Myosin heavy chain composition of single cells from avian slow skeletal muscle is strongly correlated with velocity of shortening during development

Reiser, Peter J.; Greaser, Marion L.; Moss, Richard L.

doi:10.1016/0012-1606(88)90387-9

Cited by 72 publications

(37 citation statements)

References 36 publications

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“…Two broad classes of muscle fibers have been defined based on physiological and structural criteria: rapidly contracting oxidative fibers and slowly contracting glycolytic fibers. The rate of contraction is particularly dependent on the specific isoform(s) of the myosin heavy chain (MyHC) family produced within a myofiber (Bárány, 1967;Reiser et al, 1988). Within the limb muscles, rapidly contracting muscle fibers express only MyHCs of the fast class, whereas slowly contracting muscle fibers frequently express a MyHC of the fast class, in addition to MyHCs of the slow class, which are designated slow MyHC 1, 2 and 3 in birds.…”

Section: Introductionmentioning

confidence: 99%

Regulation of myosin expression during myotome formation

et al. 2003

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The first skeletal muscle fibers to form in vertebrate embryos appear in the somitic myotome. PCR analysis and in situ hybridization with isoform-specific probes reveal differences in the temporal appearance and spatial distribution of fast and slow myosin heavy chainmRNA transcripts within myotomal fibers. Embryonic fast myosin heavy chain was the first isoform expressed, followed rapidly by slow myosin heavy chains 1 and 3, with slow myosin heavy chain 2 appearing several hours later. Neonatal fast myosin heavy chain is not expressed in myotomal fibers. Although transcripts of embryonic fast myosin heavy chain were always distributed throughout the length of myotomal fibers, the mRNA for each slow myosin heavy chain isoform was initially restricted to the centrally located myotomal fiber nuclei. As development proceeded, slow myosin heavy chain transcripts spread throughout the length of myotomal fibers in order of their appearance. Explants of segments from embryos containing neural tube, notochord and somites 7-10, when incubated overnight, become innervated by motor neurons from the neural tube and express all four myosin heavy chain genes. Removal of the neural tube and/or notochord from explants prior to incubation or addition of d-tubocurare to intact explants prevented expression of slow myosin chain 2 but expression of genes encoding the other myosin heavy chain isoforms was unaffected. Thus, expression of slow myosin heavy chain 2 is dependent on functional innervation, whereas expression of embryonic fast and slow myosin heavy chain 1 and 3are innervation independent. Implantation of sonic-hedgehog-soaked beads in vivo increased the accumulation of both fast and slow myosin heavy chain transcripts, as well as overall myotome size and individual fiber size, but had no effect on myotomal fiber phenotype. Transcripts encoding embryonic fast myosin heavy chain first appear ventrolaterally in the myotome, whereas slow myosin heavy chain transcripts first appear in fibers positioned midway between the ventrolateral and dorsomedial lips of the myotome. Therefore, models of epaxial myotome formation must account for the positioning of the oldest fibers in the more ventral-lateral region of the myotome and the youngest fibers in the dorsomedial region.

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Section: Introductionmentioning

confidence: 99%

Regulation of myosin expression during myotome formation

et al. 2003

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“…Mechanical studies of single skinned fibers (sarcolemma permeabilized or removed) have demonstrated a correlation between MHC isoforms and V max (2,3,16,24,39,40,44; for reviews see Refs. 5 and 42).…”

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Influence of myosin isoforms on contractile properties of intact muscle fibers from Rana pipiens

Lutz

Sirsi

Shapard-Palmer

et al. 2002

American Journal of Physiology-Cell Physiology

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The myosin heavy chain (MHC) and myosin light chain (MLC) isoforms in skeletal muscle of Rana pipiens have been well characterized. We measured the force-velocity (F-V) properties of single intact fast-twitch fibers from R. pipiens that contained MHC types 1 or 2 (MHC1 or MHC2) or coexpressed MHC1 and MHC2 isoforms. Velocities were measured between two surface markers that spanned most of the fiber length. MHC and MLC isoform content was quantified after mechanics analysis by SDS-PAGE. Maximal shortening velocity (V max) and velocity at half-maximal tension (VP 50) increased with percentage of MHC1 (%MHC1). Maximal specific tension (Po/CSA, where Po is isometric tension and CSA is fiber cross-sectional area) and maximal mechanical power (Wmax) also increased with %MHC1. MHC concentration was not significantly correlated with %MHC1, indicating that the influence of %MHC1 on Po/CSA and Wmax was due to intrinsic differences between MHC isoforms and not to concentration. The MLC3-to-MLC1 ratio was not significantly correlated with Vmax, VP 50, Po/CSA, or Wmax. These data demonstrate the powerful relationship between MHC isoforms and F-V properties of the two most common R. pipiens fiber types. mechanics; maximal shortening velocity; fiber type; maximal power; specific tension EXPRESSION OF A HETEROGENEOUS population of muscle cells, with a wide range of contractile properties, is a hallmark of vertebrate skeletal muscle. The differences in force-velocity (F-V) properties among muscle fiber types permit muscles to perform a wide range of mechanical tasks. Functional differences among fiber types have been correlated with myosin heavy chain (MHC) and myosin light chain (MLC) isoforms. Thus differential expression of MHC and MLC isoforms is an important determinant of functional diversity in muscular systems and is matched to the specific motor requirements of an organism.The greatest emphasis in single-fiber mechanical studies has been on determining the influence of MHC and MLC isoforms on maximal shortening velocity (V max ). Mechanical studies of single skinned fibers (sarcolemma permeabilized or removed) have demonstrated a correlation between MHC isoforms and V max (2,3,16,24,39,40,44; for reviews see Refs. 5 and 42). With the use of the in vitro motility assay, where the potential influences of thin-filament regulatory proteins and muscle activation are avoided, the correlation between speed and MHC isoforms has been corroborated (6, 18).The influence of MLC isoforms on V max is more controversial and may be variable among vertebrates. Several studies have established a significant effect of the molar ratio of essential (alkali) light chains [MLC3-to-MLC1 ratio (MLC3/MLC1)] on V max (2, 14, 25, 37, 44; for reviews see Refs. 5, 36, and 42). Independent support for the role of MLC3/MLC1 in regulating myosin kinetics has been documented in a genetic model of fish (7) and with the in vitro motility assay (26). However, in human skinned fast-twitch fibers, MLC3/ MLC1 had no influence on V max (23,24,46). In any cas...

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“…The expression of specific MyHC isoform(s) within individual muscle fibers is primarily responsible for the rate of fiber contraction, and, for convenience, each member of the MyHC family can be assigned to either a fast or a slow class based on expression in either fast or slow contracting muscle fibers. Multiple MyHC isoforms of either the fast or slow class can be coexpressed within a single muscle fiber, and some fibers coexpress isoforms of both classes (2,6).…”

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confidence: 99%

“…The myosin heavy chain (MyHC) 1 proteins expressed in striated muscle comprise a family of isoforms, members of which can be distinguished by differences in ATPase activity (1,2) and antibody immunoreactivity (3)(4)(5). The expression of specific MyHC isoform(s) within individual muscle fibers is primarily responsible for the rate of fiber contraction, and, for convenience, each member of the MyHC family can be assigned to either a fast or a slow class based on expression in either fast or slow contracting muscle fibers.…”

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confidence: 99%