Regulation of myosin heavy chain expression in adult rat hindlimb muscles during short‐term paralysis: comparison of denervation and tetrodotoxin‐induced neural inactivation

Michel, Robin N.; Parry, David; Dunn, Shannon

doi:10.1016/0014-5793(96)00618-7

Cited by 48 publications

(77 citation statements)

References 43 publications

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“…Other investigators using gel electrophoresis have also reported significant increases in the IIa-IIx and decreases in the I MHC protein bands in the denervated soleus [5,7,14]. Immunohistochemical detection of MHC protein demonstrates that changes in total MHC protein are due to coexpression in the denervated soleus fibers with increases in I/IIx [5,8] and both increases [5] and decreases [8] in I/IIa coexpression.…”

Section: Discussionmentioning

confidence: 78%

mentioning

confidence: 99%

“…Those studies that have looked at adult mammals have studied the later stages of denervation (2 weeks to 5 months; [5Ϫ8]) and have provided conflicting results regarding the effects of denervation on MHC protein expression. For example in the 14-day-denervated soleus, protein gel analysis showed a decrease in I MHC and an increase in IIa MHC [7] showed a 25% increase in soleus fibers expressing I MHC and an 88% decrease in fibers expressing IIa MHC [8].Previous studies suggest that the effects of muscle denervation are complex and dependent upon factors such as muscle fiber type, species, and developmental stage of the muscle at denervation (for review [9]). Most denervation studies have investigated fiber transformation at the protein level; however, changes at the protein level do not always correspond to changes in transcription [10].…”

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confidence: 99%

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Changes in myosin mRNA and protein expression in denervated rat soleus and tibialis anterior

Huey

Bodine

1998

European Journal of Biochemistry

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Denervation differs from other models of reduced neuromuscular activation due to the absence of a nerve-muscle connection and limited data exists regarding the effects of denervation on myosin heavy chain (MHC) expression. Thus, adult MHC expression (I, IIa, IIx, IIb) was studied in the rat soleus and tibialis anterior (TA) at the mRNA and protein levels 2, 4, 7, 10, 14, and 30 days following sciatic nerve transection. MHC protein content was quantified with SDS/PAGE and mRNA levels with the RNaseprotection assay. Control soleus consisted predominately of type I MHC mRNA and protein, however, 4 days after denervation type I MHC mRNA was significantly decreased to 41Ϯ 8% of control and continued to remain below control values. Soleus IIa mRNA was significantly elevated 7 and 10 days after denervation while IIx mRNA remained relatively constant until 30 days when it increased to 197Ϯ 23% of control. At the protein level, soleus I MHC significantly decreased to 80% of the total while IIa MHC significantly increased to 20% of the total. At 30 days, IIx MHC protein accounted for 9.4Ϯ 1.6 % of the total soleus MHC protein. In the TA, IIb mRNA was significantly decreased to 57% of control by day 4 and remained significantly decreased for up to a month. TA IIx mRNA was also significantly decreased at 10 and 30 days after denervation. Similar to the soleus, TA IIa mRNA was significantly increased over control 7Ϫ14 days after denervation. There were no significant changes in TA MHC protein profile during one month of denervation. In both the soleus and TA, denervation significantly shifted the MHC mRNA profile as early as 4 days following denervation without any corresponding changes at the protein level. Significant mRNA changes without large changes in MHC protein composition continued throughout the denervation period suggesting that the muscle may be prevented from premature functional transitions by mechanisms such as decreased mRNA stability, translational block, or increased turnover of newly synthesized proteins.Keywords : myosin heavy chain ; denervation; ribonuclease-protection assay; adaptation.The importance of the nerve in the determination and maintenance of myosin heavy chain (MHC) isoforms has been studied using experimental models including cross-reinnervation, electrical stimulation, and denervation [1]. In contrast to cross-reinnervation or electrical stimulation, denervation provides a model in which the muscle is deprived of both electrical activity and trophic factors. The majority of denervation studies have been performed in newborn animals and suggest that continuous innervation is necessary for maturation of slow muscles but not an absolute requirement for maturation of fast muscles [2,3]. In contrast, D'Albis et al. [4] reported that denervation of the soleus and gastrocnemius in 8-day-old rabbits caused both muscles to mature to the slow-type phenotype. Those studies that have looked at adult mammals have studied the later stages of denervation (2 weeks to 5 months; [5Ϫ8]) and have provided con...

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Section: Discussionmentioning

confidence: 78%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Changes in myosin mRNA and protein expression in denervated rat soleus and tibialis anterior

Huey

Bodine

1998

European Journal of Biochemistry

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“…The specificity and characterization of these mAbs against MHC isoforms have been previously established. The mAbs NOQ7-5-4D is specific to type I MHC (Narusawa et al, 1987;Petrof et al, 1992;Rubinstein and Hoh, 2000), MY-32 to all fast-type MHCs (Havenith et al, 1990;Monemi et al, 2000), SC-71 to type IIa MHC (Schiaffino et al, 1989;Stal et al, 1994;Monemi et al, 2000), ALD-58 to MHC-ton (Shafiq et al, 1984;, BA-G5 to MHC-␣ (Michel et al, 1996), F1.652 to MHC-emb (Michel et al, 1996), and N2.261 to MHC-neo (Michel et al, 1996).…”

Section: Immunocytochemistrymentioning

confidence: 99%

“…The ␣-cardiac MHC isoform, which is normally expressed in the atrium of the heart, is known to be present in various amounts in some specialized skeletal muscles such as diaphragm (Hamalainen and Pette, 1997), extraocular muscles (Wieczorec et al, 1985;Pedrosa-Domellof et al, 1992;Rushbrook et al, 1994;Rubinstein and Hoh, 2000), and masseter (Bredman et al, 1991;PedrosaDomellof et al, 1992;Stal et al, 1994;Kwa et al, 1995;Korfage et al, 2000) and in the muscle spindles (Michel et al, 1996).…”

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Adult human mylohyoid muscle fibers express slow‐tonic, α‐cardiac, and developmental myosin heavy‐chain isoforms

Wang

et al. 2004

Anat. Rec.

