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c-myc mRNA in cytoskeletal-bound polysomes in fibroblasts
J E Hesketh1, G P Campbell, P F Whitelaw
1Rowett Research Institute, Bucksburn, Aberdeen, Scotland, U.K.
Abstract:
3T3 fibroblasts were treated sequentially with 25 mM-KCl/0.05% Nonidet P40, 130 mM-KCl/0.05% Nonidet P40 and finally with 1% Nonidet P40/1% deoxycholate in order to release free, cytoskeletal-bound and membrane-bound polysomes respectively. The membrane-bound fraction was enriched in the mRNA for the membrane protein beta 2-microglobulin, whereas the cytoskeletal-bound polysomes were enriched in c-myc mRNA. Actin mRNA was present in both free and cytoskeletal-bound polysomes. The results suggest that cytoskeletal-bound polysomes are involved in the translation of specific mRNA species.
Insights
Cytoskeletal-bound polysomes translate specific messenger RNAs (mRNAs), including c-myc mRNA. This study fractionated polysomes to reveal distinct mRNA populations associated with different cellular compartments.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Polysomes, the complexes of ribosomes and mRNA, are sites of protein synthesis.
- Understanding polysome localization provides insights into the regulation of gene expression.
Purpose of the Study:
- To investigate the specific mRNA species associated with free, cytoskeletal-bound, and membrane-bound polysomes.
- To determine the role of cytoskeletal-bound polysomes in translating specific mRNAs.
Main Methods:
- Sequential extraction of polysomes from 3T3 fibroblasts using varying concentrations of KCl and detergents (Nonidet P40, deoxycholate).
- Fractionation into free, cytoskeletal-bound, and membrane-bound polysomes.
- Analysis of mRNA content within each polysome fraction.
Main Results:
- Membrane-bound polysomes were enriched in beta 2-microglobulin mRNA.
- Cytoskeletal-bound polysomes showed enrichment of c-myc mRNA.
- Actin mRNA was found in both free and cytoskeletal-bound polysomes.
Conclusions:
- Cytoskeletal-bound polysomes are specifically involved in the translation of certain mRNA types, such as c-myc mRNA.
- Differential localization of polysomes suggests compartmentalized control of protein synthesis.