Enhancement of neurite outgrowth in PC12h cells by a protease inhibitor.

Specific protease-protease inhibitor interactions have been suggested to play a role in the regulation of neurite outgrowth. We have examined the influence of exogenously added specific protease inhibitors on neurite outgrowth in PC12h cell in serum-free defined medium. Of 14 protease inhibitor species examined, only a leupeptin analogue, Ac-Leu-Leu-Nle-al was stimulatory for neurite outgrowth in the presence of nerve growth factor. Leupeptin and soybean trypsin inhibitor which had been reported to induce neurite outgrowth from sensory ganglia and neuroblastoma cells had no effect. These results suggest that an endogenous protease of a new type is involved in restricting neurite outgrowth in PC12h cell.