Semaphorin-3F Attracts The Growth Cone Of Cerebellar Granule Cells Through CGMP Signaling Pathway

During brain development, growth cone extension is guided by extracellular factors to their destination to form complex neural networks, but the underlying cellular mechanisms remain largely unclear. Semaphorin is one of the most important families of guidance factors, and Semaphorin-3F (Sema3F) is an important member in this family, which plays important roles in the development of the nervous system. Recently, mutations in the gene of Sema3F in human has been shown to closely correlated with the occurrence of several types cancer, revealing the importance of the further study of the signal transduction of this guidance factor.In order to explore the role Sema3F in the morphogenesis of cerebellum, we performed the growth cone collapse assay, the growth cone turning assay, and the explant co-culture assay to examine the potential functions of class-3 semaphorins in the guidance of growth cone extension and migration of cultured cerebellar granule cells, In addition, we investigated the signaling mechanisms underlying the action of Sema3F using pharmacological treatment.We found that neuropilin-2 (Npn2), the high-affinity receptor for Sema3F, is highly expressed in cerebellar granule cells. An extracellular gradient of Sema3F triggered an Npn2-dependent attractive turning of the growth cone of cultured cerebellar granule cells. Moreover we found that cerebellar granule cells migrated preferentially to the Sema3F-expressing cell aggregates in explant co-culture assay. Furthermore, we found that the Sema3F-triggered growth cone attraction was abolished by inhibition of the cGMP signaling pathway but not by inhibition of the cAMP signaling pathway, and the attraction was suppressed when elevating the intracellular cGMP level. Furthermore, Sema3F application could reduce the growth cone collapse induced by inhibition of basal activity of cGMP signaling pathway in granule cells.Thus, the current study suggests that Sema3F acts as a chemoattractant for the growth cone extension and the migration of cerebellar granule cells through cGMP-signaling pathway.