The continuum of hybrid IIX/IIB fibers in normal mouse muscles: MHC isoform proportions and spatial distribution within single fibers

Zhang, Min Yi; Zhang, Wei Jie; Medler, Scott

doi:10.1152/ajpregu.00402.2010

Cited by 22 publications

(38 citation statements)

References 74 publications

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“…However, although the MyHC composition differed from one muscle part to another, they did not investigate whether the MyHC composition differed over the length of a single fiber. Other studies observed a variation in MyHC composition in parts of leg muscle fibers of adult [Zhang et al, 2010] and newly weaned mice [Brummer et al, 2013] also by means of gel electrophoresis. It might be expected that muscles, which are still growing, have newly fused myoblasts (from satellite cells) that express a different MyHC isoform.…”

Section: Introductionmentioning

confidence: 87%

Myosin Heavy Chain Expression Can Vary over the Length of Jaw and Leg Muscles

Korfage¹,

Kwee²,

Everts³

et al. 2016

Cells Tissues Organs

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Muscle fiber type classification can be determined by its myosin heavy chain (MyHC) composition based on a few consecutive sections. It is generally assumed that the MyHC expression of a muscle fiber is the same over its length since neural stimulation and systemic influences are supposed to be the same over its length. We analyzed this in detail in three muscle types: the temporalis (closer) and digastricus (opener; both first brachial arch), and the medial gastrocnemius (somite). Sections of the muscles were incubated with monoclonal antibodies against various MyHC isoforms, and the distribution of these isoforms within individual fibers was followed over a distance of approximately 1 mm. The staining intensity of a fiber was measured and compared with the other fibers in the section. In the temporalis, digastricus, and gastrocnemius, 46, 11, and 15%, respectively, of their MyHC-I fibers showed a variation in the staining intensity over the length of their fibers, as well as 47, 87, and 22%, respectively, of their MyHC-IIA fibers. Most variable fibers were found amongst those with an overall relative intermediate staining intensity, which are presumably hybrid fibers. We conclude that different parts of a muscle fiber can have different fiber type compositions and, thus, contractile properties. Some muscle parts might reach their maximum contraction peak sooner or later than a muscle part a few microns further away. Next to stimulation by the nerve and systemic influences, local influences might also have an impact on the MyHC expression of the fiber.

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Section: Introductionmentioning

confidence: 87%

Myosin Heavy Chain Expression Can Vary over the Length of Jaw and Leg Muscles

Korfage¹,

Kwee²,

Everts³

et al. 2016

Cells Tissues Organs

View full text Add to dashboard Cite

show abstract

“…A total of 2,587 fibers were analyzed in this study (818 SOL,723 BR and 1,046 TA), with approximately 100 fibers sampled per animal. Each fiber was placed into a microcentrifuge tube containing ∼ 30 μl of sample buffer containing 8 M urea, 2 M thiourea, 50 m M Tris base, 75 m M dithiothreitol, 3% sodium dodecyl sulfate (SDS) and 0.004% bromophenol blue, pH 6.8 [Blough et al, 1996;Zhang et al, 2010]. Samples were heated to 65 ° C for 15 min and 10 μl of each sample was applied to the gel.…”

Section: Single Fiber Analysesmentioning

confidence: 99%

“…The presence of hundreds of individual nuclei, along with limitations in diffusional distance, means that the different myonuclear domains can contain distinct protein assemblages from one another [Pavlath et al, 1989;Newlands et al, 1998;Allen et al, 1999]. Indeed, a number of studies have demonstrated that myosin expression does vary along the length within certain single muscle fibers [Staron and Pette, 1987;Edman et al, 1988;Termin et al, 1989;Sakuma et al, 1995;Peuker and Pette, 1997;Lutz et al, 2001;Zhang et al, 2010]. While it is currently unknown how prevalent such asymmetries are in normal muscles, it is plausible that longitudinal differences in MHC content may reflect dy-namic changes in fiber type.…”

Section: Segmental Differences In Fiber Typementioning

confidence: 99%

“…Over the past several decades, we have gained an ever-increasing understanding of the diversity and complexity of individual fiber types. Fiber types that were once defined simply as 'fast' or 'slow' are in reality part of a continuum of fiber types that are difficult to classify into precise categories [Staron and Pette, 1993;Caiozzo et al, 2003;Medler and Mykles, 2003;Medler et al, 2004;Zhang et al, 2010;Schiaffino and Reggiani, 2011]. During development, fibers undergo major transitions in MHC isoform expression, with developmental isoforms being exchanged for adult MHCs [Di Maso et al, 2000;Agbulut et al, 2003;Lieber, 2010].…”

