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pp60v-src association with the cytoskeleton induces actin reorganization without affecting polymerization status
G R Felice1, P Eason, M V Nermut
1Department of Biochemistry and Cell Biology, Hunterian Institute, Royal College of Surgeons of England, London, United Kingdom.
European Journal of Cell Biology
|June 1, 1990
Summary
Rous sarcoma virus (RSV) transformation reorganizes cellular actin without depolymerization. Actin shifts from bundles to other polymeric forms, impacting cell structure and function.
Area of Science:
- Cell Biology
- Virology
- Biochemistry
Background:
- The mechanism of Rous sarcoma virus (RSV)-induced actin reorganization is poorly understood.
- Microfilament bundles are reduced after viral transformation, but the underlying actin polymerization state changes are unclear.
Purpose of the Study:
- To investigate the relationship between microfilament organization and actin polymerization state post-RSV transformation.
- To determine if actin depolymerizes or reorganizes following transformation.
Main Methods:
- Utilized a temperature-sensitive (ts) RSV mutant (LA29) in Rat-1 cells.
- Performed parallel immunofluorescence and biochemical analyses of actin, alpha-actinin, and vinculin.
- Quantified actin polymerization states in detergent-soluble and insoluble fractions.
- Confirmed actin polymeric nature using electron microscopy.
Main Results:
- RSV pp60v-src tyrosine kinase activity and cytoskeletal association were temperature-sensitive.
- Actin, alpha-actinin, and vinculin reorganization depended on kinase-active pp60v-src association with the cytoskeleton.
- Transformation led to microfilament bundle loss, but total filamentous actin quantity remained unchanged.
- Actin polymerization state was quantitatively similar at permissive and restrictive temperatures.
Conclusions:
- RSV-induced loss of microfilament bundles is due to actin reorganization, not net depolymerization.
- Polymeric actin shifts from bundles and stress fibers to other forms within the cell after transformation.
- Cellular actin organization is dynamically regulated by viral transformation.