scholarly journals Sprint training, in vitro and in vivo muscle function, and myosin heavy chain expression

1998 ◽  
Vol 84 (2) ◽  
pp. 442-449 ◽  
Author(s):  
S. D. R. Harridge ◽  
R. Bottinelli ◽  
M. Canepari ◽  
M. Pellegrino ◽  
C. Reggiani ◽  
...  
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Muscle Function ◽  
Maximal Voluntary Contraction ◽  
Voluntary Contraction ◽  
Relative Distribution ◽  
Sprint Training ◽  
Single Fibers

Harridge, S. D. R., R. Bottinelli, M. Canepari, M. Pellegrino, C. Reggiani, M. Esbjörnsson, P. D. Balsom, and B. Saltin. Sprint training, in vitro and in vivo muscle function, and myosin heavy chain expression. J. Appl. Physiol. 84(2): 442–449, 1998.—Sprint training represents the condition in which increases in muscle shortening speed, as well as in strength, might play a significant role in improving power generation. This study therefore aimed to determine the effects of sprint training on 1) the coupling between myosin heavy chain (MHC) isoform expression and function in single fibers, 2) the distribution of MHC isoforms across a whole muscle, and 3) in vivo muscle function. Seven young male subjects completed 6 wk of training (3-s sprints) on a cycle ergometer. Training was without effect on maximum shortening velocity in single fibers or in the relative distribution of MHC isoforms in either the soleus or the vastus lateralis muscles. Electrically evoked and voluntary isometric torque generation increased ( P < 0.05) after training in both the plantar flexors (+8% at 50 Hz and +16% maximal voluntary contraction) and knee extensors (+8% at 50 Hz and +7% maximal voluntary contraction). With the shortening potential of the muscles apparently unchanged, the increased strength of the major lower limb muscles is likely to have contributed to the 7% increase ( P < 0.05) in peak pedal frequency during cycling.

Control of AMP deaminase 1 binding to myosin heavy chain

1998 ◽  
Vol 275 (3) ◽  
pp. C870-C881 ◽  
Author(s):  
Ichiro Hisatome ◽  
Takayuki Morisaki ◽  
Hiroshi Kamma ◽  
Takako Sugama ◽  
Hiroko Morisaki ◽  
...  
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Sequence Similarity ◽  
Critical Role ◽  
Energy Charge ◽  
Adenylate Energy Charge ◽  
Amp Deaminase ◽  
Amino Terminal

AMP deaminase (AMPD) plays a central role in preserving the adenylate energy charge in myocytes following exercise and in producing intermediates for the citric acid cycle in muscle. Prior studies have demonstrated that AMPD1 binds to myosin heavy chain (MHC) in vitro; binding to the myofibril varies with the state of muscle contraction in vivo, and binding of AMPD1 to MHC is required for activation of this enzyme in myocytes. The present study has identified three domains in AMPD1 that influence binding of this enzyme to MHC using a cotransfection model that permits assessment of mutations introduced into the AMPD1 peptide. One domain that encompasses residues 178–333 of this 727-amino acid peptide is essential for binding of AMPD1 to MHC. This region of AMPD1 shares sequence similarity with several regions of titin, another MHC binding protein. Two additional domains regulate binding of this peptide to MHC in response to intracellular and extracellular signals. A nucleotide binding site, which is located at residues 660–674, controls binding of AMPD1 to MHC in response to changes in intracellular ATP concentration. Deletion analyses demonstrate that the amino-terminal 65 residues of AMPD1 play a critical role in modulating the sensitivity to ATP-induced inhibition of MHC binding. Alternative splicing of the AMPD1 gene product, which alters the sequence of residues 8–12, produces two AMPD1 isoforms that exhibit different MHC binding properties in the presence of ATP. These findings are discussed in the context of the various roles proposed for AMPD in energy production in the myocyte.

Differential regulation by thyroid hormones of myosin heavy chain α and β mRNAs in the rat ventricular myocardium

1989 ◽  
Vol 122 (1) ◽  
pp. 193-200 ◽  
Author(s):  
N. K. Green ◽  
J. A. Franklyn ◽  
J. A. O. Ahlquist ◽  
M. D. Gammage ◽  
M. C. Sheppard
Keyword(s):  
Myosin Heavy Chain ◽  
Cardiac Myocytes ◽  
Heavy Chain ◽  
Ventricular Myocardium ◽  
Mhc Genes ◽  
Specific Effects ◽  
Dependent Inhibition ◽  
Dose Dependent

