Figure 8

Drebrin localization in growing and differentiating C2C12 cells. (A) C2C12 cells in growth medium (GM) or differentiation medium (DM) for 1 day (D1) were fixed and immunostained for endogenous drebrin (Dbn1; green) and F-actin (red). Arrows indicate areas of overlapping enrichment for drebrin and F-actin in cell processes (GM) and at sites of cell-cell contact (D1). (B) C2C12 cells in DM for 3 days (D3) were fixed and immunostained as in part (A). Arrows show areas of overlapping enrichment for drebrin and F-actin at the tips of myotubes (left panels) and at sites of cell-cell contact between myotubes (right panels). (C) C2C12 cells were transfected with vectors encoding GFP or drebrin E-GFP. Cells were fixed, and actin was visualized by staining with phalloidin (red). GFP and exogenous drebrin expression were visualized by direct fluorescence (green). Nuclei were counterstained with 4',6-diamidino-2-phenylindole (blue). Arrows show enrichment for drebrin-GFP and F-actin. The exposure time for cultures in GM was three times as long as it was for cultures in DM (1.14 seconds vs 300 to 400 milliseconds, respectively) to visualize the lower levels of drebrin protein in cells in GM.