Single-fiber myosin heavy chain polymorphism during postnatal development: modulation by hypothyroidism

2000 ◽  
Vol 278 (4) ◽  
pp. R1099-R1106 ◽  
Author(s):  
Nick A. di Maso ◽  
Vincent J. Caiozzo ◽  
Kenneth M. Baldwin
Keyword(s):  
Myosin Heavy Chain ◽  
Postnatal Development ◽  
Heavy Chain ◽  
Time Course ◽  
Developmental Time ◽  
General Concept ◽  
Primary Objective ◽  
Single Fiber ◽  
Fiber Types ◽  
Mhc Polymorphism

The primary objective of this study was to follow the developmental time course of myosin heavy chain (MHC) isoform transitions in single fibers of the rodent plantaris muscle. Hypothyroidism was used in conjunction with single-fiber analyses to better describe a possible linkage between the neonatal and fast type IIB MHC isoforms during development. In contrast to the general concept that developmental MHC isoform transitions give rise to muscle fibers that express only a single MHC isoform, the single-fiber analyses revealed a very high degree of MHC polymorphism throughout postnatal development. In the adult state, MHC polymorphism was so pervasive that the rodent plantaris muscles contained ∼12–15 different pools of fibers (i.e., fiber types). The degree of polymorphism observed at the single-fiber level made it difficult to determine specific developmental schemes analogous to those observed previously for the rodent soleus muscle. However, hypothyroidism was useful in that it confirmed a possible link between the developmental regulation of the neonatal and fast type IIB MHC isoforms.

Differential patterns of transcript accumulation during human myogenesis

1987 ◽  
Vol 7 (11) ◽  
pp. 4100-4114
Author(s):  
P Gunning ◽  
E Hardeman ◽  
R Wade ◽  
P Ponte ◽  
W Bains ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Carbonic Anhydrase ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Time Course ◽  
Human Skeletal Muscle ◽  
Transcript Accumulation ◽  
Mrna Accumulation ◽  
Adult Human ◽  
Alpha Actin

We evaluated the extent to which muscle-specific genes display identical patterns of mRNA accumulation during human myogenesis. Cloned satellite cells isolated from adult human skeletal muscle were expanded in culture, and RNA was isolated from low- and high-confluence cells and from fusing cultures over a 15-day time course. The accumulation of over 20 different transcripts was compared in these samples with that in fetal and adult human skeletal muscle. The expression of carbonic anhydrase 3, myoglobin, HSP83, and mRNAs encoding eight unknown proteins were examined in human myogenic cultures. In general, the expression of most of the mRNAs was induced after fusion to form myotubes. However, several exceptions, including carbonic anhydrase and myoglobin, showed no detectable expression in early myotubes. Comparison of all transcripts demonstrated little, if any, identity of mRNA accumulation patterns. Similar variability was also seen for mRNAs which were also expressed in nonmuscle cells. Accumulation of mRNAs encoding alpha-skeletal, alpha-cardiac, beta- and gamma-actin, total myosin heavy chain, and alpha- and beta-tubulin also displayed discordant regulation, which has important implications for sarcomere assembly. Cardiac actin was the only muscle-specific transcript that was detected in low-confluency cells and was the major alpha-actin mRNA at all times in fusing cultures. Skeletal actin was transiently induced in fusing cultures and then reduced by an order of magnitude. Total myosin heavy-chain mRNA accumulation lagged behind that of alpha-actin. Whereas beta- and gamma-actin displayed a sharp decrease after initiation of fusion and thereafter did not change, alpha- and beta-tubulin were transiently induced to a high level during the time course in culture. We conclude that each gene may have its own unique determinants of transcript accumulation and that the phenotype of a muscle may not be determined so much by which genes are active or silent but rather by the extent to which their transcript levels are modulated. Finally, we observed that patterns of transcript accumulation established within the myotube cultures were consistent with the hypothesis that myoblasts isolated from adult tissue recapitulate a myogenic developmental program. However, we also detected a transient appearance of adult skeletal muscle-specific transcripts in high-confluence myoblast cultures. This indicates that the initial differentiation of these myoblasts may reflect a more complex process than simple recapitulation of development.

scholarly journals Mutation of the IIB myosin heavy chain gene results in muscle fiber loss and compensatory hypertrophy

2001 ◽  
Vol 280 (3) ◽  
pp. C637-C645 ◽  
Author(s):  
David L. Allen ◽  
Brooke C. Harrison ◽  
Carol Sartorius ◽  
William C. Byrnes ◽  
Leslie A. Leinwand
Keyword(s):  
Skeletal Muscle ◽  
Myosin Heavy Chain ◽  
Body Mass ◽  
Heavy Chain ◽  
Compensatory Hypertrophy ◽  
Muscle Disease ◽  
Chain Gene ◽  
Fiber Types ◽  
Mouse Skeletal Muscle ◽  
Ultrastructural Studies

