Figure 13.

Transport of mitochondria into neurites of differentiated neuroblastoma cells is impaired by overexpression of tau. Tau40-stable (a–c) and mock-transfected N2a cells (d–f) were differentiated for 2 d by addition of 1 μM retinoic acid into medium containing 0.1% fetal calf serum and fixed in methanol. Mitochondria were visualized with MitoTracker™ Green (a and d), immunostaining was done with antibodies against tubulin (b and e) and tau (c and f). It can be clearly seen that significantly fewer mitochondria are present in the neurites of tau-stable cells in contrast to control cells (compare a and d, and Table I). In addition, mitochondria in tau-stable cells appear to be more clustered in the vicinity of the MTOC (a), similar to tau-stable CHO cells. The comparable staining intensity of the cell bodies indicates that the clustering effect is not due to a lower number of mitochondria in the tau-transfected cell. Bar, 10 μm.