Developmental shift of myosin heavy chain mRNA expression due to neural factor(s) and muscle activity

The adult ventricular isoform of chicken myosin heavy chain (MHC-V) is transiently expressed in all skeletal muscle primordia analyzed and is completely repressed around embryonic days 10-12, when functional innervation is established. By ribonuclease protection assay, we demonstrated that denervation of the adult anterior latissimus dorsi muscle resulted in reexpression of MHC-V mRNA. In contrast, treatment of primary cultures of fetal breast or leg muscles with embryonic brain extract or conditioned media from glial or neuroblastoma cell lines, but not from a myogenic cell line or primary muscle cell cultures, led to inhibition of MHC-V expression. This inhibitory activity was abolished by heating and increased with protein concentration. The acquisition of both brain inhibitory activity and the competence of myogenic cells to downregulate MHC-V mRNA expression were age dependent. Furthermore, either paralysis of muscle in ovo by curare or contraction arrest of cultured myotubes resulted in persistent expression of MHC-V mRNA. Thus a putative soluble factor(s) of nerve origin as well as muscle activity are involved in the developmental downregulation of MHC-V expression in muscle primordia.

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Effects of triiodo-thyronine on angiotensin-induced cardiomyocyte hypertrophy: reversal of increased β-myosin heavy chain gene expression

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y06-043 ◽

2006 ◽

Vol 84 (8-9) ◽

pp. 935-941 ◽

Cited By ~ 21

Author(s):

Baohua Wang ◽

Jingping Ouyang ◽

Zhengyuan Xia

Keyword(s):

Gene Expression ◽

Angiotensin Ii ◽

Thyroid Hormone ◽

Cardiac Hypertrophy ◽

Atpase Activity ◽

Mrna Expression ◽

Myosin Heavy Chain ◽

Heavy Chain ◽

Ang Ii ◽

Hypertrophic Growth

Thyroid hormone-induced cardiac hypertrophy is similar to that observed in physiological hypertrophy, which is associated with high cardiac contractility and increased α-myosin heavy chain (α-MHC, the high ATPase activity isoform) expression. In contrast, angiotensin II (Ang II) induces an increase in myocardial mass with a compromised contractility accompanied by a shift from α-MHC to the fetal isoform β-MHC (the low ATPase activity isoform), which is considered as a pathological hypertrophy and inevitably leads to the development of heart failure. The present study is designed to assess the effect of thyroid hormone on angiotensin II-induced hypertrophic growth of cardiomyocytes in vitro. Cardiomyocytes were prepared from hearts of neonatal Wistar rats. The effects of Ang II and 3,3′,5-triiodo-thyronine (T3) on incorporations of [3H]-thymine and [3H]-leucine, MHC isoform mRNA expression, PKC activity, and PKC isoform protein expression were studied. Ang II enhanced [3H]-leucine incorporation, β-MHC mRNA expression, PKC activity, and PKCε expression and inhibited α-MHC mRNA expression in cardiomyocytes. T3 treatment prevented Ang II-induced increases in PKC activity, PKCε, and β-MHC mRNA overexpression and favored α-MHC mRNA expression. Thyroid hormone appears to be able to reprogram gene expression in Ang II-induced cardiac hypertrophy, and a PKC signal pathway may be involved in such remodeling process.

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Detection of a ventricular-specific myosin heavy chain in adult and developing chicken heart.

The Journal of Cell Biology ◽

10.1083/jcb.102.4.1480 ◽

1986 ◽

Vol 102 (4) ◽

pp. 1480-1484 ◽

Cited By ~ 25

Author(s):

Y Zhang ◽

S A Shafiq ◽

D Bader

Keyword(s):

Myosin Heavy Chain ◽

Heavy Chain ◽

Heart Development ◽

In Ovo ◽

Specific Expression ◽

Adult Chicken ◽

Chicken Heart ◽

Developing Heart ◽

Caudal Portion ◽

Atrial Myosin

In the present study, a monoclonal antibody (McAb), ALD19, generated against myosin of slow tonic muscle, was shown to react with the heavy chain of ventricular myosin in the adult chicken heart. With this antibody, it was possible to detect a ventricular-specific myosin during myocardial differentiation and to show that the epitope recognized by ALD19 was present from the earliest stages of ventricular differentiation and maintained throughout development only in the ventricle. A second McAb, specific for atrial myosin heavy chain (MHC) (Gonzalez-Sanchez, A., and D. Bader, 1984, Dev. Biol., 103:151-158), was used as a control to detect an atrial-specific myosin in the caudal portion of the developing heart at Hamburger-Hamilton stage 15. It was found that the appearance of ventricular MHC predated the expression of atrial MHC by approximately 1 d in ovo and that specific MHCs were always differentially distributed. While a common primordial MHC may be present in the early heart, this study showed the tissue-specific expression of a ventricular MHC during the initial stages of heart development and its differential accumulation throughout development.

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Denervation-induced changes in myosin heavy chain expression in the rat diaphragm muscle

Journal of Applied Physiology ◽

10.1152/japplphysiol.00862.2002 ◽

2003 ◽

Vol 95 (2) ◽

pp. 611-619 ◽

Cited By ~ 38

Author(s):

Paige C. Geiger ◽

Jeffrey P. Bailey ◽

Wen-Zhi Zhan ◽

Carlos B. Mantilla ◽

Gary C. Sieck

Keyword(s):

Protein Expression ◽

Mrna Expression ◽

Myosin Heavy Chain ◽

Heavy Chain ◽

Protein Isoforms ◽

Diaphragm Muscle ◽

Northern Analysis ◽

Mrna Levels ◽

Rat Diaphragm ◽

Mrna Isoforms

Unilateral denervation (Dnv) of the rat diaphragm muscle (Diam) markedly alters expression of myosin heavy chain (MHC) isoforms. After 2 wk of Diam Dnv, MHC content per half-sarcomere decreases in fibers expressing MHC2X and MHC2B. We hypothesized that changes in MHC protein expression parallel changes in MHC mRNA expression. Relative MHC isoform mRNA levels were determined by Northern analysis after 1, 3, 7, and 14 days of Dnv of the rat Diam. MHC protein expression was determined by SDS-PAGE. Changes in MHC isoform protein and mRNA expression were not concurrent. Expression of MHCSlow and MHC2X mRNA isoforms decreased dramatically by 3 days of Dnv, whereas that of MHC2A and MHC2B did not change. Expression of all MHC protein isoforms decreased by 3 days of Dnv. We observed a differential effect of rat Diam Dnv on MHC isoform protein and mRNA expression. The time course of the changes in MHC isoform mRNA and protein expression suggests a predominant effect of altered protein turnover rates on MHC protein expression instead of altered transcription after Dnv.

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