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Steady state dynamics of intermediate filament networks
K L Vikstrom1, S S Lim, R D Goldman
1Department of Cell, Molecular, and Structural Biology, Northwestern University Medical School, Chicago, Illinois 60611.
The Journal of Cell Biology
|July 1, 1992
Summary
Vimentin intermediate filaments (IF) undergo dynamic subunit exchange, as shown by fluorescence recovery after photobleaching (FRAP). This dynamic exchange occurs in living cells and is independent of filament movement.
Area of Science:
- Cell Biology
- Biochemistry
- Biophysics
Background:
- Vimentin intermediate filaments (IF) are crucial cytoskeletal components involved in cellular mechanical stability and organization.
- Understanding the dynamic nature of vimentin IF assembly and disassembly is key to comprehending cellular processes.
Purpose of the Study:
- To investigate the dynamic exchange of subunits within vimentin intermediate filaments (IF) at steady state.
- To determine if vimentin subunit dynamics are influenced by filament movement within living cells.
Main Methods:
- Utilized fluorescence recovery after photobleaching (FRAP) analysis with xrhodamine-labeled vimentin.
- Microinjected labeled vimentin into fibroblasts, allowing incorporation into the endogenous IF network.
- Visualized and analyzed fluorescence recovery in bleached regions using digital imaging fluorescence microscopy and a CCD camera.
Main Results:
- Bleached vimentin fibers demonstrated significant fluorescence recovery over short time periods, indicating dynamic exchange.
- Vimentin fibers exhibited movement in living cells, but fluorescence recovery was not dependent on this movement.
- Fluorescence recovery showed no marked polarity, suggesting a steady-state exchange of subunits along the filament length.
Conclusions:
- Vimentin intermediate filaments (IF) exhibit dynamic subunit exchange at steady state.
- This dynamic exchange is an intrinsic property of vimentin filaments and is not driven by filament movement.