Promotion of Microtubule Acetylation Inhibits Growth Cone Advance in Regenerating Axons

To examine the role of post-translational modifications of microtubules on axon growth, we manipulated the levels of microtubule acetylation by inhibiting the enzyme sirtuin-2, an NAD-dependent deacetylase, with AGK2.  Using time-lapse microscopy, we compared axon growth of regenerating axons from Helisoma trivolis  ganglia cultures during 20 minutes prior to drug treatment and 40 minutes after AGK2 treatment.  Inhibition of sirtuin-2 with AGK2 resulted in a 56% decrease in rate of advance of the leading edge of growth cones and an  87% decrease in rate of central domain advance compared to control periods. Treatment with SIRT2 inhibitor also significantly decreased growth cone and lamellipodial area in H. trivolvis axons in the same time frame due to a decrease in the area of the peripheral domain. In perfusion controls, the rate of growth cone advance and the growth cone area did not significantly change  40 minutes after perfusion with normal medium. These results suggest that increasing the  proportion of acetylated microtubules in regenerating axons reduces growth cone advance.