Relationship between intermediate filaments and microfilaments in cultured fibroblasts: Evidence for common foci during cell spreading

Kathleen J. Green*, John C. Talian, Robert D. Goldman

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

45 Scopus citations


Spreading and fully spread chick embryo fibroblasts (CEF) were examined by double‐label fluorescence microscopy using the actin‐specific probe rhodamine‐phalloidin and an antibody directed against CEF intermediate filaments (IF). During midspreading, a striking relationship became discernible: statistical analysis showed that approximately half of the cell population exhibited one or more phase‐dense, phalloidin‐binding nodules that appeared to act as foci from which IF diverged. Coincidence between actin‐containing structures and IF was not limited to these centers; IF could also frequently be seen running in close parallel arrays with stress fibers. Ultrastructural analysis confirmed the presence of non‐membrane‐bound out‐pocketings along the length of stress fibers from which 10‐nm IF diverged. These structures varied in size and shape, and displayed a dense, fine fibrillar appearance. IF and microfilaments (MF) were distinguished by size and by decoration of MF with myosin subfragment‐1. Other IF‐MF interactions were seen in cells of all stages: IF were observed to loop through stress fibers, most frequently at the cell margins. In colchicine‐treated cells, IF became redistributed into cables that often ran parallel and appeared to merge with stress fibers. Cytochalasin D‐treated CEF exhibited loose aggregates of actin‐containing material that appeared to be associated with IF. These results suggest the possibility of an interaction between actin‐containing structures and IF, particularly during cell spreading in cultured fibroblasts.

Original languageEnglish (US)
Pages (from-to)406-418
Number of pages13
JournalCell Motility and the Cytoskeleton
Issue number4
StatePublished - 1986


  • Intermediate filaments
  • focal center
  • microfilaments fibroblast cell spreading

ASJC Scopus subject areas

  • Structural Biology
  • Cell Biology


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