A developmentally regulated disappearance of slow myosin in fast-type muscles of the mouse (original) (raw)
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Journal of Muscle Research and Cell Motility, 1988
Changes in myosin synthesis during the postnatal development of the fast extensor digitorum longus (EDL) and the slow soleus muscles of the kitten were examined using immunocytochemical techniques supplemented by pyrophosphate gel electrophoresis and gel electrophoresis-derived enzyme linked immunosorbent assay (GEDELISA) of myosin isoforms. The antibodies used were monoclonals against heavy chains of slow and fast myosins and a polyclonal against foetal/embryonic myosin. In both muscles in the newborn kitten, there was a population of more mature fibres which stained strongly for slow but weakly for foetal/embryonic myosin. These fibres were considered to be primary fibres. They formed 4.8% of EDL fibres and 26.% of soleus fibres at birth, and continued to express slow myosin in adult muscles. The less mature secondary fibres stained strongly for foetal/embryonic myosin, and these could be divided into two subpopulations; fast Secondaries in which foetal/embryonic myosin was replaced by fast myosin, and slow secondaries in which the myosin was replaced by slow myosin. At 50 days the EDL had a large population of fast secondaries (83% of total fibres) and a small population of slow secondaries which gradually transformed into fast fibres with maturity. The vast majority of secondary fibres in the soleus were slow secondaries, in which slow myosin synthesis persisted in adult life. There was a restricted zone of fast secondaries in the soleus, and these gradually transformed into slow fibres in adult life. It is proposed that the emergence of primary fibres and the two populations of secondary fibres is myogenically determined.
The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology, 2006
Postnatal changes in the fiber type composition and fiber crosssectional area were investigated in the superficial (TEM1) and deep (TEM23) temporalis of male rabbits. It was hypothesized that, due to the transition from suckling to chewing during early postnatal development, the proportion of fast fiber types would decrease, while the proportion of fibers positive for myosin heavy chain (MyHC) cardiac a would increase, and that, due to the influence of testosterone during late postnatal development, the proportion of these a fibers would decrease again. Classification of the fibers types was performed by immunohistochemistry according to their MyHC content. The proportion of a fiber types significantly increased in both muscle portions from 2% and 8% for TEM1 and TEM23 at week 1 to 29% and 54% at week 8, respectively,. While in TEM1 the proportion of this fiber type did not change thereafter, it decreased again to 27% in TEM23 at week 20. The change for the fast fiber types was opposite to that of the a fiber types. Significantly more MyHC IIX fibers were found in TEM1 than in TEM23 in adult rabbits. In the first 8 weeks, the cross-sectional areas of all fibers increased. After this period, only MyHC cardiac a þ I fibers continued to increase significantly. It was concluded that there are developmental differences in the myosin heavy chain transitions of the two portions of the temporalis muscle.
Expression of myosin heavy chain isoforms in the postnatal mouse masseter muscle
Okajimas Folia Anatomica Japonica, 2009
We investigated the properties of the masseter muscle in mice from five to seven weeks of age. Myosin heavy chain (MyHC) isoforms were measured in the masseter muscle. The three types of muscle fibers (Type I, strong reaction; Type IIA, intermediate reaction; and Type IIB, weak reaction) were all present in the masseter muscle in five-weeks-old mice and seven-weeks-old mice, the three types could be clearly distinguished by their enzyme activity. The percentage of Type IIB fibers (above 50%) was the highest among all fiber types both 5-and 7-weeks-old mice. The mRNA levels for myosin slow and myosin IIb increased significantly between 5 and 7 weeks. These observations suggest that muscle fiber size, muscle fiber types and mRNA levels of the MyHC isoforms all contribute to the diminished functional adaptability of enzyme activity in the masseter muscle.
Journal of Anatomy, 2006
We investigated the early (< 8 weeks) and late (> 8 weeks) postnatal development of the fibre type composition and fibre cross-sectional area in the superficial masseter and digastric muscle of male rabbits. It was hypothesized, first, that due to the transition between suckling and chewing, during early postnatal development the increase in the proportion of slow fibre types and in fibre cross-sectional areas would be larger in the masseter than in the digastric; and second, that due to the supposed influence of testosterone during late postnatal development, the proportion of slow fibre types in both muscles would decrease. Fibre types were classified by immunostaining according to their myosin heavy chain (MyHC) content. The proportion of slow fibre types significantly increased in the masseter, from 7% at week 1 to 47% at week 8, and then decreased to 21% at week 20, while in the digastric it increased from 5% in week 1 to 19% at week 8 and remained the same thereafter. The changes in the proportion of fast fibre types were the opposite. The remarkable increase and decrease in the proportion of slow fibre types in the masseter was attributed predominantly to MyHC-cardiac α fibres. During early development, the crosssectional area of all fibres in both muscles increased. However, only the fast fibre types in the masseter continued to grow further after week 8. Before weaning, the fast fibre types in the digastric were larger than those in the masseter, but after week 8, they became larger in the masseter than in the digastric. In adult animals, masseter and digastric had the same percentage of fast fibre types, but these fibres were almost twice as large in masseter as in digastric.
