McNally. "Bacterial expression of eukaryotic contractile proteins." Cell Motility and the Cytoskeleton 14, no. 1 (1989): 3–11. http://dx.doi.org/10.1002/cm.970140104.

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19

Ibitayo, Adenike I., Jeanette Sladick, Sony Tuteja, Otto Louis-Jacques, Hirotaka Yamada, Guy Groblewski, Michael Welsh, and Khalil N. Bitar. "HSP27 in signal transduction and association with contractile proteins in smooth muscle cells." American Journal of Physiology-Gastrointestinal and Liver Physiology 277, no. 2 (August 1, 1999): G445—G454. http://dx.doi.org/10.1152/ajpgi.1999.277.2.g445.

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Sustained smooth muscle contraction is mediated by protein kinase C (PKC) through a signal transduction cascade leading to contraction. Heat-shock protein 27 (HSP27) appears to be the link between these two major events, i.e., signal transduction and sustained smooth muscle contraction. We have investigated the involvement of HSP27 in signal transduction and HSP27 association with contractile proteins (e.g., actin, myosin, tropomyosin, and caldesmon) resulting in sustained smooth muscle contraction. We have carried out confocal microscopy to investigate the cellular reorganization and colocalization of proteins and immunoprecipitation of HSP27 with actin, myosin, tropomyosin, and caldesmon as detected by sequential immunoblotting. Our results indicate that 1) translocation of Raf-1 to the membrane when stimulated with ceramide is inhibited by vasoactive intestinal peptide (VIP), a relaxant neuropeptide; 2) PKC-α and mitogen-activated protein kinase translocate and colocalize on the membrane in response to ceramide, and PKC-α translocation is inhibited by VIP; 3) HSP27 colocalizes with actin when contraction occurs; and 4) HSP27 immunoprecipitates with actin and with the contractile proteins myosin, tropomyosin, and caldesmon. We propose a model in which HSP27 is involved in sustained smooth muscle contraction and modulates the interaction of actin, myosin, tropomyosin, and caldesmon.

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20

Bitar, Khalil N. "V. Aging and gastrointestinal smooth muscle: from signal transduction to contractile proteins." American Journal of Physiology-Gastrointestinal and Liver Physiology 284, no. 1 (January 1, 2003): G1—G7. http://dx.doi.org/10.1152/ajpgi.00264.2002.

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The object of this theme is to offer new perspectives on the effect of aging on signal-transduction pathways associated with agonist-induced contraction of smooth muscle cells from the colon. Smooth muscle cells from old rats (32 mo old) exhibit limited cell length distribution and diminished contractility. The observed reduced contractile response may be due to the effect of aging on signal-transduction pathways, especially an inhibition of the tyrosine kinase-Src kinase pathway, a reduced activation of the PKC pathway, and a reduced association of contractile proteins [heat shock protein 27 (HSP27)-tropomyosin, HSP27-actin, actin-myosin]. Levels of HSP27 phosphorylation are also reduced compared with adult rats.

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21

Stephens, N. L., C. Y. Seow, A. J. Halayko, and H. Jiang. "The biophysics and biochemistry of smooth muscle contraction." Canadian Journal of Physiology and Pharmacology 70, no. 4 (April 1, 1992): 515–31. http://dx.doi.org/10.1139/y92-067.

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In this review the biophysics and biochemistry of smooth muscle contraction are dealt with. We describe a new model for the study of bronchial smooth muscle, which facilitates study of cellular contractile mechanisms. A new concept emerging is that study of steady-state mechanical parameters such as maximal isometric force (Po) velocity is inadequate because two types of crossbridges (normally cycling (NBR) and latch) seem to be sequentially active during smooth muscle contraction. Thus quick-release techniques are required to characterize the force–velocity properties of the two types of bridges. Pathophysiological processes that affect the muscle's shortening ability seem to affect the early NBRs only. With respect to maximal shortening capacity of the smooth muscle, the role of loading is very important. The differences between isotonic, elastic, and viscous loading are considerable. Ultimately, the time course and magnitude of loading should exactly resemble that operative in vivo. Once again, it is the characteristic of loading in the early phase of contraction that is crucial, as most of the shortening in smooth muscle occurs early in the contraction. While the maximum force developed by smooth muscle per unit cross-sectional area is the same as for striated muscle, the velocity is 50 times less. The properties of the series and parallel elastic elements of smooth muscle are described. The latter, when in compression mode, acts as an internal resistance to shortening and probably limits it. Isotonic relaxation has therefore not been studied in smooth muscle. We have developed a shortening parameter that is independent of the load on the muscle and of the initial length of the muscle's contractile element. We report the novel observation that isotonically relaxing smooth muscle reactivates itself, resulting in terminal slowing of the relaxation process. With respect to the biochemistry of smooth muscle contraction, contractile (actin isoforms, myosin heavy and light chains and their isoforms), regulatory (calmodulin–4 Ca2+, myosin light chain kinase, myosin light chain and its phosphorylation, tropomyosin, caldesmon, and calponin), and cytoskeletal (chiefly desmin and vimentin) proteins are discussed. While the kinase activates the contractile system, caldesmon and calponin modulate the activity downward. The cytoskeletal proteins desmin, vimentin, and α-actinin could constitute the muscle cell's internal resistor.Key words: smooth muscle mechanics, force–velocity, smooth muscle, internal resistor, smooth muscle retardation, contractile proteins, regulatory proteins.

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22

Qi, M., K. Ojamaa, E. G. Eleftheriades, I. Klein, and A. M. Samarel. "Regulation of rat ventricular myosin heavy chain expression by serum and contractile activity." American Journal of Physiology-Cell Physiology 267, no. 2 (August 1, 1994): C520—C528. http://dx.doi.org/10.1152/ajpcell.1994.267.2.c520.

