Expression of cardiac myosin light chain 2 during embryonic heart development in medaka fish, Oryzias latipes, and phylogenetic relationship with other myosin light chains

It has been demonstrated that embryonic chicken gizzard smooth muscle contains a unique embryonic myosin light chain of 23,000 mol wt, called L23 (Katoh, N., and S. Kubo, 1978, Biochem. Biophys. Acta, 535:401-411; Takano-Ohmuro, H., T. Obinata, T. Mikawa, and T. Masaki, 1983, J. Biochem. (Tokyo), 93:903-908). When we examined myosins in developing chicken ventricular and pectoralis muscles by two-dimensional gel electrophoresis, the myosin light chain (Le) that completely comigrates with L23 was detected in both striated muscles at early developmental stages. Two monoclonal antibodies, MT-53f and MT-185d, were applied to characterize the embryonic light chain Le of striated muscles. Both monoclonal antibodies were raised to fast skeletal muscle myosin light chains; the former antibody is specific to fast muscle myosin light chains 1 and 3, whereas the latter recognizes not only fast muscle myosin light chains but also the embryonic smooth muscle light chain L23. The immunoblots combined with both one- and two-dimensional gel electrophoresis showed that Le reacts with MT-185d but not with MT-53f. These results strongly indicate that Le is identical to L23 and that embryonic chicken skeletal, cardiac, and smooth muscles express a common embryo-specific myosin light chain.

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Myosin light chain kinase-regulated endothelial cell contraction: the relationship between isometric tension, actin polymerization, and myosin phosphorylation.

The Journal of Cell Biology ◽

10.1083/jcb.130.3.613 ◽

1995 ◽

Vol 130 (3) ◽

pp. 613-627 ◽

Cited By ~ 329

Author(s):

Z M Goeckeler ◽

R B Wysolmerski

Keyword(s):

Endothelial Cell ◽

Light Chain ◽

Isometric Contraction ◽

Myosin Light Chain Kinase ◽

Myosin Light Chain ◽

Myosin Ii ◽

Isometric Tension ◽

Stress Fibers ◽

Light Chains ◽

Myosin Light Chains

The phosphorylation of regulatory myosin light chains by the Ca2+/calmodulin-dependent enzyme myosin light chain kinase (MLCK) has been shown to be essential and sufficient for initiation of endothelial cell retraction in saponin permeabilized monolayers (Wysolmerski, R. B. and D. Lagunoff. 1990. Proc. Natl. Acad. Sci. USA. 87:16-20). We now report the effects of thrombin stimulation on human umbilical vein endothelial cell (HUVE) actin, myosin II and the functional correlate of the activated actomyosin based contractile system, isometric tension development. Using a newly designed isometric tension apparatus, we recorded quantitative changes in isometric tension from paired monolayers. Thrombin stimulation results in a rapid sustained isometric contraction that increases 2- to 2.5-fold within 5 min and remains elevated for at least 60 min. The phosphorylatable myosin light chains from HUVE were found to exist as two isoforms, differing in their molecular weights and isoelectric points. Resting isometric tension is associated with a basal phosphorylation of 0.54 mol PO4/mol myosin light chain. After thrombin treatment, phosphorylation rapidly increases to 1.61 mol PO4/mol myosin light chain within 60 s and remains elevated for the duration of the experiment. Myosin light chain phosphorylation precedes the development of isometric tension and maximal phosphorylation is maintained during the sustained phase of isometric contraction. Tryptic phosphopeptide maps from both control and thrombin-stimulated cultures resolve both monophosphorylated Ser-19 and diphosphorylated Ser-19/Thr-18 peptides indicative of MLCK activation. Changes in the polymerization of actin and association of myosin II correlate temporally with the phosphorylation of myosin II and development of isometric tension. Activation results in a 57% increase in F-actin content within 90 s and 90% of the soluble myosin II associates with the reorganizing F-actin. Furthermore, the disposition of actin and myosin II undergoes striking reorganization. F-actin initially forms a fine network of filaments that fills the cytoplasm and then reorganizes into prominent stress fibers. Myosin II rapidly forms discrete aggregates associated with the actin network and by 2.5 min assumes a distinct periodic distribution along the stress fibers.

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Repression of the cardiac myosin light chain-2 gene in skeletal muscle requires site-specific association of antithetic regulator, Nished, and HDACs

Journal of Cellular and Molecular Medicine ◽

10.1111/j.1582-4934.2008.00525.x ◽

2008 ◽

Vol 13 (8b) ◽

pp. 1952-1961

Author(s):

Sumy Mathew ◽

Josephine Galatioto ◽

Eduardo Mascareno ◽

M.A.Q. Siddiqui

Keyword(s):

Skeletal Muscle ◽

Light Chain ◽

Myosin Light Chain ◽

Cardiac Myosin ◽

Site Specific ◽

Myosin Light Chain 2 ◽

Specific Association

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A single transcription factor binds to two divergent sequence elements with a common function in cardiac myosin light chain-2 promoter.

