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Nuclear protein redistribution in heat-shocked cells
R L Warters1, G L Chu, R S Wong
1Department of Radiology, University of Utah Health Sciences Center, Salt Lake City 84132.
Journal of Cellular Physiology
|February 1, 1993
Summary
Heating Chinese hamster ovary cells increased nuclear protein mass. This was linked to greater binding of proteins to DNA and the nuclear matrix, affecting DNA repair enzymes.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Hyperthermia can induce cellular stress responses.
- Nuclear proteins play critical roles in DNA replication and repair.
Purpose of the Study:
- To investigate the effects of heat stress on nuclear protein mass and composition.
- To determine the association of these changes with DNA repair enzyme activity.
Main Methods:
- Isolation of nuclei from Chinese hamster ovary cells subjected to heat stress (45°C and 45.5°C).
- Quantification of total nuclear protein mass.
- Fractional recovery analysis of DNA polymerase alpha and beta, and DNA topoisomerase activity.
- Differential extraction of nuclear proteins using 2.0 M NaCl to assess solubility, DNA-association, and nuclear matrix-association.
Main Results:
- Total nuclear protein mass increased in heated cells.
- Fractional recovery of DNA polymerase alpha and beta, and DNA topoisomerase activity increased.
- Soluble nuclear proteins (2.0 M NaCl soluble) decreased by 0.5 fold.
- DNA-associated and nuclear matrix-associated protein mass significantly increased (2.2 and 3.4 fold, respectively).
Conclusions:
- Heat stress leads to an increase in nuclear protein mass in Chinese hamster ovary cells.
- This increase is attributed to enhanced binding or precipitation of nuclear proteins onto DNA and the nuclear matrix.
- The observed changes may contribute to altered DNA replication and repair activities under thermal stress.