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Some adult cranial muscles have been reported to contain unusual myosin heavy-chain (MHC) isoforms (i.e., slow-tonic, ␣-cardiac, embryonic, and neonatal), which exhibit distinct contractile properties. In this study, adult human mylohyoid (MH) muscles obtained from autopsies were investigated to detect the unusual MHC isoforms. For comparison, the biceps brachii and masseter muscles of the same subjects were also examined. Serial cross-sections from the muscles studied were incubated with a panel of isoform-specific anti-MHC monoclonal antibodies that distinguish major and unusual MHC isoforms. On average, the slow type I and fast type II MHC-containing fibers in the MH muscle accounted for 54% and 46% of the fibers, respectively. In contrast to limb and trunk muscles, the adult human MH muscle was characterized by a large proportion of hybrid fibers (85%) and a small percentage of pure fibers (15%; P Ͻ 0.01). Of the fast fiber types, the proportion of the type IIa MHC-containing fibers (92%) was much greater than that of the type IIx MHC-containing fibers (8%; P Ͻ 0.01). Our data demonstrated that the adult human MH fibers expressed the unusual MHC isoforms that were also identified in the masseter, but not in the biceps brachii. These isoforms were demonstrated by immunocytochemistry and confirmed by electrophoretic immunoblotting. Fiber-to-fiber comparisons showed that the unusual MHC isoforms were coexpressed with the major MHC isoforms (i.e., MHCI, IIa, and IIx), thus forming various major/unusual (or m/u) MHC hybrid fiber types. Interestingly, the unusual MHC isoforms were expressed in a fiber type-specific manner. The slow-tonic and ␣-cardiac MHC isoforms were coexpressed predominantly with slow type I MHC isoform, whereas the developmental MHC isoforms (i.e., embryonic and neonatal) coexisted primarily with fast type IIa MHC isoform. There were no MH fibers that expressed exclusively unusual MHC isoforms. Approximately 81% of the slow type I MHC-containing fibers expressed slow-tonic and ␣-cardiac MHC isoforms, whereas 80% of the fast type IIa MHC-containing fibers expressed neonatal MHC isoform. The m/u hybrid fibers (82% of the total fiber population) were found to constitute the predominant fiber types in the adult human MH muscle. At least seven m/u MHC hybrid fiber types were identified in the adult human MH muscle. The most common m/u hybrid fiber types were found to be the MHCI/slow-tonic/␣-cardiac and MHCIIa/neonatal, which accounted for 39% and 33% of the total fiber population, respectively. The multiplicity of MHC isoforms in the adult MH fibers is believed to be related to embryonic origin, innervation pattern, and unique functional requirements.

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Persistence of hybrid fibers in rat soleus after spinal cord transection

1999

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The effects of a chronic (up to 360 days) reduction in neuromuscular activity (defined as electrical activation and loading) on myosin heavy chain (MHC) isoform expression in the rat soleus muscle were studied. A complete mid-thoracic (T7-T8) spinal cord transection (ST) was used to induce a reduction in soleus muscle neuromuscular activity. Electrophoretic analyses revealed that MHC-I was progressively decreased after ST, accounting for approx. 90% of the total soleus MHC in controls and only approx. 12% 1 year after ST. The reductions in the proportion of MHC-I were countered by increases in MHC-IIa and MHC-IIx with the increase in MHC-IIx preceding the increase in MHC-IIa. Curiously, MHC-IIb was expressed only at very low levels. Thus, a complete transformation from predominantly MHC-I to MHC-IIb did not occur. Many fibers (up to approx. 80%) contained multiple MHCs (hybrid fibers) after ST. The proportion of hybrid fibers was maintained at a high level (approx. 50%) 1 year after ST. These data suggest that: 1) a prolonged reduction in neuromuscular activity was not sufficient to induce high level MHC-IIb expression by the soleus muscle; and 2) hybrid fibers were not simply transitional fibers. Thus, it appears that under appropriate conditions hybrid fibers may represent a ''stable'' fiber phenotype. Anat

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Regulation of myosin heavy chain expression in adult rat hindlimb muscles during short‐term paralysis: comparison of denervation and tetrodotoxin‐induced neural inactivation

Cited by 48 publications

References 43 publications

Changes in myosin mRNA and protein expression in denervated rat soleus and tibialis anterior

Changes in myosin mRNA and protein expression in denervated rat soleus and tibialis anterior

Adult human mylohyoid muscle fibers express slow‐tonic, α‐cardiac, and developmental myosin heavy‐chain isoforms

Persistence of hybrid fibers in rat soleus after spinal cord transection

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