Identification and characterization of a novel member of murine semaphorin family

The semaphorin gene family contains a large number of secreted type or transmembrane type proteins, and some of them function as the repulsive and attractive cues of axon guidance during development. Here we report a novel member of murine class 3 semaphorin genes, semaphorin 3G (Sema3G), mapped on chromosome 14. In adulthood, Sema3G is mainly expressed in the lung and kidney, and a little in the brain. Interestingly, in the adult rodent brain Sema3G is expressed only in the granular layer of the cerebellum, as determined by Northern blot and in situ hybridization analyses. We also found that Sema3G binds Neuropilin-2, but not Neuropilin-1, and induces the repulsion of sympathetic axons, but not dorsal root ganglion axons, indicating that Sema3G utilizes Neuropilin-2 as a receptor to repel specific types of axons.