The fast skeletal IIb gene is the source of most myosin heavy chain (MyHC) in adult mouse skeletal muscle. We have examined the effects of a null mutation in the IIb MyHC gene on the growth and morphology of mouse skeletal muscle. Loss in muscle mass of several head and hindlimb muscles correlated with amounts of IIb MyHC expressed in that muscle in wild types. Decreased mass was accompanied by decreases in mean fiber number, and immunological and ultrastructural studies revealed fiber pathology. However, mean cross-sectional area was increased in all fiber types, suggesting compensatory hypertrophy. Loss of muscle and body mass was not attributable to impaired chewing, and decreased food intake as a softer diet did not prevent the decrease in body mass. Thus loss of the major MyHC isoform produces fiber loss and fiber pathology reminiscent of muscle disease.

scholarly journals Regulation of an antisense RNA with the transition of neonatal to IIb myosin heavy chain during postnatal development and hypothyroidism in rat skeletal muscle

2012 ◽  
Vol 302 (7) ◽  
pp. R854-R867 ◽  
Author(s):  
Clay E. Pandorf ◽  
Weihua Jiang ◽  
Anqi X. Qin ◽  
Paul W. Bodell ◽  
Kenneth M. Baldwin ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Myosin Heavy Chain ◽  
Postnatal Development ◽  
Heavy Chain ◽  
Antisense Rna ◽  
Transcriptional Repression ◽  
Mhc Genes ◽  
Regulatory Model ◽  
A Site ◽  
Comparative Phylogenetic Analysis

Postnatal development of fast skeletal muscle is characterized by a transition in expression of myosin heavy chain (MHC) isoforms, from primarily neonatal MHC at birth to primarily IIb MHC in adults, in a tightly coordinated manner. These isoforms are encoded by distinct genes, which are separated by ∼17 kb on rat chromosome 10. The neonatal-to-IIb MHC transition is inhibited by a hypothyroid state. We examined RNA products [mRNA, pre-mRNA, and natural antisense transcript (NAT)] of developmental and adult-expressed MHC genes (embryonic, neonatal, I, IIa, IIx, and IIb) at 2, 10, 20, and 40 days after birth in normal and thyroid-deficient rat neonates treated with propylthiouracil. We found that a long noncoding antisense-oriented RNA transcript, termed bII NAT, is transcribed from a site within the IIb-Neo intergenic region and across most of the IIb MHC gene. NATs have previously been shown to mediate transcriptional repression of sense-oriented counterparts. The bII NAT is transcriptionally regulated during postnatal development and in response to hypothyroidism. Evidence for a regulatory mechanism is suggested by an inverse relationship between IIb MHC and bII NAT in normal and hypothyroid-treated muscle. Neonatal MHC transcription is coordinately expressed with bII NAT. A comparative phylogenetic analysis also suggests that bII NAT-mediated regulation has been a conserved trait of placental mammals for most of the eutherian evolutionary history. The evidence in support of the regulatory model implicates long noncoding antisense RNA as a mechanism to coordinate the transition between neonatal and IIb MHC during postnatal development.

Enzymatic plasticity of medial gastrocnemius fibers in the adult chronic spinal cat

1990 ◽  
Vol 259 (3) ◽  
pp. C507-C514 ◽  
Author(s):  
B. Jiang ◽  
R. R. Roy ◽  
V. R. Edgerton
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Fiber Type ◽  
Motor Units ◽  
Glycolytic Enzyme ◽  
Medial Gastrocnemius ◽  
Fiber Types ◽  
Cross Sectional ◽  
Fast Myosin ◽  
Weight Support

The metabolic plasticity of single fibers in adult cat medial gastrocnemius (MG) 6 mo after complete spinal cord transection (Sp) at T12-T13 was studied. Some Sp cats were trained to weight support (Sp-WS) 30 min/day beginning 1 mo posttransection. Cross-sectional area, succinate dehydrogenase (SDH), alpha-glycerophosphate dehydrogenase (GPD), and myofibrillar adenosinetriphosphatase (ATPase) activities were determined in fibers identified in frozen serial sections. Fibers were categorized as light or dark based on myosin ATPase staining, alkaline preincubation. The percentage of dark ATPase fibers was higher in Sp and Sp-WS (approximately 85%) than in control (approximately 60%). All dark ATPase fibers reacted positively to a fast myosin heavy chain monoclonal antibody. In both spinal groups, a higher percentage of dark ATPase fibers reacted to both fast and slow myosin heavy chain antibodies than in controls. Neither Sp nor Sp-WS cats showed fiber atrophy. Compared with control, SDH activity was decreased in both fiber types of Sp cats. Daily weight-support training ameliorated this adaptation. There were no differences among the three groups in mean GPD and ATPase activities for either fiber type. There was a slight tendency, however, for spinal cats to have higher GPD and ATPase activities (independent of type) than control, probably reflecting the larger proportion of dark ATPase fibers in these cats. These observations indicate that 6 mo after spinalization in adult cats, some of the fibers of a fast muscle became "faster" and developed oxidative and glycolytic enzyme profiles that normally are exhibited in fast fatigable motor units.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Single-Fiber Myosin Heavy-Chain Isoform Composition of Rodent Laryngeal Muscle