Journal of muscle research and cell motility, 2000
The contractile properties of muscle fibres are, in part, determined by the myosin heavy chain (MyHC) isoforms they express. Using monoclonal antibodies, we show that at least three forms of slow twitch MyHC accumulate sequentially during mouse fetal development and that slow MyHC maturation in slow fibres occurs before expression of the adult fast MyHCs in fast fibres. Expression of deletion derivatives of beta-cardiac MyHC cDNA shows that the slow MyHC epitopes that are detected in adult but not in young animals are located near the N-terminus. The same N-terminal region of various fast MyHC molecules contains a conserved epitope that can, on occasions, be observed when slow MyHC cDNA is expressed in non-muscle cells. The results raise the possibility that the N-terminal epitopes result from post-translational modification of the MyHC and that a sequence of slow and fast MyHC isoform post-translational modifications plays a significant role during development of murine muscle fibres.
Immunocytochemical demonstration of myosin heavy chain expression in human muscle
Journal of The Neurological Sciences, 1989
Three new monoclonal antibodies are shown by immunocytochemical techniques to recognise the adult fast, slow and neonatal myosin heavy chain (MHC) isoforms in adult and fetal human muscle. In fetal muscle of 17-20 weeks of gestation, slow MHC was present only in primary myotubes. Secondary myotubes contained neonatal MHC with different levels of fast and some embryonic MHC. We confirmed the presence of tertiary myotubes in the fetal muscle (Draeger et al. (1987)J. Neurol. Sci., 81: 19-43) and show that these contained fast, neonatal and possibly some embryonic MHC. Fast MHC was therefore present in secondary and tertiary myotubes at least as early as 17 days of gestation.
The Anatomical Record, 2003
Our knowledge of the temporal expression of postnatal (adult) fast myosin heavy chain (MyHC) isoforms (2a, 2x, and 2b) in prenatal muscles is limited. Using the pig as a target species and large-animal model, we report on the qualitative and quantitative expression of the major post- and prenatal MyHC isoforms during gestation, as determined by TaqMan real-time PCR and immunohistochemistry. We found that postnatal fast MyHC mRNAs and proteins were expressed much earlier in the pig (gestation day 35) than was previously reported in small mammals. There was a high degree of coexpression and colocalisation of pre- and postnatal MyHC mRNAs and proteins in prenatal muscles. During a period of prenatal muscle growth (gestation days 35–77), relative expression of MyHC isoforms (embryonic > 2a > 2x > 2b) correlated with the gene order in the skeletal MyHC cluster, which suggests the possible presence of cis-acting elements on the same side as the MyHC embryonic gene associated with temporal regulation. Anat Rec Part A 273A:731–740, 2003. © 2003 Wiley-Liss, Inc.
Myosin heavy chain isoform transitions in canine skeletal muscles during postnatal growth
Journal of Anatomy, 2006
To gain a better understanding of the normal characteristics of developing canine muscles, myosin heavy chain (MHC) isoform expression was analysed in the axial and limb skeletal muscles of 18 young dogs whose ages ranged from the late prenatal stage to 6 months. We compared the results of immunohistochemistry using ten monoclonal antibodies, specific to different MHC isoforms, and enzyme-histochemical reactions, which demonstrate the activity of myofibrillar ATPase, succinate dehydrogenase (SDH) and α-glycerophosphate dehydrogenase (α-GPDH). In the skeletal muscles of fetuses and neonatal dogs the developmental isoforms MHC-emb and MHC-neo were prevalent. In all muscles the primary fibres, located centrally in each muscle fascicle, strongly expressed the slow isoform MHC-I. The adult fast isoform MHC-IIa was first noted in some of the secondary fibres on fetal day 55. During the first 10 days after birth, the expression of MHC-emb declined, as did that of MHC-neo during the second and third weeks. Correspondingly, the expression of MHC-IIa, and later, of MHC-I increased in the secondary fibres. Between the sixth week and second month the expression of MHC-IIx became prominent. The slow rhomboideus muscle exhibited an early expression of the slow isoform in the secondary fibres. Our results indicate that the timing of muscle maturation depends on its activity immediately following birth. The fastest developing muscle was the diaphragm, followed by the fast muscles. A pronounced changeover from developmental to adult isoforms was noted at 4-6 weeks of age, which coincides with the increased physical activity of puppies.
Histochemistry and Cell Biology, 1996
The hypothesis that the limited adaptive range observed in fast rat muscles in regard to expression of the slow myosin is due to intrinsic properties of their myogenic stem cells was tested by examining myosin heavy chain (MHC) expression in regenerated rat extensor digitorum longus (EDL) and soleus (SOL) muscles. The muscles were injured by bupivacaine, transplanted to the SOL muscle bed and innervated by the SOL nerve. Three months later, muscle fibre types were determined. MHC expression in muscle fibres was demonstrated immunohistochemically and analysed by SDS-glycerol gel electrophoresis. Regenerated EDL transplants became very similar to the control SOL muscles and indistinguishable from the SOL transplants. Slow type 1 fibres predominated and the slow MHC-1 isoform was present in more than 90% of all muscle fibres. It contributed more than 80% of total MHC content in the EDL transplants. About 7% of fibres exhibited MHC-2a and about 7% of fibres coexpressed MHC-1 and MHC-2a. MHC-2x/d contributed about 5-10% of the whole MHCs in regenerated EDL and SOL transplants. The restricted adaptive range of adult rat EDL muscle in regard to the synthesis of MHC-1 is not rooted in muscle progenitor cells; it is probably due to an irreversible maturation-related change switching off the gene for the slow MHC isoform.& b d y :