Related Experiment Videos
Protein and RNA synthesis in the skeletal muscle of hereditary dystrophic mouse
Abstract:
Protein and RNA contents in muscle of normal and hereditary dystrophic mice C57BL/6J-dy/dy were reexamined on the basis of DNA. It was observed that protein and RNA contents in dystrophic muscle decreased at the early stage of the disease, in disagreement with the reported results on a wet weight basis, in which RNA content in dystrophic muscle had been found to increase. Rates of protein and RNA systhesis in the early stage of the disease were also determined with a concomitant check of the specific activities of free amino acids and free nucleotides. The rates of both protein and RNA synthesis (i.e., specific activities of protein and RNA) were higher in the dystrophic muscle, but when they were expressed on a DNA basis, the total protein synthesis per cell was the same as that of normal muscle and the total RNA synthesis per cell showed a smaller increase in dystrophic muscle. These apparent increases of protein and RNA synthesis were discussed in connection with the decreased protein and RNA contents in the cells of dystrophic muscle. The synthesized RNAs seemed to contain mRNA on the basis of sedimentation character and Millipore filter binding ability. However, no particular RNA was mainly synthesized in dystrophic muscle.
Insights
In hereditary muscular dystrophy mice, muscle protein and RNA content decreases early, contrary to previous findings. Protein and RNA synthesis rates per cell are similar or slightly increased, despite lower overall cellular content.
Area of Science:
- Biochemistry
- Molecular Biology
- Genetics
Background:
- Hereditary muscular dystrophy in C57BL/6J-dy/dy mice affects muscle composition.
- Previous studies reported increased RNA content in dystrophic muscle on a wet weight basis.
Purpose of the Study:
- To reexamine protein and RNA content and synthesis rates in dystrophic mouse muscle.
- To clarify discrepancies in reported RNA content changes.
- To investigate the relationship between synthesis rates and cellular content.
Main Methods:
- Quantification of protein and RNA content normalized to DNA.
- Measurement of protein and RNA synthesis rates.
- Analysis of specific activities of free amino acids and nucleotides.
- Characterization of synthesized RNA using sedimentation and filter binding assays.
Main Results:
- Dystrophic muscle showed decreased protein and RNA content per DNA basis.
- Protein and RNA synthesis rates per cell were comparable or slightly elevated in dystrophic muscle.
- Synthesized RNAs exhibited characteristics of messenger RNA (mRNA).
- No specific RNA species was predominantly synthesized in dystrophic muscle.
Conclusions:
- The observed decrease in muscle protein and RNA content in early-stage dystrophy is significant.
- Apparent increases in synthesis rates per cell do not compensate for the reduced cellular content.
- The study provides a revised understanding of molecular changes in hereditary muscular dystrophy.