2000 ◽  
Vol 126 (7) ◽  
pp. 874 ◽  
Author(s):  
Ya Zhen Wu ◽  
Michael J. Baker ◽  
Roger L. Crumley ◽  
Vincent J. Caiozzo
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Single Fiber ◽  
Laryngeal Muscle ◽  
Myosin Heavy Chain Isoform

Kinetic properties of myosin heavy chain isoforms in mouse skeletal muscle: comparison with rat, rabbit, and human and correlation with amino acid sequence

2004 ◽  
Vol 287 (6) ◽  
pp. C1725-C1732 ◽  
Author(s):  
Oleg Andruchov ◽  
Olena Andruchova ◽  
Yishu Wang ◽  
Stefan Galler
Keyword(s):  
Skeletal Muscle ◽  
Amino Acid ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Actin Binding ◽  
Kinetic Properties ◽  
Fiber Types ◽  
Mouse Skeletal Muscle ◽  
Structural Variability ◽  
Kinetics Of

Stretch activation kinetics were investigated in skinned mouse skeletal muscle fibers of known myosin heavy chain (MHC) isoform content to assess kinetic properties of different myosin heads while generating force. The time to peak of stretch-induced delayed force increase ( t3) was strongly correlated with MHC isoforms [ t3 given in ms for fiber types containing specified isoforms; means ± SD with n in parentheses: MHCI 680 ± 108 ( 13 ), MHCIIa 110.5 ± 10.7 ( 23 ), MHCIIx(d) 46.2 ± 5.2 ( 20 ), MHCIIb 23.5 ± 3.3 (76)]. This strong correlation suggests different kinetics of force generation of different MHC isoforms in the following order:MHCIIb > MHCIIx(d) > MHCIIa ≫ MHCI. For rat, rabbit, and human skeletal muscles the same type of correlation was found previously. The kinetics decreases slightly with increasing body mass. Available amino acid sequences were aligned to quantify the structural variability of MHC isoforms of different animal species. The variation in t3 showed a correlation with the structural variability of specific actin-binding loops (so-called loop 2 and loop 3) of myosin heads ( r = 0.74). This suggests that alterations of amino acids in these loops contribute to the different kinetics of myosin heads of various MHC isoforms.

Single-fiber myosin heavy chain polymorphism: how many patterns and what proportions?

2003 ◽  
Vol 285 (3) ◽  
pp. R570-R580 ◽  
Author(s):  
Vincent J. Caiozzo ◽  
Michael J. Baker ◽  
Karen Huang ◽  
Harvey Chou ◽  
Ya Zhen Wu ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Muscle Fibers ◽  
Myosin Heavy Chain Isoforms ◽  
Single Fiber ◽  
Myosin Heavy Chain Isoform ◽  
Skeletal Muscle Fibers ◽  
Velocity Relationship ◽  
Force Velocity

Previous studies have reported the existence of skeletal muscle fibers that coexpress multiple myosin heavy chain isoforms. These surveys have usually been limited to studying the polymorphic profiles of skeletal muscle fibers from a limited number of muscles (i.e., usually <4). Additionally, few studies have considered the functional implications of polymorphism. Hence, the primary objective of this study was to survey a relatively large number of rat skeletal muscle/muscle regions and muscle fibers ( n≈ 5,000) to test the hypothesis that polymorphic fibers represent a larger fraction of the total pool of fibers than do so-called monomorphic fibers, which express only one myosin heavy chain isoform. Additionally, we used Hill's statistical model of the force-velocity relationship to differentiate the functional consequences of single-fiber myosin heavy chain isoform distributions found in these muscles. The results demonstrate that most muscles and regions of rodent skeletal muscles contain large proportions of polymorphic fibers, with the exception of muscles such as the slow soleus muscle and white regions of fast muscles. Several muscles were also found to have polymorphic profiles that are not consistent with the I↔IIA↔IIX↔IIB scheme of muscle plasticity. For instance, it was found that the diaphragm muscle normally contains I/IIX fibers. Functionally, the high degree of polymorphism may 1) represent a strategy for producing a spectrum of contractile properties that far exceeds that simply defined by the presence of four myosin heavy chain isoforms and 2) result in relatively small differences in function as defined by the force-velocity relationship.

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