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To quantitatively analyze the effects of serum stimulation and contractile activity and their interaction on cellular growth and cardiac myosin heavy chain (MHC) gene expression, spontaneously contracting neonatal rat ventricular myocytes in primary culture were maintained in serum-free growth medium or growth medium supplemented with fetal bovine serum. Contractile activity in paired cultures was inhibited by addition of the calcium channel blocker verapamil (10 microM) to the culture medium. Both serum stimulation and contractile activity produced myocyte hypertrophy as assessed by increases in total protein, total RNA, protein-to-DNA ratios, and total MHC protein content. MHC isoenzyme analysis indicated that both MHC-alpha and MHC-beta proteins accumulated in response to serum stimulation and/or contractile activity. The increases in MHC-beta protein resulting from serum stimulation and contractile activity occurred in parallel with increases in MHC-beta mRNA. In contrast, MHC-alpha mRNA levels were relatively unaffected by serum stimulation but appeared to decrease in response to contractile activity. The protein kinase inhibitor staurosporine (5 nM) reduced MHC-beta expression in serum-free, contracting cultures and also prevented the serum-induced increase in MHC-beta mRNA observed in both contracting and arrested myocytes. Staurosporine also increased MHC-alpha mRNA levels in serum-free, contracting, and verapamil-arrested myocytes. These data suggest that both humoral and mechanical factors regulate MHC isoenzyme expression and cellular growth in neonatal ventricular myocytes.

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23

Månsson, Alf. "Hypothesis: Single Actomyosin Properties Account for Ensemble Behavior in Active Muscle Shortening and Isometric Contraction." International Journal of Molecular Sciences 21, no. 21 (November 9, 2020): 8399. http://dx.doi.org/10.3390/ijms21218399.

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Muscle contraction results from cyclic interactions between myosin II motors and actin with two sets of proteins organized in overlapping thick and thin filaments, respectively, in a nearly crystalline lattice in a muscle sarcomere. However, a sarcomere contains a huge number of other proteins, some with important roles in muscle contraction. In particular, these include thin filament proteins, troponin and tropomyosin; thick filament proteins, myosin binding protein C; and the elastic protein, titin, that connects the thin and thick filaments. Furthermore, the order and 3D organization of the myofilament lattice may be important per se for contractile function. It is possible to model muscle contraction based on actin and myosin alone with properties derived in studies using single molecules and biochemical solution kinetics. It is also possible to reproduce several features of muscle contraction in experiments using only isolated actin and myosin, arguing against the importance of order and accessory proteins. Therefore, in this paper, it is hypothesized that “single molecule actomyosin properties account for the contractile properties of a half sarcomere during shortening and isometric contraction at almost saturating Ca concentrations”. In this paper, existing evidence for and against this hypothesis is reviewed and new modeling results to support the arguments are presented. Finally, further experimental tests are proposed, which if they corroborate, at least approximately, the hypothesis, should significantly benefit future effective analysis of a range of experimental studies, as well as drug discovery efforts.

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Szymanski, Pawel T., Grazyna Szymanska, and Raj K. Goyal. "Differences in calmodulin and calmodulin-binding proteins in phasic and tonic smooth muscles." American Journal of Physiology-Cell Physiology 282, no. 1 (January 1, 2002): C94—C104. http://dx.doi.org/10.1152/ajpcell.00257.2001.

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To determine whether densities of calmodulin (CaM) and CaM-binding proteins are related to phasic and tonic behavior of smooth muscles, we quantified these proteins in the opossum esophageal body (EB) and lower esophageal sphincter (LES), which represent phasic and tonic smooth muscles, respectively. Gel electrophoresis, immunoprecipitation, Western blot, and hemagglutinin epitope-tagged CaM (HA-CaM) overlay assay with quantitative scanning densitometry and phosphorylation measurements were used. Total protein content in the two smooth muscles was similar (∼30 mg protein/g frozen tissue). Total tissue concentration of CaM was significantly (25%) higher in EB than in LES ( P < 0.05). HA-CaM-binding proteins were qualitatively similar in LES and EB extracts. Myosin, myristoylated alanine-rich C kinase substrate protein, Ca2+/CaM kinase II, and calponin contents were also similar in the two muscles. However, content and total activity of myosin light chain kinase (MLCK) and content of caldesmon (CaD) were three- to fourfold higher in EB than in LES. Increased CaM and MLCK content may allow for a wide range of contractile force varying from complete relaxation in the basal state to a large-amplitude, high-velocity contraction in EB phasic muscle. Increased content of CaD, which provides a braking mechanism on contraction, may further contribute to the phasic contractile behavior. In contrast, low CaM, MLCK, and CaD content may be responsible for a small range of contractile force seen in tonic muscle of LES.

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25

Yamaguchi, Osamu. "CONTRACTILE PROTEINS AND CALCIUM ION IN UROLOGY." Japanese Journal of Urology 86, no. 7 (1995): 1193–207. http://dx.doi.org/10.5980/jpnjurol1989.86.1193.

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26

Shneider, Mikhail, Sergey Buth, Brian Ho, Marek Basler, John Mekalanos, and Petr Leiman. "Central spike proteins of contractile ejection systems." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C579. http://dx.doi.org/10.1107/s2053273314094200.

