Figure 2

Specific anti-sense morpholino knockdown of Homer1 expression causes a reversal in growth cone turning. (A) Control morphant and (B) Homer1 morphant growth cones labelled for Homer1b/c (red) and f-actin (green) after 6 hours in culture. (C) Homer1 knockdown in growth cones was quantified by determining pixel intensity corrected for growth cone area and normalised to control morphant growth cones (100%). Numbers indicate growth cones imaged over three separate dishes. (D) Western blot of B-35 neuroblastoma cell protein extracts loaded with control (C), and Homer1 (H) morpholinos. Partial knockdown was achieved at 12 hours and significant knockdown at 24 hours. (E) Average growth cone turning angles after 30 minutes in gradients of Netrin-1, brain derived neurotrophic factor (BDNF) or Sema-3a after a 4 to 6 hour treatment with control morpholino (open bars) or Homer1 morpholino (shaded bars). (F) Control or Homer1 morpholinos did not have any significant effect on overall axon extension rates (compare Figures 1B and 2E). Significant differences from control values are marked as: ***P < 0.0005; Mann-Whitney U-test. Error bars indicate standard error of the mean. Scale bar for (A, B) is 5 μm.