It has previously been suggested that the spin trap agent alpha-phenyl-N-tert-butylnitrone (PBN) induces neurite outgrowth through activation of the Ras-ERK pathway in PC12 cells. However, the chemical properties of PBN contributing to its biological function and the detailed mechanism for the activation of Ras by PBN remain unknown. This study demonstrates that the hydrophobic structure of PBN is related to the activation of Ras, by comparing with hydrophilic analogues of PBN. [(14)C]-labelled PBN was found to localize in the lipid fraction and activate Ras indirectly. On the other hand, neurite outgrowth by PBN was inhibited by a nitric oxide (NO) scavenger. Moreover, the neurite outgrowth induced by PBN and the NO donor NOR4 was inhibited by the dominant negative Ras or MAPK/ERK inhibitor. Taken together, these results suggest that PBN is incorporated into the plasma membrane and induces neurite outgrowth in PC12 cells by activating the Ras-ERK pathway through NO release.
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