During development, neurons require axon guidance to the appropriate target cells. This mechanism is regulated by synaptic secretory and adhesion molecules. We have recently reported that protein tyrosine phosphatase δ (PTPδ) mediates semaphorin 3A ( Sema3A) signaling. As PTPδ possesses a sulfated glycan binding region at the N-terminus, we examined the role of this regions in Sema3A-signaling. We constructed a PTPδ mutant harbouring sulfated glycan binding region mutation (AAGAA). Alkaline-phosphatase fused PTPδ ectodomain (AP-PTPδ) bound to Sema3A receptor neuropilin-1 (NRP1) expressed in COS-7 cells. This binding was significantly attenuated in AP-PTPδ (AAGAA) mutant compared with the wild type (Wt). We next investigated Sema3A-induced growth cone collapse activity for cultured dorsal root ganglion (DRG) neurons expressed Wt or AAGAA. As we previously reported, Sema3A response was attenuated in Ptpδ-/- DRG neurons and rescued with the overexpression of Wt. In contrast, AAGAA did not rescue the phenotype. The mutant showed no alteration of the protein localization in the growth cones. These results suggest that glycan binding region of PTPδ may participate in the Sema3A-signaling through the interaction with NRP1.

To: abstract pdf