scholarly journals Metabolism of myosin heavy chain in steady-state chick skeletal muscle cultures

1981 ◽  
Vol 194 (1) ◽  
pp. 241-247 ◽  
Author(s):  
R B Young ◽  
O C Dombroske
Keyword(s):  
Steady State ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Horse Serum ◽  
Absolute Rate ◽  
Direct Proportion ◽  
Breakdown Rate ◽  
Breakdown Rates ◽  
Muscle Cultures ◽  
Chain Synthesis

Synthesis, accumulation and breakdown of the 200000-mol.wt. heavy subunit of myosin were analysed over an 11 day period in muscle cell cultures isolated from the leg muscle of 12-day chick embryos. Muscle cells accumulated myosin heavy chain rapidly from days 2 to 5 and maintained a maximum, constant myosin-heavy-chain concentration between days 7 and 11. Myosin-heavy-chain content and breakdown rate were compared in steady-state muscle cultures grown either in the presence of an optimum batch of horse serum (control) or in the presence of horse serum that had been pre-selected for its ability to inhibit several-fold the rate of synthesis of myosin heavy chain (inhibitory). The quantity of myosin heavy chain in the inhibited cultures was decreased in direct proportion to the decrease in the rate of synthesis of myosin heavy chain; however, the half-lives of myosin heavy chain (control, 17.7h; inhibitory, 17.0h) were virtually identical. In contrast, the absolute rate of breakdown of myosin heavy chain, expressed as molecules/min per nucleus, was approx. 5-fold lower in the inhibited cultures (4.3 × 10(3) molecules/min per nucleus) than in the control cultures (21.7 × 10(3) molecules/min per nucleus). Thus, inhibition of myosin-heavy-chain synthesis in this case was accompanied by diminished myosin-heavy-chain concentration and absolute breakdown rate at the altered steady state, but relative myosin-heavy-chain breakdown rates were unchanged.

scholarly journals Effect of creatine on contents of myosin heavy chain and myosin-heavy-chain mRNA in steady-state chicken muscle-cell cultures

1984 ◽  
Vol 218 (3) ◽  
pp. 871-876 ◽  
Author(s):  
R B Young ◽  
R M Denome
Keyword(s):  
Steady State ◽  
Myosin Heavy Chain ◽  
Muscle Cell ◽  
Cell Cultures ◽  
Heavy Chain ◽  
Synthesis Rate ◽  
Adult Skeletal Muscle ◽  
Muscle Cultures ◽  
Chain Synthesis

Embryonic-chick muscle cells reach a steady state with respect to protein metabolism after approx. 1 week in cell culture. To determine if this steady state could be altered by the administration of agents that have been reported to stimulate myosin heavy-chain synthesis, 7-day muscle-cell cultures were treated with 0-1 mM-creatine. Incorporation of [3H]leucine into myosin heavy chain was stimulated by 30-40% at the optimum creatine concentration (0.2 mM), but this stimulation was blocked when actinomycin D (10 micrograms/ml) was also present. However, the quantity of myosin-heavy-chain mRNA as measured by hybridization in vitro was only 15% higher in creatine-treated cultures, and was therefore not entirely responsible for the observed effect. It is important to note that creatine only exerted its action on myosin-heavy-chain synthesis rate in steady-state cultures; creatine was ineffective in altering this rate in rapidly differentiating 3-day muscle cultures. Finally, muscle-cell cultures that had been grown for the entire 7-day culture period in the presence of 0.2 mM-creatine were assayed for quantity of myosin heavy chain. Control and creatine-treated cultures contained 12.7 +/- 1.5 and 20.5 +/- 1.8 micrograms/dish respectively. In conclusion, creatine apparently enhances the quantity of myosin heavy chain in steady-state embryonic muscle-cell cultures, but it probably does not mediate regulation of myosin content in adult skeletal muscle.

scholarly journals Contractile activity is required for the expression of neonatal myosin heavy chain in embryonic chick pectoral muscle cultures.

1986 ◽  
Vol 103 (6) ◽  
pp. 2153-2161 ◽  
Author(s):  
L C Cerny ◽  
E Bandman
Keyword(s):  
Monoclonal Antibody ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Contractile Activity ◽  
Pectoral Muscle ◽  
Chicken Muscle ◽  
High K ◽  
Muscle Cultures ◽  
Spontaneous Contractions

