The majority of calf muscle cell messenger RNAs contain poly(A)

Area of Science:

• Molecular Biology
• Cell Biology
• Biochemistry

Background:

• Previous research investigated messenger RNA (mRNA) metabolism in calf muscle cells using poly(A) content as a proxy.
• The role of polyadenylation in mRNA metabolism in these cells requires direct examination.

Purpose of the Study:

• To directly quantify the proportion of mRNA containing poly(A) in cultured calf muscle cells.
• To validate the use of poly(A) content as a measure of overall mRNA metabolism in these cells.
• To assess the translational efficiency of calf muscle mRNA in a heterologous cell-free system.

Main Methods:

• Separation of poly(A)-containing (poly(A)+) and poly(A)-lacking (poly(A)-) RNA using oligo(dT)-cellulose chromatography.
• In vitro translation of separated RNA fractions and total RNA in a reconstituted cell-free protein-synthesis system.
• Analysis of mRNA translation by measuring the formation of initiation complexes using radiolabeled poly(A)+ RNA in reticulocyte lysates.

Main Results:

• The majority of mRNA in both prefusion and postfusion cultured calf muscle cells contains poly(A).
• Quantitative analysis revealed that 70-90% of actin mRNA is poly(A)-containing.
• Experiments demonstrated that the bulk of calf muscle mRNA can be translated in a heterologous cell-free system.

Conclusions:

• Differential polyadenylation is not a significant factor in mRNA metabolism in cultured muscle cells.
• The direct measurement of poly(A) content is a valid method for assessing overall mRNA metabolism in these cells.
• Cell-free systems are suitable for studying mRNA polyadenylation in cultured muscle cells.