IIx and slow myosin expression follow mitochondrial increases in transforming muscle fibers

1993 ◽  
Vol 265 (1) ◽  
pp. C79-C84 ◽  
Author(s):  
J. Jacobs-El ◽  
W. Ashley ◽  
B. Russell
Keyword(s):  
Fiber Type ◽  
Fiber Types ◽  
Myosin Isoforms ◽  
Metabolic Demand ◽  
Type Conversion ◽  
Oxidative Potential ◽  
Slow Myosin ◽  
Fiber Analysis ◽  
Mrna Content ◽  
Isoform Expression

Metabolic profile and contractile isoform expression commonly define classic fiber types in skeletal muscle. Little is known about how metabolic requirements determine expression of fast IIx and slow myosin isoforms in muscles undergoing fiber type conversion. Tibialis anterior muscles from female New Zealand White rabbits were stimulated continuously at 10 Hz for 4-21 days. Quantitative fiber analysis was made for oxidative potential by histochemistry and for fast IIx and slow myosin mRNA content by in situ hybridization. In control muscle we found 3 +/- 0.27% fibers coexpress both fast IIx and slow myosin mRNA and so were not assignable to a classic fiber type. After stimulation, increase in fiber oxidative potential was detectable by 4 days and preceded IIx mRNA increases on a fiber-by-fiber basis. Slow myosin transcripts were detected by 7 days in fibers with higher oxidative levels. Coexpression of IIx and slow transcripts peaked at 22 +/- 2.5% of fibers by 7 days. IIx then declined, leaving slow myosin expressed in 62 +/- 0.45% of fibers by 3 wk. We conclude that during fiber type transformation individual fibers can transcribe two myosin mRNAs synchronously. Metabolic demand precedes and may be linked to IIx and slow myosin isoform expression.

Regulation of fiber size, oxidative potential, and capillarization in human muscle by resistance exercise

1999 ◽  
Vol 276 (2) ◽  
pp. R591-R596 ◽  
Author(s):  
H. Green ◽  
C. Goreham ◽  
J. Ouyang ◽  
M. Ball-Burnett ◽  
D. Ranney
Keyword(s):  
Fiber Type ◽  
Vastus Lateralis ◽  
Succinic Dehydrogenase ◽  
Quadriceps Muscle ◽  
Cellular Tissue ◽  
Cross Sectional Area ◽  
Fiber Types ◽  
Sectional Area ◽  
Oxidative Potential ◽  
Cross Sectional

To examine the hypothesis that increases in fiber cross-sectional area mediated by high-resistance training (HRT) would result in a decrease in fiber capillarization and oxidative potential, regardless of fiber type, we studied six untrained males (maximum oxygen consumption, 45.6 ± 2.3 ml ⋅ kg−1 ⋅ min−1; mean ± SE) participating in a 12-wk program designed to produce a progressive hypertrophy of the quadriceps muscle. The training sessions, which were conducted 3 times/wk, consisted of three sets of three exercises, each performed for 6–8 repetitions maximum (RM). Measurements of fiber-type distribution obtained from tissue extracted from the vastus lateralis at 0, 4, 7, and 12 wk indicated reductions ( P < 0.05) in type IIB fibers (15.1 ± 2.1% vs. 7.2 ± 1.3%) by 4 wk in the absence of changes in the other fiber types (types I, IIA, and IIAB). Training culminated in a 17% increase ( P < 0.05) in cross-sectional area by 12 wk with initial increases observed at 4 wk. The increase was independent of fiber type-specific changes. The number of capillaries in contact with each fiber type increased by 12 wk, whereas capillary contacts-to-fiber area ratios remained unchanged. In a defined cross-sectional field, HRT also increased the capillaries per fiber at 12 wk. Training failed to alter cellular oxidative potential, as measured by succinic dehydrogenase (SDH) activity, regardless of fiber type and training duration. It is concluded that modest hypertrophy induced by HRT does not compromise cellular tissue capillarization and oxidative potential regardless of fiber type.

scholarly journals Rbfox1 is required for myofibril development and maintaining fiber type–specific isoform expression in Drosophila muscles

2022 ◽  
Vol 5 (4) ◽  
pp. e202101342
Author(s):  
Elena Nikonova ◽  
Amartya Mukherjee ◽  
Ketaki Kamble ◽  
Christiane Barz ◽  
Upendra Nongthomba ◽  
...  
Keyword(s):  
Alternative Splicing ◽  
Muscle Development ◽  
Rna Binding ◽  
Troponin I ◽  
Rna Binding Proteins ◽  
Fiber Type ◽  
Structural Defects ◽  
Specific Gene ◽  
Fiber Types ◽  
Isoform Expression

