Regenerating motor neurons express Nna1, a novel ATP/GTP-binding protein related to zinc carboxypeptidases

To identify genes involved in axon regeneration, differential screening was applied to RNA isolated from spinal cord of mice subjected to sciatic nerve transection or crush injury. A 4-kb transcript, termed nna1, was identified that was rapidly induced in affected motor neurons in both paradigms. The levels of nna1 transcript levels declined in motor neurons within 1-2 weeks after nerve crush, coincident with target reinnervation. If reinnervation was blocked by nerve cut and ligation, nna1 was continuously expressed in motor neurons. In addition, in situ analysis of developing embryonic nervous tissue showed nna1 was highly expressed in differentiating neurons, but not proliferating populations. Nna1 is predicted to be a zinc carboxypeptidase that contains nuclear localization signals and an ATP/GTP binding motif. Cultured neurons transfected with green fluorescent protein (GFP)-nna1 expressed GFP-Nna1 in cytoplasmic and nuclear compartments. Thus, Nna1 may contribute to nuclear signaling events in differentiating and regenerating neurons.