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Most myosin heavy chain mRNA in L6E9 rat myotubes has a short poly(A) tail
Abstract:
The mRNA for rat muscle myosin heavy chain (MHC) was isolated from L6E9 myotubes by two rounds of sucrose density gradient centrifugation followed by fractionation on an agarose/polyacrylamide gel. The purity of the mRNA isolated was determined by translation in vitro, peptide analysis of the in vitro product and comparison with authentic MHC, analysis of the kinetics of hybridization with cDNA prepared with this RNA, and titration analysis of total cytoplasmic RNA from muscle and nonmuscle sources. By using the MHC cDNA as probe of myogenic differentiation, it was observed that the level of cytoplasmic MHC mRNA increased approximately 200-fold as the dividing myoblast differentiated into the fused myotube. Titration analysis of RNAs fractionated by oligo(dT)-cellulose chromatography indicated that the majority of the increase occurred in that RNA population that failed to bind to an oligo(dT)-cellulose column.
Insights
Researchers isolated messenger RNA (mRNA) for rat muscle myosin heavy chain (MHC) during cell differentiation. They found a significant 200-fold increase in MHC mRNA levels as myoblasts transformed into myotubes.
Area of Science:
- Molecular Biology
- Cellular Biology
- Biochemistry
Background:
- Muscle myosin heavy chain (MHC) is crucial for muscle contraction.
- Understanding the regulation of MHC gene expression during myogenesis is essential for comprehending muscle development and function.
Purpose of the Study:
- To isolate and characterize the messenger RNA (mRNA) for rat muscle myosin heavy chain (MHC).
- To investigate the changes in MHC mRNA levels during the differentiation of myoblasts into myotubes.
Main Methods:
- Isolation of rat muscle MHC mRNA from L6E9 myotubes using sucrose density gradient centrifugation and gel electrophoresis.
- Purity assessment via in vitro translation, peptide analysis, and cDNA hybridization kinetics.
- Quantification of MHC mRNA levels during myogenic differentiation using cDNA as a probe.
- Analysis of RNA populations using oligo(dT)-cellulose chromatography.
Main Results:
- Isolated and purified rat muscle MHC mRNA.
- Demonstrated a 200-fold increase in cytoplasmic MHC mRNA levels during the differentiation of myoblasts into fused myotubes.
- Identified that the majority of this increase in MHC mRNA occurred in RNA fractions that did not bind to oligo(dT)-cellulose.
Conclusions:
- Myogenic differentiation is accompanied by a substantial, specific increase in muscle MHC mRNA.
- The observed increase in MHC mRNA during differentiation suggests complex post-transcriptional regulatory mechanisms, potentially involving polyadenylation status.