Session: MP27: Sexual Function/Dysfunction: Basic Research & Pathophysiology
MP27-01: Targeted depletion of Fidgetin-like 2 (FL2) promotes nerve regeneration and improves both erectile and bladder function outcomes in a rodent model of radical prostatectomy.
Introduction: Damage to the cavernous nerves (CN) during radical prostatectomy (RP) commonly results in urogenital dysfunction, which includes bladder and erectile dysfunction (ED). We recently identified fidgetin-like 2 (FL2) as a negative regulator of microtubule dynamics which when depleted in nerve cells in vitro accelerates axonal outgrowth, and in an in vivo model of RP promotes nerve regeneration and improves erectile function outcomes. We have expanded upon these studies to determine if FL2 depletion might also improve bladder function outcomes following CN injury. Methods: To study the effects of FL2 depletion on axon growth and on the microtubule (MT) cytoskeleton within the axon shaft in vitro, dissociated dorsal root ganglion (DRG) neurons were transduced with AAV5 containing a plasmid encoding FL2 or scrambled small hairpin RNA (shRNA) and a GFP reporter. Five-days after treatment, neurons were assessed for neurite growth, fixed and immunostained for MT. As a model of CN injury, rats underwent CN transection. At the site and time of injury, control- or FL2-siRNA was applied. Voiding function was evaluated 1 week post-injury, using the voided stain on paper (VSOP) method. At 2 weeks CN regeneration was assessed visually and erectile function was assessed by cavernosometry. Results: In vitro FL2 knockdown in neurons enhanced average neurite length and growth rate. Animals treated withFL2-siRNA had significantly lower voiding frequency and higher voided volume per micturition when compared to animals treated with control-siRNA. There was visible regeneration of the CN in 7 out of 8 animals treated with FL2-siRNA (with no observed regeneration in animals treated with control-siRNA). In animals in which there was sufficient CN regeneration to allow electrostimulation, FL2-siRNA treated animals had significantly improved erectile function compared to controls. Conclusions: FL2-depletion after CN injury results in visible regeneration of the CN, with improved erectile and bladder function outcomes. Our work suggests that depleting FL2 promotes nerve regeneration through directly enhancing the growth rate of injured axons. Overall, we have identified FL2 as a promising therapeutic target for promoting CN regeneration and functional recovery of urogenital function after iatrogenic nerve injury resulting from the surgical procedures of RP. SOURCE OF Funding: NIH/NIDDK
