FIGURE 10.

Egr-1 overexpression causes microtubule instability in rat primary hippocampal neurons in culture. Rat primary hippocampal neurons infected with the indicated virus were analyzed by either Western blot analysis or immunocytochemistry. A, representative Western blot of extracts of neurons infected with Ln-Egr-1 or Ln-vector using antibodies against unstable microtubules (Tyr-tubulin), stable microtubules (Ac-tubulin), and total tubulin (β-tubulin). B, the relative amounts determined from Western blots representing A as in Fig. 8. Values are the mean ± S.E. from three different cultures. *, p < 0.03; **, p < 0.005 (t test). C and D, immunocytochemistry. Shown are Ln-vector- or Ln-Egr-1-infected neurons stained for Tyr-tubulin, Myc (Myc-Egr-1), β-tubulin, and merge (co-localization). Scale bar, 15 μm. E and F, the indicated virus-infected neurons were treated with the Cdk5 inhibitor roscovitine (rosco) or vehicle and then analyzed by Western blot analysis. E, Western blot. F, relative amount. The relative amounts of phosphorylated tau and Tyr-tubulin were determined as in B. *, p < 0.005 (t test).