Myosin heavy chain expression within the tapered ends of skeletal muscle fibers

Rosser, Benjamin W. C.; Waldbillig, Donna M.; Lovo, Stacey; Armstrong, Jacalyn D.; Bandman, Everett

doi:10.1002/ar.1092420404

Cited by 19 publications

(20 citation statements)

References 71 publications

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“…The role of the tongue in mastication places it under compressive stresses not associated with appendicular muscle and places it at risk for accidental biting, and the low level of developmental MHC mRNA in the tongue body suggests that fiber regeneration is not routine. MHC-neo has been reported to be expressed in the tapered ends of fibers, particularly in birds [Rosser et al, 1995], and the low level of MHC-neo we found in tongue homogenates is consistent with expression restricted to very few fibers or fiber subdomains, such as tapered ends.…”

Section: Developmental and Unconventional Mhc Expressionsupporting

confidence: 87%

Sarcomeric Myosin Expression in the Tongue Body of Humans, Macaques and Rats

Rahnert

Sokoloff²,

Burkholder³

2009

Cells Tissues Organs

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Expression of developmental and unconventional myosin heavy chain (MHC) isoforms in some adult head and neck muscles is thought to reflect specific contractile demands of muscle fibers active during kinematically complex movements. Mammalian tongue muscles are active during oromotor behaviors that encompass a wide range of tongue movement speeds and tongue shape changes (e.g. respiration, oral transport, swallowing, rejection), but the extent to which tongue muscles express developmental and unconventional MHC is not known. Quantitative PCR was used to determine the mRNA content of conventional MHC-beta, MHC-2a, MHC-2b and MHC-2x, the developmental isoforms embryonic MHC and neonatal MHC and the unconventional isoforms atrial/cardiac-α MHC (MHC-alpha), extraocular MHC, masseter MHC and slow tonic MHC in tongue body muscles of the rat, macaque and human. In all species, conventional MHC isoforms predominate. MHC-2b and MHC-2x account for 98% of total MHC mRNA in the rat. MHC-2a, MHC-2x and MHC-beta account for 94% of total MHC mRNA in humans and 96% of total MHC mRNA in macaque. With the exception of MHC-alpha in humans (5%), developmental and unconventional MHC mRNA represents less than 0.3% of total MHC mRNA. We conclude that in these species, there is limited expression of developmental and unconventional MHC and that diversity of tongue body muscle fiber contractile properties is achieved primarily by MHC-beta, MHC-2a, MHC-2x and MHC-2b. Whether expression of MHC-alpha mRNA in tongue is unique to humans or present in other hominoids awaits further investigation.

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Section: Developmental and Unconventional Mhc Expressionsupporting

confidence: 87%

Sarcomeric Myosin Expression in the Tongue Body of Humans, Macaques and Rats

Rahnert

Sokoloff²,

Burkholder³

2009

Cells Tissues Organs

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“…A study of transverse and longitudinal sections showed that the small fibre which expressed IGF-1 mRNA also express the neonatal myosin heavy chain (MyHC). It has also been shown that small diameter fibres containing neonatal MyHC are the tapered ends of the larger fibres terminating within the belly of the muscle (Rosser et al, 1995). Longitudinal growth of skeletal muscle is facilitated by the addition of new sarco- meres to the ends of the existing myofibrils (Williams & Goldspink, 1971, 1973 and the initial stage involves the laying down of neonatal myosin (Rosser et al, 1995).…”

Section: Discussionmentioning

confidence: 99%

“…This work showed that IGF-1 gene expression is not confined to the satellite cells but is up-regulated in the muscle fibres themselves. In transverse sections the IGF-1 message was localized to large muscle fibre but tended to be expressed strongly in the small fibres which represent the tapered ends of fibres terminating in the muscle belly (Rosser et al, 1995). In a few muscles some evidence of degeneration and regeneration was noted with high IGF-1 mRNA levels.…”

Section: Localization Of Igf-1 Mrna In Normal and Stretched Musclementioning

confidence: 94%

Cloning and characterization of an IGF-1 isoform expressed in skeletal muscle subjected to stretch

Yang

Alnaqeeb

Simpson

et al. 1996

J Muscle Res Cell Motil

274

211

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To ascertain if IGF-1 is a regulator of local muscle growth, total RNA was extracted from rabbit muscle induced to undergo rapid hypertrophy using active stretch and from control muscles. This was analysed by Northern hybridization with a 280 base pair probe containing sequences derived from exons 3 and 4 of the insulin-like growth factor 1 gene. Two types of insulin-like growth factor 1 mRNA were shown to be strong expressed in the stretched muscles. In situ hybridization using the same probe (280 base pair) showed that IGF-1 is strongly expressed in muscle that is induced to grow rapidly and is expressed in the muscle fibres themselves. Using RT-PCR a single insulin-like growth factor 1 isoform cDNA (IGF-1Ea) could be cloned from the normal resting muscles. However, an additional isoform of insulin-like growth factor 1 (insulin-like growth factor 1Eb) was found to be expressed in stretched muscle undergoing hypertrophy. The E domain sequence of the additional isoform differs from the liver insulin-like growth factor 1Ea by the presence a 52 base pair insert. This changes the reading frame of the derived carboxyl-terminal resulting in a different precursor insulin-like growth factor 1 isoform. This insulin-like growth factor 1 mRNA probably encodes the precursor insulin-like growth factor 1 isoform that is responsible for local muscle growth regulation in response to mechanical stimulation. To confirm that alternative splicing of the insulin-like growth factor 1 gene occurs in muscle in response to physical activity, oligonucleotide primers were made which specifically amplify the cDNAs of two isoforms (insulin-like growth factors 1Ea and Eb) in the human as well as the rabbit. Following altered physical activity for 2 h to 6 days, appreciable levels of insulin-like growth factor 1Eb (in human the Ec) isoform were detected in skeletal muscle by using RT-PCR. In contrast very little if any of this splice variant could be detected in control muscle not subjected to stretch or extra physical activity.

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“…In maturing rat SOL muscles, regional asymmetries in fiber type are present in single fibers between 3 and 4 weeks of age, but these fibers then become more homogeneous over time [Sakuma et al, 1995]. In developing bird muscles, neonatal MHC is expressed at the growing ends of the fibers, but adult MHCs are found at the muscle mid-regions [Rosser et al, 1995]. We found that in many cases, one end of the fiber differed in MHC content as compared with the rest of the fiber ( fig.…”

Section: Segmental Differences In Fiber Typementioning

confidence: 99%

Hybrid Fibers Transform into Distinct Fiber Types in Maturing Mouse Muscles

Brummer

Zhang

Piddoubny

et al. 2013

Cells Tissues Organs

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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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Myosin heavy chain expression within the tapered ends of skeletal muscle fibers

Cited by 19 publications

References 71 publications

Sarcomeric Myosin Expression in the Tongue Body of Humans, Macaques and Rats

Sarcomeric Myosin Expression in the Tongue Body of Humans, Macaques and Rats

Cloning and characterization of an IGF-1 isoform expressed in skeletal muscle subjected to stretch

Hybrid Fibers Transform into Distinct Fiber Types in Maturing Mouse Muscles

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