Systematic variation in myosin expression along extraocular muscle fibres of the adult rat

Jacoby, J.; Ko, Kyung Ae; Weiss, Carlos O.; Rushbrook, Julie Ivory

doi:10.1007/bf01833323

Cited by 85 publications

(62 citation statements)

References 44 publications

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“…It is interesting to note that, in the extraocular muscle, some fibres react with all three antibodies (asterisks in Fig.·3), many fibres react with two of them (circles in Fig.·3) and one fibre reacts only with anti 2B (hash mark in Fig.·3). As described in previous studies (Jacoby et al, 1990;Lucas and Hoh, 1997), hybrid fibres are particularly abundant in extraocular muscles.…”

Section: Mhc Isoform Expression In Bovine Musclessupporting

confidence: 74%

“…Several MHC isoforms are expressed in extraocular muscles, as suggested by published evidence on various animal species [mouse (Porter et al, 2001), rat (Wieczorek et al, 1985;Rubinstein and Hoh, 2000), rabbit (Briggs and Schachat, 2002;Lucas and Hoh, 2003)]. In particular, MHC-Eo (Sartore et al, 1987), developmental MHCs (Jacoby et al, 1990) and ␣ cardiac MHC (Wieczorek et al, 1985;Lucas and Hoh, 2003) can be expressed in extraocular muscles. Whether such peculiar expression should be related to the embryological origin or to the specialized contractile requirements of extraocular muscles is a matter of speculation.…”

Section: Discussionmentioning

confidence: 94%

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Expression of eight distinct MHC isoforms in bovine striated muscles:evidence for MHC-2B presence only in extraocular muscles

Toniolo

Maccatrozzo

Patruno

et al. 2005

Journal of Experimental Biology

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This study aimed to analyse the expression of myosin heavy chain (MHC) isoforms in bovine muscles, with particular attention to the MHC-2B gene. Diaphragm, longissimus dorsi, masseter, several laryngeal muscles and two extraocular muscles (rectus lateralis and retractor bulbi) were sampled in adult male Bos taurus (age 18-24·months, mass 400-500·kg) and analysed by RT-PCR, gel electrophoresis and immunohistochemistry. Transcripts and proteins corresponding to eight MHC isoforms were identified: MHC-␣ ␣ and MHC-␤ ␤/slow (or MHC-1), two developmental isoforms (MHC-embryonic and MHC-neonatal), three adult fast isoforms (MHC-2A

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Section: Mhc Isoform Expression In Bovine Musclessupporting

confidence: 74%

Section: Discussionmentioning

confidence: 94%

Expression of eight distinct MHC isoforms in bovine striated muscles:evidence for MHC-2B presence only in extraocular muscles

Toniolo

Maccatrozzo

Patruno

et al. 2005

Journal of Experimental Biology

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“…We show here that EH-Myom1, the J. D. Porter and others (Agarkova et al, 2000), is not restricted to embryonic cardiac muscle but is also expressed in adult EOM. Adult EOM is known to use several other traits of cardiac and embryonic skeletal muscle in meeting its distinct functional roles (Cheng and Porter, 2002;Jacoby et al, 1990;Khanna et al, 2003;McLoon and Wirtschafter, 1996;Porter et al, 2001a;Rushbrook et al, 1994) and then may have the phenotypic plasticity and need to express EH-myomesin. Our data further suggest that EHMyom1 is not restricted to embryonic cardiac muscle and EOM but rather is present in adult heart and is detected at trace levels in adult hindlimb muscle.…”

Section: Discussionmentioning

confidence: 99%

Postnatal suppression of myomesin, muscle creatine kinase and the M-line in rat extraocular muscle

Porter

Merriam

Gong

et al. 2003

Journal of Experimental Biology

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SUMMARYThe M-line and its associated creatine kinase (CK) M-isoform (CK-M) are ubiquitous features of skeletal and cardiac muscle. The M-line maintains myosin myofilaments in register, links the contractile apparatus to the cytoskeleton for external force transfer and localizes CK-based energy storage and transfer to the site of highest ATP demand. We establish here that the muscle group responsible for movements of the eye, extraocular muscle (EOM),is divergent from other striated muscles in lacking both an M-line and its associated CK-M. Although an M-line forms during myogenesis, both in vivo and in vitro, it is actively repressed after birth. Transcripts of the major M-line structural proteins, myomesin 1 and myomesin 2, follow the same pattern of postnatal downregulation, while the embryonic heart-specific EH-myomesin 1 transcript is expressed early and retained in adult eye muscle. By immunocytochemistry, myomesin protein is absent from adult EOM sarcomeres. M-line suppression does not occur in organotypic co-culture with oculomotor motoneurons, suggesting that the mechanism for suppression may lie in muscle group-specific activation or workload patterns experienced only in vivo. The M-line is, however, still lost in dark-reared rats, despite the developmental delay this paradigm produces in the visuomotor system and EOMs. EOM was low in all CK isoform transcripts except for the sarcomeric mitochondrial (Ckmt2) isoform. Total CK enzyme activity of EOM was one-third that of hindlimb muscle. These findings are singularly unique among fast-twitch skeletal muscles. Since EOM exhibits isoform diversity for other sarcomeric proteins, the M-line/CK-M divergence probably represents a key physiological adaptation for the unique energetics and functional demands placed on this muscle group in voluntary and reflexive eye movements.