Protein isoform transitions confer muscle fibers with distinct properties and are regulated by differential transcription and alternative splicing. RNA-binding Fox protein 1 (Rbfox1) can affect both transcript levels and splicing, and is known to contribute to normal muscle development and physiology in vertebrates, although the detailed mechanisms remain obscure. In this study, we report that Rbfox1 contributes to the generation of adult muscle diversity in Drosophila. Rbfox1 is differentially expressed among muscle fiber types, and RNAi knockdown causes a hypercontraction phenotype that leads to behavioral and eclosion defects. Misregulation of fiber type–specific gene and splice isoform expression, notably loss of an indirect flight muscle–specific isoform of Troponin-I that is critical for regulating myosin activity, leads to structural defects. We further show that Rbfox1 directly binds the 3′-UTR of target transcripts, regulates the expression level of myogenic transcription factors myocyte enhancer factor 2 and Salm, and both modulates expression of and genetically interacts with the CELF family RNA-binding protein Bruno1 (Bru1). Rbfox1 and Bru1 co-regulate fiber type–specific alternative splicing of structural genes, indicating that regulatory interactions between FOX and CELF family RNA-binding proteins are conserved in fly muscle. Rbfox1 thus affects muscle development by regulating fiber type–specific splicing and expression dynamics of identity genes and structural proteins.

Time course adaptations in rat skeletal muscle isomyosins during compensatory growth and regression

1987 ◽  
Vol 63 (5) ◽  
pp. 2111-2121 ◽  
Author(s):  
R. W. Tsika ◽  
R. E. Herrick ◽  
K. M. Baldwin
Keyword(s):  
Skeletal Muscle ◽  
Atpase Activity ◽  
Time Course ◽  
Compensatory Growth ◽  
Myosin Isoforms ◽  
Plantaris Muscle ◽  
Slow Myosin ◽  
Protein Pool ◽  
Isoform Expression ◽  
Myofibril Protein

The purpose of this study was to ascertain the time course of change during both compensatory growth (hypertrophy) and subsequent growth regression on myosin isoform expression in rodent fast-twitch plantaris muscle in response to functional overload (induced by removal of synergists). Peak hypertrophy of the plantaris muscle (92%) occurred after 9 wk of overload. After 7 wk of overload regression (induced by a model of hindlimb unweighting), muscle weight returned to within 30% of control values. Myofibril protein content (mg/g muscle) remained relatively constant throughout the overload period but became significantly depressed relative to control values after 7 wk of regression. However, when expressed on a per muscle basis (mg/muscle) no differences existed at this time point (t = 7 wk regression). The distribution of native myosin isoforms in the myofibril protein pool of the overloaded plantaris muscle reflected a progressive increase (23% at t = 9 wk; P less than 0.001) in the relative proportion of slow myosin (Sm). This change was also accompanied by increases in intermediate myosin (Im) as well as the repression of the fast myosin one (Fm1) isoform (P less than 0.001). These shifts in Sm and Fm1 isoform expression were gradually reversed during the regression period, whereas Im remained elevated relative to control values. These adaptive changes in myosin isoform expression during both hypertrophy and regression were further supported by concomitant shifts in both myosin adenosinetriphosphatase (ATPase) activity (decreased during overload) and slow myosin light chain (SLC) expression. However, during regression the changes in myosin isoform expression and myosin ATPase were not as synchronous as they were during overload. Estimation of the mixed myosin heavy chain (MHC) half-life (t 1/2), using a linear model that assumes zero-order synthesis and first-order degradation kinetics, revealed t 1/2 values of approximately 19 and 10 days for the overload and regression periods, respectively. Collectively these data suggest that 1) skeletal muscle myosin isoforms and corresponding ATPase activity are in a dynamic state of change, although not completely synchronous, in response to altered muscle stress, and 2) the kinetics of change in the mixed MHC protein pool are slower during compensatory growth compared with regression of growth.

scholarly journals Myogenin is required for late but not early aspects of myogenesis during mouse development.

