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Cytoplasmic intermediate filaments are stably associated with nuclear matrices and potentially modulate their
Genrich V Tolstonog1, Michael Sabasch, Peter Traub
1Max-Planck-Institut für Zellbiologie, Rosenhof, 68526 Ladenburg, Germany.
DNA and Cell Biology
|May 23, 2002
Summary
Cytoplasmic intermediate filaments (cIFs) tightly associate with the nucleus, suggesting a role in nuclear activities. These filaments are integral to the karyoskeleton, connecting with nuclear matrix components and genomic DNA.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Cytoplasmic intermediate filaments (cIFs) are known to associate with the nucleus.
- Previous studies suggest vimentin, a type of cIF, can crosslink with genomic DNA, including nuclear matrix attachment regions (MARs).
Purpose of the Study:
- To investigate the potential role of cIFs as complementary nuclear matrix elements.
- To determine the association of cIFs with the nuclear lamina and matrix.
Main Methods:
- Nuclei from cultured cells were subjected to Li-diiodosalicylate (LIS) extraction to prepare nuclear matrices.
- Analysis was performed using immunofluorescence microscopy and immunoblotting with antibodies against lamin B and cIF proteins.
- Double-immunogold electron microscopy was used to visualize the ultrastructural association.
Main Results:
- Vimentin IFs remained tenaciously attached to intact nuclei and broken nuclear remnants, often in alignment with the nuclear lamina (lamin B).
- LIS extraction did not reduce cIF content in nuclear matrices, indicating strong association.
- Electron microscopy revealed a close proximity (approx. 30 nm) between vimentin IFs and lamin B.
Conclusions:
- Cytoplasmic intermediate filaments (cIFs) are tightly interconnected with nuclear matrix structural elements.
- cIFs are likely complementary or integral constituents of the karyoskeleton.
- The association of cIFs with MARs and genomic DNA further supports their nuclear role.