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 Comparative analysis of the transcriptomes of EDL, psoas, and soleus muscles from mice

BMC Genomics ◽  
2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Pabodha Hettige ◽  
Uzma Tahir ◽  
Kiisa C. Nishikawa ◽  
Matthew J. Gage
Keyword(s):  
Skeletal Muscles ◽  
Striated Muscle ◽  
Fiber Type ◽  
Expression Patterns ◽  
Fiber Types ◽  
Muscle Adaptation ◽  
Myosin Heavy Chain Isoform ◽  
Genes Encoding ◽  
Slow Twitch ◽  
Fast Twitch

Abstract Background Individual skeletal muscles have evolved to perform specific tasks based on their molecular composition. In general, muscle fibers are characterized as either fast-twitch or slow-twitch based on their myosin heavy chain isoform profiles. This approach made sense in the early days of muscle studies when SDS-PAGE was the primary tool for mapping fiber type. However, Next Generation Sequencing tools permit analysis of the entire muscle transcriptome in a single sample, which allows for more precise characterization of differences among fiber types, including distinguishing between different isoforms of specific proteins. We demonstrate the power of this approach by comparing the differential gene expression patterns of extensor digitorum longus (EDL), psoas, and soleus from mice using high throughput RNA sequencing. Results EDL and psoas are typically classified as fast-twitch muscles based on their myosin expression pattern, while soleus is considered a slow-twitch muscle. The majority of the transcriptomic variability aligns with the fast-twitch and slow-twitch characterization. However, psoas and EDL exhibit unique expression patterns associated with the genes coding for extracellular matrix, myofibril, transcription, translation, striated muscle adaptation, mitochondrion distribution, and metabolism. Furthermore, significant expression differences between psoas and EDL were observed in genes coding for myosin light chain, troponin, tropomyosin isoforms, and several genes encoding the constituents of the Z-disk. Conclusions The observations highlight the intricate molecular nature of skeletal muscles and demonstrate the importance of utilizing transcriptomic information as a tool for skeletal muscle characterization.

α-Catalytic subunits of 5′AMP-activated protein kinase display fiber-specific expression and are upregulated by chronic low-frequency stimulation in rat muscle

2007 ◽  
Vol 293 (3) ◽  
pp. R1325-R1334 ◽  
Author(s):  
Charles T. Putman ◽  
Karen J. B. Martins ◽  
Maria E. Gallo ◽  
Gary D. Lopaschuk ◽  
Jean A. Pearcey ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Fiber Type ◽  
Expression Patterns ◽  
Low Frequency ◽  
Medial Gastrocnemius ◽  
Immunocytochemical Staining ◽  
Fiber Types ◽  
Specific Expression ◽  
Ampk Signaling ◽  
Amp Activated Protein Kinase

5′-AMP-activated protein kinase (AMPK) signaling initiates adaptive changes in skeletal muscle fibers that restore homeostatic energy balance. The purpose of this investigation was to examine, in rats, the fiber-type protein expression patterns of the α-catalytic subunit isoforms in various skeletal muscles, and changes in their respective contents within the tibialis anterior (TA) after chronic low-frequency electrical stimulation (CLFS; 10 Hz, 10 h daily), applied for 4 ± 1.2 or 25 ± 4.8 days. Immunocytochemical staining of soleus (SOL) and medial gastrocnemius (MG) showed that 86 ± 4.1 to 97 ± 1.4% of type IIA fibers stained for both the α1- and α2-isoforms progressively decreased to 63 ± 12.2% of type IID/X and 9 ± 2.4% of IIB fibers. 39 ± 11.4% of IID/X and 83 ± 7.9% of IIB fibers expressed only the α2 isoform in the MG, much of which was localized within nuclei. α1 and α2 contents, assessed by immunoblot, were lowest in the white gastrocnemius [WG; 80% myosin heavy chain (MHC) IIb; 20% MHCIId/x]. Compared with the WG, α1 content was 1.6 ± 0.08 ( P < 0.001) and 1.8 ± 0.04 ( P < 0.0001)-fold greater in the red gastrocnemius (RG: 13%, MHCIIa) and SOL (21%, MHCIIa), respectively, and increased in proportion to MHCIIa content. Similarly, α2 content was 1.4 ± 0.10 ( P < 0.02) and 1.5 ± 0.07 ( P < 0.001)-fold greater in RG and SOL compared with WG. CLFS induced 1.43 ± 0.13 ( P < 0.007) and 1.33 ± 0.08 ( P < 0.009)-fold increases in the α1 and α2 contents of the TA and coincided with the transition of faster type IIB and IID/X fibers toward IIA fibers. These findings indicate that fiber types differ with regard to their capacity for AMPK signaling and that this potential is increased by CLFS.