Molecular and Cellular Biology ◽

10.1128/mcb.12.3.1107 ◽

1992 ◽

Vol 12 (3) ◽

pp. 1107-1116 ◽

Cited By ~ 16

Author(s):

P Qasba ◽

E Lin ◽

M D Zhou ◽

A Kumar ◽

M A Siddiqui

Keyword(s):

Transcription Factor ◽

Gene Transcription ◽

Light Chain ◽

Myosin Light Chain ◽

Cardiac Myosin ◽

Divergent Sequence ◽

Specific Element ◽

Myosin Light Chain 2 ◽

Sequence Elements ◽

Gel Shift

The cardiac myosin light chain-2 (MLC-2) gene promoter contains several positive and negative cis-acting sequences that are involved in the regulation of its expression. We describe here the properties of two activator sequences, elements A and P, and their DNA-binding factors (ABFs). Element A (CCAAAAGTGG), located at -61, has homology with the evolutionarily conserved sequence CC(A/T)6GG, present in the genes of many contractile proteins. Element P (TAACCTTGAAAGC), located 114 bp upstream of element A, is conserved in both chicken and rat cardiac MLC-2 gene promoters. Deletion mutagenesis demonstrated that these two elements are involved in the positive regulation of MLC-2 gene transcription. At least two sequence-specific element A-binding proteins, ABF-1 and ABF-2, were identified by gel shift analysis of the fractionated cardiac nuclear proteins. ABF-1 binds to element A with strict dependence on the internal element A sequence AAAAGT. In contrast, ABF-2 exhibits a relaxed sequence requirement, as it recognizes the consensus CArG and CCAAT box sequences as well. ABF-2 also recognizes the distal element P despite the fact that the sequences of elements A and P are divergent. DNase I footprinting, methylation interference, and gel shift analyses demonstrated unequivocally that the element A-DNA affinity-purified protein ABF-2 binds to element P with sequence specificity. Since both elements A and P play a positive regulatory role in MLC-2 gene transcription and bind to a single protein (ABF-2), it would appear that ABF-2 is a key transcription factor with the ability to recognize divergent sequence elements involved in a common regulatory pathway during myogenesis.

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Transcriptional regulation of the cardiac myosin light chain 2 gene under normal and stress conditions

American Journal of Hypertension ◽

10.1016/0895-7061(95)97490-i ◽

1995 ◽

Vol 8 (4) ◽

pp. 31A

Author(s):

E MASCARENO

Keyword(s):

Transcriptional Regulation ◽

Light Chain ◽

Myosin Light Chain ◽

Stress Conditions ◽

Cardiac Myosin ◽

Myosin Light Chain 2

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Effect of muscle length on isometric stress and myosin light chain phosphorylation in gallbladder smooth muscle

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1991.260.6.g920 ◽

1991 ◽

Vol 260 (6) ◽

pp. G920-G924 ◽

Cited By ~ 4

Author(s):

R. J. Washabau ◽

M. B. Wang ◽

C. L. Dorst ◽

J. P. Ryan

Keyword(s):

Smooth Muscle ◽

Guinea Pig ◽

Light Chain ◽

Myosin Light Chain ◽

Muscle Length ◽

Stress Sensitivity ◽

Light Chains ◽

Myosin Light Chains ◽

Myosin Light Chain Phosphorylation ◽

Myofilament Activation

These experiments were designed to characterize the effect of muscle length on isometric stress, sensitivity to stimulation, and phosphorylation of the 20,000-Da myosin light chains in guinea pig gallbladder smooth muscle. Basal, active, and total isometric stress were determined in acetylcholine- or K(+)-treated (10(-4) M ACh, 80 mM KCl) muscle strips at 0.6-1.3 times the optimal muscle length (Lo) for isometric stress development. The effect of muscle length on the sensitivity to ACh and K+ was determined in cumulative dose-response experiments (10(-8) to 10(-4) M ACh, 10-80 mM KCl) at 0.7, 1.0, and 1.3 Lo. The effect of muscle length on myosin light chain phosphorylation was determined in ACh- or K(+)-treated (10(-4) M ACh, 80 mM KCl) muscle strips at 0.7, 1.0, and 1.3 Lo. In gallbladder smooth muscle, 1) active isometric stresses at 0.7 and 1.3 Lo were less than active isometric stress at 1.0 Lo; 2) the sensitivity of developed stress was similar at 1.0 and 1.3 Lo but decreased at 0.7 Lo; 3) the decline in isometric stress and sensitivity at 0.7 Lo was associated with reduced levels of phosphorylated myosin light chain; and 4) the decline in isometric stress at 1.3 Lo was not associated with reduced amounts of phosphorylated myosin light chain. These results suggest that the decline in active stress and sensitivity at short muscle lengths (L less than Lo) in gallbladder smooth muscle is due, at least in part, to decreases in the activation of the myofilaments. The decline in active isometric stress at long muscle lengths (L greater than Lo) is not due to changes in myofilament activation.

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