A member of the tumor necrosis factor receptor superfamily, TROY, is expressed in the CNS of embryonic and adult mice. In the present study, we characterized TROY-expressing cells in the embryonic and postnatal forebrain. In the early embryonic forebrain, TROY was highly expressed in nestin-positive neuroepithelial cells and radial glial cells, but not in microtubule-associated protein 2-positive postmitotic neurons. During the late embryonic and postnatal development, expression of TROY was observed in radial glial cells and astrocytes, whereas its expression was not detected in neuronal lineage cells. In addition, TROY was exclusively expressed in Musashi-1-positive multipotent/glial progenitors in the postnatal subventricular zone. To investigate the functions of TROY in neural development, we overexpressed TROY in PC12 cells and established stably expressing cell clones. As expected, the signals from overexpressed TROY were constitutively transduced via the activation of the nuclear factor-kappaB and the c-Jun N-terminal kinase pathways in such clones. In addition, upregulation of negative basic helix-loop-helix transcription factors, HES-5 and Id2 proteins, was observed in the TROY-overexpressing clones. Interestingly, the overexpression of TROY in PC12 cells strongly inhibited nerve growth factor-induced neurite outgrowth with reduction of some markers of differentiated neurons, such as neurofilament 150 kDa and neuron-specific beta-tubulin. These findings suggest that the signaling from TROY regulates neuronal differentiation at least in part.