1995 ◽  
Vol 128 (4) ◽  
pp. 563-576 ◽  
Author(s):  
J M Venuti ◽  
J H Morris ◽  
J L Vivian ◽  
E N Olson ◽  
W H Klein
Keyword(s):  
Perinatal Death ◽  
Fiber Type ◽  
Expression Patterns ◽  
Regulatory Protein ◽  
Fiber Types ◽  
Myosin Isoforms ◽  
Mouse Development ◽  
Helix Loop Helix ◽  
Embryonic And Fetal Development ◽  
Targeted Mutation

Mice with a targeted mutation in the myogenic basic helix-loop-helix regulatory protein myogenin have severe muscle defects resulting in perinatal death. In this report, the effect of myogenin's absence on embryonic and fetal development is investigated. The initial events of somite differentiation occurred normally in the myogenin-mutant embryos. During primary myogenesis, muscle masses in mutant embryos developed simultaneously with control siblings, although muscle differentiation within the mutant muscle masses was delayed. More dramatic effects were observed when secondary myofibers form. During this time, very little muscle formation took place in the mutants, suggesting that the absence of myogenin affected secondary myogenesis more severely than primary myogenesis. Monitoring mutant neonates with fiber type-specific myosin isoforms indicated that different fiber types were present in the residual muscle. No evidence was found to indicate that myogenin was required for the formation of muscle in one region of the embryo and not another. The expression patterns of a MyoD-lacZ transgene in myogenin-mutant embryos demonstrated that myogenin was not essential for the activation of the MyoD gene. Together, these results indicate that late stages of embryogenesis are more dependent on myogenin than early stages, and that myogenin is not required for the initial aspects of myogenesis, including myotome formation and the appearance of myoblasts.

scholarly journals Rbfox1 is required for myofibril development and maintaining fiber-type specific isoform expression in Drosophila muscles

2021 ◽  
Author(s):  
Elena Nikonova ◽  
Ketaki Kamble ◽  
Amartya Mukherjee ◽  
Christiane Barz ◽  
Upendra Nongthomba ◽  
...  
Keyword(s):  
Muscle Development ◽  
Rna Binding ◽  
Troponin I ◽  
Rna Binding Proteins ◽  
Fiber Type ◽  
Specific Gene ◽  
Fiber Types ◽  
Transcript Levels ◽  
Splice Isoform ◽  
Isoform Expression

Protein isoform transitions confer distinct properties on muscle fibers and are regulated predominantly by differential transcription and alternative splicing. RNA-binding Fox protein 1 (Rbfox1) can affect both transcript levels and splicing, and is known to control skeletal muscle function. However, the detailed mechanisms by which Rbfox1 contributes to normal muscle development and physiology remain obscure. In this study, we report that Rbfox1 contributes to the generation of adult muscle diversity in Drosophila. Rbfox1 is differentially expressed in tubular and fibrillar muscle fiber types. RNAi knockdown of Rbfox1 leads to a loss of flight, climbing and jumping ability, as well as eclosion defects. Myofibers in knockdown muscle are frequently torn, and sarcomeres are hypercontracted. These defects arise from mis-regulation of fiber-type specific gene and splice isoform expression, notably loss of an IFM-specific isoform of Troponin-I that is critical for regulating myosin activity. We find that Rbfox1 influences mRNA transcript levels through 1) direct binding of 3'-UTRs of target transcripts as well as 2) through regulation of myogenic transcription factors, including Mef2, Exd and Salm. Moreover, Rbfox1 modulates splice isoform expression through 1) direct regulation of target splice events in structural genes and 2) regulation of the CELF-family RNA-binding protein Bruno1. Our data indicate that cross-regulatory interactions observed between FOX and CELF family RNA-binding proteins in vertebrates are conserved between their counterparts, Rbfox1 and Bruno1 in flies. Rbfox1 thus affects muscle development by regulation of both fiber-type specific gene and gene isoform expression dynamics of identity genes and structural proteins.

Muscle Fiber Types, Characteristics and Meat Quality

2013 ◽  
Vol 634-638 ◽  
pp. 1263-1267
Author(s):  
Lin Su ◽  
Hui Li ◽  
Xue Xin ◽  
Yan Duan ◽  
Xiao Qing Hua ◽  
...  
Keyword(s):  
Meat Quality ◽  
Muscle Fiber ◽  
Fiber Type ◽  
Influence Factors ◽  
Muscle Fiber Type ◽  
Basic Unit ◽  
Muscle Fiber Types ◽  
Fiber Types ◽  
Type Conversion ◽  
Fiber Type Distribution

Muscle fiber is the basic unit of muscle tissue, this paper summarized the types of muscle fiber of animals, the influence factors of muscle fiber type distribution and the muscle fiber type conversion in the process of growth constantly. Discuss the important effect of muscle fiber type on meat quality.

