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Direct visualization of a protein nuclear architecture
M J Hendzel1, F Boisvert, D P Bazett-Jones
1Department of Cell Biology and Anatomy, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada T2N 4N1.
Molecular Biology of the Cell
|June 8, 1999
Summary
A protein network, or karyoskeleton, exists within the cell nucleus, challenging previous models. This nuclear architecture is distinct from nucleoproteins and interacts with chromatin.
Area of Science:
- Cell Biology
- Molecular Biology
- Biophysics
Background:
- The existence and nature of a nuclear architecture analogous to the cytoskeleton (karyoskeleton) have been debated.
- Previous visualization methods required chromatin elution, limiting acceptance of a stable nuclear structure.
- The composition of nuclear fine structures has remained unclear.
Purpose of the Study:
- To investigate the composition of the nuclear fine structure in unfractionated cells.
- To determine if a protein-based nuclear architecture exists independently of chromatin.
- To establish a method for ultrastructural characterization of the nuclear protein network.
Main Methods:
- Utilized analytical electron microscopy with electron spectroscopic imaging for quantitative elemental analysis.
- Examined fixed whole cells, avoiding fractionation or chromatin elution.
- Analyzed the composition of fine structures within interchromatin regions of the cell nucleus.
Main Results:
- The majority of fine structures in interchromatin regions are not nucleoprotein.
- These structures are compositionally similar to cytoplasmic protein networks.
- This study provides the first demonstration of a protein network in unfractionated cells.
Conclusions:
- A distinct protein-based nuclear architecture (karyoskeleton) exists within the cell nucleus.
- This architecture is not solely composed of nucleoproteins and is present in intact cells.
- The developed method allows ultrastructural analysis of the karyoskeleton's interaction with nuclear components.