scholarly journals Identification of sequences necessary for the association of cardiac myosin subunits.

1991 ◽  
Vol 113 (3) ◽  
pp. 585-590 ◽  
Author(s):  
E M McNally ◽  
M M Bravo-Zehnder ◽  
L A Leinwand
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Light Chain ◽  
Myosin Light Chain ◽  
Carboxyl Terminus ◽  
Amino Terminus ◽  
Cardiac Myosin ◽  
Amino Acid Region ◽  
Myosin Subunits ◽  
Acid Region

To begin to understand the nature of myosin subunit assembly, we determined the region of a vertebrate sarcomeric myosin heavy chain required for binding of light chain 1. We coexpressed in Escherichia coli segments of the rat alpha cardiac myosin heavy chain which spanned the carboxyl terminus of subfragment 1 and the amino terminus of subfragment 2 with a full-length rat cardiac myosin light chain 1. A 16 amino acid region of the myosin heavy chain (residues 792-808) was shown to be required for myosin light chain 1 binding in an immunoprecipitation assay.

Morphometry and muscle gene expression in hypertrophied hearts from polyomavirus large T antigen transgenic mice

1995 ◽  
Vol 269 (1) ◽  
pp. H86-H95 ◽  
Author(s):  
E. Holder ◽  
B. Mitmaker ◽  
L. Alpert ◽  
L. Chalifour
Keyword(s):  
Transgenic Mice ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Light Chain ◽  
Myosin Light Chain ◽  
Troponin I ◽  
T Antigen ◽  
Large T Antigen ◽  
Cross Sectional

Transgenic mice expressing polyomavirus large T antigen (PVLT) in cardiomyocytes develop a cardiac hypertrophy in adulthood. Morphometric analysis identified cardiomyocytes enlarged up to ninefold in cross-sectional area in the adult transgenic hearts compared with normal age-matched nontransgenic hearts. Most enlarged cardiomyocytes were found in the subendocardium, whereas normal-sized cardiomyocytes were localized to the midmyocardium. Transgenic hearts did not express detectable skeletal muscle actin mRNA or protein, or skeletal troponin I isoform mRNA. Some, but not all, transgenic hearts expressed an increase in the beta-myosin heavy chain mRNA. All five transgenic mice tested had increased expression of atrial natriuretic factor (ANF) mRNA. Whereas normal hearts expressed three myosin light chain proteins of 19, 16, and 15 kDa, we found that the 19-kDa myosin light chain was not observed in the transgenic hearts. We conclude that adult, PVLT-expressing, transgenic mice developed enlarged cardiomyocytes with an increase in beta-myosin heavy chain and ANF mRNA expression, but a widespread skeletal isoform usage was not present in these transgenic mice. The adult transgenic hearts thus display histological and molecular changes similar to those found in hypertrophy induced by a pressure overload in vivo.

scholarly journals Electrophoretic analysis of proteins from single bovine muscle fibres

1981 ◽  
Vol 195 (1) ◽  
pp. 317-327 ◽  
Author(s):  
O A Young ◽  
C L Davey
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Light Chain ◽  
Myosin Light Chain ◽  
Fibre Types ◽  
Type I ◽  
Slow Fibre ◽  
Slow Myosin ◽  
Fast Myosin ◽  
Fast Myosin Heavy Chain