ABSTRACT The effect of tri-iodothyronine (T3) treatment on myocardial levels of α and β myosin heavy chain (MHC) mRNAs in the rat was defined in vivo and in vitro. Dose–response experiments were performed in intact hypothyroid and euthyroid rats; in addition, studies in vitro examined the effect of T3 on MHC mRNAs in neonatal cardiac myocytes in primary culture. Specific α and β MHC mRNAs were determined by Northern blot and dot hybridization to oligonucleotide probes complementary to the 3′ untranslated regions of the MHC genes. An increase in myocardial β MHC mRNA was demonstrated in hypothyroidism, accompanied by a reduction in α MHC mRNA. Marked differences in the sensitivity of α and β MHC mRNAs to T3 replacement were found; a dose-dependent increase in α mRNA was evident at 6 h after T3 treatment, in the absence of consistent effects on β mRNA, whereas 72 h after T3 replacement was commenced, stimulatory effects of T3 on α MHC mRNA, evident at all doses, were accompanied by a dose-dependent inhibition of β MHC mRNA. No effect of thyroid status on actin mRNA was found, indicating the specificity of MHC gene regulation. T3 treatment of cardiac myocytes in vitro exerted similar actions on MHC mRNAs to those found in vivo, with a more marked influence on α than β MHC mRNA. These studies of the action of T3 in vivo and in vitro have thus demonstrated specific effects of T3 on pretranslational regulation of the α and β MHC genes, influences which differ not only in terms of stimulation or inhibition, but also in magnitude of effect. Journal of Endocrinology (1989) 122, 193–200

Molecular characterization of a developmentally regulated porcine skeletal myosin heavy chain gene and its 5′ regulatory region

1995 ◽  
Vol 108 (4) ◽  
pp. 1779-1789 ◽  
Author(s):  
K.C. Chang ◽  
K. Fernandes ◽  
M.J. Dauncey
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Transcriptional Start Site ◽  
Regulatory Region ◽  
Chain Gene ◽  
Specific Expression ◽  
Slow Fibre ◽  
Skeletal Myosin

Members of the myosin heavy chain (MyHC) gene family show developmental stage- and spatial-specificity of expression. We report on the characterization and identification of a porcine skeletal fast MyHC gene, including its corresponding 5′ end cDNA and 5′ regulatory region. This MyHC isoform was found exclusively in skeletal muscles from about the last quarter of gestation through to adulthood. Expression of this isoform was higher postnatally and its spatial distribution resembled a rosette cluster; each with a ring of fast fibres surrounding a central slow fibre. This rosette pattern was absent in the adult diaphragm but about 20% of the fibres continued to express this MyHC isoform. Further in vivo expression studies, in a variety of morphologically and functionally diverse muscles, showed that this particular skeletal MyHC isoform was expressed in fast oxidative-glycolytic fibres, suggesting that it was the equivalent of the fast IIA isoform. Two domains in the upstream regulatory region were found to confer differentiation-specific expression on C2 myotubes (−1007 to -828 and -455 to -101), based on in vitro transient expression assays using the chloramphenicol acetyltransferase (CAT) reporter gene. Interestingly, for high levels of CAT expression to occur, a 3′ region, extending from the transcriptional start site to part. of intron 2, must be present in all the DNA constructs used.

Developmental pattern of mouse skeletal myosin heavy chain gene transcripts in vivo and in vitro

Cell ◽  
1987 ◽  
Vol 49 (1) ◽  
pp. 121-129 ◽  
Author(s):  
André Weydert ◽  
Paul Barton ◽  
A.John Harris ◽  
Christian Pinset ◽  
Margaret Buckingham
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Developmental Pattern ◽  
Chain Gene ◽  
Heavy Chain Gene ◽  
Myosin Heavy Chain Gene ◽  
Skeletal Myosin ◽  
Gene Transcripts

scholarly journals MyoD, myogenin independent differentiation of primordial myoblasts in mouse somites.

1992 ◽  
Vol 116 (5) ◽  
pp. 1243-1255 ◽  
Author(s):  
M G Cusella-De Angelis ◽  
G Lyons ◽  
C Sonnino ◽  
L De Angelis ◽  
E Vivarelli ◽  
...  
Keyword(s):  
Embryonic Development ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Posttranscriptional Regulation ◽  
Proximal Region ◽  
Limb Bud ◽  
Northern Analysis ◽  
Myogenic Cells

The accumulation of two myogenic regulatory proteins, MyoD and myogenin, was investigated by double-immunocytochemistry and correlated with myosin heavy chain expression in different classes of myoblasts in culture and during early myogenesis in vivo. During in vitro differentiation of fetal myoblasts, MyoD-positive cells were detected first, followed by the appearance of cells positive for both MyoD and myogenin and finally by the appearance of differentiated myocytes and myotubes expressing myosin heavy chain (MHC). A similar pattern of expression was observed in cultures of embryonic and satellite cells. In contrast, most myogenic cells isolated from newly formed somites, expressed MHC in the absence of detectable levels of myogenin or MyoD. In vivo, the appearance of both myogenin and MyoD proteins was only detected at 10.5 d postcoitum (d.p.c.), when terminally differentiated muscle cells could already be identified in the myotome. Parasagittal sections of the caudal myotomes of 10.5-d-old embryos showed that expression of contractile proteins preceded the expression of myogenin or MyoD and, when coexpressed, MHC and myogenin did not co-localize within all the cells of the myotome. In the limb bud, however, many myogenin (or MyoD) positive/MHC negative cells could be observed in the proximal region at day 11. During further embryonic development the expression of these proteins remained constant in all the muscle anlagens examined, decreasing to a low level during the late fetal period. Western and Northern analysis confirmed that the myogenin protein could only be detected after 10.5 d.p.c. while the corresponding message was clearly present at 9.5 d.p.c., strongly suggesting a posttranscriptional regulation of myogenin during this stage of embryonic development. These data show that the first myogenic cells which appear in the mouse myotome, and can be cultured from it, accumulate muscle structural proteins in their cytoplasm without expressing detectable levels of myogenin protein (although the message is clearly accumulated). Neither MyoD message or protein are detectable in these cells, which may represent a distinct myogenic population whose role in development remains to be established.

