Characterization of Konjac Ceramide (kCer) Binding to Sema3A Receptor Nrp1.

Konjac ceramide (kCer) can be prepared by a chemoenzymatic method as previously published (Usuki, S.; Tamura, N.; Sakai, S.; Tamura, T.; Mukai, K.; Igarashi, Y. Biochem. Biophys. Rep. 5, 160-167 (2016)). Thus prepared kCer showed an activation effect on Sema3A signaling pathway to induce phosphorylation of CRMP2 and microtubule depolymerizaion, resulting in opposing NGF-induced neurite outgrowth. In the present study, we have shown that kCer is a potential Sema3A-like ligand that has a competitive effect on Sema3A binding to a cell surface receptor Nrp1, but animal-type ceramides have no effect on Sema3A binding to Nrp1. In addition, kCer showed a direct molecular interaction with Nrp1, but animal-type ceramides, C16Cer, C18Cer, and C24Cer show no specific bindings to Nrp1. Further, kCer showed an additive effect to activate the Sema3A signaling pathway together with low-dose Sema3A but a reversed effect to inhibit this pathway when combined with high-dose Sema3A.