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Contractile tails of bacteriophages and related systems - R-type pyocins, the Serratia entomophila antifeeding prophage, the Photorhabdus Virulence Cassette, and the Type VI Secretion System (T6SS) - contain a special spike-shaped protein complex, which is involved in breaching the target cell envelope during infection. We have identified the genes and determined crystal structures for several spike proteins from phages, pyocins, and T6SS, and established a paradigm for their organization and function. The architecture of spike proteins is remarkably well conserved at the level of tertiary structure, but the corresponding genes and amino acid sequences have undergone huge rearrangements with domains becoming separate genes that are very far away from each other in the genome. Large bacteriophages and T6SS have the most complex spikes, in which the tip is a small protein that forms a very sharp conical extension on the spike. The membrane-attacking tip is stabilized by a buried Fe or Zn ion. The spike tip proteins belong to the PAAR (Proline-Alanine-Alanine-aRginine) repeat domain superfamily with several thousand members in the GenBank. PAAR repeat proteins from T6SS are often extended by a domain with a putative effector function (nuclease, DNases, peptidases, etc.) or by a transthyretin domain. PAAR knockout mutants of Vibrio cholerae and Acinetobacter baylyi have either reduced or completely abolished T6SS activity, showing that PAAR proteins are essential for T6SS function and can play an important role in building of the T6SS machine and/or target cell membrane piercing. The unique HMM profile of PAAR repeat proteins makes it possible to identify their orthologs in all T6SS and contractile tail phages including T4, phiKZ, P1, etc. Complete structures (including the tip protein) of phage T4 central spike and T6SS spike of Vibrio cholerae will be presented and discussed.

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Malhotra, A. "Regulation of contractile proteins in diabetic heart." Cardiovascular Research 34, no. 1 (April 1997): 34–40. http://dx.doi.org/10.1016/s0008-6363(97)00059-x.

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Morkin, E. "Chronic Adaptations in Contractile Proteins: Genetic Regulation." Annual Review of Physiology 49, no. 1 (March 1987): 545–54. http://dx.doi.org/10.1146/annurev.ph.49.030187.002553.

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Andres, J., A. Moczarska, D. Stepkowski, and I. Kakol. "Contractile proteins in globally “stunned” rabbit myocardium." Basic Research in Cardiology 86, no. 3 (May 1991): 219–26. http://dx.doi.org/10.1007/bf02190601.

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Watanabe, Sadanori, Yoshikazu Ando, Shingo Yasuda, Hiroshi Hosoya, Naoki Watanabe, Toshimasa Ishizaki, and Shuh Narumiya. "mDia2 Induces the Actin Scaffold for the Contractile Ring and Stabilizes Its Position during Cytokinesis in NIH 3T3 Cells." Molecular Biology of the Cell 19, no. 5 (May 2008): 2328–38. http://dx.doi.org/10.1091/mbc.e07-10-1086.

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mDia proteins are mammalian homologues of Drosophila diaphanous and belong to the formin family proteins that catalyze actin nucleation and polymerization. Although formin family proteins of nonmammalian species such as Drosophila diaphanous are essential in cytokinesis, whether and how mDia proteins function in cytokinesis remain unknown. Here we depleted each of the three mDia isoforms in NIH 3T3 cells by RNA interference and examined this issue. Depletion of mDia2 selectively increased the number of binucleate cells, which was corrected by coexpression of RNAi-resistant full-length mDia2. mDia2 accumulates in the cleavage furrow during anaphase to telophase, and concentrates in the midbody at the end of cytokinesis. Depletion of mDia2 induced contraction at aberrant sites of dividing cells, where contractile ring components such as RhoA, myosin, anillin, and phosphorylated ERM accumulated. Treatment with blebbistatin suppressed abnormal contraction, corrected localization of the above components, and revealed that the amount of F-actin at the equatorial region during anaphase/telophase was significantly decreased with mDia2 RNAi. These results demonstrate that mDia2 is essential in mammalian cell cytokinesis and that mDia2-induced F-actin forms a scaffold for the contractile ring and maintains its position in the middle of a dividing cell.

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Simpson, D. G., W. W. Sharp, T. K. Borg, R. L. Price, L. Terracio, and A. M. Samarel. "Mechanical regulation of cardiac myocyte protein turnover and myofibrillar structure." American Journal of Physiology-Cell Physiology 270, no. 4 (April 1, 1996): C1075—C1087. http://dx.doi.org/10.1152/ajpcell.1996.270.4.c1075.

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Mechanical forces play an essential role in regulating the synthesis and assembly of contractile proteins into the sarcomeres of cardiac myocytes. To examine if physical forces might also regulate the turnover of contractile proteins at a posttranslational site of control, beating and nonbeating neonatal cardiac myocytes (NCM) were subjected to a 5% static stretch. The L-type calcium channel blocker nifedipine (12 microM) was used to inhibit contraction. Pulse-chase biosynthetic labeling experiments demonstrated that contractile arrest accelerated the loss of isotopic tracer from the total myofibrillar protein fraction, myosin heavy chain (MHC), and actin, but not desmin. Myofibrillar abnormalities developed in parallel with these metabolic changes. A 5% static load appeared to partially stabilize myofibrillar structure in nonbeating NCM and suppressed the loss of isotopic tracer from the total myofibrillar protein fraction, MHC, and actin in beating and nonbeating NCM. Contractile activity and/or a static stretch promoted the accumulation of MHC, actin, and desmin. Applying a static load to myocytes that lacked preexisting myofibrils did not promote the assembly of sarcomeres or alter protein turnover. These data indicate that the turnover of MHC and actin is correlated with the organizational state of the myofibrillar apparatus.

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Tsuji, Tsuyoshi, Yoshimi Ohga, Yoshiro Yoshikawa, Susumu Sakata, Takehisa Abe, Nobuoki Tabayashi, Shuichi Kobayashi, et al. "Rat cardiac contractile dysfunction induced by Ca2+ overload: possible link to the proteolysis of α-fodrin." American Journal of Physiology-Heart and Circulatory Physiology 281, no. 3 (September 1, 2001): H1286—H1294. http://dx.doi.org/10.1152/ajpheart.2001.281.3.h1286.