Molecular genetic truncation analysis of filament assembly and phosphorylation domains of Dictyostelium myosin heavy chain

1994 ◽  
Vol 107 (10) ◽  
pp. 2875-2886 ◽  
Author(s):  
R.J. Lee ◽  
T.T. Egelhoff ◽  
J.A. Spudich
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Molecular Motor ◽  
Molecular Genetic ◽  
Surface Receptors ◽  
Cell Functions ◽  
Filament Assembly ◽  
Carboxy Terminal

Conventional myosin (‘myosin II’) is a major component of the cytoskeleton in a wide variety of eukaryotic cells, ranging from lower amoebae to mammalian fibroblasts and neutrophils. Gene targeting technologies available in the Dictyostelium discoideum system have provided the first genetic proof that this molecular motor protein is essential for normal cytokinesis, capping of cell surface receptors, normal chemotactic cell locomotion and morphogenetic shape changes during development. Although the roles of myosin in a variety of cell functions are becoming clear, the mechanisms that regulate myosin assembly into functional bipolar filaments within cells are poorly understood. Dictyostelium is currently the only system where mutant forms of myosin can be engineered in vitro, then expressed in their native context in cells that are devoid of the wild-type isoform. We have utilized this technology in combination with nested truncation and deletion analysis to map domains of the myosin tail necessary for in vivo and in vitro filament assembly, and for normal myosin heavy chain (MHC) phosphorylation. This analysis defines a region of 35 amino acids within the tail that is critical for filament formation both for purified myosin molecules and for myosin within the in vivo setting. Phosphorylation analysis of these mutants in intact cytoskeletons demonstrates that the carboxy-terminal tip of the myosin heavy chain is required for complete phosphorylation of the myosin tail.

scholarly journals Targeted disruption of the Dictyostelium RMLC gene produces cells defective in cytokinesis and development.

1994 ◽  
Vol 127 (6) ◽  
pp. 1933-1944 ◽  
Author(s):  
P Chen ◽  
B D Ostrow ◽  
S R Tafuri ◽  
R L Chisholm
Keyword(s):  
Myosin Heavy Chain ◽  
Conformational Changes ◽  
Heavy Chain ◽  
Biochemical Study ◽  
Neck Region ◽  
Light Chains ◽  
Dictyostelium Cell ◽  
Wild Type

Conventional myosin has two different light chains bound to the neck region of the molecule. It has been suggested that the light chains contribute to myosin function by providing structural support to the neck region, therefore amplifying the conformational changes in the head following ATP hydrolysis (Rayment et al., 1993). The regulatory light chain is also believed to be important in regulating the actin-activated ATPase and myosin motor function as assayed by an in vitro motility assay (Griffith et al., 1987). Despite extensive in vitro biochemical study, little is known regarding RMLC function and its regulatory role in vivo. To better understand the importance and contribution of RMLC in vivo, we engineered Dictyostelium cell lines with a disrupted RMLC gene. Homologous recombination between the introduced gene disruption vector and the chromosomal RMLC locus (mlcR) resulted in disruption of the RMLC-coding region, leading to cells devoid of both the RMLC transcript and the 18-kD RMLC polypeptide. RMLC-deficient cells failed to divide in suspension, becoming large and multinucleate, and could not complete development following starvation. These results, similar to those from myosin heavy chain mutants (DeLozanne et al., 1987; Manstein et al., 1989), suggest the RMLC subunit is required for normal cytokinesis and cell motility. In contrast to the myosin heavy chain mutants, however, the mlcR cells are able to cap cell surface receptors following concanavilin A treatment. By immunofluorescence microscopy, RMLC null cells exhibited myosin localization patterns different from that of wild-type cells. The myosin localization in RMLC null cells also varied depending upon whether the cells were cultured in suspension or on a solid substrate. In vitro, purified RMLC- myosin assembled to form thick filaments comparable to wild-type myosin, but the filaments then exhibit abnormal disassembly properties. These results indicate that in vivo RMLC is necessary for myosin function.

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