scholarly journals Novel single skeletal muscle fiber analysis reveals a fiber type-selective effect of acute exercise on glucose uptake

2016 ◽  
Vol 311 (5) ◽  
pp. E818-E824 ◽  
Author(s):  
Gregory D. Cartee ◽  
Edward B. Arias ◽  
Carmen S. Yu ◽  
Mark W. Pataky
Keyword(s):  
Skeletal Muscle ◽  
Glucose Uptake ◽  
Fiber Type ◽  
Exercise Session ◽  
Type I ◽  
Fiber Types ◽  
Single Fibers ◽  
Fiber Analysis ◽  
New Findings ◽  
Insulin Dependent

One exercise session can induce subsequently elevated insulin sensitivity that is largely attributable to greater insulin-stimulated glucose uptake by skeletal muscle. Because skeletal muscle is a heterogeneous tissue comprised of diverse fiber types, our primary aim was to determine exercise effects on insulin-independent and insulin-dependent glucose uptake by single fibers of different fiber types. We hypothesized that each fiber type featuring elevated insulin-independent glucose uptake immediately postexercise (IPEX) would be characterized by increased insulin-dependent glucose uptake at 3.5 h postexercise (3.5hPEX). Rat epitrochlearis muscles were isolated and incubated with 2-[3H]deoxyglucose. Muscles from IPEX and sedentary (SED) controls were incubated without insulin. Muscles from 3.5hPEX and SED controls were incubated ± insulin. Glucose uptake (2-[3H]deoxyglucose accumulation) and fiber type (myosin heavy chain isoform expression) were determined for single fibers dissected from the muscles. Major new findings included the following: 1) insulin-independent glucose uptake was increased IPEX in single fibers of each fiber type (types I, IIA, IIB, IIBX, and IIX), 2) glucose uptake values from insulin-stimulated type I and IIA fibers exceeded the values for the other fiber types, 3) insulin-stimulated glucose uptake for type IIX exceeded IIB fibers, and 4) the 3.5hPEX group vs. SED had greater insulin-stimulated glucose uptake in type I, IIA, IIB, and IIBX but not type IIX fibers. Insulin-dependent glucose uptake was increased at 3.5hPEX in each fiber type except for IIX fibers, although insulin-independent glucose uptake was increased IPEX in all fiber types (including type IIX). Single fiber analysis enabled the discovery of this fiber type-related difference for postexercise, insulin-stimulated glucose uptake.

Enhancement of hybrid-fiber types in rat soleus muscle after clenbuterol administration during hindlimb unloading

2004 ◽  
Vol 82 (5) ◽  
pp. 311-318 ◽  
Author(s):  
F Picquet ◽  
L De-Doncker ◽  
M Falempin
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Fiber Type ◽  
Myosin Heavy Chain Isoforms ◽  
Hindlimb Unloading ◽  
Fiber Types ◽  
Myosin Isoforms ◽  
Fast Myosin ◽  
Contractile Parameters ◽  
Fast Myosin Heavy Chain

Our objective was to determine the effects of a clenbuterol (CB) treatment orally administered (2 mg per kg) to rats submitted to 14 days of hindlimb unloading (HU). The morphological and the contractile properties as well as the myosin heavy chain isoforms contained in each fiber type were determined in whole soleus muscles. As classically described after HU, a decrease in muscle wet weight and in body mass associated with a loss of muscular force, an evolution of the contractile parameters towards those of a fast muscle type, and the emergence of fast myosin heavy chain isoforms were observed. The CB treatment in the HU rats helped reduce the decrease in 1) muscle and body weights, 2) force and 3) the proportion of slow fibers, without preventing the emergence of fast myosin isoforms. Clenbuterol induced a complex remodelling of the muscle typing promoting the combination of both slow and fast myosin isoforms within one fiber. To conclude, our data demonstrate that CB administration partially counteracts the effects produced by HU, and they allow us to anticipate advances in the treatment of muscular atrophy.Key words: β2 agonist, clenbuterol, soleus, contractile parameters, myosin, immunohistochemistry, simulated microgravity, countermeasure.