A number of single fibres were isolated by dissection of four bovine masseter (ma) muscles, three rectus abdominis (ra) muscles and eight sternomandibularis (sm) muscles. By histochemical criteria these muscles contain respectively, solely slow fibres (often called type I), predominantly fast fibres (type II), and a mixture of fast and slow. The fibres were analysed by conventional sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and the gels stained with Coomassie Blue. Irrespective of the muscle, every fibre could be classed into one of two broad groups based on the mobility of proteins in the range 135000-170000 daltons. When zones containing myosin heavy chain were cut from the single-fibre gel tracks and ‘mapped’ [Cleveland, Fischer, Kirschner & Laemmli (1977) J. Biol. Chem. 252, 1102-1106] with Staphylococcus proteinase, it was found that one group always contained fast myosin heavy chain, whereas the second group always contained the slow form. Moreover, a relatively fast-migrating alpha-tropomyosin was associated with the fast myosin group and a slow-migrating form with the slow myosin group. All fibres also contained beta-tropomyosin; the coexistence of alpha- and beta-tropomyosin is at variance with evidence that alpha-tropomyosin is restricted to fast fibres [Dhoot & Perry (1979) Nature (London) 278, 714-718]. Fast fibres containing the expected fast light chains and troponins I and C fast were identified in the three ra muscles, but in only four sm muscles. In three other sm muscles, all the fast fibres contained two troponins I and an additional myosin light chain that was more typical of myosin light chain 1 slow. The remaining sm muscle contained a fast fibre type that was similar to the first type, except that its myosin light chain 1 was more typical of the slow polymorph. Troponin T was bimorphic in all fast fibres from a ra muscles and in at least some fast fibres from one sm muscle. Peptide ‘mapping’ revealed two forms of fast myosin heavy chain distributed among fast fibres. Each form was associated with certain other proteins. Slow myosin heavy chain was unvarying in three slow fibre types identified. Troponin I polymorphs were the principal indicator of slow fibre types. The myofibrillar polymorphs identified presumably contribute to contraction properties, but beyond cud chewing involving ma muscle, nothing is known of the conditions that gave rise to the variable fibre composites in sm and ra muscles.

Three-dimensional compartmentalization of myosin heavy chain and myosin light chain isoforms in dog thyroarytenoid muscle

2006 ◽  
Vol 290 (5) ◽  
pp. C1446-C1458 ◽  
Author(s):  
Mark Bergrin ◽  
Sabahattin Bicer ◽  
Christine A. Lucas ◽  
Peter J. Reiser
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Light Chain ◽  
Myosin Light Chain ◽  
Expression Patterns ◽  
Shortening Velocity ◽  
Single Fibers ◽  
Isoform Expression ◽  
Thyroarytenoid Muscle ◽  
Mhc Iib

The thyroarytenoid muscle, a vocal fold adductor, has important roles in airway protection (e.g., prevention of aspiration) and phonation. Isoform expression of myosin heavy chain (MHC), a major determinant of muscle-shortening velocity, has been reported to be heterogeneous in this muscle in several mammals, differing markedly between the medial and lateral divisions. The objective was to determine the isoform expression patterns of both MHC and myosin light chain (MLC), with the latter having a modulatory role in determining shortening velocity, to further test whether the expression of both myosin subunits differs in multiple specific sites within the divisions of the dog thyroarytenoid muscle, potentially revealing even greater compartmentalization in this muscle. Our results indicate the existence of large gradients in the relative levels of individual MHC isoforms in the craniocaudal axis along the medial layer (i.e., airflow axis), where levels of MHC-I and MHC-IIA are low at both ends of the axis and high in the middle and MHC-IIB has a reciprocal distribution. The lateral layer is more uniform, with high levels of MHC-IIB throughout. The level of MHC-IID is relatively constant along the axis in both layers. Large differences exist in the distribution of MHC isoforms among single fibers isolated from sites along the craniocaudal axis, especially in the lateral layer. Systematic regional variations are apparent in the MLC isoform composition of single fibers as well, including some MLC isoform combinations that are not observed in dog limb muscles. Variations of MHC and MLC isoform expression in the dog thyroarytenoid muscle are greater than previously recognized and suggest an even broader range of contractile properties within this multifunctional muscle.

scholarly journals Regulatory light chain phosphorylation augments length-dependent contraction in PTU-treated rats

2018 ◽  
Vol 151 (1) ◽  
pp. 66-76 ◽  
Author(s):  
Jason J. Breithaupt ◽  
Hannah C. Pulcastro ◽  
Peter O. Awinda ◽  
David C. DeWitt ◽  
Bertrand C.W. Tanner
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Light Chain ◽  
Myosin Heavy Chain Isoforms ◽  
Regulatory Light Chain ◽  
Cardiac Myosin ◽  
Myosin Heavy Chain Isoform ◽  
Cross Bridge ◽  
Detachment Rate ◽  
Length Dependent Activation