The expression of neonatal myosin heavy chain (MHC) was examined in developing embryonic chicken muscle cultures using a monoclonal antibody (2E9) that has been shown to be specific for that isoform (Bandman, E., 1985, Science (Wash. DC), 227: 780-782). After 1 wk in vitro some myotubes could be stained with the antibody, and the number of cells that reacted with 2E9 increased with time in culture. All myotubes always stained with a second monoclonal antibody that reacted with all MHC isoforms (AG19) or with a third monoclonal antibody that reacted with the embryonic but not the neonatal MHC (EB165). Quantitation by ELISA of an extract from 2-wk cultures demonstrated that the neonatal MHC represented between 10 and 15% of the total myosin. The appearance of the neonatal isoform was inhibited by switching young cultures to medium with a higher [K+] which has been shown to block spontaneous contractions of myotubes in culture. Furthermore, if mature cultures that reacted with the neonatal antibody were placed into high [K+] medium, neonatal MHC disappeared from virtually all myotubes within 3 d. The effect of high [K+] medium was reversible. When cultures maintained in high [K+] medium for 2 wk were placed in standard medium, which permitted the resumption of contractile activity, within 24 h cells began to react with the neonatal specific antibody, and by 72 h many myotubes were strongly positive. Since similar results were also obtained by inhibiting spontaneous contractions with tetrodotoxin, we suggest that the development of contractile activity is not only associated with the maturation of myotubes in culture, but may also be the signal that induces the expression of the neonatal MHC.

Glutamine prevents downregulation of myosin heavy chain synthesis and muscle atrophy from glucocorticoids

1995 ◽  
Vol 268 (4) ◽  
pp. E730-E734 ◽  
Author(s):  
R. C. Hickson ◽  
S. M. Czerwinski ◽  
L. E. Wegrzyn
Keyword(s):  
Protein Synthesis ◽  
Myosin Heavy Chain ◽  
Muscle Mass ◽  
Muscle Atrophy ◽  
Heavy Chain ◽  
Total Protein ◽  
Female Rats ◽  
Glucocorticoid Treatment ◽  
Precursor Pool ◽  
Chain Synthesis

The aims of this study were to determine whether glutamine infusion prevents the decline in protein synthesis and muscle wasting associated with repeated glucocorticoid treatment. Hormone (cortisol acetate, 100 mg.kg body wt-1.day-1) and vehicle (carboxymethyl cellulose)-treated female rats were infused with either saline or glutamine (240 mM, 0.75 ml/h) for a 7-day period. Glutamine infusion attenuated the decline of plantaris muscle glutamine concentration (3.0 +/- 0.2 vs. 2.3 +/- 0.2 mumol/g) and prevented > 70% of the total muscle mass losses due to the glucocorticoid injections. Fractional synthesis rates of myosin heavy chain (MHC) and total protein were determined after constant [3H]leucine infusion from the leucyl-tRNA precursor pool, which was similar in all groups (range 4.8 +/- 0.5 to 6.3 +/- 0.4 disintegrations.min-1.pmol-1). MHC synthesis rates (%/day) in plantaris muscles were reduced to approximately 40% of controls (4.2/9.4). Although glutamine had no effect on MHC synthesis in vehicle-treated animals (10.1/9.4), it prevented 50% (7.6/4.2) of the hormone-induced decline in MHC synthesis rates. The same results were obtained with total protein synthesis measurements. Changes in muscle mass did not appear related to estimates of protein breakdown. In conclusion, these data show that glutamine infusion is effective therapy in counteracting glucocorticoid-induced muscle atrophy. Atrophy attenuation appears related to maintaining muscle glutamine levels, which in turn may limit the glucocorticoid-mediated downregulation of MHC synthesis.

Trophic effect of a sciatic nerve extract on fast and slow myosin heavy chain synthesis

1981 ◽  
Vol 241 (5) ◽  
pp. C269-C272 ◽  
Author(s):  
M. C. Thibault ◽  
A. S. Havaranis ◽  
S. M. Heywood
Keyword(s):  
Sciatic Nerve ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Messenger Rna ◽  
Sodium Dodecyl ◽  
Muscle Cells ◽  
Trophic Effect ◽  
Stage Of Development ◽  
Slow Type ◽  
Chain Synthesis

Myosin heavy chain (MHC) synthesis in cultures from chick pectoralis muscle cells was determined by [35S]methionine incorporation. Two types of MHC, migrating as 200,000-dalton components on sodium dodecyl sulfate polyacrylamide gels, were distinguished with antibodies against adult fast and slow MHC. Their synthesis was revealed by autoradiography. The effect of a sciatic nerve extract on the synthesis of the two types of MHC was also determined. Control experiments show that fast MHC is primarily synthesized in 48-h cultures. At a later stage of development (5- to 7-day cultures), slow MHC is also produced. The nerve extract promotes muscle cell differentiation and stimulates the synthesis of the slow type of MHC at an earlier stage of development (i.e., at 48 h as compared with 5-7 day in controlled cultures). It is concluded therefore that presumptive fast muscle cells in culture synthesize initially fast MHC and later both types of MHC (slow and fast). These results also suggest that the sciatic nerve extract is capable either of activating the transcription of the structural gene for slow MHC or of activating the translation of preexisting messenger RNA coding for this protein.