Differential apoptosis-related protein expression, mitochondrial properties, proteolytic enzyme activity, and DNA fragmentation between skeletal muscles

2011 ◽  
Vol 300 (3) ◽  
pp. R531-R543 ◽  
Author(s):  
Elliott M. McMillan ◽  
Joe Quadrilatero
Keyword(s):  
Skeletal Muscle ◽  
Cytochrome C ◽  
Protein Expression ◽  
Dna Fragmentation ◽  
Fiber Type ◽  
Reactive Oxygen Species Generation ◽  
Permeability Transition ◽  
Type I ◽  
Fiber Types ◽  
Oxidative Potential

Increased skeletal muscle apoptosis has been associated with a number of conditions including aging, disuse, and cardiovascular disease. Skeletal muscle is a complex tissue comprised of several fiber types with unique properties. To date, no report has specifically examined apoptotic differences across muscles or fiber types. Therefore, we measured several apoptotic indices in healthy rat red (RG) and white gastrocnemius (WG) muscle, as well as examined the expression of several key proteins across fiber types in a mixed muscle (mixed gastrocnemius). The protein content of apoptosis-inducing factor (AIF), apoptosis repressor with caspase recruitment domain (ARC), Bax, Bcl-2, cytochrome c, heat shock protein 70 (Hsp70), and second mitochondria-derived activator of caspases (Smac) were significantly ( P < 0.05) higher in RG vs. WG muscle. Cytosolic AIF, cytochrome c, and Smac as well as nuclear AIF were also significantly ( P < 0.05) higher in RG compared with WG muscle. In addition, ARC protein expression was related to muscle fiber type and found to be highest ( P < 0.001) in type I fibers. Similarly, AIF protein expression was differentially expressed across fibers; however, AIF was correlated to oxidative potential ( P < 0.001). Caspase-3, -8, and -9 activity, calpain activity, and DNA fragmentation (a hallmark of apoptosis) were also significantly higher ( P < 0.05) in RG compared with WG muscle. Furthermore, total muscle reactive oxygen species generation, as well as Ca2+-induced permeability transition pore opening and loss of membrane potential in isolated mitochondria were greater in RG muscle. Collectively, these data suggest that a number of apoptosis-related indices differ between muscles and fiber types. Given these findings, muscle and fiber-type differences in apoptotic protein expression, signaling, and susceptibility should be considered when studying cell death processes in skeletal muscle.

Muscle fiber type comparison of PDH kinase activity and isoform expression in fed and fasted rats

2001 ◽  
Vol 280 (3) ◽  
pp. R661-R668 ◽  
Author(s):  
Sandra J. Peters ◽  
Robert A. Harris ◽  
George J. F. Heigenhauser ◽  
Lawrence L. Spriet
Keyword(s):  
Pyruvate Dehydrogenase ◽  
Fiber Type ◽  
Pyruvate Dehydrogenase Complex ◽  
Mrna Level ◽  
Pyruvate Dehydrogenase Kinase ◽  
Kinetic Properties ◽  
Fiber Types ◽  
Mrna Content ◽  
Fast Twitch ◽  
Fasted Rats

Fiber type specificity for expression of all three rat skeletal muscle pyruvate dehydrogenase kinase (PDK) isoforms (PDK1, 2, and 4) was determined in fed and 24-h fasted rats. PDK activity and isoform protein and mRNA contents were determined in white gastrocnemius (WG; fast-twitch glycolytic), red gastrocnemius (RG; fast-twitch oxidative), and soleus (Sol; slow-twitch oxidative) muscles. PDK activity was lower in WG compared with oxidative muscles (RG, Sol) in both fed and fasted rats. PDK activities from fed muscles were 0.12 ± 0.04, 0.30 ± 0.01, and 0.36 ± 0.08 min−1 in WG, Sol, and RG, respectively, and increased in fasted muscles (0.36 ± 0.09, 0.68 ± 0.18, and 0.80 ± 0.14 min−1). This correlated with increased PDK4 protein and to a lesser extent with PDK4 mRNA. PDK2 protein was not different between fiber types in fed or fasted rats, but PDK2 mRNA content was twofold greater in RG from fasted rats compared with fed rats. PDK1 was unaltered by fasting in all muscle types at both the protein and mRNA level, but in both fed and fasted rats had much greater protein and mRNA content in the oxidative vs. glycolytic muscles. In conclusion, PDK activity and PDK1 and 4 protein and mRNA were lower in glycolytic vs. oxidative muscles from fed and fasted rats. Fasting for 24 h induced a two- to threefold increase in PDK activity that was mainly due to increases in PDK4 protein and mRNA. PDK1 and 2 protein and mRNA were generally unaltered by fasting in all fiber types, except for increased PDK2 mRNA in the fast oxidative fibers. Because the PDK isoforms vary greatly in their kinetic properties, their relative proportions in the three fiber types at any given time during fasting could significantly alter the acute regulation of the pyruvate dehydrogenase complex.

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