Mechanical properties of skinned single fibers of identified types from rat diaphragm

1987 ◽  
Vol 253 (2) ◽  
pp. C210-C218 ◽  
Author(s):  
T. J. Eddinger ◽  
R. L. Moss
Keyword(s):  
Fiber Type ◽  
Regulatory Protein ◽  
Sodium Dodecyl ◽  
Maximum Velocity ◽  
Protein Composition ◽  
Size Difference ◽  
Fiber Types ◽  
Rat Diaphragm ◽  
Cross Sectional ◽  
Fiber Size

Maximum isometric tension (Po), maximum velocity of shortening (Vmax), and tension-pCa (i.e., -log[Ca2+]) relationships were determined in single skinned fibers from rat diaphragm. Histochemistry (myosin-ATPase) and sodium dodecyl sulfate (SDS) gel electrophoresis were performed on these same fibers to determine fiber type and protein composition. Physiologically fast fibers were found to have larger cross-sectional areas (CSA) and produced more tension per CSA and were less sensitive to [Ca2+] than physiologically slow fibers. Fast fibers were typed histochemically as type II and contained myosin heavy chains (MHC) and light chains (LC) of the fast type, whereas the slow fibers contained slow MHC and LC. There were also corresponding differences in the regulatory protein composition of these two fiber types. The histochemical sections confirmed a significant fiber size difference between the type IIa and IIb fibers. When fiber size was used to separate the fast fibers into two groups, type IIb fibers were found to have significantly greater Vmax and tension per CSA than the type IIa fibers. Although there were no noticeable differences in MHC composition between the type IIa and IIb fibers, there were some differences in the myosin LC and regulatory protein content.

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.

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.

scholarly journals The ATPase cycle of Human Muscle Myosin II Isoforms: Adaptation of a single mechanochemical cycle for different physiological roles

2019 ◽  
Author(s):  
Chloe A. Johnson ◽  
Jonathan Walklate ◽  
Marina Svicevic ◽  
Srboljub M. Mijailovich ◽  
Carlos Vera ◽  
...  
Keyword(s):  
Muscle Fiber ◽  
Striated Muscle ◽  
Fiber Type ◽  
Duty Ratio ◽  
Muscle Fiber Types ◽  
Fiber Types ◽  
Myosin Isoforms ◽  
Shortening Velocity ◽  
Load Dependence ◽  
Cross Bridge

AbstractStriated muscle myosins are encoded by a large gene family in all mammals, including human. These isoforms define several of the key characteristics of the different striated muscle fiber types including maximum shortening velocity. We have previously used recombinant isoforms of the motor domains of eight different human myosin isoforms to define the actin.myosin cross-bridge cycle in solution. Here, we use a recently developed modeling approach MUSICO to explore how well the experimentally defined cross-bridge cycles for each isoform in solution can predict the characteristics of muscle fiber contraction including duty ratio, shortening velocity, ATP economy and the load dependence of these parameters. The work shows that the parameters of the cross-bridge cycle predict many of the major characteristics of each muscle fiber type and raises the question of what sequence changes are responsible for these characteristics.

scholarly journals A Candidate RNAi Screen Reveals Diverse RNA-Binding Protein Phenotypes in Drosophila Flight Muscle

2021 ◽  
Author(s):  
Shao-Yen Kao ◽  
Elena Nikonova ◽  
Sabrina Chaabane ◽  
Albiona Sabani ◽  
Alexandra Martitz ◽  
...  
Keyword(s):  
Alternative Splicing ◽  
Rna Processing ◽  
Muscle Development ◽  
Rna Binding ◽  
Flight Muscle ◽  
Rna Binding Proteins ◽  
Fiber Type ◽  
Expression Patterns ◽  
Fine Tuning ◽  
Fiber Types

The proper regulation of RNA processing is critical for muscle development and the fine-tuning of contractile ability between muscle fiber-types. RNA binding proteins (RBPs) regulate the diverse steps in RNA processing including alternative splicing, which generates fiber-type specific isoforms of structural proteins that confer contractile sarcomeres with distinct biomechanical properties. Alternative splicing is disrupted in muscle diseases such as myotonic dystrophy and dilated cardiomyopathy, and is altered after intense exercise as well as with aging. It is therefore important to understand splicing and RBP function, but currently only a small fraction of the hundreds of annotated RBPs expressed in muscle have been characterized. Here we demonstrate the utility of Drosophila as a genetic model system to investigate basic developmental mechanisms of RBP function in myogenesis. We find that RBPs exhibit dynamic temporal and fiber-type specific expression patterns in mRNA-Seq data and display muscle-specific phenotypes. We performed knockdown with 105 RNAi hairpins targeting 35 RBPs and report associated lethality, flight, myofiber and sarcomere defects, including flight muscle phenotypes for Doa, Rm62, mub, mbl, sbr, and clu. Interestingly, knockdown phenotypes of spliceosome components, as highlighted by phenotypes for A-complex components SF1 and Hrb87F (hnRNPA1), revealed level- and temporal-dependent myofibril defects. We further show that splicing mediated by SF1 and Hrb87F is necessary for Z-disc stability and proper myofibril development, and strong knockdown of either gene results in impaired localization of Kettin to the Z-disc. Our results expand the number of RBPs with a described phenotype in muscle and underscore the diversity in myofibril and transcriptomic phenotypes associated with splicing defects. Drosophila is thus a useful model to gain disease-relevant insight into cellular and molecular phenotypes observed when expression levels of splicing factors, spliceosome components and splicing dynamics are altered.

