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Persistence of messenger RNA through mitosis in HeLa cells
Abstract:
The decrease in protein synthesis which occurs in mammalian cells during cell division is associated with significant disaggregation of polyribosomes. For determining whether messenger RNA survives this disaggregation, the reformation of polyribosomes was investigated in synchronized HeLa cells as they progressed from metaphase into interphase in the presence of 2 microg/ml Actinomycin D. The persistence of messenger during cell division was evidenced by: (1) a progressive increase in the rate of protein synthesis in both treated and untreated cells for 45 min after metaphase; (2) reformation of polyribosomes, as determined by both sucrose gradients and electron microscopy, within 30 min after the addition of Actinomycin D to metaphase cells; (3) the persistence of approximately 50% of the rapidly labeled nonribosomal RNA which had associated with polyribosomes just before metaphase; (4) the resumption of synthesis, following cell division, of 6 selected peptides in Actinomycin-treated cells.
Insights
Messenger RNA persists through cell division, evidenced by polyribosome reformation and continued protein synthesis even with Actinomycin D treatment. This indicates mRNA
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Protein synthesis decreases during mammalian cell division, linked to polyribosome disaggregation.
- The fate of messenger RNA (mRNA) during this process is not fully understood.
Purpose of the Study:
- To determine if messenger RNA survives polyribosome disaggregation during cell division.
- To investigate mRNA persistence in synchronized HeLa cells transitioning from metaphase to interphase.
Main Methods:
- Utilized Actinomycin D (2 microg/ml) to inhibit new RNA synthesis.
- Analyzed polyribosome reformation using sucrose gradients and electron microscopy.
- Tracked the persistence of rapidly labeled nonribosomal RNA associated with polyribosomes.
- Monitored protein synthesis rates and the resumption of specific peptide synthesis.
Main Results:
- Protein synthesis rates progressively increased post-metaphase in both treated and untreated cells.
- Polyribosomes reformed within 30 minutes of Actinomycin D addition to metaphase cells.
- Approximately 50% of pre-metaphase polyribosome-associated rapidly labeled nonribosomal RNA persisted.
- Actinomycin D-treated cells resumed synthesis of 6 selected peptides after cell division.
Conclusions:
- Messenger RNA persists through mammalian cell division.
- The disaggregation of polyribosomes during cell division does not lead to irreversible mRNA loss.
- Reformed polyribosomes utilize pre-existing mRNA for protein synthesis post-division.