Force production by actin–myosin cross-bridges in cardiac muscle is regulated by thin-filament proteins and sarcomere length (SL) throughout the heartbeat. Prior work has shown that myosin regulatory light chain (RLC), which binds to the neck of myosin heavy chain, increases cardiac contractility when phosphorylated. We recently showed that cross-bridge kinetics slow with increasing SLs, and that RLC phosphorylation amplifies this effect, using skinned rat myocardial strips predominantly composed of the faster α-cardiac myosin heavy chain isoform. In the present study, to assess how RLC phosphorylation influences length-dependent myosin function as myosin motor speed varies, we used a propylthiouracil (PTU) diet to induce >95% expression of the slower β-myosin heavy chain isoform in rat cardiac ventricles. We measured the effect of RLC phosphorylation on Ca2+-activated isometric contraction and myosin cross-bridge kinetics (via stochastic length perturbation analysis) in skinned rat papillary muscle strips at 1.9- and 2.2-µm SL. Maximum tension and Ca2+ sensitivity increased with SL, and RLC phosphorylation augmented this response at 2.2-µm SL. Subtle increases in viscoelastic myocardial stiffness occurred with RLC phosphorylation at 2.2-µm SL, but not at 1.9-µm SL, thereby suggesting that RLC phosphorylation increases β-myosin heavy chain binding or stiffness at longer SLs. The cross-bridge detachment rate slowed as SL increased, providing a potential mechanism for prolonged cross-bridge attachment to augment length-dependent activation of contraction at longer SLs. Length-dependent slowing of β-myosin heavy chain detachment rate was not affected by RLC phosphorylation. Together with our previous studies, these data suggest that both α- and β-myosin heavy chain isoforms show a length-dependent activation response and prolonged myosin attachment as SL increases in rat myocardial strips, and that RLC phosphorylation augments length-dependent activation at longer SLs. In comparing cardiac isoforms, however, we found that β-myosin heavy chain consistently showed greater length-dependent sensitivity than α-myosin heavy chain. Our work suggests that RLC phosphorylation is a vital contributor to the regulation of myocardial contractility in both cardiac myosin heavy chain isoforms.

scholarly journals The expression of myosin genes in developing skeletal muscle in the mouse embryo.

1990 ◽  
Vol 111 (4) ◽  
pp. 1465-1476 ◽  
Author(s):  
G E Lyons ◽  
M Ontell ◽  
R Cox ◽  
D Sassoon ◽  
M Buckingham
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Light Chain ◽  
Myosin Light Chain ◽  
Muscle Development ◽  
Minor Component ◽  
Light Chain Gene ◽  
Skeletal Myosin

Using in situ hybridization, we have investigated the temporal sequence of myosin gene expression in the developing skeletal muscle masses of mouse embryos. The probes used were isoform-specific, 35S-labeled antisense cRNAs to the known sarcomeric myosin heavy chain and myosin alkali light chain gene transcripts. Results showed that both cardiac and skeletal myosin heavy chain and myosin light chain mRNAs were first detected between 9 and 10 d post coitum (p.c.) in the myotomes of the most rostral somites. Myosin transcripts appeared in more caudal somites at later stages in a developmental gradient. The earliest myosin heavy chain transcripts detected code for the embryonic skeletal (MHCemb) and beta-cardiac (MHC beta) isoforms. Perinatal myosin heavy chain (MHCpn) transcripts begin to accumulate at 10.5 d p.c., which is much earlier than previously reported. At this stage, MHCemb is the major MHC transcript. By 12.5 d p.c., MHCpn and MHCemb mRNAs are present to an equal extent, and by 15.5 d p.c. the MHCpn transcript is the major MHC mRNA detected. Cardiac MHC beta transcripts are always present as a minor component. In contrast, the cardiac MLC1A mRNA is initially more abundant than that encoding the skeletal MLC1F isoform. By 12.5 d p.c. the two MLC mRNAs are present at similar levels, and by 15.5 d p.c., MLC1F is the predominant MLC transcript detected. Transcripts for the ventricular/slow (MLC1V) and another fast skeletal myosin light chain (MLC3F) are not detected in skeletal muscle before 15 d p.c., which marks the beginning of the fetal stage of muscle development. This is the first stage at which we can detect differences in expression of myosin genes between developing muscle fibers. We conclude that, during the development of the myotome and body wall muscles, different myosin genes follow independent patterns of activation and accumulation. The data presented are the first detailed study of myosin gene expression at these early stages of skeletal muscle development.

