Figure 10.
Quantitation of mitochondrial clustering after overexpression of tau, drug treatment, and inhibition of dynein. The distribution of mitochondria was quantified as described in Materials and Methods. A minimum of 30 cells were analyzed per experiment (n). In mock-transfected cells, mitochondria occupy up to 65% of the total cell area. The same is true in cells stably transfected with K23, a tau construct lacking the microtubule-binding repeats (CHO-K23). This value drops to ∼30% in tau40-stable cells (CHO-tau). Treatment of the stably transfected cells with either nocodazole or taxotere restores the wild-type distribution of mitochondria (CHO-tau nocodazole or CHO-tau taxotere, respectively). The same effect can be seen after transfection with dynamitin (CHO-tau transfection dynamitin), but not after transfection of EGFP as a control protein (CHO-tau transfection EGFP; P < 0.0001, two-tailed Student's t test). Removal of nocodazole again leads to clustering of mitochondria at the nucleus (CHO-tau noc. removal; 4 h).