Abstract
Focal adhesions (FAs) play important roles in keeping cell morphology. However, how FAs change during cell adhesion is not clear yet. In this study, we observed change in FA morphology during adhesion process of MC3T3-E1 cells to substrate. We plated the cells whose cycle had been synchronized by serum starvation on glass bottom dishes and cultured for 10 min to 24 h, and stained F-actin, vinculin and nucleus. We measured cell area, aCell, mean area of each FA, aFA, number of FAs per cell, nFA. aCell, aFA, and nFA increased monotonously until 1 h. While aCell continued to increase, aFA and nFA had complex time course that had a downtrend with ups and downs until 12 h and had a simple uptrend afterwards. These might indicate that aFA, and nFA increased in order to strengthen the adhesion of cell to substrate in the early stage of adhesion. We also found that aFA, and nFA of FAs outside the nucleus had a positive correlation to the cell area outside the nucleus until 50 min while nFA of FAs beneath the nucleus had a positive correlation to the area of nucleus after 1 h. This may indicate that the FAs in the two areas have different roles in cell adhesion.