Effects of aging on in vivo synthesis of skeletal muscle myosin heavy-chain and sarcoplasmic protein in humans

1997 ◽  
Vol 273 (4) ◽  
pp. E790-E800 ◽  
Author(s):  
P. Balagopal ◽  
Olav E. Rooyackers ◽  
Deborah B. Adey ◽  
Philip A. Ades ◽  
K. Sreekumaran Nair
Keyword(s):  
Myosin Heavy Chain ◽  
Old Age ◽  
Muscle Mass ◽  
Heavy Chain ◽  
Contractile Function ◽  
Contractile Protein ◽  
Whole Body ◽  
Synthesis Rate ◽  
Sarcoplasmic Protein ◽  
Chain Synthesis

A decline in muscle mass and contractile function are prominent features of the sarcopenia of old age. Because myosin heavy chain is an important contractile protein, it was hypothesized that synthesis of this protein decreases in sarcopenia. The fractional synthesis rate of myosin heavy chain was measured simultaneously with rates of mixed muscle and sarcoplasmic proteins from the increment of [13C]leucine in these proteins purified from serial needle biopsy samples taken from 24 subjects (age: from 20 to 92 yr) during a primed continuous infusion ofl-[1-13C]leucine. A decline in synthesis rate of mixed muscle protein ( P < 0.01) and whole body protein ( P < 0.01) was observed from young to middle age with no further change with advancing age. An age-related decline of myosin heavy-chain synthesis rate was also observed ( P < 0.01), with progressive decline occurring from young, through middle, to old age. However, sarcoplasmic protein synthesis did not decline with age. Myosin heavy-chain synthesis rate was correlated with measures of muscle strength ( P < 0.05), circulating insulin-like growth factor I ( P < 0.01), and dehydroepiandrosterone sulfate ( P < 0.05) in men and women and free testosterone levels in men ( P < 0.01). A decline in the synthesis rate of myosin heavy chain implies a decreased ability to remodel this important muscle contractile protein and likely contributes to the declining muscle mass and contractile function in the elderly.

Skeletal Muscle Myosin Heavy Chain Synthesis in Type 1 Diabetes

Diabetes ◽  
1997 ◽  
Vol 46 (8) ◽  
pp. 1336-1340 ◽  
Author(s):  
M. R. Charlton ◽  
P. Balagopal ◽  
K. S. Nair
Keyword(s):  
Skeletal Muscle ◽  
Type 1 Diabetes ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Skeletal Muscle Myosin ◽  
Chain Synthesis ◽  
Muscle Myosin

Myosin heavy chain turnover and glucocorticoid deterrence by exercise in muscle

1989 ◽  
Vol 67 (6) ◽  
pp. 2311-2315 ◽  
Author(s):  
S. M. Czerwinski ◽  
R. Zak ◽  
T. T. Kurowski ◽  
M. T. Falduto ◽  
R. C. Hickson
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Treated Group ◽  
Treadmill Running ◽  
Female Rats ◽  
Constant Infusion ◽  
Endurance Running ◽  
Glucocorticoid Treatment ◽  
Breakdown Rate ◽  
Precursor Pool

This study was undertaken to determine whether regular endurance running, of the type known to attenuate glucocorticoid-induced muscle atrophy, produces a reversal of the glucocorticoid-mediated suppression of myosin heavy chain (MHC) synthesis. Female rats were arbitrarily assigned to one of four groups. There were two sedentary groups that received either a vehicle (1% aqueous carboxymethyl cellulose) or cortisol acetate (100 mg/kg body wt) for 11 consecutive days and two exercise (treadmill running 29 m/min, 90 min/day, for 11 consecutive days) groups that received the activity simultaneously with either vehicle or steroid treatments. Protein synthesis measurements were performed by constant infusion of [3H]leucine. Fractional synthesis rates of MHC were determined from the leucyl-tRNA precursor pool, which was similar in all groups (range 2.85 +/- 0.32 to 3.51 +/- 0.43 dpm/pmol). Exercise prevented 30% of the plantaris muscle mass loss as the result of cortisol acetate treatment. MHC synthesis rates (%/day) in plantaris muscles of sedentary animals were reduced by glucocorticoid treatment to 65% (6.2/9.5) of the vehicle-treated group. Exercise did not alter this depression of MHC synthesis. The combination of exercise and glucocorticoid treatment reduced the calculated MHC breakdown rate (%/day) to 80% (-8.0/-10.1) of the rate resulting from hormone treatment alone and 60% (-8.0/-13.3) of the rate resulting from exercise alone. These results show that endurance exercise does not reverse the glucocorticoid inhibition of MHC synthesis in muscle but may act through reducing MHC breakdown.

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