Section: Introductionmentioning

confidence: 99%

“…In mouse, the overall fiber type distribution is lower than in the rat, being highly skewed toward the fastest IIB fiber type. Nevertheless, certain mouse muscles contain 25-50% of their fibers as hybrids [Glaser et al, 2010;Zhang et al, 2010]. In the muscles of both of these rodents, the most prevalent hybrid fiber types are the IIX/IIB hybrids, which represent roughly 70-90% of all the hybrid fibers [Caiozzo et al, 2003;Glaser et al, 2010;Zhang et al, 2010].…”

Section: Introductionmentioning

confidence: 99%

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Hybrid Fibers Transform into Distinct Fiber Types in Maturing Mouse Muscles

Brummer

Zhang

Piddoubny

et al. 2013

Cells Tissues Organs

Self Cite

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The role of hybrid fibers as intermediates in fiber type transformations is not completely understood. In some cases hybrids are clearly transitional fibers changing from one type to another, but in others they represent phenotypically stable fibers in normal muscles. In the current study, our goal was to understand the fate of hybrid fibers in fiber type transitions that take place during muscle maturation. Previous studies have reported high proportions of hybrid fibers during postnatal development, but few have followed the fate of these fibers past the time of weaning. We quantified proportions of hybrid fibers in three different mouse skeletal muscles from newly weaned to 6-month-old mice. Hybrid fibers were very prevalent in the brachioradialis (BR) and tibialis anterior (TA) muscles from newly weaned mice, where they constituted 50 and 40% of the fibers, respectively. These hybrids declined steadily to about 15-30% over the next several months. In the soleus muscle the proportion of hybrids did not change, but constituted approximately 20% of fibers. The reduction in IIX/IIB hybrids resulted from different processes in the BR and the TA. In the BR, the reduction was coincident with an increase in type IIX fibers. In the TA, the number of IIX/IIB hybrids was inversely correlated with the proportion of IIB fibers. These patterns reveal that the role of hybrid fibers as intermediates in muscle development is complex. Some hybrid fibers in maturing muscles represent transitional fiber types, while others are phenotypically stable. Moreover, the fate of transitional fibers may be distinct among similar fiber types within different muscles.

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How Animals Move: Comparative Lessons on Animal Locomotion

Schaeffer

Lindstedt

2013

Comprehensive Physiology

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Comparative physiology often provides unique insights in animal structure and function. It is specifically through this lens that we discuss the fundamental properties of skeletal muscle and animal locomotion, incorporating variation in body size and evolved difference among species. For example, muscle frequencies in vivo are highly constrained by body size, which apparently tunes muscle use to maximize recovery of elastic recoil potential energy. Secondary to this constraint, there is an expected linking of skeletal muscle structural and functional properties. Muscle is relatively simple structurally, but by changing proportions of the few muscle components, a diverse range of functional outputs is possible. Thus, there is a consistent and predictable relation between muscle function and myocyte composition that illuminates animal locomotion. When animals move, the mechanical properties of muscle diverge from the static textbook force-velocity relations described by A. V. Hill, as recovery of elastic potential energy together with force and power enhancement with activation during stretch combine to modulate performance. These relations are best understood through the tool of work loops. Also, when animals move, locomotion is often conveniently categorized energetically. Burst locomotion is typified by high-power outputs and short durations while sustained, cyclic, locomotion engages a smaller fraction of the muscle tissue, yielding lower force and power. However, closer examination reveals that rather than a dichotomy, energetics of locomotion is a continuum. There is a remarkably predictable relationship between duration of activity and peak sustainable performance.

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The continuum of hybrid IIX/IIB fibers in normal mouse muscles: MHC isoform proportions and spatial distribution within single fibers

Cited by 22 publications

References 74 publications

Myosin Heavy Chain Expression Can Vary over the Length of Jaw and Leg Muscles

Myosin Heavy Chain Expression Can Vary over the Length of Jaw and Leg Muscles

Hybrid Fibers Transform into Distinct Fiber Types in Maturing Mouse Muscles

How Animals Move: Comparative Lessons on Animal Locomotion

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