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The aim of the present study was to examine the mechanisms of Ca2+ overload-induced contractile dysfunction in rat hearts independent of ischemia and acidosis. Experiments were performed on 30 excised cross-circulated rat heart preparations. After hearts were exposed to high Ca2+, there was a contractile failure associated with a parallel downward shift of the linear relation between myocardial O2 consumption per beat and systolic pressure-volume area (index of a total mechanical energy per beat) in left ventricles from all seven hearts that underwent the protocol. This result suggested a decrease in O2consumption for total Ca2+ handling in excitation-contraction coupling. In the hearts that underwent the high Ca2+ protocol and had contractile failure, we found marked proteolysis of a cytoskeleton protein, α-fodrin, whereas other proteins were unaffected. A calpain inhibitor suppressed the contractile failure by high Ca2+, the decrease in O2 consumption for total Ca2+ handling, and membrane α-fodrin degradation. We conclude that the exposure to high Ca2+ may induce contractile dysfunction possibly by suppressing total Ca2+ handling in excitation-contraction coupling and degradation of membrane α-fodrin via activation of calpain.

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Lake, N. "Loss of cardiac myofibrils: mechanism of contractile deficits induced by taurine deficiency." American Journal of Physiology-Heart and Circulatory Physiology 264, no. 4 (April 1, 1993): H1323—H1326. http://dx.doi.org/10.1152/ajpheart.1993.264.4.h1323.

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It is well established that taurine deficiency is associated with myocardial contractile dysfunction; however, the mechanism is unknown. As a follow-up to finding reduced force generation in taurine-depleted rat cardiac trabeculae, using either calcium or strontium activation, this study examined alterations in ventricular fine structure and contractile proteins in animals made taurine deficient by in vivo treatment with a taurine transport antagonist, guanidinoethane sulfonate. Observations of ventricular ultrastructure showed disordered contractile filaments and clear losses of myofibrillar bundles in association with taurine deficiency. Biochemical analyses of ventricular contractile proteins using polyacrylamide gel electrophoresis confirmed losses of the major sarcomeric proteins, myosin and actin. These findings provide a possible mechanism for the contractile deficits and cardiomyopathy described in taurine-deficient animals.

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Wong, Wai-Shiu, and Ralf G. Rahwan. "Pharmacological actions of the calcium antagonist propyl-methylenedioxyindene in skinned vascular smooth muscle." Canadian Journal of Physiology and Pharmacology 66, no. 8 (August 1, 1988): 1041–47. http://dx.doi.org/10.1139/y88-170.

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Previous studies provided strong evidence that propyl-methylenedioxyindene (pr-MDI) interfered with calcium at an intracellular site. To further characterize the mechanism of action of pr-MDI, its pharmacological actions on chemically skinned vascular smooth muscle were examined. Rat caudal artery strips were chemically skinned with saponin (0.15 mg/mL for 1 h). The efficiency of the skinning was evidenced by a loss of contractile response to 74 mM K+. The intactness of the regulatory and contractile proteins was ascertained by the ability of the skinned tissue to contract in response to Ca2+ (free Ca2+ concentration of 10−4 or 10−6 M). Caffeine (25 mM) induced contraction was used as an index of the functional integrity of the sarcoplasmic reticulum in the skinned preparations. Contraction of the skinned artery with a free Ca2+ concentration of 10−6 M was significantly obtunded by 1 × 10−4 M trifluoperazine (a calmodulin antagonist) but not by 1 × 10−4 M pr-MDI. Contraction of the skinned artery evoked by 25 mM caffeine in the absence of extracellular calcium was significantly obtunded by 1 × 10−4 M pr-MDI but not by 1 × 10−6 M nifedipine (a calcium channel blocker). The results indicate that pr-MDI acts intracellularly to block calcium mobilization from the sarcoplasmic reticulum without directly interfering with the regulatory and contractile proteins.

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Swynghedauw, B. "Developmental and functional adaptation of contractile proteins in cardiac and skeletal muscles." Physiological Reviews 66, no. 3 (July 1, 1986): 710–71. http://dx.doi.org/10.1152/physrev.1986.66.3.710.

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The goal of this review is to summarize our knowledge of the plasticity of striated muscles in terms of contractile proteins. During development or when the working conditions are changed, the intrinsic physiological properties of both cardiac and skeletal muscles are modified. These modifications generally adapt the muscle to the new environmental requirements. One of the best examples is compensatory overload obtained in fast skeletal muscle by synergistic tenotomy and in a fast ventricle, such as in rats, by aortic banding. In both cases, after a few weeks the initial speed of shortening for the unloaded muscle drops, whereas the maximum tension developed remains unchanged. Heat measurements show that efficiency (i.e., g work/mol ATP) is improved at the fiber level. The fast skeletal muscle becomes slow, fatigue resistant, and then more adapted to endurance. For the ventricle as a whole to become slow is beneficial only if one contraction is considered; however, it is detrimental in terms of cardiac output and leads finally to failure. This adaptational process is partly explained by quantitative and qualitative changes in contractile proteins. Protein synthesis is rapidly enhanced and muscles hypertrophy, which in turn multiplies the contractile units and for the cardiac cylinder normalizes the wall stress. In the meantime the structure and, for myosin, the biological activity of several contractile proteins are modified. These modifications are very unlikely to be posttranscriptional and are in fact explained by several isoform shifts. In both tissues, for example, the expression of the gene coding for a fast myosin (MHCf in skeletal muscle, alpha-MHC in ventricles) is repressed and that of the gene coding for a slow myosin (beta-MHC in both tissues) is stimulated. This is accompanied by a coordinated increase in synthesis of other contractile proteins and, in skeletal muscle only, by isoform shifts of myosin light chains and of the TM-TN regulatory system. Other changes are less well understood. During development it has recently been discovered that three different MHCs (MHCemb, MHCneo, and MHCf) appear sequentially in fast skeletal muscle, which explains, for example, several contradictions of immunological cross-reactions. Currently, however, the functional significance of this finding is unknown, and the well-known decrease of shortening velocity observed in cardiac and skeletal muscles during fetal life is unexplained in terms of contractile proteins.(ABSTRACT TRUNCATED AT 400 WORDS)

