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Measurement of Calcium Fluctuations Within the Sarcoplasmic Reticulum of Cultured Smooth Muscle Cells Using FRET-based Confocal Imaging
Published on: June 20, 2016
mRNA for cardiac calcium channel is expressed during development of skeletal muscle
1Department of Physiology, Colorado State University, Fort Collins 80523.
Abstract:
During the early development of skeletal muscle, cardiac isotypes of several contractile proteins are known to be transiently expressed. We report here that skeletal muscle developing in vivo, as well as primary cultures derived from skeletal muscle, express mRNA encoding the cardiac dihydropyridine-sensitive calcium channel. The mRNA is detectable at high concentration at the earliest stage tested in vivo and diminishes rapidly in concentration as myofibers mature. The concentration of the cardiac calcium channel mRNA also diminishes during the in vivo development of skeletal muscle in a genetically paralyzed mouse (mdg), indicating that muscle contractile activity is not necessary for the down-regulation. In contrast, mRNA for the skeletal muscle-specific calcium channel accumulates gradually in developing skeletal muscle. A similar temporal pattern of expression is also seen in primary cultures of skeletal myotubes. These results raise the question of whether the cardiac calcium channel may be functionally important during the early development of skeletal myofibers.
Insights
Skeletal muscle cells transiently express cardiac calcium channel mRNA during early development. This expression decreases with maturation, independent of muscle activity, suggesting a potential role in early muscle development.
Area of Science:
- Molecular Biology
- Developmental Biology
- Muscle Physiology
Background:
- Cardiac protein isotypes are transiently expressed during skeletal muscle development.
- Dihydropyridine-sensitive calcium channels play crucial roles in muscle function.
Purpose of the Study:
- To investigate the expression patterns of cardiac and skeletal calcium channel mRNA during skeletal muscle development.
- To determine if muscle contractile activity influences the down-regulation of cardiac calcium channel mRNA.
Main Methods:
- Analysis of mRNA expression in developing skeletal muscle in vivo.
- Study of primary skeletal muscle cell cultures.
- Comparison of expression in normal and genetically paralyzed mice (mdg).
Main Results:
- Skeletal muscle expresses cardiac calcium channel mRNA at high levels during early development, which rapidly declines with maturation.
- Cardiac calcium channel mRNA down-regulation occurs independently of muscle contractile activity.
- Skeletal muscle-specific calcium channel mRNA gradually accumulates during development.
Conclusions:
- The cardiac calcium channel is transiently expressed in developing skeletal muscle.
- Muscle activity is not required for the decrease in cardiac calcium channel mRNA levels.
- The functional significance of the cardiac calcium channel in early skeletal myogenesis warrants further investigation.
