Background: 

We have shown before that Cx43 enhances the migration of HeLa cells and of endothelial precursor cells in a channel-independent manner. The enhanced cell migration is associated with an increased activation of p38 MAPK. Since cell migration is characterized by dynamic changes of the actin cytoskeleton we analysed the influence of Cx43 on actin cytoskeletal modifications.

Methodology: 

HeLa cells were stably transfected with Cx43, or Cx43 mutants either encoding the N-terminal (Cx43NT; AA 1-257) or the C-terminal part (Cx43CT; AA 257–382) tagged with GFP. Empty-vector transfected cells (CTL) were used as a control. Cell migration was studied using a standard wound assay (Ibidi).

Results: 

Migration of HeLa cells expressing Cx43 or Cx43CT (without channel-forming capacity) was significantly enhanced compared to Cx43NT or CTL. Staining of the actin cytoskeleton with phalloidin revealed that migrating HeLa cells expressing Cx43 or Cx43CT exhibited significant more filopodia per single cell (mean ± SEM: Cx43: 30±7; Cx43CT: 21±4) as compared to HeLa cells expressing Cx43NT or CTL cells (Cx43NT: 13±4; CTL: 12±3; n=4). Inhibition of p38 activation by SB203580 significantly decreased the amount of filopodia in Cx43 cells but not in CTL cells, analysed on cover slips (Cx43: 61±6; Cx43+SB: 42±5; CTL: 41±4; CTL+SB: 33±4; n=7).

Conclusion: 

Our findings suggest that the enhancing effect of Cx43 on cell migration is associated with a p38-dependent increase in the number of filopodia. Further analyses are necessary to clarify how Cx43 contributes to the activation of p38 e.g. by stabilization of key proteins involved in regulation of cell migration.