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Wen, Yujia, Irene Stavrou, Kirill Bersuker, Rebecca J. Brady, Arturo De Lozanne, and Theresa J. O'Halloran. "AP180-Mediated Trafficking of Vamp7B Limits Homotypic Fusion of Dictyostelium Contractile Vacuoles." Molecular Biology of the Cell 20, no. 20 (October 15, 2009): 4278–88. http://dx.doi.org/10.1091/mbc.e09-03-0243.

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Clathrin-coated vesicles play an established role in endocytosis from the plasma membrane, but they are also found on internal organelles. We examined the composition of clathrin-coated vesicles on an internal organelle responsible for osmoregulation, the Dictyostelium discoideum contractile vacuole. Clathrin puncta on contractile vacuoles contained multiple accessory proteins typical of plasma membrane–coated pits, including AP2, AP180, and epsin, but not Hip1r. To examine how these clathrin accessory proteins influenced the contractile vacuole, we generated cell lines that carried single and double gene knockouts in the same genetic background. Single or double mutants that lacked AP180 or AP2 exhibited abnormally large contractile vacuoles. The enlarged contractile vacuoles in AP180-null mutants formed because of excessive homotypic fusion among contractile vacuoles. The SNARE protein Vamp7B was mislocalized and enriched on the contractile vacuoles of AP180-null mutants. In vitro assays revealed that AP180 interacted with the cytoplasmic domain of Vamp7B. We propose that AP180 directs Vamp7B into clathrin-coated vesicles on contractile vacuoles, creating an efficient mechanism for regulating the internal distribution of fusion-competent SNARE proteins and limiting homotypic fusions among contractile vacuoles. Dictyostelium contractile vacuoles offer a valuable system to study clathrin-coated vesicles on internal organelles within eukaryotic cells.

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Nedachi, Taku, Hiroyasu Hatakeyama, Tatsuyoshi Kono, Masaaki Sato, and Makoto Kanzaki. "Characterization of contraction-inducible CXC chemokines and their roles in C2C12 myocytes." American Journal of Physiology-Endocrinology and Metabolism 297, no. 4 (October 2009): E866—E878. http://dx.doi.org/10.1152/ajpendo.00104.2009.

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Physical exercise triggers the release of several cytokines/chemokines from working skeletal muscles, but the underlying mechanism(s) by which skeletal muscles decipher and respond to highly complex contractile stimuli remains largely unknown. In an effort to investigate the regulatory mechanisms of the expressions of two contraction-inducible CXC chemokines, CXCL1/KC and CXCL5/LIX, in contracting skeletal muscle cells, we took advantage of our in vitro exercise model using highly developed contractile C2C12 myotubes, which acquire properties similar to those of in vivo skeletal muscle via manipulation of Ca2+ transients with electric pulse stimulation (EPS). Production of these CXC chemokines was immediately augmented by EPS-evoked contractile activity in a manner dependent on the activities of JNK and NF-κB, but not p38, ERK1/2, or calcineurin. Intriguingly, exposure of myotubes to cyclic mechanical stretch also induced expression of these CXC chemokines; however, a much longer period of stimulation (∼12 h) was required, despite rapid JNK phosphorylation. We also demonstrate herein that CXCL1/KC and CXCL5/LIX have the ability to raise intracellular Ca2+ concentrations via CXCR2-mediated activation of pertussis toxin-sensitive Gαi proteins in C2C12 myoblasts, an action at least partially responsible for their migration and differentiation. Although we revealed a possible negative feedback regulation of their own production in response to the contractile activity in differentiated myotubes, exogenous administration of these CXC chemokines did not acutely influence either insulin-induced Akt phosphorylation or GLUT4 translocation in C2C12 myotubes. Taken together, these data shed light on the fundamental characteristics of contraction-inducible CXC chemokine production and their potential roles in skeletal muscle cells.

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Powers, Scott K., and Malcolm J. Jackson. "Exercise-Induced Oxidative Stress: Cellular Mechanisms and Impact on Muscle Force Production." Physiological Reviews 88, no. 4 (October 2008): 1243–76. http://dx.doi.org/10.1152/physrev.00031.2007.

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The first suggestion that physical exercise results in free radical-mediated damage to tissues appeared in 1978, and the past three decades have resulted in a large growth of knowledge regarding exercise and oxidative stress. Although the sources of oxidant production during exercise continue to be debated, it is now well established that both resting and contracting skeletal muscles produce reactive oxygen species and reactive nitrogen species. Importantly, intense and prolonged exercise can result in oxidative damage to both proteins and lipids in the contracting myocytes. Furthermore, oxidants can modulate a number of cell signaling pathways and regulate the expression of multiple genes in eukaryotic cells. This oxidant-mediated change in gene expression involves changes at transcriptional, mRNA stability, and signal transduction levels. Furthermore, numerous products associated with oxidant-modulated genes have been identified and include antioxidant enzymes, stress proteins, DNA repair proteins, and mitochondrial electron transport proteins. Interestingly, low and physiological levels of reactive oxygen species are required for normal force production in skeletal muscle, but high levels of reactive oxygen species promote contractile dysfunction resulting in muscle weakness and fatigue. Ongoing research continues to probe the mechanisms by which oxidants influence skeletal muscle contractile properties and to explore interventions capable of protecting muscle from oxidant-mediated dysfunction.