scholarly journals The myosin light chain 1 isoform associated with masticatory myosin heavy chain in mammals and reptiles is embryonic/atrial MLC1

2010 ◽  
Vol 213 (10) ◽  
pp. 1633-1642 ◽  
Author(s):  
P. J. Reiser ◽  
S. Bicer ◽  
R. Patel ◽  
Y. An ◽  
Q. Chen ◽  
...  
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Light Chain ◽  
Myosin Light Chain

Immunocytochemical localization of 155 kDa myosin light chain kinase and myosin heavy chain in bovine brain

1995 ◽  
Vol 682 (1-2) ◽  
pp. 212-214 ◽  
Author(s):  
Hiroyuki Shimada ◽  
Teruo Shimizu ◽  
Hideto Kuwayama ◽  
Masashi Suzuki ◽  
Ryozo Nagai ◽  
...  
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Light Chain ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Bovine Brain ◽  
Immunocytochemical Localization

scholarly journals Masticatory (`superfast') myosin heavy chain and embryonic/atrial myosin light chain 1 in rodent jaw-closing muscles

2009 ◽  
Vol 212 (16) ◽  
pp. 2511-2519 ◽  
Author(s):  
P. J. Reiser ◽  
S. Bicer ◽  
Q. Chen ◽  
L. Zhu ◽  
N. Quan
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Light Chain ◽  
Myosin Light Chain ◽  
Atrial Myosin

Expression of MRF4, a myogenic helix-loop-helix protein, produces multiple changes in the myogenic program of BC3H-1 cells

1992 ◽  
Vol 12 (6) ◽  
pp. 2484-2492
Author(s):  
N E Block ◽  
J B Miller
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Light Chain ◽  
Myosin Light Chain ◽  
Myogenic Regulatory Factors ◽  
Regulatory Factors ◽  
Myosin Heavy Chain Isoform ◽  
Helix Loop Helix ◽  
Fast Myosin ◽  
Myogenic Program

Expression of MRF4, a myogenic regulatory factor of the basic helix-loop-helix type, produced multiple changes in the myogenic program of the BC3H-1 cell line. BC3H-1 cells that stably expressed exogenous MRF4 were prepared and termed BR cell lines. Upon differentiation, the BR cells were found to have three muscle-specific properties (endogenous MyoD expression, myoblast fusion, and fast myosin light-chain 1 expression) that the parent BC3H-1 cells did not have. Of the four known myogenic regulatory factors (MyoD, myogenin, Myf-5, and MRF4), only MRF4 was capable of activating expression of the endogenous BC3H-1 myoD gene. In addition, the pattern of Myf-5 expression in BR cells was the opposite of that in BC3H-1 cells. Myf-5 expression was low in BR myoblasts and showed a small increase upon myotube formation, whereas Myf-5 expression was high in BC3H-1 myoblasts and decreased upon differentiation. Though the MRF4-transfected BR cells fused to form large myotubes and expressed fast myosin light-chain 1, the pattern of myosin heavy-chain isoform expression was the same in the BR and the nonfusing parent BC3H-1 cells, suggesting that factors in addition to the MyoD family members regulate myosin heavy-chain isoform expression patterns in BC3H-1 cells. In contrast to the changes produced by MRF4 expression, overexpression of Myf-5 did not alter BC3H-1 myogenesis. The results suggest that differential expression of the myogenic regulatory factors of the MyoD family may be one mechanism for generating cells with diverse myogenic phenotypes.

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