scholarly journals ProFiT: eine MS-basierte Methode zur Skelettmuskelfasertypisierung

BIOspektrum ◽  
2021 ◽  
Vol 27 (7) ◽  
pp. 719-722
Author(s):  
Sebastian Kallabis ◽  
Marcus Krüger
Keyword(s):  
Dynamic Range ◽  
Fiber Type ◽  
Expression Patterns ◽  
High Dynamic Range ◽  
Fiber Types ◽  
Protein Abundance ◽  
Low Protein ◽  
High Dynamic ◽  
First Time ◽  
Molecular Expression

AbstractSkeletal muscle tissue is composed of different fiber types which differ in their metabolic activity and molecular expression patterns. Mass spectrometric analyses revealed muscle fiber-specific traits but the number of detected proteins is limited due to low protein abundance and high dynamic range. We have developed a new LC-MS/MS method to circumvent the bottleneck of low protein abundance and we have applied this method to measure fiber type-specific phosphoproteomes for the first time.

scholarly journals A Candidate RNAi Screen Reveals Diverse RNA-Binding Protein Phenotypes in Drosophila Flight Muscle

Cells ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 2505
Author(s):  
Shao-Yen Kao ◽  
Elena Nikonova ◽  
Sabrina Chaabane ◽  
Albiona Sabani ◽  
Alexandra Martitz ◽  
...  
Keyword(s):  
Alternative Splicing ◽  
Rna Processing ◽  
Muscle Development ◽  
Rna Binding ◽  
Flight Muscle ◽  
Rna Binding Proteins ◽  
Fiber Type ◽  
Expression Patterns ◽  
Fine Tuning ◽  
Fiber Types

The proper regulation of RNA processing is critical for muscle development and the fine-tuning of contractile ability among muscle fiber-types. RNA binding proteins (RBPs) regulate the diverse steps in RNA processing, including alternative splicing, which generates fiber-type specific isoforms of structural proteins that confer contractile sarcomeres with distinct biomechanical properties. Alternative splicing is disrupted in muscle diseases such as myotonic dystrophy and dilated cardiomyopathy and is altered after intense exercise as well as with aging. It is therefore important to understand splicing and RBP function, but currently, only a small fraction of the hundreds of annotated RBPs expressed in muscle have been characterized. Here, we demonstrate the utility of Drosophila as a genetic model system to investigate basic developmental mechanisms of RBP function in myogenesis. We find that RBPs exhibit dynamic temporal and fiber-type specific expression patterns in mRNA-Seq data and display muscle-specific phenotypes. We performed knockdown with 105 RNAi hairpins targeting 35 RBPs and report associated lethality, flight, myofiber and sarcomere defects, including flight muscle phenotypes for Doa, Rm62, mub, mbl, sbr, and clu. Knockdown phenotypes of spliceosome components, as highlighted by phenotypes for A-complex components SF1 and Hrb87F (hnRNPA1), revealed level- and temporal-dependent myofibril defects. We further show that splicing mediated by SF1 and Hrb87F is necessary for Z-disc stability and proper myofibril development, and strong knockdown of either gene results in impaired localization of kettin to the Z-disc. Our results expand the number of RBPs with a described phenotype in muscle and underscore the diversity in myofibril and transcriptomic phenotypes associated with splicing defects. Drosophila is thus a powerful model to gain disease-relevant insight into cellular and molecular phenotypes observed when expression levels of splicing factors, spliceosome components and splicing dynamics are altered.

Myosin isoforms in mammalian skeletal muscle

1994 ◽  
Vol 77 (2) ◽  
pp. 493-501 ◽  
Author(s):  
S. Schiaffino ◽  
C. Reggiani
Keyword(s):  
Skeletal Muscle ◽  
Fiber Type ◽  
Mammalian Species ◽  
Maximum Velocity ◽  
Fiber Types ◽  
Myosin Isoforms ◽  
Mammalian Skeletal Muscle ◽  
Differential Distribution ◽  
Specific Regulation

Skeletal muscles of different mammalian species contain four major myosin heavy-chain (MHC) isoforms: the “slow” or beta-MHC and the three “fast” IIa-, IIx-, and IIb-MHCs; and three major myosin light-chain (MLC) isoforms, the “slow” MLC1s and the two “fast” MLC1f and MLC3f. The differential distribution of the MHCs defines four major fiber types containing a single MHC isoform and a number of intermediate hybrid fiber populations containing both beta/slow- and IIa-MHC, IIa- and IIx-MHC, or IIx- and IIb-MHC. The IIa-, IIx-, and IIb-MHCs were first detected in neonatal muscles, and their expression in developing and adult muscle is regulated by neural, hormonal, and mechanical factors. The transcriptional mechanisms responsible for the fiber type-specific regulation of MHC and MLC gene expression are not known and are presently being explored by in vivo transfection experiments. The functional role of MHC isoforms has been in part clarified by correlated biochemical-physiological studies on single skinned fibers: these studies, in agreement with results from in vitro motility assays, indicate that both MHC and MLC isoforms determine the maximum velocity of shortening of skeletal muscle fibers.

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