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Nakayama, Yasunori, Miyako Takaki, Kunihisa Kohno, Junichi Araki, and Hiroyuki Suga. "Mechanoenergetics of the Negative Inotropism of Isoflurane in the Canine Left Ventricle." Anesthesiology 87, no. 1 (July 1, 1997): 82–93. http://dx.doi.org/10.1097/00000542-199707000-00012.

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Background The mechanisms underlying the negative inotropic effects of isoflurane are incompletely understood. One suggested mechanism is that isoflurane may decrease Ca2+ sensitivity of contractile proteins. If so, more free calcium would be needed to activate contractile proteins to the same degree, which would impose a greater requirement for myocardial oxygen consumption used in the cycling of calcium. In this study, the authors use the excised, cross-circulated, canine heart model and the volume servopump technique to measure the effects of isoflurane on Emax (a contractile index) and on the relationship between pressure-volume area (PVA, a measure of total mechanical energy) and myocardial oxygen consumption per beat (VO2). Methods Effects of intracoronary isoflurane infused via a precoronary oxygenator on myocardial mechanoenergetics were studied during isovolumic contractions. The authors measured left ventricular (LV) pressure, LV volume, coronary flow, and arteriovenous oxygen content difference and computed Emax, VO2 and PVA at 0, 1.0, 1.5, and 2.0% isoflurane. From these data, the authors obtained oxygen costs of PVA and Emax in control subjects and in those receiving 2.0% isoflurane. Results Emax, PVA, and VO2 dose-dependently decreased by similar degrees (P < 0.05). Isoflurane did not change the oxygen costs at 1.5% and 2.0% concentration (P < 0.05). Conclusions These mechanoenergetic findings suggest that the primary method by which isoflurane decreases contractility is not by decreasing Ca2+ sensitivity of contractile proteins but mainly by decreasing Ca2+ handling in the excitation-contraction coupling without myocardial oxygen wasting effect.

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Dekkers, Bart G. J., Dedmer Schaafsma, S. Adriaan Nelemans, Johan Zaagsma, and Herman Meurs. "Extracellular matrix proteins differentially regulate airway smooth muscle phenotype and function." American Journal of Physiology-Lung Cellular and Molecular Physiology 292, no. 6 (June 2007): L1405—L1413. http://dx.doi.org/10.1152/ajplung.00331.2006.

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Changes in the ECM and increased airway smooth muscle (ASM) mass are major contributors to airway remodeling in asthma and chronic obstructive pulmonary disease. It has recently been demonstrated that ECM proteins may differentially affect proliferation and expression of phenotypic markers of cultured ASM cells. In the present study, we investigated the functional relevance of ECM proteins in the modulation of ASM contractility using bovine tracheal smooth muscle (BTSM) preparations. The results demonstrate that culturing of BSTM strips for 4 days in the presence of fibronectin or collagen I depressed maximal contraction (Emax) both for methacholine and KCl, which was associated with decreased contractile protein expression. By contrast, both fibronectin and collagen I increased proliferation of cultured BTSM cells. Similar effects were observed for PDGF. Moreover, PDGF augmented fibronectin- and collagen I-induced proliferation in an additive fashion, without an additional effect on contractility or contractile protein expression. The fibronectin-induced depression of contractility was blocked by the integrin antagonist Arg-Gly-Asp-Ser (RGDS) but not by its negative control Gly-Arg-Ala-Asp-Ser-Pro (GRADSP). Laminin, by itself, did not affect contractility or proliferation but reduced the effects of PDGF on these parameters. Strong relationships were found between the ECM-induced changes in Emax in BTSM strips and their proliferative responses in BSTM cells and for Emax and contractile protein expression. Our results indicate that ECM proteins differentially regulate both phenotype and function of intact ASM.

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Janson, L. W., J. Kolega, and D. L. Taylor. "Modulation of contraction by gelation/solation in a reconstituted motile model." Journal of Cell Biology 114, no. 5 (September 1, 1991): 1005–15. http://dx.doi.org/10.1083/jcb.114.5.1005.

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The actin-based cytoskeleton is a dynamic component of living cells with major structural and contractile properties involved in fundamental cellular processes. The action of actin-binding proteins can decrease or increase the gel structure. Changes in the actin-based cytoskeleton have long been thought to modulate the myosin II-based contractions involved in these cellular processes, but there has been some debate concerning whether maximal gelation increases or decreases contractile activity. To address this question, we have examined how contractile activity is modulated by the extent of actin gelation. The model system consists of physiologically relevant concentrations and molar ratios of actin filaments (whose lengths are controlled by gelsolin), the actin-cross-linking protein filamin, and smooth muscle myosin II. This system has been studied at the macroscopic and light microscopic levels to relate the gel structure to the rate of contraction. We present results which show that while a minimal amount of structure is necessary to transmit the contractile force, increasing the gel structure inhibits the rate of contraction, despite an increase in the actin-activated Mg(2+)-ATPase activity of myosin. Decreasing the total myosin concentration also inhibits the rate of contraction. Application of cytochalasin D to one side of the contractile network increases the rate of contraction and also induces movement comparable to flare streaming observed in isolated amoeba cytoplasm. These results are interpreted relative to current models of the relationship between the state of gelation and contraction and to the potential effects of such a relationship in the living cell.

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McArdle, A., D. Pattwell, A. Vasilaki, R. D. Griffiths, and M. J. Jackson. "Contractile activity-induced oxidative stress: cellular origin and adaptive responses." American Journal of Physiology-Cell Physiology 280, no. 3 (March 1, 2001): C621—C627. http://dx.doi.org/10.1152/ajpcell.2001.280.3.c621.

