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Isolation of Translating Ribosomes Containing Peptidyl-tRNAs for Functional and Structural Analyses
Published on: February 25, 2011
Ribosomal slowdown mediates translational arrest during cellular division.
Gilad Sivan1, Nancy Kedersha, Orna Elroy-Stein
1Department of Cell Research and Immunology, George S Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel.
Molecular and Cellular Biology
|August 1, 2007
Summary
Cellular division transiently inhibits global mRNA translation. Mitotic cells show reduced translational activity, with elongation slowdown protecting mRNAs for rapid G1 phase resumption.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Global messenger RNA (mRNA) translation is known to be transiently inhibited during cellular division.
- Understanding the precise mechanisms and implications of this translational regulation is crucial for comprehending cell cycle progression.
Purpose of the Study:
- To investigate the stage of mRNA translation affected during mitosis.
- To elucidate the functional consequences of altered translation during cell division.
Main Methods:
- Analysis of polysome heavy fractions in mitotic versus cycling cells.
- Assessment of stress granule formation upon translational initiation inhibition.
- Evaluation of 80S ribosomal complex stability and polysome disassembly resistance.
- Measurement of ribosome transit time during mitosis.
Main Results:
- Mitotic cells possess heavy polysomes but exhibit significantly lower translational activity compared to cycling cells.
- Mitotic cells do not form stress granules when translational initiation is inhibited, indicating translation is not arrested at initiation.
- Mitotic polysomes are more resistant to disassembly, and ribosome transit time increases, suggesting elongation slowdown.
- Elongation slowdown during mitosis ensures polysome retention and mRNA protection.
Conclusions:
- Translational attenuation during mitosis primarily occurs during the elongation stage, not initiation.
- Slowing ribosome elongation protects mRNAs and facilitates rapid translation resumption upon entering the G(1) phase.
- This mechanism ensures efficient protein synthesis immediately after cell division.
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