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“…Denervation studies suggest motoneurons play a n important role in suppressing immature isoforms of myosin in postnatal muscle (Cerny and Bandman, 1987;Schiaffino et al, 1988;Jakubiec-Puka et al, 1990). In the extraocular muscle, a slow tonic muscle with multiple neural endplate bands that traverse the muscle a t regular intervals, embryonic myosin is expressed distal to, but not within endplate bands (Jacoby et al, 1989), suggesting a greater likelihood of embryonic myosin expression with increasing distance from the endplate band. The ALD muscle is also a slow tonic muscle with multiple endplate bands (Hess, 1970).…”

Section: Non-uniform Patterns Of Protein Expressionmentioning

confidence: 99%

Role of satellite cells in altering myosin expression during avian skeletal muscle hypertrophy

McCormick

Schultz

1994

Developmental Dynamics

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This study examined whether satellite cells express an embryonic isoform of myosin upon fusion with hypertrophying muscle fibers. Anterior latissimus dorsi (ALD) muscle hypertrophy was induced in adult chickens by weighting one wing. One and 7 days of wingweighting produced significant increases in ALD muscle wet weight and in the number of mature fibers expressing ventricular-like embryonic (V-EMB) myosin. V-EMB myosin expression could be an event during regeneration of fibers injured by overload or part of the hypertrophy process itself. Although there was an increase in both the number of damaged fibers and the number of mature fibers expressing embryonic myosin after wingweighting, results from this study suggest that these two events were not necessarily related. The apparent health of fibers expressing V-EMB myosin and the lack of correlation between the numbers of damaged and V-EMB myosin positive fibers (r = 0.20) suggest that embryonic myosin expression in mature fibers was likely a feature of the hypertrophy process itself. The appearance of V-EMB myosin in mature fibers 1 day after wing weighting suggests that the change in myosin expression did not involve satellite cells since 24 hr is too short a time to permit more than limited satellite cell fusion. The relationship between satellite cells and embryonic myosin expression was examined more closely by labeling dividing satellite cells and their progeny with 5-bromo-2-deoxyuridine, and then colocalizing labeled myofiber nuclei and embryonic myosin in consecutive transverse sections of hypertrophied ALD muscle. One week of wingweighting resulted in marked increases in myofiber nuclear labeling index and myofiber nuclear density compared to contralatera1 control. V-EMB myosin was not expressed uniformly throughout individual fibers, but rather in discrete regions of varying length. Many V-EMB myosin positive regions had a higher labeled nuclear density than V-EMB myosin negative regions indicating that V-EMB myosin expression was associated with an accumulation of satellite cell progeny in a restricted area. However, it was also clear that satellite cell progeny were not the sole source of V-EMB myosin since labeled nuclei were completely absent from 41% of the V-EMB positive regions. Furthermore, the 0 1994 WILEY-LISS, INC.presence of new nuclei did not result in obligatory expression of embryonic myosin because many V-EMB negative regions had a high labeled nuclear density. Thus, recently incorporated nuclei arising by satellite cell division are implicated as one, but not the sole source of embryonic myosin in hypertrophying muscle. These observations suggest that the non-uniform pattern of embryonic myosin expression in hypertrophying muscle resulted from differences in nuclear activity, not necessarily the addition of new nuclei.

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Systematic variation in myosin expression along extraocular muscle fibres of the adult rat

Cited by 85 publications

References 44 publications

Expression of eight distinct MHC isoforms in bovine striated muscles:evidence for MHC-2B presence only in extraocular muscles

Expression of eight distinct MHC isoforms in bovine striated muscles:evidence for MHC-2B presence only in extraocular muscles

Postnatal suppression of myomesin, muscle creatine kinase and the M-line in rat extraocular muscle

Role of satellite cells in altering myosin expression during avian skeletal muscle hypertrophy

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