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Previous studies have reported that oxidizing free radical species are generated during exercise, and there has been considerable interest in the potential effects of these on exercising tissues. We hypothesized that contracting skeletal muscle was a major source of oxidizing free radical species and that untrained skeletal muscle would adapt to the oxidative stress of a single short period of contractile activity by upregulation of the activity of cytoprotective proteins in the absence of overt cellular damage. Fifteen minutes of aerobic contractile activity was found to induce a rapid release of superoxide anions from mouse skeletal muscle in vivo, and studies with contracting cultured skeletal muscle myotubes confirmed that this was due to release from myocytes rather than other cell types present within muscle tissue in vivo. This increased oxidant production caused a rapid, transient reduction in muscle protein thiol content, followed by increases in the activities of superoxide dismutase and catalase and in content of heat shock proteins. These changes occurred in the absence of overt damage to the muscle cells.

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Di Biase, Valentina, and Clara Franzini-Armstrong. "Evolution of skeletal type e–c coupling." Journal of Cell Biology 171, no. 4 (November 14, 2005): 695–704. http://dx.doi.org/10.1083/jcb.200503077.

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The functional separation between skeletal and cardiac muscles, which occurs at the threshold between vertebrates and invertebrates, involves the evolution of separate contractile and control proteins for the two types of striated muscles, as well as separate mechanisms of contractile activation. The functional link between electrical excitation of the surface membrane and activation of the contractile material (known as excitation–contraction [e–c] coupling) requires the interaction between a voltage sensor in the surface membrane, the dihydropyridine receptor (DHPR), and a calcium release channel in the sarcoplasmic reticulum, the ryanodine receptor (RyR). Skeletal and cardiac muscles have different isoforms of the two proteins and present two structurally and functionally distinct modes of interaction. We use structural clues to trace the evolution of the dichotomy from a single, generic type of e–c coupling to a diversified system involving a novel mechanism for skeletal muscle activation. Our results show that a significant structural transition marks the protochordate to the Craniate evolutionary step, with the appearance of skeletal muscle–specific RyR and DHPR isoforms.

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van Beurden, H. E., J. W. Von den Hoff, R. Torensma, J. C. Maltha, and A. M. Kuijpers-Jagtman. "Myofibroblasts in Palatal Wound Healing: Prospects for the Reduction of Wound Contraction after Cleft Palate Repair." Journal of Dental Research 84, no. 10 (October 2005): 871–80. http://dx.doi.org/10.1177/154405910508401002.

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The surgical closure of orofacial clefts is considered to impair maxillary growth and dento-alveolar development. Wound contraction and subsequent scar tissue formation, during healing of these surgical wounds, contribute largely to these growth disturbances. The potential to minimize wound contraction and subsequent scarring by clinical interventions depends on the surgeon’s knowledge of the events responsible for these phenomena. Fibroblasts initiate wound contraction, but proto-myofibroblasts and mature myofibroblasts are by far the most important cells in this process. Myofibroblasts are characterized by their cytoskeleton, which contains alpha-smooth-muscle actin. Additionally, their contractile apparatus contains bundles of actin microfilaments and associated contractile proteins, such as non-muscle myosin. This contractile apparatus is thought to be the major force-generating element involved in wound contraction. After closure of the wound, the myofibroblasts disappear by apoptosis, and a less cellular scar is formed. A reduction of contraction and scarring might be obtained by inhibition of myofibroblast differentiation, stimulation of their de-differentiation, stimulation of myofibroblast apoptosis, or impairment of myofibroblast function. In this review, we will discuss all of these possibilities, which ultimately may lead to a better outcome of cleft palate surgery.

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Podpalova, O. "Muscle contraction dynamics during chronic alcoholization." Bulletin of Taras Shevchenko National University of Kyiv. Series: Biology 79, no. 3 (2019): 63–68. http://dx.doi.org/10.17721/1728_2748.2019.79.63-68.

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Alcoholic myopathy is considered a multifactorial disease. The mechanisms leading to the development of muscle pathology in the case of excessive alcohol consumption have several implementation options. Chronic alcohol intake and acute alcohol intoxication can reduce the rate of protein synthesis, including myofibrillar proteins, leading to at least 2 functional changes in contractile processes: increased relaxation time and inadequate, incorrect muscle contraction. Chronic alcohol abuse contributes to the impairment of muscle contraction, including the reduction of the force and mechanokinetic parameters of contraction, which may be the result of the ultrastructural organization disruption of myocytes and their atrophy, because ethanol is able to interact directly on membrane structures. Impaired membrane structures and increased Ca2+ -ATPase activity lead to changes in calcium homeostasis and impaired muscle contractile function.Alcohol myopathy is also represents by skeletal muscles weakness, which is caused by a decreasement of the relative weight of myosin, desmin, actin and troponin, titin and nebulin, as ethanol and acetaldehyde act like as potent inhibitors of synthesis of myofibilar and sarcoplasmic proteins. The purpose of the study was to compare the dynamics of the parameters of skeletal muscle contraction of alcoholic rats using electrical stimulation with different relaxation times. In the first series of the experiment, we performed stimulation of m.tibialis rats with electrical pulses of 2.3.4.5 seconds. With a relaxation period of 30 s. In the next series of experiments, we increased the relaxation time to 1 min. in these stimulating conditions, myopathic muscles tend to increase the relaxation time rather than qualitatively or quantitatively change the dynamics of its contractile processes.

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Parkman, Henry P., Arlene N. James, and James P. Ryan. "The contractile action of platelet-activating factor on gallbladder smooth muscle." American Journal of Physiology-Gastrointestinal and Liver Physiology 279, no. 1 (July 1, 2000): G67—G72. http://dx.doi.org/10.1152/ajpgi.2000.279.1.g67.

