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Conformational changes in rat liver chromatin after liver regeneration
The Biochemical Journal
|March 1, 1981
Summary
Histone H3 accessibility in rat liver chromatin increases during DNA synthesis after hepatectomy. This change is reversible with salt or detergent, indicating dynamic chromatin structure.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- Chromatin structure plays a crucial role in regulating DNA accessibility and gene expression.
- Histone H3 is a core component of chromatin, and its accessibility can change during cellular processes.
- Liver regeneration involves significant changes in DNA synthesis and chromatin organization.
Purpose of the Study:
- To investigate the accessibility of histone H3 in rat liver chromatin during degeneration and regeneration.
- To correlate changes in histone H3 accessibility with DNA synthesis rates.
- To explore the molecular basis of altered histone H3 accessibility.
Main Methods:
- Utilized N-Pyrenemaleimide, a fluorescent probe, to label histone H3 in rat liver chromatin.
- Isolated chromatin from rat liver at various time points post-hepatectomy.
- Assessed histone H3 accessibility using fluorescence measurements and probe binding assays.
- Analyzed chromatin structure using high salt and detergent treatments.
- Measured tryptophan fluorescence and histone H3 polarization.
- Performed electrophoresis to analyze histone H3 subclasses.
Main Results:
- Histone H3 accessibility increased by 40-50% during peak DNA synthesis (18-24 h post-hepatectomy).
- This increased accessibility was reversed by high salt (2 M-NaCl) or detergent treatment.
- Enhanced tryptophan fluorescence suggested synthesis of non-histone proteins.
- Histone H3 polarization remained unchanged, indicating no significant chromatin aggregation or dissociation.
- No differences in probe binding to mononucleosomes or histone H3 subclasses were observed.
Conclusions:
- Histone H3 accessibility in rat liver chromatin is dynamically regulated during liver regeneration.
- Increased DNA synthesis correlates with enhanced histone H3 accessibility, likely due to structural changes rather than altered histone composition.
- The findings suggest a mechanism for modulating DNA accessibility during active cell proliferation.