068 Depletion of the Microtubule Severing Enzyme Fidgetin-like 2 Promotes Nerve Regeneration and Improves Erectile Function in a Rodent Model of Radical Prostatectomy

Damage to the cavernous nerves (CN) during radical prostatectomy (RP) often causes erectile dysfunction (ED). We recently identified the microtubule (MT) regulatory protein fidgetin-like 2 (FL2) to be a promising therapeutic target for promoting cutaneous wound healing. We subsequently discovered that FL2 is also expressed in neurons, where it localizes to growth cones. Knockdown of FL2 in cultured neurons significantly enhanced the rate of axon growth, which led us to hypothesize that FL2 might be an effective target for enhancing nerve regeneration after injury. Here, using a rodent model of RP, we tested the hypothesis that local depletion of FL2 after cavernous nerve injury will promote nerve regeneration and improve erectile function. Three rat models of CN injury were used: mild (a smooth clamp applied for 2 minutes to the CN), moderate (a serrated clamp applied for 4 minutes to the CN) and severe (CN transection). After injury, a heparin sulfate microgel containing control- or FL2-siRNA was applied directly to the wound. Erectile function was assessed at several time points after injury by measuring the intracorporal pressure/blood pressure (ICP/BP) ratio following electro-stimulation of the CN. To study the effects of FL2 depletion on axon growth and on the microtubule cytoskeleton within the axon shaft, dissociated adult rodent dorsal root ganglion (DRG) neurons were transduced with AAV5 containing a plasmid encoding FL2 or scrambled small hairpin RNA (shRNA) and a GFP reporter. 5 days after treatment, neurons were replated for live monitoring of neurite growth, then fixed and immunostained for microtubules.