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Platelet-activating factor (PAF) may be a mediator of some sequelae of cholecystitis, a disorder with gallbladder motor dysfunction. The aims of this study were to determine the effect and mechanism of PAF on gallbladder muscle. Exogenous administration of PAF-16 or PAF-18 caused dose-dependent contractions of gallbladder muscle strips in vitro with threshold doses of 1 ng/ml and 10 ng/ml, respectively. The PAF-induced contractions were not significantly reduced by TTX, atropine, or hexamethonium but were significantly inhibited with the PAF receptor antagonists ginkolide B and CV-3988. The PAF-induced contraction was reduced by indomethacin. Preventing influx of extracellular calcium with a calcium-free solution nearly abolished the PAF contractile response. Nifedipine inhibited the PAF contractile response, whereas ryanodine had no effect. Pertussis toxin reduced the PAF contractile response. In conclusion, PAF causes gallbladder contraction through specific PAF receptors on gallbladder muscle. These PAF receptors appear to be linked to a prostaglandin-mediated mechanism and to pertussis toxin-sensitive G proteins. The contractile response is largely mediated through the utilization of extracellular calcium influx through voltage-dependent calcium channels.

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Ijpma, Gijs, Linda Kachmar, Alice Panariti, Oleg S. Matusovsky, Dara Torgerson, Andrea Benedetti, and Anne-Marie Lauzon. "Intrapulmonary airway smooth muscle is hyperreactive with a distinct proteome in asthma." European Respiratory Journal 56, no. 1 (April 16, 2020): 1902178. http://dx.doi.org/10.1183/13993003.02178-2019.

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Constriction of airways during asthmatic exacerbation is the result of airway smooth muscle (ASM) contraction. Although it is generally accepted that ASM is hypercontractile in asthma, this has not been unambiguously demonstrated. Whether airway hyperresponsiveness (AHR) is the result of increased ASM mass alone or also increased contractile force generation per unit of muscle directly determines the potential avenues for treatment.To assess whether ASM is hypercontractile we performed a series of mechanics measurements on isolated ASM from intrapulmonary airways and trachealis from human lungs. We analysed the ASM and whole airway proteomes to verify if proteomic shifts contribute to changes in ASM properties.We report an increase in isolated ASM contractile stress and stiffness specific to asthmatic human intrapulmonary bronchi, the site of increased airway resistance in asthma. Other contractile parameters were not altered. Principal component analysis (PCA) of unbiased mass spectrometry data showed clear clustering of asthmatic subjects with respect to ASM specific proteins. The whole airway proteome showed upregulation of structural proteins. We did not find any evidence for a difference in the regulation of myosin activity in the asthmatic ASM.In conclusion, we showed that ASM is indeed hyperreactive at the level of intrapulmonary airways in asthma. We identified several proteins that are upregulated in asthma that could contribute to hyperreactivity. Our data also suggest enhanced force transmission associated with enrichment of structural proteins in the whole airway. These findings may lead to novel directions for treatment development in asthma.

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Watabe, Shugo. "Temperature plasticity of contractile proteins in fish muscle." Journal of Experimental Biology 205, no. 15 (August 1, 2002): 2231–36. http://dx.doi.org/10.1242/jeb.205.15.2231.

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SUMMARY Three myosin heavy chain isoforms with different actin-activated Mg2+-ATPase activities were found in the fast skeletal muscle from carp (Cyprinus carpio) acclimated to 10 and 30°C. The composition of three types of myosin heavy chain was dependent on acclimation temperature,demonstrating the presence of temperature-specific myosin isoforms in carp. Subsequently, the temperature-dependence of the sliding velocity of fluorescent F-actin in myosins isolated from 10°C- and 30°C-acclimated carp was measured. At 8°C, the filament velocity was three times higher for myosin from 10°C- than from 30°C-acclimated fish. Activation energies (Ea) for the sliding velocity of F-actin were 63 and 111 kJ mol-1 for myosins from 10°C- and 30°C-acclimated fish, respectively. Activation energy for actin-activated Mg2+-ATPase activity was 0.46 kJ mol-1 in myosin from 10°C-acclimated fish and 0.54 kJ mol-1 in myosin from 30°C-acclimated fish. The inactivation rate constant(KD) of Ca2+-ATPase was 7.5×10-4s-1 at 30°C for myosin from 10°C-acclimated fish, which was approximately twice that for myosin from 30°C-acclimated fish. It is suggested that these differences in thermostability reflect a more flexible structure of the myosin molecule in cold-acclimated carp, which results in a reduced activation enthalpy for contraction and, hence, a higher sliding velocity at low temperatures. Structural analysis of cDNAs encoding the carp myosin heavy chain demonstrated striking differences in two surface loops of myosin subfragment-1 (S1), loops 1 and 2, between the 10°C and 30°C types, which were predominantly expressed in carp acclimated to 10°C and 30°C, respectively. Chimeric myosins composed of Dictyostelium discoideum myosin backbones with loop sequences of carp S1 heavy chain isoforms demonstrated that the diversity of the loop 2 sequence of carp S1 affected the Vmax of actin-activated Mg2+-ATPase activity.

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Ulrich, Paul N., Veronica Jimenez, Miyoung Park, Vicente P. Martins, James Atwood, Kristen Moles, Dalis Collins, et al. "Identification of Contractile Vacuole Proteins in Trypanosoma cruzi." PLoS ONE 6, no. 3 (March 18, 2011): e18013. http://dx.doi.org/10.1371/journal.pone.0018013.

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Akella, Arvind Babu, Edmund H. Sonnenblick, and Jag Gulati. "Alterations in myocardial contractile proteins in diabetes mellitus." Coronary Artery Disease 7, no. 2 (February 1996): 124–32. http://dx.doi.org/10.1097/00019501-199602000-00005.

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Journal articles on the topic 'Contractile Proteins'

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